diff --git "a/SOURCE_DOCUMENTS/dataset3.txt" "b/SOURCE_DOCUMENTS/dataset3.txt" deleted file mode 100644--- "a/SOURCE_DOCUMENTS/dataset3.txt" +++ /dev/null @@ -1,21623 +0,0 @@ -One of the wettest wet seasons in northern Australia transformed - -large areas of the country’s desert landscape over the course of many months in 2023. A string -of major rainfall events that dropped 690 millimeters (27 inches) between October 2022 and -April 2023 made it the sixth-wettest season on record since 1900–1901.This series of false-color -images illustrates the rainfall’s months-long effects downstream in the Lake Eyre Basin. Water -appears in shades of blue, vegetation is green, and bare land is brown. The images were acquired - -by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite between -January and July 2023.In the January 22 image (left), water was coursing through seasonally -dry channels of the Georgina River and Eyre Creek following weeks of heavy rains in northern -Queensland. By April 21 (middle), floodwaters had reached further downstream after another -intense period of precipitation in March. This scene shows that water had filled in some of - -the north-northwest trending ridges that are part of a vast fossil landscape of wind-formed -dunes, while vegetation had emerged in wet soil upstream. Then by July 26 (right), the riverbed -had filled with even more vegetation.The Georgina River and Eyre Creek drain approximately -210,000 square kilometers (81,000 square miles), nearly the area of the United Kingdom. Visible -in the lower part of the images, the lake gets refreshed about every three years; when it - -reaches especially high levels, it may take 18 months to 2 years to dry up. Two smaller neighboring -lakes flood seasonally. These three lakes and surrounding floodplains support hundreds of -thousands of waterbirds and are designated as an Important Bird Area.Seasonal flooding is -a regular occurrence in these desert river systems. However, the events of the 2022-2023 rainy -season stood out in several ways. They occurred while La Niña conditions were in place over - -the tropical Pacific Ocean. (The wettest seasons in northern Australia have all occurred during -La Niña years, according to Australia’s Bureau of Meteorology.) In addition, major rains occurring -in succession, as was the case with the January and March events, have the overall effect -of prolonging floods. That’s because vegetation that grows after the first event slows down -the pulse of water that comes through in the next rain event.The high water has affected both - -local communities and ecosystems. Floods have inundated cattle farms and isolated towns on -temporary islands. At the same time, they are a natural feature of the “boom-and-bust” ecology -of Channel Country, providing habitat and nutrients that support biodiversity.NASA Earth Observatory -image by Wanmei Liang, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview. Story by -Lindsey Doermann.View this area in EO ExplorerRepeated heavy rains in Australia set off waves - -of new growth across Channel Country.Image of the Day for August 7, 2023 Image of the Day -Land Water View more Images of the Day: Floods The waves off the coast of Teahupo’o can heave -a crushing amount of water toward the shore and onto unlucky surfers. Image of the Day Water -Waves of heavy rainfall left towns and farmland under water in October 2022. Image of the -Day Water Floods Acquired February 26, 2011, and February 5, 2011, these false-color images - -show the impact of heavy rains in marshy areas southeast of Georgetown, Guyana. Land Floods -January 22 - July 26, 2023JPEGOne of the wettest wet seasons in northern Australia transformed -large areas of the country’s desert landscape over the course of many months in 2023. A string -of major rainfall events that dropped 690 millimeters (27 inches) between October 2022 and -April 2023 made it the sixth-wettest season on record since 1900–1901.This series of false-color - -images illustrates the rainfall’s months-long effects downstream in the Lake Eyre Basin. Water -appears in shades of blue, vegetation is green, and bare land is brown. The images were acquired -by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite between -January and July 2023.In the January 22 image (left), water was coursing through seasonally -dry channels of the Georgina River and Eyre Creek following weeks of heavy rains in northern - -Queensland. By April 21 (middle), floodwaters had reached further downstream after another -intense period of precipitation in March. This scene shows that water had filled in some of -the north-northwest trending ridges that are part of a vast fossil landscape of wind-formed -dunes, while vegetation had emerged in wet soil upstream. Then by July 26 (right), the riverbed -had filled with even more vegetation.The Georgina River and Eyre Creek drain approximately - -210,000 square kilometers (81,000 square miles), nearly the area of the United Kingdom. Visible -in the lower part of the images, the lake gets refreshed about every three years; when it -reaches especially high levels, it may take 18 months to 2 years to dry up. Two smaller neighboring -lakes flood seasonally. These three lakes and surrounding floodplains support hundreds of -thousands of waterbirds and are designated as an Important Bird Area.Seasonal flooding is - -a regular occurrence in these desert river systems. However, the events of the 2022-2023 rainy -season stood out in several ways. They occurred while La Niña conditions were in place over -the tropical Pacific Ocean. (The wettest seasons in northern Australia have all occurred during -La Niña years, according to Australia’s Bureau of Meteorology.) In addition, major rains occurring -in succession, as was the case with the January and March events, have the overall effect - -of prolonging floods. That’s because vegetation that grows after the first event slows down -the pulse of water that comes through in the next rain event.The high water has affected both -local communities and ecosystems. Floods have inundated cattle farms and isolated towns on -temporary islands. At the same time, they are a natural feature of the “boom-and-bust” ecology -of Channel Country, providing habitat and nutrients that support biodiversity.NASA Earth Observatory - -image by Wanmei Liang, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview. Story by -Lindsey Doermann.View this area in EO ExplorerRepeated heavy rains in Australia set off waves -of new growth across Channel Country.Image of the Day for August 7, 2023 Image of the Day -Land Water View more Images of the Day: Floods The waves off the coast of Teahupo’o can heave -a crushing amount of water toward the shore and onto unlucky surfers. Image of the Day Water - -Waves of heavy rainfall left towns and farmland under water in October 2022. Image of the -Day Water Floods Acquired February 26, 2011, and February 5, 2011, these false-color images -show the impact of heavy rains in marshy areas southeast of Georgetown, Guyana. Land Floods -August 25, 2023JPEGSeptember 18, 2023JPEGAugust 25, 2023September 18, 2023August 25, 2023JPEGSeptember -18, 2023JPEGSeptember 18, 2023JPEGHeavy rain from a cyclone in the Mediterranean inundated - -cities along the northeastern coast of Libya in early September 2023, causing thousands of -deaths. The port city of Derna (Darnah), home to about 90,000 people, was one of the worst -hit by the storm and suffered extensive flooding and damage. On September 10 and 11, over -100 millimeters (4 inches) of rain fell on Derna. The city lies at the end of a long, narrow -valley, called a wadi, which is dry except during the rainy season. Floods triggered two dams - -along the wadi to collapse. The failure of the second dam, located just one kilometer inland -of Derna, unleashed 3- to 7-meter-high floodwater that tore through the city. According to -news reports, the flash floods destroyed roads and swept entire neighborhoods out to sea. -The images above show the city before and after the storm. The image on the right, acquired -by the Operational Land Imager-2 (OLI-2) on Landsat 9 on September 18, shows eroded banks - -of Wadi Derna near where it meets the Mediterranean. Water just off the coast appears muddier -than in the image on the left, which shows the same area on August 25 and was acquired by -Landsat 8. Preliminary estimates by the United Nations Satellite Center (UNOSAT) indicate -that 3,100 buildings in Derna were damaged by rushing water. According to the UN International -Organization for Migration (IOM), about 40,000 people in the country were displaced by the - -storm, and 30,000 of those were displaced from Derna. Tropical-like cyclones in the Mediterranean, -or “medicanes,” develop only once or twice a year, according to NOAA, and typically form in -autumn. According to meteorologists at Yale Climate Connections, this storm was the deadliest -in Africa’s recorded history. A recent assessment by scientists at World Weather Attribution -estimated that precipitation received by the region was a one-in-300 to one-in-600-year event. - -NASA Earth Observatory images by Lauren Dauphin, using Landsat data from the U.S. Geological -Survey. Story by Emily Cassidy.View this area in EO ExplorerFlash floods in the port city -destroyed roads and swept neighborhoods out to sea.Image of the Day for September 21, 2023 -Image of the Day Land Water Floods Human Presence View more Images of the Day:The melting -of frozen rivers and snowpack, and the heavy rains of late spring and summer, can send rivers - -out of their banks.A Mediterranean cyclone contributed to deadly flooding along the country’s -coastline. Image of the Day Land Water Floods Record rainfall inundated towns and farmland -in the country’s Thessaly region. Image of the Day Water Floods Human Presence A stalled storm -dropped three feet of rain over four days on the Thessaly region, triggering extensive flooding. -Image of the Day Atmosphere Floods An isolated low-pressure system produced torrential downpours - -in Spain and carried Saharan dust along its path. Image of the Day Atmosphere Land Floods -Human Presence January 22 - July 26, 2023JPEGOne of the wettest wet seasons in northern Australia -transformed large areas of the country’s desert landscape over the course of many months in -2023. A string of major rainfall events that dropped 690 millimeters (27 inches) between October -2022 and April 2023 made it the sixth-wettest season on record since 1900–1901.This series - -of false-color images illustrates the rainfall’s months-long effects downstream in the Lake -Eyre Basin. Water appears in shades of blue, vegetation is green, and bare land is brown. -The images were acquired by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s -Terra satellite between January and July 2023.In the January 22 image (left), water was coursing -through seasonally dry channels of the Georgina River and Eyre Creek following weeks of heavy - -rains in northern Queensland. By April 21 (middle), floodwaters had reached further downstream -after another intense period of precipitation in March. This scene shows that water had filled -in some of the north-northwest trending ridges that are part of a vast fossil landscape of -wind-formed dunes, while vegetation had emerged in wet soil upstream. Then by July 26 (right), -the riverbed had filled with even more vegetation.The Georgina River and Eyre Creek drain - -approximately 210,000 square kilometers (81,000 square miles), nearly the area of the United -Kingdom. Visible in the lower part of the images, the lake gets refreshed about every three -years; when it reaches especially high levels, it may take 18 months to 2 years to dry up. -Two smaller neighboring lakes flood seasonally. These three lakes and surrounding floodplains -support hundreds of thousands of waterbirds and are designated as an Important Bird Area.Seasonal - -flooding is a regular occurrence in these desert river systems. However, the events of the -2022-2023 rainy season stood out in several ways. They occurred while La Niña conditions were -in place over the tropical Pacific Ocean. (The wettest seasons in northern Australia have -all occurred during La Niña years, according to Australia’s Bureau of Meteorology.) In addition, -major rains occurring in succession, as was the case with the January and March events, have - -the overall effect of prolonging floods. That’s because vegetation that grows after the first -event slows down the pulse of water that comes through in the next rain event.The high water -has affected both local communities and ecosystems. Floods have inundated cattle farms and -isolated towns on temporary islands. At the same time, they are a natural feature of the “boom-and-bust” -ecology of Channel Country, providing habitat and nutrients that support biodiversity.NASA - -Earth Observatory image by Wanmei Liang, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview. -Story by Lindsey Doermann.View this area in EO ExplorerRepeated heavy rains in Australia set -off waves of new growth across Channel Country.Image of the Day for August 7, 2023 Image of -the Day Land Water View more Images of the Day: Floods The waves off the coast of Teahupo’o -can heave a crushing amount of water toward the shore and onto unlucky surfers. Image of the - -Day Water Waves of heavy rainfall left towns and farmland under water in October 2022. Image -of the Day Water Floods Acquired February 26, 2011, and February 5, 2011, these false-color -images show the impact of heavy rains in marshy areas southeast of Georgetown, Guyana. Land -Floods August 25, 2023JPEGSeptember 18, 2023JPEGAugust 25, 2023September 18, 2023August 25, -2023JPEGSeptember 18, 2023JPEGSeptember 18, 2023JPEGHeavy rain from a cyclone in the Mediterranean - -inundated cities along the northeastern coast of Libya in early September 2023, causing thousands -of deaths. The port city of Derna (Darnah), home to about 90,000 people, was one of the worst -hit by the storm and suffered extensive flooding and damage. On September 10 and 11, over -100 millimeters (4 inches) of rain fell on Derna. The city lies at the end of a long, narrow -valley, called a wadi, which is dry except during the rainy season. Floods triggered two dams - -along the wadi to collapse. The failure of the second dam, located just one kilometer inland -of Derna, unleashed 3- to 7-meter-high floodwater that tore through the city. According to -news reports, the flash floods destroyed roads and swept entire neighborhoods out to sea. -The images above show the city before and after the storm. The image on the right, acquired -by the Operational Land Imager-2 (OLI-2) on Landsat 9 on September 18, shows eroded banks - -of Wadi Derna near where it meets the Mediterranean. Water just off the coast appears muddier -than in the image on the left, which shows the same area on August 25 and was acquired by -Landsat 8. Preliminary estimates by the United Nations Satellite Center (UNOSAT) indicate -that 3,100 buildings in Derna were damaged by rushing water. According to the UN International -Organization for Migration (IOM), about 40,000 people in the country were displaced by the - -storm, and 30,000 of those were displaced from Derna. Tropical-like cyclones in the Mediterranean, -or “medicanes,” develop only once or twice a year, according to NOAA, and typically form in -autumn. According to meteorologists at Yale Climate Connections, this storm was the deadliest -in Africa’s recorded history. A recent assessment by scientists at World Weather Attribution -estimated that precipitation received by the region was a one-in-300 to one-in-600-year event. - -NASA Earth Observatory images by Lauren Dauphin, using Landsat data from the U.S. Geological -Survey. Story by Emily Cassidy.View this area in EO ExplorerFlash floods in the port city -destroyed roads and swept neighborhoods out to sea.Image of the Day for September 21, 2023 -Image of the Day Land Water Floods Human Presence View more Images of the Day:The melting -of frozen rivers and snowpack, and the heavy rains of late spring and summer, can send rivers - -out of their banks.A Mediterranean cyclone contributed to deadly flooding along the country’s -coastline. Image of the Day Land Water Floods Record rainfall inundated towns and farmland -in the country’s Thessaly region. Image of the Day Water Floods Human Presence A stalled storm -dropped three feet of rain over four days on the Thessaly region, triggering extensive flooding. -Image of the Day Atmosphere Floods An isolated low-pressure system produced torrential downpours - -in Spain and carried Saharan dust along its path. Image of the Day Atmosphere Land Floods -Human Presence July 2002 - June 2022JPEGThe deep-blue sea is turning a touch greener. While -that may not seem as consequential as, say, record warm sea surface temperatures, the color -of the ocean surface is indicative of the ecosystem that lies beneath. Communities of phytoplankton, -microscopic photosynthesizing organisms, abound in near-surface waters and are foundational - -to the aquatic food web and carbon cycle. This shift in the water’s hue confirms a trend expected -under climate change and signals changes to ecosystems within the global ocean, which covers -70 percent of Earth’s surface. Researchers led by B. B. Cael, a principal scientist at the -U.K.’s National Oceanography Centre, revealed that 56 percent of the global sea surface has -undergone a significant change in color in the past 20 years. After analyzing ocean color - -data from the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument on NASA’s Aqua -satellite, they found that much of the change stems from the ocean turning more green. The -map above highlights the areas where ocean surface color changed between 2002 and 2022, with -darker shades of green representing more-significant differences (higher signal-to-noise ratio). -By extension, said Cael, “these are places we can detect a change in the ocean ecosystem in - -the last 20 years.” The study focused on tropical and subtropical regions, excluding higher -latitudes, which are dark for part of the year, and coastal waters, where the data are naturally -very noisy. The black dots on the map indicate the area, covering 12 percent of the ocean’s -surface, where chlorophyll levels also changed over the study period. Chlorophyll has been -the go-to measurement for remote sensing scientists to gauge phytoplankton abundance and productivity. - -However, those estimates use only a few colors in the visible light spectrum. The values shown -in green are based on the whole gamut of colors and therefore capture more information about -the ecosystem as a whole. A long time series from a single sensor is relatively rare in the -remote sensing world. As the Aqua satellite was celebrating its 20th year in orbit in 2022—far -exceeding its design life of 6 years—Cael wondered what long term trends could be discovered - -in the data. In particular, he was curious what might have been missed in all the ocean color -information it had collected. “There’s more encoded in the data than we actually make use -of,” he said. By going big with the data, the team discerned an ocean color trend that had -been predicted by climate modeling, but one that was expected to take 30-40 years of data -to detect using satellite-based chlorophyll estimates. That’s because the natural variability - -in chlorophyll is high relative to the climate change trend. The new method, incorporating -all visible light, was robust enough to confirm the trend in 20 years. At this stage, it is -difficult to say what exact ecological changes are responsible for the new hues. However, -the authors posit, they could result from different assemblages of plankton, more detrital -particles, or other organisms such as zooplankton. It is unlikely the color changes come from - -materials such as plastics or other pollutants, said Cael, since they are not widespread enough -to register at large scales. “What we do know is that in the last 20 years, the ocean has -become more stratified,” he said. Surface waters have absorbed excess heat from the warming -climate, and as a result, they are less prone to mixing with deeper, more nutrient-rich layers. -This scenario would favor plankton adapted to a nutrient-poor environment. The areas of ocean - -color change align well with where the sea has become more stratified, said Cael, but there -is no such overlap with sea surface temperature changes. More insights into Earth’s aquatic -ecosystems may soon be on the way. NASA’s PACE (Plankton, Aerosol, Cloud, ocean Ecosystem) -satellite, set to launch in 2024, will return observations in finer color resolution. The -new data will enable researchers to infer more information about ocean ecology, such as the - -diversity of phytoplankton species and the rates of phytoplankton growth. NASA Earth Observatory -image by Wanmei Liang, using data from Cael, B. B., et al. (2023). Story by Lindsey Doermann.Two -decades of satellite measurements show that the sea surface is shading toward green.Image -of the Day for October 2, 2023 Image of the Day Life Water View more Images of the Day:Datasets -from the Sentinel-6 Michael Freilich satellite will build upon three decades of sea level - -measurements. Image of the Day Heat Water Remote Sensing Image of the Day Life Water Image -of the Day Water The use of plastic on farms has become so common in recent decades that there -there’s a term for it—plasticulture. Image of the Day Human Presence January 22 - July 26, -2023JPEGOne of the wettest wet seasons in northern Australia transformed large areas of the -country’s desert landscape over the course of many months in 2023. A string of major rainfall - -events that dropped 690 millimeters (27 inches) between October 2022 and April 2023 made it -the sixth-wettest season on record since 1900–1901.This series of false-color images illustrates -the rainfall’s months-long effects downstream in the Lake Eyre Basin. Water appears in shades -of blue, vegetation is green, and bare land is brown. The images were acquired by the Moderate -Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite between January and - -July 2023.In the January 22 image (left), water was coursing through seasonally dry channels -of the Georgina River and Eyre Creek following weeks of heavy rains in northern Queensland. -By April 21 (middle), floodwaters had reached further downstream after another intense period -of precipitation in March. This scene shows that water had filled in some of the north-northwest -trending ridges that are part of a vast fossil landscape of wind-formed dunes, while vegetation - -had emerged in wet soil upstream. Then by July 26 (right), the riverbed had filled with even -more vegetation.The Georgina River and Eyre Creek drain approximately 210,000 square kilometers -(81,000 square miles), nearly the area of the United Kingdom. Visible in the lower part of -the images, the lake gets refreshed about every three years; when it reaches especially high -levels, it may take 18 months to 2 years to dry up. Two smaller neighboring lakes flood seasonally. - -These three lakes and surrounding floodplains support hundreds of thousands of waterbirds -and are designated as an Important Bird Area.Seasonal flooding is a regular occurrence in -these desert river systems. However, the events of the 2022-2023 rainy season stood out in -several ways. They occurred while La Niña conditions were in place over the tropical Pacific -Ocean. (The wettest seasons in northern Australia have all occurred during La Niña years, - -according to Australia’s Bureau of Meteorology.) In addition, major rains occurring in succession, -as was the case with the January and March events, have the overall effect of prolonging floods. -That’s because vegetation that grows after the first event slows down the pulse of water that -comes through in the next rain event.The high water has affected both local communities and -ecosystems. Floods have inundated cattle farms and isolated towns on temporary islands. At - -the same time, they are a natural feature of the “boom-and-bust” ecology of Channel Country, -providing habitat and nutrients that support biodiversity.NASA Earth Observatory image by -Wanmei Liang, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview. Story by Lindsey -Doermann.View this area in EO ExplorerRepeated heavy rains in Australia set off waves of new -growth across Channel Country.Image of the Day for August 7, 2023 Image of the Day Land Water - -View more Images of the Day: Floods The waves off the coast of Teahupo’o can heave a crushing -amount of water toward the shore and onto unlucky surfers. Image of the Day Water Waves of -heavy rainfall left towns and farmland under water in October 2022. Image of the Day Water -Floods Acquired February 26, 2011, and February 5, 2011, these false-color images show the -impact of heavy rains in marshy areas southeast of Georgetown, Guyana. Land Floods August - -25, 2023JPEGSeptember 18, 2023JPEGAugust 25, 2023September 18, 2023August 25, 2023JPEGSeptember -18, 2023JPEGSeptember 18, 2023JPEGHeavy rain from a cyclone in the Mediterranean inundated -cities along the northeastern coast of Libya in early September 2023, causing thousands of -deaths. The port city of Derna (Darnah), home to about 90,000 people, was one of the worst -hit by the storm and suffered extensive flooding and damage. On September 10 and 11, over - -100 millimeters (4 inches) of rain fell on Derna. The city lies at the end of a long, narrow -valley, called a wadi, which is dry except during the rainy season. Floods triggered two dams -along the wadi to collapse. The failure of the second dam, located just one kilometer inland -of Derna, unleashed 3- to 7-meter-high floodwater that tore through the city. According to -news reports, the flash floods destroyed roads and swept entire neighborhoods out to sea. - -The images above show the city before and after the storm. The image on the right, acquired -by the Operational Land Imager-2 (OLI-2) on Landsat 9 on September 18, shows eroded banks -of Wadi Derna near where it meets the Mediterranean. Water just off the coast appears muddier -than in the image on the left, which shows the same area on August 25 and was acquired by -Landsat 8. Preliminary estimates by the United Nations Satellite Center (UNOSAT) indicate - -that 3,100 buildings in Derna were damaged by rushing water. According to the UN International -Organization for Migration (IOM), about 40,000 people in the country were displaced by the -storm, and 30,000 of those were displaced from Derna. Tropical-like cyclones in the Mediterranean, -or “medicanes,” develop only once or twice a year, according to NOAA, and typically form in -autumn. According to meteorologists at Yale Climate Connections, this storm was the deadliest - -in Africa’s recorded history. A recent assessment by scientists at World Weather Attribution -estimated that precipitation received by the region was a one-in-300 to one-in-600-year event. -NASA Earth Observatory images by Lauren Dauphin, using Landsat data from the U.S. Geological -Survey. Story by Emily Cassidy.View this area in EO ExplorerFlash floods in the port city -destroyed roads and swept neighborhoods out to sea.Image of the Day for September 21, 2023 - -Image of the Day Land Water Floods Human Presence View more Images of the Day:The melting -of frozen rivers and snowpack, and the heavy rains of late spring and summer, can send rivers -out of their banks.A Mediterranean cyclone contributed to deadly flooding along the country’s -coastline. Image of the Day Land Water Floods Record rainfall inundated towns and farmland -in the country’s Thessaly region. Image of the Day Water Floods Human Presence A stalled storm - -dropped three feet of rain over four days on the Thessaly region, triggering extensive flooding. -Image of the Day Atmosphere Floods An isolated low-pressure system produced torrential downpours -in Spain and carried Saharan dust along its path. Image of the Day Atmosphere Land Floods -Human Presence July 2002 - June 2022JPEGThe deep-blue sea is turning a touch greener. While -that may not seem as consequential as, say, record warm sea surface temperatures, the color - -of the ocean surface is indicative of the ecosystem that lies beneath. Communities of phytoplankton, -microscopic photosynthesizing organisms, abound in near-surface waters and are foundational -to the aquatic food web and carbon cycle. This shift in the water’s hue confirms a trend expected -under climate change and signals changes to ecosystems within the global ocean, which covers -70 percent of Earth’s surface. Researchers led by B. B. Cael, a principal scientist at the - -U.K.’s National Oceanography Centre, revealed that 56 percent of the global sea surface has -undergone a significant change in color in the past 20 years. After analyzing ocean color -data from the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument on NASA’s Aqua -satellite, they found that much of the change stems from the ocean turning more green. The -map above highlights the areas where ocean surface color changed between 2002 and 2022, with - -darker shades of green representing more-significant differences (higher signal-to-noise ratio). -By extension, said Cael, “these are places we can detect a change in the ocean ecosystem in -the last 20 years.” The study focused on tropical and subtropical regions, excluding higher -latitudes, which are dark for part of the year, and coastal waters, where the data are naturally -very noisy. The black dots on the map indicate the area, covering 12 percent of the ocean’s - -surface, where chlorophyll levels also changed over the study period. Chlorophyll has been -the go-to measurement for remote sensing scientists to gauge phytoplankton abundance and productivity. -However, those estimates use only a few colors in the visible light spectrum. The values shown -in green are based on the whole gamut of colors and therefore capture more information about -the ecosystem as a whole. A long time series from a single sensor is relatively rare in the - -remote sensing world. As the Aqua satellite was celebrating its 20th year in orbit in 2022—far -exceeding its design life of 6 years—Cael wondered what long term trends could be discovered -in the data. In particular, he was curious what might have been missed in all the ocean color -information it had collected. “There’s more encoded in the data than we actually make use -of,” he said. By going big with the data, the team discerned an ocean color trend that had - -been predicted by climate modeling, but one that was expected to take 30-40 years of data -to detect using satellite-based chlorophyll estimates. That’s because the natural variability -in chlorophyll is high relative to the climate change trend. The new method, incorporating -all visible light, was robust enough to confirm the trend in 20 years. At this stage, it is -difficult to say what exact ecological changes are responsible for the new hues. However, - -the authors posit, they could result from different assemblages of plankton, more detrital -particles, or other organisms such as zooplankton. It is unlikely the color changes come from -materials such as plastics or other pollutants, said Cael, since they are not widespread enough -to register at large scales. “What we do know is that in the last 20 years, the ocean has -become more stratified,” he said. Surface waters have absorbed excess heat from the warming - -climate, and as a result, they are less prone to mixing with deeper, more nutrient-rich layers. -This scenario would favor plankton adapted to a nutrient-poor environment. The areas of ocean -color change align well with where the sea has become more stratified, said Cael, but there -is no such overlap with sea surface temperature changes. More insights into Earth’s aquatic -ecosystems may soon be on the way. NASA’s PACE (Plankton, Aerosol, Cloud, ocean Ecosystem) - -satellite, set to launch in 2024, will return observations in finer color resolution. The -new data will enable researchers to infer more information about ocean ecology, such as the -diversity of phytoplankton species and the rates of phytoplankton growth. NASA Earth Observatory -image by Wanmei Liang, using data from Cael, B. B., et al. (2023). Story by Lindsey Doermann.Two -decades of satellite measurements show that the sea surface is shading toward green.Image - -of the Day for October 2, 2023 Image of the Day Life Water View more Images of the Day:Datasets -from the Sentinel-6 Michael Freilich satellite will build upon three decades of sea level -measurements. Image of the Day Heat Water Remote Sensing Image of the Day Life Water Image -of the Day Water The use of plastic on farms has become so common in recent decades that there -there’s a term for it—plasticulture. Image of the Day Human Presence August 16, 2023JPEGThe - -Canary Islands were at the center of a mélange of natural events in summer 2023. The Moderate -Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this assemblage -of phenomena off the coast of Africa on August 16, 2023.In the center of the scene, smoke -is seen rising from a wildfire burning on Tenerife in the Canary Islands. The blaze started -amid hot and dry conditions on August 15 in forests surrounding the Teide Volcano. Authorities - -issued evacuation orders to five villages, and responders focused on containing the fire’s -spread and protecting residential areas near the coast, according to news reports. Other fires -have burned on the Canary Islands this summer, including on La Palma in July.To the west, -a swirling cloud moves across the Atlantic. Cloud vortices appear routinely downwind of the -Canary Islands—sometimes in great abundance—and are produced when the tall volcanic peaks - -disrupt the air flowing past them.Elsewhere in the atmosphere, dust from the Sahara Desert -was lofted out over the ocean. The river of dust crossing the Atlantic was more pronounced -in previous days, when it reached islands in the Caribbean. Traveling on the Saharan Air Layer, -dust sometimes makes it even further west toward Central America and the U.S. states of Florida -and Texas.To round out the list, the patch of bright blue off the Moroccan coast is most likely - -a bloom of phytoplankton. While the exact cause and composition of the bloom cannot be determined -from this image, mineral-rich desert dust has been shown to set off bursts of phytoplankton -growth.In addition to the Earth’s processes seen here, one remote sensing artifact is present. -A diagonal streak of sunglint makes part of this scene appear washed out. Sunglint, an effect -that occurs when sunlight reflects off the surface of the water at the same angle that a satellite - -sensor views it, is also the reason for the light-colored streaks trailing off the islands.NASA -Earth Observatory image by Wanmei Liang, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview. -Story by Lindsey Doermann.View this area in EO ExplorerAn assortment of natural phenomena -visible from space appeared together in one image.Image of the Day for August 17, 2023 Image -of the Day Atmosphere Land Water View more Images of the Day:Flights were grounded as visibility - -was severely hampered by a Calima event. Image of the Day Atmosphere Land Dust and Haze Human -Presence In one frame International Space Station astronauts were able to capture the evolution -of fringing reefs to atolls. As with the Hawaiian Islands, these volcanic hot spot islands -become progressively older to the northwest. As these islands move away from their magma sources -they erode and subside. Image of the Day Land Water The dry, volcanic terrain of this Canary - -Island is suitable for lichen and crops … and for training astronauts. Image of the Day Land -The event, known locally as “la calima,” turned skies orange and degraded air quality in Gran -Canaria and neighboring islands. Image of the Day Atmosphere Land Dust and Haze January 22 -- July 26, 2023JPEGOne of the wettest wet seasons in northern Australia transformed large -areas of the country’s desert landscape over the course of many months in 2023. A string of - -major rainfall events that dropped 690 millimeters (27 inches) between October 2022 and April -2023 made it the sixth-wettest season on record since 1900–1901.This series of false-color -images illustrates the rainfall’s months-long effects downstream in the Lake Eyre Basin. Water -appears in shades of blue, vegetation is green, and bare land is brown. The images were acquired -by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite between - -January and July 2023.In the January 22 image (left), water was coursing through seasonally -dry channels of the Georgina River and Eyre Creek following weeks of heavy rains in northern -Queensland. By April 21 (middle), floodwaters had reached further downstream after another -intense period of precipitation in March. This scene shows that water had filled in some of -the north-northwest trending ridges that are part of a vast fossil landscape of wind-formed - -dunes, while vegetation had emerged in wet soil upstream. Then by July 26 (right), the riverbed -had filled with even more vegetation.The Georgina River and Eyre Creek drain approximately -210,000 square kilometers (81,000 square miles), nearly the area of the United Kingdom. Visible -in the lower part of the images, the lake gets refreshed about every three years; when it -reaches especially high levels, it may take 18 months to 2 years to dry up. Two smaller neighboring - -lakes flood seasonally. These three lakes and surrounding floodplains support hundreds of -thousands of waterbirds and are designated as an Important Bird Area.Seasonal flooding is -a regular occurrence in these desert river systems. However, the events of the 2022-2023 rainy -season stood out in several ways. They occurred while La Niña conditions were in place over -the tropical Pacific Ocean. (The wettest seasons in northern Australia have all occurred during - -La Niña years, according to Australia’s Bureau of Meteorology.) In addition, major rains occurring -in succession, as was the case with the January and March events, have the overall effect -of prolonging floods. That’s because vegetation that grows after the first event slows down -the pulse of water that comes through in the next rain event.The high water has affected both -local communities and ecosystems. Floods have inundated cattle farms and isolated towns on - -temporary islands. At the same time, they are a natural feature of the “boom-and-bust” ecology -of Channel Country, providing habitat and nutrients that support biodiversity.NASA Earth Observatory -image by Wanmei Liang, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview. Story by -Lindsey Doermann.View this area in EO ExplorerRepeated heavy rains in Australia set off waves -of new growth across Channel Country.Image of the Day for August 7, 2023 Image of the Day - -Land Water View more Images of the Day: Floods The waves off the coast of Teahupo’o can heave -a crushing amount of water toward the shore and onto unlucky surfers. Image of the Day Water -Waves of heavy rainfall left towns and farmland under water in October 2022. Image of the -Day Water Floods Acquired February 26, 2011, and February 5, 2011, these false-color images -show the impact of heavy rains in marshy areas southeast of Georgetown, Guyana. Land Floods - -August 25, 2023JPEGSeptember 18, 2023JPEGAugust 25, 2023September 18, 2023August 25, 2023JPEGSeptember -18, 2023JPEGSeptember 18, 2023JPEGHeavy rain from a cyclone in the Mediterranean inundated -cities along the northeastern coast of Libya in early September 2023, causing thousands of -deaths. The port city of Derna (Darnah), home to about 90,000 people, was one of the worst -hit by the storm and suffered extensive flooding and damage. On September 10 and 11, over - -100 millimeters (4 inches) of rain fell on Derna. The city lies at the end of a long, narrow -valley, called a wadi, which is dry except during the rainy season. Floods triggered two dams -along the wadi to collapse. The failure of the second dam, located just one kilometer inland -of Derna, unleashed 3- to 7-meter-high floodwater that tore through the city. According to -news reports, the flash floods destroyed roads and swept entire neighborhoods out to sea. - -The images above show the city before and after the storm. The image on the right, acquired -by the Operational Land Imager-2 (OLI-2) on Landsat 9 on September 18, shows eroded banks -of Wadi Derna near where it meets the Mediterranean. Water just off the coast appears muddier -than in the image on the left, which shows the same area on August 25 and was acquired by -Landsat 8. Preliminary estimates by the United Nations Satellite Center (UNOSAT) indicate - -that 3,100 buildings in Derna were damaged by rushing water. According to the UN International -Organization for Migration (IOM), about 40,000 people in the country were displaced by the -storm, and 30,000 of those were displaced from Derna. Tropical-like cyclones in the Mediterranean, -or “medicanes,” develop only once or twice a year, according to NOAA, and typically form in -autumn. According to meteorologists at Yale Climate Connections, this storm was the deadliest - -in Africa’s recorded history. A recent assessment by scientists at World Weather Attribution -estimated that precipitation received by the region was a one-in-300 to one-in-600-year event. -NASA Earth Observatory images by Lauren Dauphin, using Landsat data from the U.S. Geological -Survey. Story by Emily Cassidy.View this area in EO ExplorerFlash floods in the port city -destroyed roads and swept neighborhoods out to sea.Image of the Day for September 21, 2023 - -Image of the Day Land Water Floods Human Presence View more Images of the Day:The melting -of frozen rivers and snowpack, and the heavy rains of late spring and summer, can send rivers -out of their banks.A Mediterranean cyclone contributed to deadly flooding along the country’s -coastline. Image of the Day Land Water Floods Record rainfall inundated towns and farmland -in the country’s Thessaly region. Image of the Day Water Floods Human Presence A stalled storm - -dropped three feet of rain over four days on the Thessaly region, triggering extensive flooding. -Image of the Day Atmosphere Floods An isolated low-pressure system produced torrential downpours -in Spain and carried Saharan dust along its path. Image of the Day Atmosphere Land Floods -Human Presence July 2002 - June 2022JPEGThe deep-blue sea is turning a touch greener. While -that may not seem as consequential as, say, record warm sea surface temperatures, the color - -of the ocean surface is indicative of the ecosystem that lies beneath. Communities of phytoplankton, -microscopic photosynthesizing organisms, abound in near-surface waters and are foundational -to the aquatic food web and carbon cycle. This shift in the water’s hue confirms a trend expected -under climate change and signals changes to ecosystems within the global ocean, which covers -70 percent of Earth’s surface. Researchers led by B. B. Cael, a principal scientist at the - -U.K.’s National Oceanography Centre, revealed that 56 percent of the global sea surface has -undergone a significant change in color in the past 20 years. After analyzing ocean color -data from the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument on NASA’s Aqua -satellite, they found that much of the change stems from the ocean turning more green. The -map above highlights the areas where ocean surface color changed between 2002 and 2022, with - -darker shades of green representing more-significant differences (higher signal-to-noise ratio). -By extension, said Cael, “these are places we can detect a change in the ocean ecosystem in -the last 20 years.” The study focused on tropical and subtropical regions, excluding higher -latitudes, which are dark for part of the year, and coastal waters, where the data are naturally -very noisy. The black dots on the map indicate the area, covering 12 percent of the ocean’s - -surface, where chlorophyll levels also changed over the study period. Chlorophyll has been -the go-to measurement for remote sensing scientists to gauge phytoplankton abundance and productivity. -However, those estimates use only a few colors in the visible light spectrum. The values shown -in green are based on the whole gamut of colors and therefore capture more information about -the ecosystem as a whole. A long time series from a single sensor is relatively rare in the - -remote sensing world. As the Aqua satellite was celebrating its 20th year in orbit in 2022—far -exceeding its design life of 6 years—Cael wondered what long term trends could be discovered -in the data. In particular, he was curious what might have been missed in all the ocean color -information it had collected. “There’s more encoded in the data than we actually make use -of,” he said. By going big with the data, the team discerned an ocean color trend that had - -been predicted by climate modeling, but one that was expected to take 30-40 years of data -to detect using satellite-based chlorophyll estimates. That’s because the natural variability -in chlorophyll is high relative to the climate change trend. The new method, incorporating -all visible light, was robust enough to confirm the trend in 20 years. At this stage, it is -difficult to say what exact ecological changes are responsible for the new hues. However, - -the authors posit, they could result from different assemblages of plankton, more detrital -particles, or other organisms such as zooplankton. It is unlikely the color changes come from -materials such as plastics or other pollutants, said Cael, since they are not widespread enough -to register at large scales. “What we do know is that in the last 20 years, the ocean has -become more stratified,” he said. Surface waters have absorbed excess heat from the warming - -climate, and as a result, they are less prone to mixing with deeper, more nutrient-rich layers. -This scenario would favor plankton adapted to a nutrient-poor environment. The areas of ocean -color change align well with where the sea has become more stratified, said Cael, but there -is no such overlap with sea surface temperature changes. More insights into Earth’s aquatic -ecosystems may soon be on the way. NASA’s PACE (Plankton, Aerosol, Cloud, ocean Ecosystem) - -satellite, set to launch in 2024, will return observations in finer color resolution. The -new data will enable researchers to infer more information about ocean ecology, such as the -diversity of phytoplankton species and the rates of phytoplankton growth. NASA Earth Observatory -image by Wanmei Liang, using data from Cael, B. B., et al. (2023). Story by Lindsey Doermann.Two -decades of satellite measurements show that the sea surface is shading toward green.Image - -of the Day for October 2, 2023 Image of the Day Life Water View more Images of the Day:Datasets -from the Sentinel-6 Michael Freilich satellite will build upon three decades of sea level -measurements. Image of the Day Heat Water Remote Sensing Image of the Day Life Water Image -of the Day Water The use of plastic on farms has become so common in recent decades that there -there’s a term for it—plasticulture. Image of the Day Human Presence August 16, 2023JPEGThe - -Canary Islands were at the center of a mélange of natural events in summer 2023. The Moderate -Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this assemblage -of phenomena off the coast of Africa on August 16, 2023.In the center of the scene, smoke -is seen rising from a wildfire burning on Tenerife in the Canary Islands. The blaze started -amid hot and dry conditions on August 15 in forests surrounding the Teide Volcano. Authorities - -issued evacuation orders to five villages, and responders focused on containing the fire’s -spread and protecting residential areas near the coast, according to news reports. Other fires -have burned on the Canary Islands this summer, including on La Palma in July.To the west, -a swirling cloud moves across the Atlantic. Cloud vortices appear routinely downwind of the -Canary Islands—sometimes in great abundance—and are produced when the tall volcanic peaks - -disrupt the air flowing past them.Elsewhere in the atmosphere, dust from the Sahara Desert -was lofted out over the ocean. The river of dust crossing the Atlantic was more pronounced -in previous days, when it reached islands in the Caribbean. Traveling on the Saharan Air Layer, -dust sometimes makes it even further west toward Central America and the U.S. states of Florida -and Texas.To round out the list, the patch of bright blue off the Moroccan coast is most likely - -a bloom of phytoplankton. While the exact cause and composition of the bloom cannot be determined -from this image, mineral-rich desert dust has been shown to set off bursts of phytoplankton -growth.In addition to the Earth’s processes seen here, one remote sensing artifact is present. -A diagonal streak of sunglint makes part of this scene appear washed out. Sunglint, an effect -that occurs when sunlight reflects off the surface of the water at the same angle that a satellite - -sensor views it, is also the reason for the light-colored streaks trailing off the islands.NASA -Earth Observatory image by Wanmei Liang, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview. -Story by Lindsey Doermann.View this area in EO ExplorerAn assortment of natural phenomena -visible from space appeared together in one image.Image of the Day for August 17, 2023 Image -of the Day Atmosphere Land Water View more Images of the Day:Flights were grounded as visibility - -was severely hampered by a Calima event. Image of the Day Atmosphere Land Dust and Haze Human -Presence In one frame International Space Station astronauts were able to capture the evolution -of fringing reefs to atolls. As with the Hawaiian Islands, these volcanic hot spot islands -become progressively older to the northwest. As these islands move away from their magma sources -they erode and subside. Image of the Day Land Water The dry, volcanic terrain of this Canary - -Island is suitable for lichen and crops … and for training astronauts. Image of the Day Land -The event, known locally as “la calima,” turned skies orange and degraded air quality in Gran -Canaria and neighboring islands. Image of the Day Atmosphere Land Dust and Haze July 17, 2023JPEGFour -funnel-shaped estuarine inlets, collectively known as Rías Baixas, line the coast of Galicia, -in northwest Spain. The nutrient-rich water in these inlets supports a wealth of marine life, - -making the Galicia coast one of the most productive places for aquaculture.On July 17, 2023, -the Operational Land Imager-2 (OLI-2) on Landsat 9, acquired this image of the Rías de Arousa -(Arousa estuary), the largest and northernmost of the inlets. Small dots skirt the coasts -of the embayment. In most cases, these dots are rectangular rafts designed for raising bivalves -like mussels. Buoys keep the lattice mussel rafts afloat on the surface of the water, and - -hundreds of ropes are suspended into the water column from each structure. Mussels attach -to the ropes and filter feed on phytoplankton and other suspended organic particles. The rafts -allow for high yields of mussels in a small area of the water. The Rías Baixas are on the -northern end of the Canary current and are in a major upwelling zone. Upwelling, which brings -colder, nutrient-rich water up from the bottom of the ocean, typically occurs in this area - -between April and October. Much of the mussel production in the Rías Baixas occurs during -this time, as the mollusks filter feed on nutrients and plentiful phytoplankton supported -by upwelling. Spain is the top mussel producing country in the world. Rías de Arousa alone -contains over 2,400 mussel rafts, producing about 40 percent of Europe’s mussels. NASA Earth -Observatory image by Wanmei Liang, using Landsat data from the U.S. Geological Survey. Story - -by Emily Cassidy. Buoys keep the lattice mussel rafts afloat on the surface of the water, -and hundreds of ropes are suspended into the water column from each structure. Mussels attach -to the ropes and filter feed on phytoplankton and other suspended organic particles. The rafts -allow for high yields of mussels in a small area of the water. The Rías Baixas are on the -northern end of the Canary current and are in a major upwelling zone. Upwelling, which brings - -colder, nutrient-rich water up from the bottom of the ocean, typically occurs in this area -between April and October. Much of the mussel production in the Rías Baixas occurs during -this time, as the mollusks filter feed on nutrients and plentiful phytoplankton supported -by upwelling. Spain is the top mussel producing country in the world. Rías de Arousa alone -contains over 2,400 mussel rafts, producing about 40 percent of Europe’s mussels. NASA Earth - -Observatory image by Wanmei Liang, using Landsat data from the U.S. Geological Survey. Story -by Emily Cassidy.View this area in EO ExplorerThe estuarine inlets of Spain’s Galicia coast -are some of the most productive places to grow mussels.Image of the Day for September 19, -2023 Image of the Day Water Human Presence View more Images of the Day: Dust and Haze This -image shows Tropical Cyclones Eric and Fanele near Madagascar on January 19, 2009. Atmosphere - -Water Severe Storms This natural-color image shows Saharan dust forming an S-shaped curve -off the western coast of Africa, and passing directly over Cape Verde. Atmosphere Land Dust -and Haze Acquired March 8, 2010, this true-color image shows two icebergs, Iceberg B-09B and -an iceberg recently broken off the Mertz Glacier, floating in the Southern Ocean, just off -the George V Coast. Water Snow and Ice Sea and Lake Ice January 22 - July 26, 2023JPEGOne - -of the wettest wet seasons in northern Australia transformed large areas of the country’s -desert landscape over the course of many months in 2023. A string of major rainfall events -that dropped 690 millimeters (27 inches) between October 2022 and April 2023 made it the sixth-wettest -season on record since 1900–1901.This series of false-color images illustrates the rainfall’s -months-long effects downstream in the Lake Eyre Basin. Water appears in shades of blue, vegetation - -is green, and bare land is brown. The images were acquired by the Moderate Resolution Imaging -Spectroradiometer (MODIS) on NASA’s Terra satellite between January and July 2023.In the January -22 image (left), water was coursing through seasonally dry channels of the Georgina River -and Eyre Creek following weeks of heavy rains in northern Queensland. By April 21 (middle), -floodwaters had reached further downstream after another intense period of precipitation in - -March. This scene shows that water had filled in some of the north-northwest trending ridges -that are part of a vast fossil landscape of wind-formed dunes, while vegetation had emerged -in wet soil upstream. Then by July 26 (right), the riverbed had filled with even more vegetation.The -Georgina River and Eyre Creek drain approximately 210,000 square kilometers (81,000 square -miles), nearly the area of the United Kingdom. Visible in the lower part of the images, the - -lake gets refreshed about every three years; when it reaches especially high levels, it may -take 18 months to 2 years to dry up. Two smaller neighboring lakes flood seasonally. These -three lakes and surrounding floodplains support hundreds of thousands of waterbirds and are -designated as an Important Bird Area.Seasonal flooding is a regular occurrence in these desert -river systems. However, the events of the 2022-2023 rainy season stood out in several ways. - -They occurred while La Niña conditions were in place over the tropical Pacific Ocean. (The -wettest seasons in northern Australia have all occurred during La Niña years, according to -Australia’s Bureau of Meteorology.) In addition, major rains occurring in succession, as was -the case with the January and March events, have the overall effect of prolonging floods. -That’s because vegetation that grows after the first event slows down the pulse of water that - -comes through in the next rain event.The high water has affected both local communities and -ecosystems. Floods have inundated cattle farms and isolated towns on temporary islands. At -the same time, they are a natural feature of the “boom-and-bust” ecology of Channel Country, -providing habitat and nutrients that support biodiversity.NASA Earth Observatory image by -Wanmei Liang, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview. Story by Lindsey - -Doermann.View this area in EO ExplorerRepeated heavy rains in Australia set off waves of new -growth across Channel Country.Image of the Day for August 7, 2023 Image of the Day Land Water -View more Images of the Day: Floods The waves off the coast of Teahupo’o can heave a crushing -amount of water toward the shore and onto unlucky surfers. Image of the Day Water Waves of -heavy rainfall left towns and farmland under water in October 2022. Image of the Day Water - -Floods Acquired February 26, 2011, and February 5, 2011, these false-color images show the -impact of heavy rains in marshy areas southeast of Georgetown, Guyana. Land Floods August -25, 2023JPEGSeptember 18, 2023JPEGAugust 25, 2023September 18, 2023August 25, 2023JPEGSeptember -18, 2023JPEGSeptember 18, 2023JPEGHeavy rain from a cyclone in the Mediterranean inundated -cities along the northeastern coast of Libya in early September 2023, causing thousands of - -deaths. The port city of Derna (Darnah), home to about 90,000 people, was one of the worst -hit by the storm and suffered extensive flooding and damage. On September 10 and 11, over -100 millimeters (4 inches) of rain fell on Derna. The city lies at the end of a long, narrow -valley, called a wadi, which is dry except during the rainy season. Floods triggered two dams -along the wadi to collapse. The failure of the second dam, located just one kilometer inland - -of Derna, unleashed 3- to 7-meter-high floodwater that tore through the city. According to -news reports, the flash floods destroyed roads and swept entire neighborhoods out to sea. -The images above show the city before and after the storm. The image on the right, acquired -by the Operational Land Imager-2 (OLI-2) on Landsat 9 on September 18, shows eroded banks -of Wadi Derna near where it meets the Mediterranean. Water just off the coast appears muddier - -than in the image on the left, which shows the same area on August 25 and was acquired by -Landsat 8. Preliminary estimates by the United Nations Satellite Center (UNOSAT) indicate -that 3,100 buildings in Derna were damaged by rushing water. According to the UN International -Organization for Migration (IOM), about 40,000 people in the country were displaced by the -storm, and 30,000 of those were displaced from Derna. Tropical-like cyclones in the Mediterranean, - -or “medicanes,” develop only once or twice a year, according to NOAA, and typically form in -autumn. According to meteorologists at Yale Climate Connections, this storm was the deadliest -in Africa’s recorded history. A recent assessment by scientists at World Weather Attribution -estimated that precipitation received by the region was a one-in-300 to one-in-600-year event. -NASA Earth Observatory images by Lauren Dauphin, using Landsat data from the U.S. Geological - -Survey. Story by Emily Cassidy.View this area in EO ExplorerFlash floods in the port city -destroyed roads and swept neighborhoods out to sea.Image of the Day for September 21, 2023 -Image of the Day Land Water Floods Human Presence View more Images of the Day:The melting -of frozen rivers and snowpack, and the heavy rains of late spring and summer, can send rivers -out of their banks.A Mediterranean cyclone contributed to deadly flooding along the country’s - -coastline. Image of the Day Land Water Floods Record rainfall inundated towns and farmland -in the country’s Thessaly region. Image of the Day Water Floods Human Presence A stalled storm -dropped three feet of rain over four days on the Thessaly region, triggering extensive flooding. -Image of the Day Atmosphere Floods An isolated low-pressure system produced torrential downpours -in Spain and carried Saharan dust along its path. Image of the Day Atmosphere Land Floods - -Human Presence July 2002 - June 2022JPEGThe deep-blue sea is turning a touch greener. While -that may not seem as consequential as, say, record warm sea surface temperatures, the color -of the ocean surface is indicative of the ecosystem that lies beneath. Communities of phytoplankton, -microscopic photosynthesizing organisms, abound in near-surface waters and are foundational -to the aquatic food web and carbon cycle. This shift in the water’s hue confirms a trend expected - -under climate change and signals changes to ecosystems within the global ocean, which covers -70 percent of Earth’s surface. Researchers led by B. B. Cael, a principal scientist at the -U.K.’s National Oceanography Centre, revealed that 56 percent of the global sea surface has -undergone a significant change in color in the past 20 years. After analyzing ocean color -data from the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument on NASA’s Aqua - -satellite, they found that much of the change stems from the ocean turning more green. The -map above highlights the areas where ocean surface color changed between 2002 and 2022, with -darker shades of green representing more-significant differences (higher signal-to-noise ratio). -By extension, said Cael, “these are places we can detect a change in the ocean ecosystem in -the last 20 years.” The study focused on tropical and subtropical regions, excluding higher - -latitudes, which are dark for part of the year, and coastal waters, where the data are naturally -very noisy. The black dots on the map indicate the area, covering 12 percent of the ocean’s -surface, where chlorophyll levels also changed over the study period. Chlorophyll has been -the go-to measurement for remote sensing scientists to gauge phytoplankton abundance and productivity. -However, those estimates use only a few colors in the visible light spectrum. The values shown - -in green are based on the whole gamut of colors and therefore capture more information about -the ecosystem as a whole. A long time series from a single sensor is relatively rare in the -remote sensing world. As the Aqua satellite was celebrating its 20th year in orbit in 2022—far -exceeding its design life of 6 years—Cael wondered what long term trends could be discovered -in the data. In particular, he was curious what might have been missed in all the ocean color - -information it had collected. “There’s more encoded in the data than we actually make use -of,” he said. By going big with the data, the team discerned an ocean color trend that had -been predicted by climate modeling, but one that was expected to take 30-40 years of data -to detect using satellite-based chlorophyll estimates. That’s because the natural variability -in chlorophyll is high relative to the climate change trend. The new method, incorporating - -all visible light, was robust enough to confirm the trend in 20 years. At this stage, it is -difficult to say what exact ecological changes are responsible for the new hues. However, -the authors posit, they could result from different assemblages of plankton, more detrital -particles, or other organisms such as zooplankton. It is unlikely the color changes come from -materials such as plastics or other pollutants, said Cael, since they are not widespread enough - -to register at large scales. “What we do know is that in the last 20 years, the ocean has -become more stratified,” he said. Surface waters have absorbed excess heat from the warming -climate, and as a result, they are less prone to mixing with deeper, more nutrient-rich layers. -This scenario would favor plankton adapted to a nutrient-poor environment. The areas of ocean -color change align well with where the sea has become more stratified, said Cael, but there - -is no such overlap with sea surface temperature changes. More insights into Earth’s aquatic -ecosystems may soon be on the way. NASA’s PACE (Plankton, Aerosol, Cloud, ocean Ecosystem) -satellite, set to launch in 2024, will return observations in finer color resolution. The -new data will enable researchers to infer more information about ocean ecology, such as the -diversity of phytoplankton species and the rates of phytoplankton growth. NASA Earth Observatory - -image by Wanmei Liang, using data from Cael, B. B., et al. (2023). Story by Lindsey Doermann.Two -decades of satellite measurements show that the sea surface is shading toward green.Image -of the Day for October 2, 2023 Image of the Day Life Water View more Images of the Day:Datasets -from the Sentinel-6 Michael Freilich satellite will build upon three decades of sea level -measurements. Image of the Day Heat Water Remote Sensing Image of the Day Life Water Image - -of the Day Water The use of plastic on farms has become so common in recent decades that there -there’s a term for it—plasticulture. Image of the Day Human Presence August 16, 2023JPEGThe -Canary Islands were at the center of a mélange of natural events in summer 2023. The Moderate -Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this assemblage -of phenomena off the coast of Africa on August 16, 2023.In the center of the scene, smoke - -is seen rising from a wildfire burning on Tenerife in the Canary Islands. The blaze started -amid hot and dry conditions on August 15 in forests surrounding the Teide Volcano. Authorities -issued evacuation orders to five villages, and responders focused on containing the fire’s -spread and protecting residential areas near the coast, according to news reports. Other fires -have burned on the Canary Islands this summer, including on La Palma in July.To the west, - -a swirling cloud moves across the Atlantic. Cloud vortices appear routinely downwind of the -Canary Islands—sometimes in great abundance—and are produced when the tall volcanic peaks -disrupt the air flowing past them.Elsewhere in the atmosphere, dust from the Sahara Desert -was lofted out over the ocean. The river of dust crossing the Atlantic was more pronounced -in previous days, when it reached islands in the Caribbean. Traveling on the Saharan Air Layer, - -dust sometimes makes it even further west toward Central America and the U.S. states of Florida -and Texas.To round out the list, the patch of bright blue off the Moroccan coast is most likely -a bloom of phytoplankton. While the exact cause and composition of the bloom cannot be determined -from this image, mineral-rich desert dust has been shown to set off bursts of phytoplankton -growth.In addition to the Earth’s processes seen here, one remote sensing artifact is present. - -A diagonal streak of sunglint makes part of this scene appear washed out. Sunglint, an effect -that occurs when sunlight reflects off the surface of the water at the same angle that a satellite -sensor views it, is also the reason for the light-colored streaks trailing off the islands.NASA -Earth Observatory image by Wanmei Liang, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview. -Story by Lindsey Doermann.View this area in EO ExplorerAn assortment of natural phenomena - -visible from space appeared together in one image.Image of the Day for August 17, 2023 Image -of the Day Atmosphere Land Water View more Images of the Day:Flights were grounded as visibility -was severely hampered by a Calima event. Image of the Day Atmosphere Land Dust and Haze Human -Presence In one frame International Space Station astronauts were able to capture the evolution -of fringing reefs to atolls. As with the Hawaiian Islands, these volcanic hot spot islands - -become progressively older to the northwest. As these islands move away from their magma sources -they erode and subside. Image of the Day Land Water The dry, volcanic terrain of this Canary -Island is suitable for lichen and crops … and for training astronauts. Image of the Day Land -The event, known locally as “la calima,” turned skies orange and degraded air quality in Gran -Canaria and neighboring islands. Image of the Day Atmosphere Land Dust and Haze July 17, 2023JPEGFour - -funnel-shaped estuarine inlets, collectively known as Rías Baixas, line the coast of Galicia, -in northwest Spain. The nutrient-rich water in these inlets supports a wealth of marine life, -making the Galicia coast one of the most productive places for aquaculture.On July 17, 2023, -the Operational Land Imager-2 (OLI-2) on Landsat 9, acquired this image of the Rías de Arousa -(Arousa estuary), the largest and northernmost of the inlets. Small dots skirt the coasts - -of the embayment. In most cases, these dots are rectangular rafts designed for raising bivalves -like mussels. Buoys keep the lattice mussel rafts afloat on the surface of the water, and -hundreds of ropes are suspended into the water column from each structure. Mussels attach -to the ropes and filter feed on phytoplankton and other suspended organic particles. The rafts -allow for high yields of mussels in a small area of the water. The Rías Baixas are on the - -northern end of the Canary current and are in a major upwelling zone. Upwelling, which brings -colder, nutrient-rich water up from the bottom of the ocean, typically occurs in this area -between April and October. Much of the mussel production in the Rías Baixas occurs during -this time, as the mollusks filter feed on nutrients and plentiful phytoplankton supported -by upwelling. Spain is the top mussel producing country in the world. Rías de Arousa alone - -contains over 2,400 mussel rafts, producing about 40 percent of Europe’s mussels. NASA Earth -Observatory image by Wanmei Liang, using Landsat data from the U.S. Geological Survey. Story -by Emily Cassidy. Buoys keep the lattice mussel rafts afloat on the surface of the water, -and hundreds of ropes are suspended into the water column from each structure. Mussels attach -to the ropes and filter feed on phytoplankton and other suspended organic particles. The rafts - -allow for high yields of mussels in a small area of the water. The Rías Baixas are on the -northern end of the Canary current and are in a major upwelling zone. Upwelling, which brings -colder, nutrient-rich water up from the bottom of the ocean, typically occurs in this area -between April and October. Much of the mussel production in the Rías Baixas occurs during -this time, as the mollusks filter feed on nutrients and plentiful phytoplankton supported - -by upwelling. Spain is the top mussel producing country in the world. Rías de Arousa alone -contains over 2,400 mussel rafts, producing about 40 percent of Europe’s mussels. NASA Earth -Observatory image by Wanmei Liang, using Landsat data from the U.S. Geological Survey. Story -by Emily Cassidy.View this area in EO ExplorerThe estuarine inlets of Spain’s Galicia coast -are some of the most productive places to grow mussels.Image of the Day for September 19, - -2023 Image of the Day Water Human Presence View more Images of the Day: Dust and Haze This -image shows Tropical Cyclones Eric and Fanele near Madagascar on January 19, 2009. Atmosphere -Water Severe Storms This natural-color image shows Saharan dust forming an S-shaped curve -off the western coast of Africa, and passing directly over Cape Verde. Atmosphere Land Dust -and Haze Acquired March 8, 2010, this true-color image shows two icebergs, Iceberg B-09B and - -an iceberg recently broken off the Mertz Glacier, floating in the Southern Ocean, just off -the George V Coast. Water Snow and Ice Sea and Lake Ice May 18, 2023JPEGSeptember 7, 2023JPEGMay -18, 2023September 7, 2023May 18, 2023JPEGSeptember 7, 2023JPEGSeptember 7, 2023JPEGAfter going -dry in 2018, Laguna de Aculeo has begun to refill. NASA satellites began to detect water pooling -in the parched lake in late-August, after an intense winter storm dropped as much as 370 millimeters - -(15 inches) of rain on some parts of central Chile. The storm was fueled by an atmospheric -river and exacerbated by the rugged terrain in central Chile.When the Operational Land Imager-2 -(OLI-2) on Landsat 9 acquired this image (right) on September 7, 2023, Laguna de Aculeo covered -about 5 square kilometers (2 square miles) to a depth of roughly 1 meter (3 feet). The other -image (left) shows the dried water body on May 18, 2023, before the wet winter weather arrived. - -Although it has refilled somewhat, water spans only half the area it did up to 2010 and contains -a quarter of the water volume, explained René Garreaud, an Earth scientist at the University -of Chile. Seasonal changes and the influx of water have led to widespread greening of the -landscape around the lake.Researchers have assessed that ongoing development and water use -in the nearby community of Paine, increasing water use by farmers and in homes and pools, - -as well as several years of drought, likely contributed to the drawdown of the lake. Annual -rainfall deficits that averaged 38 percent between 2010 and 2018 likely played a large role, -according to one analysis from a team of researchers from the University of Chile.Before 2010, -the shallow water body was a popular haven for boaters, swimmers, and water skiers, but the -water hasn’t yet pooled up enough for swimmers or boaters to return. It is also unclear how - -long the new water in Aculeo will persist. “Atmospheric rivers in June and August delivered -substantial precipitation along the high terrain and foothills that have giv­­en us a welcome -interruption to the drought,” Garreaud said. “But Aculeo is a small, shallow lagoon that can -fill up rapidly, and it's only partly filled. Bigger reservoirs and aquifers will take much -longer to recover.”NASA Earth Observatory images by Lauren Dauphin, using Landsat data from - -the U.S. Geological Survey. Story by Adam Voiland.View this area in EO ExplorerThe drought -in Chile isn’t over, but recent late-winter rains provided enough moisture for water to start -pooling up again.Image of the Day for September 16, 2023 Image of the Day Life Water View -more Images of the Day:Data from winter 2022-2023 show the greatest net gain of water in nearly -22 years, but groundwater levels still suffer from years of drought. Image of the Day Land - -Water As a persistent drought drags on, water levels are dropping at a key reservoir that -supplies Santiago. Image of the Day Land Water A new web tool designed by NASA applied scientists -could help the tribe anticipate and respond to drought. Image of the Day Water Human Presence -Remote Sensing For more than 100 years, groups in the western United States have fought over -water. During the 1880s, sheep ranchers and cattle ranchers argued over drinking water for - -their livestock on the high plains. In 1913, the city of Los Angeles began to draw water away -from small agricultural communities in Owen Valley, leaving a dusty dry lake bed. In the late -1950s, construction of the Glen Canyon Dam catalyzed the American environmental movement. -Today, farmers are fighting fishermen, environmentalists, and Native American tribes over -the water in the Upper Klamath River Basin. The Landsat 7 satellite, launched by NASA and - -operated by the U.S. Geological Survey, documented an extreme drought in the area along the -California/Oregon border in the spring of 2001. Image of the Day Land Life January 22 - July -26, 2023JPEGOne of the wettest wet seasons in northern Australia transformed large areas of -the country’s desert landscape over the course of many months in 2023. A string of major rainfall -events that dropped 690 millimeters (27 inches) between October 2022 and April 2023 made it - -the sixth-wettest season on record since 1900–1901.This series of false-color images illustrates -the rainfall’s months-long effects downstream in the Lake Eyre Basin. Water appears in shades -of blue, vegetation is green, and bare land is brown. The images were acquired by the Moderate -Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite between January and -July 2023.In the January 22 image (left), water was coursing through seasonally dry channels - -of the Georgina River and Eyre Creek following weeks of heavy rains in northern Queensland. -By April 21 (middle), floodwaters had reached further downstream after another intense period -of precipitation in March. This scene shows that water had filled in some of the north-northwest -trending ridges that are part of a vast fossil landscape of wind-formed dunes, while vegetation -had emerged in wet soil upstream. Then by July 26 (right), the riverbed had filled with even - -more vegetation.The Georgina River and Eyre Creek drain approximately 210,000 square kilometers -(81,000 square miles), nearly the area of the United Kingdom. Visible in the lower part of -the images, the lake gets refreshed about every three years; when it reaches especially high -levels, it may take 18 months to 2 years to dry up. Two smaller neighboring lakes flood seasonally. -These three lakes and surrounding floodplains support hundreds of thousands of waterbirds - -and are designated as an Important Bird Area.Seasonal flooding is a regular occurrence in -these desert river systems. However, the events of the 2022-2023 rainy season stood out in -several ways. They occurred while La Niña conditions were in place over the tropical Pacific -Ocean. (The wettest seasons in northern Australia have all occurred during La Niña years, -according to Australia’s Bureau of Meteorology.) In addition, major rains occurring in succession, - -as was the case with the January and March events, have the overall effect of prolonging floods. -That’s because vegetation that grows after the first event slows down the pulse of water that -comes through in the next rain event.The high water has affected both local communities and -ecosystems. Floods have inundated cattle farms and isolated towns on temporary islands. At -the same time, they are a natural feature of the “boom-and-bust” ecology of Channel Country, - -providing habitat and nutrients that support biodiversity.NASA Earth Observatory image by -Wanmei Liang, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview. Story by Lindsey -Doermann.View this area in EO ExplorerRepeated heavy rains in Australia set off waves of new -growth across Channel Country.Image of the Day for August 7, 2023 Image of the Day Land Water -View more Images of the Day: Floods The waves off the coast of Teahupo’o can heave a crushing - -amount of water toward the shore and onto unlucky surfers. Image of the Day Water Waves of -heavy rainfall left towns and farmland under water in October 2022. Image of the Day Water -Floods Acquired February 26, 2011, and February 5, 2011, these false-color images show the -impact of heavy rains in marshy areas southeast of Georgetown, Guyana. Land Floods August -25, 2023JPEGSeptember 18, 2023JPEGAugust 25, 2023September 18, 2023August 25, 2023JPEGSeptember - -18, 2023JPEGSeptember 18, 2023JPEGHeavy rain from a cyclone in the Mediterranean inundated -cities along the northeastern coast of Libya in early September 2023, causing thousands of -deaths. The port city of Derna (Darnah), home to about 90,000 people, was one of the worst -hit by the storm and suffered extensive flooding and damage. On September 10 and 11, over -100 millimeters (4 inches) of rain fell on Derna. The city lies at the end of a long, narrow - -valley, called a wadi, which is dry except during the rainy season. Floods triggered two dams -along the wadi to collapse. The failure of the second dam, located just one kilometer inland -of Derna, unleashed 3- to 7-meter-high floodwater that tore through the city. According to -news reports, the flash floods destroyed roads and swept entire neighborhoods out to sea. -The images above show the city before and after the storm. The image on the right, acquired - -by the Operational Land Imager-2 (OLI-2) on Landsat 9 on September 18, shows eroded banks -of Wadi Derna near where it meets the Mediterranean. Water just off the coast appears muddier -than in the image on the left, which shows the same area on August 25 and was acquired by -Landsat 8. Preliminary estimates by the United Nations Satellite Center (UNOSAT) indicate -that 3,100 buildings in Derna were damaged by rushing water. According to the UN International - -Organization for Migration (IOM), about 40,000 people in the country were displaced by the -storm, and 30,000 of those were displaced from Derna. Tropical-like cyclones in the Mediterranean, -or “medicanes,” develop only once or twice a year, according to NOAA, and typically form in -autumn. According to meteorologists at Yale Climate Connections, this storm was the deadliest -in Africa’s recorded history. A recent assessment by scientists at World Weather Attribution - -estimated that precipitation received by the region was a one-in-300 to one-in-600-year event. -NASA Earth Observatory images by Lauren Dauphin, using Landsat data from the U.S. Geological -Survey. Story by Emily Cassidy.View this area in EO ExplorerFlash floods in the port city -destroyed roads and swept neighborhoods out to sea.Image of the Day for September 21, 2023 -Image of the Day Land Water Floods Human Presence View more Images of the Day:The melting - -of frozen rivers and snowpack, and the heavy rains of late spring and summer, can send rivers -out of their banks.A Mediterranean cyclone contributed to deadly flooding along the country’s -coastline. Image of the Day Land Water Floods Record rainfall inundated towns and farmland -in the country’s Thessaly region. Image of the Day Water Floods Human Presence A stalled storm -dropped three feet of rain over four days on the Thessaly region, triggering extensive flooding. - -Image of the Day Atmosphere Floods An isolated low-pressure system produced torrential downpours -in Spain and carried Saharan dust along its path. Image of the Day Atmosphere Land Floods -Human Presence July 2002 - June 2022JPEGThe deep-blue sea is turning a touch greener. While -that may not seem as consequential as, say, record warm sea surface temperatures, the color -of the ocean surface is indicative of the ecosystem that lies beneath. Communities of phytoplankton, - -microscopic photosynthesizing organisms, abound in near-surface waters and are foundational -to the aquatic food web and carbon cycle. This shift in the water’s hue confirms a trend expected -under climate change and signals changes to ecosystems within the global ocean, which covers -70 percent of Earth’s surface. Researchers led by B. B. Cael, a principal scientist at the -U.K.’s National Oceanography Centre, revealed that 56 percent of the global sea surface has - -undergone a significant change in color in the past 20 years. After analyzing ocean color -data from the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument on NASA’s Aqua -satellite, they found that much of the change stems from the ocean turning more green. The -map above highlights the areas where ocean surface color changed between 2002 and 2022, with -darker shades of green representing more-significant differences (higher signal-to-noise ratio). - -By extension, said Cael, “these are places we can detect a change in the ocean ecosystem in -the last 20 years.” The study focused on tropical and subtropical regions, excluding higher -latitudes, which are dark for part of the year, and coastal waters, where the data are naturally -very noisy. The black dots on the map indicate the area, covering 12 percent of the ocean’s -surface, where chlorophyll levels also changed over the study period. Chlorophyll has been - -the go-to measurement for remote sensing scientists to gauge phytoplankton abundance and productivity. -However, those estimates use only a few colors in the visible light spectrum. The values shown -in green are based on the whole gamut of colors and therefore capture more information about -the ecosystem as a whole. A long time series from a single sensor is relatively rare in the -remote sensing world. As the Aqua satellite was celebrating its 20th year in orbit in 2022—far - -exceeding its design life of 6 years—Cael wondered what long term trends could be discovered -in the data. In particular, he was curious what might have been missed in all the ocean color -information it had collected. “There’s more encoded in the data than we actually make use -of,” he said. By going big with the data, the team discerned an ocean color trend that had -been predicted by climate modeling, but one that was expected to take 30-40 years of data - -to detect using satellite-based chlorophyll estimates. That’s because the natural variability -in chlorophyll is high relative to the climate change trend. The new method, incorporating -all visible light, was robust enough to confirm the trend in 20 years. At this stage, it is -difficult to say what exact ecological changes are responsible for the new hues. However, -the authors posit, they could result from different assemblages of plankton, more detrital - -particles, or other organisms such as zooplankton. It is unlikely the color changes come from -materials such as plastics or other pollutants, said Cael, since they are not widespread enough -to register at large scales. “What we do know is that in the last 20 years, the ocean has -become more stratified,” he said. Surface waters have absorbed excess heat from the warming -climate, and as a result, they are less prone to mixing with deeper, more nutrient-rich layers. - -This scenario would favor plankton adapted to a nutrient-poor environment. The areas of ocean -color change align well with where the sea has become more stratified, said Cael, but there -is no such overlap with sea surface temperature changes. More insights into Earth’s aquatic -ecosystems may soon be on the way. NASA’s PACE (Plankton, Aerosol, Cloud, ocean Ecosystem) -satellite, set to launch in 2024, will return observations in finer color resolution. The - -new data will enable researchers to infer more information about ocean ecology, such as the -diversity of phytoplankton species and the rates of phytoplankton growth. NASA Earth Observatory -image by Wanmei Liang, using data from Cael, B. B., et al. (2023). Story by Lindsey Doermann.Two -decades of satellite measurements show that the sea surface is shading toward green.Image -of the Day for October 2, 2023 Image of the Day Life Water View more Images of the Day:Datasets - -from the Sentinel-6 Michael Freilich satellite will build upon three decades of sea level -measurements. Image of the Day Heat Water Remote Sensing Image of the Day Life Water Image -of the Day Water The use of plastic on farms has become so common in recent decades that there -there’s a term for it—plasticulture. Image of the Day Human Presence August 16, 2023JPEGThe -Canary Islands were at the center of a mélange of natural events in summer 2023. The Moderate - -Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this assemblage -of phenomena off the coast of Africa on August 16, 2023.In the center of the scene, smoke -is seen rising from a wildfire burning on Tenerife in the Canary Islands. The blaze started -amid hot and dry conditions on August 15 in forests surrounding the Teide Volcano. Authorities -issued evacuation orders to five villages, and responders focused on containing the fire’s - -spread and protecting residential areas near the coast, according to news reports. Other fires -have burned on the Canary Islands this summer, including on La Palma in July.To the west, -a swirling cloud moves across the Atlantic. Cloud vortices appear routinely downwind of the -Canary Islands—sometimes in great abundance—and are produced when the tall volcanic peaks -disrupt the air flowing past them.Elsewhere in the atmosphere, dust from the Sahara Desert - -was lofted out over the ocean. The river of dust crossing the Atlantic was more pronounced -in previous days, when it reached islands in the Caribbean. Traveling on the Saharan Air Layer, -dust sometimes makes it even further west toward Central America and the U.S. states of Florida -and Texas.To round out the list, the patch of bright blue off the Moroccan coast is most likely -a bloom of phytoplankton. While the exact cause and composition of the bloom cannot be determined - -from this image, mineral-rich desert dust has been shown to set off bursts of phytoplankton -growth.In addition to the Earth’s processes seen here, one remote sensing artifact is present. -A diagonal streak of sunglint makes part of this scene appear washed out. Sunglint, an effect -that occurs when sunlight reflects off the surface of the water at the same angle that a satellite -sensor views it, is also the reason for the light-colored streaks trailing off the islands.NASA - -Earth Observatory image by Wanmei Liang, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview. -Story by Lindsey Doermann.View this area in EO ExplorerAn assortment of natural phenomena -visible from space appeared together in one image.Image of the Day for August 17, 2023 Image -of the Day Atmosphere Land Water View more Images of the Day:Flights were grounded as visibility -was severely hampered by a Calima event. Image of the Day Atmosphere Land Dust and Haze Human - -Presence In one frame International Space Station astronauts were able to capture the evolution -of fringing reefs to atolls. As with the Hawaiian Islands, these volcanic hot spot islands -become progressively older to the northwest. As these islands move away from their magma sources -they erode and subside. Image of the Day Land Water The dry, volcanic terrain of this Canary -Island is suitable for lichen and crops … and for training astronauts. Image of the Day Land - -The event, known locally as “la calima,” turned skies orange and degraded air quality in Gran -Canaria and neighboring islands. Image of the Day Atmosphere Land Dust and Haze July 17, 2023JPEGFour -funnel-shaped estuarine inlets, collectively known as Rías Baixas, line the coast of Galicia, -in northwest Spain. The nutrient-rich water in these inlets supports a wealth of marine life, -making the Galicia coast one of the most productive places for aquaculture.On July 17, 2023, - -the Operational Land Imager-2 (OLI-2) on Landsat 9, acquired this image of the Rías de Arousa -(Arousa estuary), the largest and northernmost of the inlets. Small dots skirt the coasts -of the embayment. In most cases, these dots are rectangular rafts designed for raising bivalves -like mussels. Buoys keep the lattice mussel rafts afloat on the surface of the water, and -hundreds of ropes are suspended into the water column from each structure. Mussels attach - -to the ropes and filter feed on phytoplankton and other suspended organic particles. The rafts -allow for high yields of mussels in a small area of the water. The Rías Baixas are on the -northern end of the Canary current and are in a major upwelling zone. Upwelling, which brings -colder, nutrient-rich water up from the bottom of the ocean, typically occurs in this area -between April and October. Much of the mussel production in the Rías Baixas occurs during - -this time, as the mollusks filter feed on nutrients and plentiful phytoplankton supported -by upwelling. Spain is the top mussel producing country in the world. Rías de Arousa alone -contains over 2,400 mussel rafts, producing about 40 percent of Europe’s mussels. NASA Earth -Observatory image by Wanmei Liang, using Landsat data from the U.S. Geological Survey. Story -by Emily Cassidy. Buoys keep the lattice mussel rafts afloat on the surface of the water, - -and hundreds of ropes are suspended into the water column from each structure. Mussels attach -to the ropes and filter feed on phytoplankton and other suspended organic particles. The rafts -allow for high yields of mussels in a small area of the water. The Rías Baixas are on the -northern end of the Canary current and are in a major upwelling zone. Upwelling, which brings -colder, nutrient-rich water up from the bottom of the ocean, typically occurs in this area - -between April and October. Much of the mussel production in the Rías Baixas occurs during -this time, as the mollusks filter feed on nutrients and plentiful phytoplankton supported -by upwelling. Spain is the top mussel producing country in the world. Rías de Arousa alone -contains over 2,400 mussel rafts, producing about 40 percent of Europe’s mussels. NASA Earth -Observatory image by Wanmei Liang, using Landsat data from the U.S. Geological Survey. Story - -by Emily Cassidy.View this area in EO ExplorerThe estuarine inlets of Spain’s Galicia coast -are some of the most productive places to grow mussels.Image of the Day for September 19, -2023 Image of the Day Water Human Presence View more Images of the Day: Dust and Haze This -image shows Tropical Cyclones Eric and Fanele near Madagascar on January 19, 2009. Atmosphere -Water Severe Storms This natural-color image shows Saharan dust forming an S-shaped curve - -off the western coast of Africa, and passing directly over Cape Verde. Atmosphere Land Dust -and Haze Acquired March 8, 2010, this true-color image shows two icebergs, Iceberg B-09B and -an iceberg recently broken off the Mertz Glacier, floating in the Southern Ocean, just off -the George V Coast. Water Snow and Ice Sea and Lake Ice May 18, 2023JPEGSeptember 7, 2023JPEGMay -18, 2023September 7, 2023May 18, 2023JPEGSeptember 7, 2023JPEGSeptember 7, 2023JPEGAfter going - -dry in 2018, Laguna de Aculeo has begun to refill. NASA satellites began to detect water pooling -in the parched lake in late-August, after an intense winter storm dropped as much as 370 millimeters -(15 inches) of rain on some parts of central Chile. The storm was fueled by an atmospheric -river and exacerbated by the rugged terrain in central Chile.When the Operational Land Imager-2 -(OLI-2) on Landsat 9 acquired this image (right) on September 7, 2023, Laguna de Aculeo covered - -about 5 square kilometers (2 square miles) to a depth of roughly 1 meter (3 feet). The other -image (left) shows the dried water body on May 18, 2023, before the wet winter weather arrived. -Although it has refilled somewhat, water spans only half the area it did up to 2010 and contains -a quarter of the water volume, explained René Garreaud, an Earth scientist at the University -of Chile. Seasonal changes and the influx of water have led to widespread greening of the - -landscape around the lake.Researchers have assessed that ongoing development and water use -in the nearby community of Paine, increasing water use by farmers and in homes and pools, -as well as several years of drought, likely contributed to the drawdown of the lake. Annual -rainfall deficits that averaged 38 percent between 2010 and 2018 likely played a large role, -according to one analysis from a team of researchers from the University of Chile.Before 2010, - -the shallow water body was a popular haven for boaters, swimmers, and water skiers, but the -water hasn’t yet pooled up enough for swimmers or boaters to return. It is also unclear how -long the new water in Aculeo will persist. “Atmospheric rivers in June and August delivered -substantial precipitation along the high terrain and foothills that have giv­­en us a welcome -interruption to the drought,” Garreaud said. “But Aculeo is a small, shallow lagoon that can - -fill up rapidly, and it's only partly filled. Bigger reservoirs and aquifers will take much -longer to recover.”NASA Earth Observatory images by Lauren Dauphin, using Landsat data from -the U.S. Geological Survey. Story by Adam Voiland.View this area in EO ExplorerThe drought -in Chile isn’t over, but recent late-winter rains provided enough moisture for water to start -pooling up again.Image of the Day for September 16, 2023 Image of the Day Life Water View - -more Images of the Day:Data from winter 2022-2023 show the greatest net gain of water in nearly -22 years, but groundwater levels still suffer from years of drought. Image of the Day Land -Water As a persistent drought drags on, water levels are dropping at a key reservoir that -supplies Santiago. Image of the Day Land Water A new web tool designed by NASA applied scientists -could help the tribe anticipate and respond to drought. Image of the Day Water Human Presence - -Remote Sensing For more than 100 years, groups in the western United States have fought over -water. During the 1880s, sheep ranchers and cattle ranchers argued over drinking water for -their livestock on the high plains. In 1913, the city of Los Angeles began to draw water away -from small agricultural communities in Owen Valley, leaving a dusty dry lake bed. In the late -1950s, construction of the Glen Canyon Dam catalyzed the American environmental movement. - -Today, farmers are fighting fishermen, environmentalists, and Native American tribes over -the water in the Upper Klamath River Basin. The Landsat 7 satellite, launched by NASA and -operated by the U.S. Geological Survey, documented an extreme drought in the area along the -California/Oregon border in the spring of 2001. Image of the Day Land Life September 16, 2023JPEGSeptember -10, 2021JPEGSeptember 16, 2023September 10, 2021September 16, 2023JPEGSeptember 10, 2021JPEGSeptember - -10, 2021JPEGMonths of excessive heat and drought parched the Mississippi River in the summer -and early fall of 2023. In September, low water levels limited barge shipments downriver and -threatened drinking water supplies in some Louisiana communities, according to the Associated -Press.Water levels were especially low near Memphis, Tennessee. The images above show the -Mississippi River near Memphis on September 16, 2023 (left), compared to September 10, 2021 - -(right). The river was significantly slimmed down in 2023, exposing some of the river bottom.This -is the second year in a row drought has caused the river to fall to near-record lows at many -gauges. On September 26, 2023, the river level at a gauge in Memphis was -10.26 feet, close -to the record low level, -10.81 feet, measured at the same place on October 21, 2022. That -was the lowest level recorded there since the start of National Weather Service records in - -1954. Water levels, or “gauge heights,” do not indicate the depth of a stream; rather, they -are measured with respect to a chosen reference point. That is why some gauge height measurements -are negative.Farther upstream, water levels at New Madrid, Missouri, have been around -5 feet—near -the minimum operating level—since early September 2023. Water levels on the Mississippi normally -decline in the fall and winter, and in 2022, the river did not get that low until mid-October. - -September 26, 2023JPEGA hot, dry summer is the main reason water levels dropped so low in -2023. Across the globe, temperatures in summer 2023 were 1.2°C (2.1°F) warmer than average. -In the U.S., Louisiana and Mississippi experienced their hottest Augusts on record, according -to NOAA.The U.S. Drought Monitor map above—the product of a partnership between the U.S. Department -of Agriculture, the National Oceanic and Atmospheric Administration, and the University of - -Nebraska-Lincoln—shows conditions during the week of September 20-26, 2023. The map depicts -drought intensity in progressive shades of orange to red. It is based on an analysis of climate, -soil, and water condition measurements from more than 350 federal, state, and local observers -around the country. NASA contributes measurements and models that aid the drought monitoring -effort.During that week, about 38 percent of the contiguous U.S. was experiencing drought. - -Lack of precipitation and high temperatures over several months severely dried out soils in -states along the Mississippi River Valley. The Drought Monitor reported that 80 percent of -soils in Louisiana were dry (short or very short on water) as of September 24. And for most -states in the river valley, over 50 percent of topsoil was dry or very dry.Shallow conditions -along the river interrupted normal shipments of goods. According to the Associated Press, - -barge companies reduced the weight carried in many shipments in September because the river -was not deep enough to accommodate their normal weight. Much of U.S. grain exports are transported -down the Mississippi, and according to AP, the cost of these shipments from St. Louis southward -has risen 77 percent above the three-year average. The lack of freshwater flowing into the -Gulf of Mexico has also allowed saltwater to make its way up the river and into some water - -treatment plants in southern Louisiana, according to the Associated Press. Some parts of Plaquemines -Parish are under drinking water advisories and have relied on bottled water for cooking and -drinking since June.Significant rainfall would be needed to flush out saltwater in the river -in Plaquemines. According to the National Weather Service’s Lower Mississippi River Forecast -Center, the forecast does not look promising. If enough rainfall doesn’t arrive before mid-to-late - -October, saltwater could make its way to New Orleans.NASA Earth Observatory images by Lauren -Dauphin, using Landsat data from the U.S. Geological Survey and data from the United States -Drought Monitor at the University of Nebraska-Lincoln. Story by Emily Cassidy.View this area -in EO ExplorerIn September, low water levels made it more challenging to ship goods down the -river and allowed a wedge of saltwater to move upstream.Image of the Day for October 1, 2023 - -Image of the Day Water Drought View more Images of the Day:Persistent dry conditions can affect -water resources, ecosystems, and agriculture.Severe drought is reducing the number of daily -passages on the transoceanic shipping route. Image of the Day Water Human Presence Prolonged -drought in Kansas set the stage for what may be one of the state’s smallest wheat harvests -in decades. Image of the Day Land Water Drought The most severe drought in 70 years of record - -keeping threatens the Horn of Africa with famine. Image of the Day Land Water Drought Low -water levels are making it difficult to ship goods down the river and allowing a wedge of -saltwater to move upstream. Image of the Day Land Water Human Presence Remote Sensing January -22 - July 26, 2023JPEGOne of the wettest wet seasons in northern Australia transformed large -areas of the country’s desert landscape over the course of many months in 2023. A string of - -major rainfall events that dropped 690 millimeters (27 inches) between October 2022 and April -2023 made it the sixth-wettest season on record since 1900–1901.This series of false-color -images illustrates the rainfall’s months-long effects downstream in the Lake Eyre Basin. Water -appears in shades of blue, vegetation is green, and bare land is brown. The images were acquired -by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite between - -January and July 2023.In the January 22 image (left), water was coursing through seasonally -dry channels of the Georgina River and Eyre Creek following weeks of heavy rains in northern -Queensland. By April 21 (middle), floodwaters had reached further downstream after another -intense period of precipitation in March. This scene shows that water had filled in some of -the north-northwest trending ridges that are part of a vast fossil landscape of wind-formed - -dunes, while vegetation had emerged in wet soil upstream. Then by July 26 (right), the riverbed -had filled with even more vegetation.The Georgina River and Eyre Creek drain approximately -210,000 square kilometers (81,000 square miles), nearly the area of the United Kingdom. Visible -in the lower part of the images, the lake gets refreshed about every three years; when it -reaches especially high levels, it may take 18 months to 2 years to dry up. Two smaller neighboring - -lakes flood seasonally. These three lakes and surrounding floodplains support hundreds of -thousands of waterbirds and are designated as an Important Bird Area.Seasonal flooding is -a regular occurrence in these desert river systems. However, the events of the 2022-2023 rainy -season stood out in several ways. They occurred while La Niña conditions were in place over -the tropical Pacific Ocean. (The wettest seasons in northern Australia have all occurred during - -La Niña years, according to Australia’s Bureau of Meteorology.) In addition, major rains occurring -in succession, as was the case with the January and March events, have the overall effect -of prolonging floods. That’s because vegetation that grows after the first event slows down -the pulse of water that comes through in the next rain event.The high water has affected both -local communities and ecosystems. Floods have inundated cattle farms and isolated towns on - -temporary islands. At the same time, they are a natural feature of the “boom-and-bust” ecology -of Channel Country, providing habitat and nutrients that support biodiversity.NASA Earth Observatory -image by Wanmei Liang, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview. Story by -Lindsey Doermann.View this area in EO ExplorerRepeated heavy rains in Australia set off waves -of new growth across Channel Country.Image of the Day for August 7, 2023 Image of the Day - -Land Water View more Images of the Day: Floods The waves off the coast of Teahupo’o can heave -a crushing amount of water toward the shore and onto unlucky surfers. Image of the Day Water -Waves of heavy rainfall left towns and farmland under water in October 2022. Image of the -Day Water Floods Acquired February 26, 2011, and February 5, 2011, these false-color images -show the impact of heavy rains in marshy areas southeast of Georgetown, Guyana. Land Floods - -August 25, 2023JPEGSeptember 18, 2023JPEGAugust 25, 2023September 18, 2023August 25, 2023JPEGSeptember -18, 2023JPEGSeptember 18, 2023JPEGHeavy rain from a cyclone in the Mediterranean inundated -cities along the northeastern coast of Libya in early September 2023, causing thousands of -deaths. The port city of Derna (Darnah), home to about 90,000 people, was one of the worst -hit by the storm and suffered extensive flooding and damage. On September 10 and 11, over - -100 millimeters (4 inches) of rain fell on Derna. The city lies at the end of a long, narrow -valley, called a wadi, which is dry except during the rainy season. Floods triggered two dams -along the wadi to collapse. The failure of the second dam, located just one kilometer inland -of Derna, unleashed 3- to 7-meter-high floodwater that tore through the city. According to -news reports, the flash floods destroyed roads and swept entire neighborhoods out to sea. - -The images above show the city before and after the storm. The image on the right, acquired -by the Operational Land Imager-2 (OLI-2) on Landsat 9 on September 18, shows eroded banks -of Wadi Derna near where it meets the Mediterranean. Water just off the coast appears muddier -than in the image on the left, which shows the same area on August 25 and was acquired by -Landsat 8. Preliminary estimates by the United Nations Satellite Center (UNOSAT) indicate - -that 3,100 buildings in Derna were damaged by rushing water. According to the UN International -Organization for Migration (IOM), about 40,000 people in the country were displaced by the -storm, and 30,000 of those were displaced from Derna. Tropical-like cyclones in the Mediterranean, -or “medicanes,” develop only once or twice a year, according to NOAA, and typically form in -autumn. According to meteorologists at Yale Climate Connections, this storm was the deadliest - -in Africa’s recorded history. A recent assessment by scientists at World Weather Attribution -estimated that precipitation received by the region was a one-in-300 to one-in-600-year event. -NASA Earth Observatory images by Lauren Dauphin, using Landsat data from the U.S. Geological -Survey. Story by Emily Cassidy.View this area in EO ExplorerFlash floods in the port city -destroyed roads and swept neighborhoods out to sea.Image of the Day for September 21, 2023 - -Image of the Day Land Water Floods Human Presence View more Images of the Day:The melting -of frozen rivers and snowpack, and the heavy rains of late spring and summer, can send rivers -out of their banks.A Mediterranean cyclone contributed to deadly flooding along the country’s -coastline. Image of the Day Land Water Floods Record rainfall inundated towns and farmland -in the country’s Thessaly region. Image of the Day Water Floods Human Presence A stalled storm - -dropped three feet of rain over four days on the Thessaly region, triggering extensive flooding. -Image of the Day Atmosphere Floods An isolated low-pressure system produced torrential downpours -in Spain and carried Saharan dust along its path. Image of the Day Atmosphere Land Floods -Human Presence July 2002 - June 2022JPEGThe deep-blue sea is turning a touch greener. While -that may not seem as consequential as, say, record warm sea surface temperatures, the color - -of the ocean surface is indicative of the ecosystem that lies beneath. Communities of phytoplankton, -microscopic photosynthesizing organisms, abound in near-surface waters and are foundational -to the aquatic food web and carbon cycle. This shift in the water’s hue confirms a trend expected -under climate change and signals changes to ecosystems within the global ocean, which covers -70 percent of Earth’s surface. Researchers led by B. B. Cael, a principal scientist at the - -U.K.’s National Oceanography Centre, revealed that 56 percent of the global sea surface has -undergone a significant change in color in the past 20 years. After analyzing ocean color -data from the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument on NASA’s Aqua -satellite, they found that much of the change stems from the ocean turning more green. The -map above highlights the areas where ocean surface color changed between 2002 and 2022, with - -darker shades of green representing more-significant differences (higher signal-to-noise ratio). -By extension, said Cael, “these are places we can detect a change in the ocean ecosystem in -the last 20 years.” The study focused on tropical and subtropical regions, excluding higher -latitudes, which are dark for part of the year, and coastal waters, where the data are naturally -very noisy. The black dots on the map indicate the area, covering 12 percent of the ocean’s - -surface, where chlorophyll levels also changed over the study period. Chlorophyll has been -the go-to measurement for remote sensing scientists to gauge phytoplankton abundance and productivity. -However, those estimates use only a few colors in the visible light spectrum. The values shown -in green are based on the whole gamut of colors and therefore capture more information about -the ecosystem as a whole. A long time series from a single sensor is relatively rare in the - -remote sensing world. As the Aqua satellite was celebrating its 20th year in orbit in 2022—far -exceeding its design life of 6 years—Cael wondered what long term trends could be discovered -in the data. In particular, he was curious what might have been missed in all the ocean color -information it had collected. “There’s more encoded in the data than we actually make use -of,” he said. By going big with the data, the team discerned an ocean color trend that had - -been predicted by climate modeling, but one that was expected to take 30-40 years of data -to detect using satellite-based chlorophyll estimates. That’s because the natural variability -in chlorophyll is high relative to the climate change trend. The new method, incorporating -all visible light, was robust enough to confirm the trend in 20 years. At this stage, it is -difficult to say what exact ecological changes are responsible for the new hues. However, - -the authors posit, they could result from different assemblages of plankton, more detrital -particles, or other organisms such as zooplankton. It is unlikely the color changes come from -materials such as plastics or other pollutants, said Cael, since they are not widespread enough -to register at large scales. “What we do know is that in the last 20 years, the ocean has -become more stratified,” he said. Surface waters have absorbed excess heat from the warming - -climate, and as a result, they are less prone to mixing with deeper, more nutrient-rich layers. -This scenario would favor plankton adapted to a nutrient-poor environment. The areas of ocean -color change align well with where the sea has become more stratified, said Cael, but there -is no such overlap with sea surface temperature changes. More insights into Earth’s aquatic -ecosystems may soon be on the way. NASA’s PACE (Plankton, Aerosol, Cloud, ocean Ecosystem) - -satellite, set to launch in 2024, will return observations in finer color resolution. The -new data will enable researchers to infer more information about ocean ecology, such as the -diversity of phytoplankton species and the rates of phytoplankton growth. NASA Earth Observatory -image by Wanmei Liang, using data from Cael, B. B., et al. (2023). Story by Lindsey Doermann.Two -decades of satellite measurements show that the sea surface is shading toward green.Image - -of the Day for October 2, 2023 Image of the Day Life Water View more Images of the Day:Datasets -from the Sentinel-6 Michael Freilich satellite will build upon three decades of sea level -measurements. Image of the Day Heat Water Remote Sensing Image of the Day Life Water Image -of the Day Water The use of plastic on farms has become so common in recent decades that there -there’s a term for it—plasticulture. Image of the Day Human Presence August 16, 2023JPEGThe - -Canary Islands were at the center of a mélange of natural events in summer 2023. The Moderate -Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this assemblage -of phenomena off the coast of Africa on August 16, 2023.In the center of the scene, smoke -is seen rising from a wildfire burning on Tenerife in the Canary Islands. The blaze started -amid hot and dry conditions on August 15 in forests surrounding the Teide Volcano. Authorities - -issued evacuation orders to five villages, and responders focused on containing the fire’s -spread and protecting residential areas near the coast, according to news reports. Other fires -have burned on the Canary Islands this summer, including on La Palma in July.To the west, -a swirling cloud moves across the Atlantic. Cloud vortices appear routinely downwind of the -Canary Islands—sometimes in great abundance—and are produced when the tall volcanic peaks - -disrupt the air flowing past them.Elsewhere in the atmosphere, dust from the Sahara Desert -was lofted out over the ocean. The river of dust crossing the Atlantic was more pronounced -in previous days, when it reached islands in the Caribbean. Traveling on the Saharan Air Layer, -dust sometimes makes it even further west toward Central America and the U.S. states of Florida -and Texas.To round out the list, the patch of bright blue off the Moroccan coast is most likely - -a bloom of phytoplankton. While the exact cause and composition of the bloom cannot be determined -from this image, mineral-rich desert dust has been shown to set off bursts of phytoplankton -growth.In addition to the Earth’s processes seen here, one remote sensing artifact is present. -A diagonal streak of sunglint makes part of this scene appear washed out. Sunglint, an effect -that occurs when sunlight reflects off the surface of the water at the same angle that a satellite - -sensor views it, is also the reason for the light-colored streaks trailing off the islands.NASA -Earth Observatory image by Wanmei Liang, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview. -Story by Lindsey Doermann.View this area in EO ExplorerAn assortment of natural phenomena -visible from space appeared together in one image.Image of the Day for August 17, 2023 Image -of the Day Atmosphere Land Water View more Images of the Day:Flights were grounded as visibility - -was severely hampered by a Calima event. Image of the Day Atmosphere Land Dust and Haze Human -Presence In one frame International Space Station astronauts were able to capture the evolution -of fringing reefs to atolls. As with the Hawaiian Islands, these volcanic hot spot islands -become progressively older to the northwest. As these islands move away from their magma sources -they erode and subside. Image of the Day Land Water The dry, volcanic terrain of this Canary - -Island is suitable for lichen and crops … and for training astronauts. Image of the Day Land -The event, known locally as “la calima,” turned skies orange and degraded air quality in Gran -Canaria and neighboring islands. Image of the Day Atmosphere Land Dust and Haze July 17, 2023JPEGFour -funnel-shaped estuarine inlets, collectively known as Rías Baixas, line the coast of Galicia, -in northwest Spain. The nutrient-rich water in these inlets supports a wealth of marine life, - -making the Galicia coast one of the most productive places for aquaculture.On July 17, 2023, -the Operational Land Imager-2 (OLI-2) on Landsat 9, acquired this image of the Rías de Arousa -(Arousa estuary), the largest and northernmost of the inlets. Small dots skirt the coasts -of the embayment. In most cases, these dots are rectangular rafts designed for raising bivalves -like mussels. Buoys keep the lattice mussel rafts afloat on the surface of the water, and - -hundreds of ropes are suspended into the water column from each structure. Mussels attach -to the ropes and filter feed on phytoplankton and other suspended organic particles. The rafts -allow for high yields of mussels in a small area of the water. The Rías Baixas are on the -northern end of the Canary current and are in a major upwelling zone. Upwelling, which brings -colder, nutrient-rich water up from the bottom of the ocean, typically occurs in this area - -between April and October. Much of the mussel production in the Rías Baixas occurs during -this time, as the mollusks filter feed on nutrients and plentiful phytoplankton supported -by upwelling. Spain is the top mussel producing country in the world. Rías de Arousa alone -contains over 2,400 mussel rafts, producing about 40 percent of Europe’s mussels. NASA Earth -Observatory image by Wanmei Liang, using Landsat data from the U.S. Geological Survey. Story - -by Emily Cassidy. Buoys keep the lattice mussel rafts afloat on the surface of the water, -and hundreds of ropes are suspended into the water column from each structure. Mussels attach -to the ropes and filter feed on phytoplankton and other suspended organic particles. The rafts -allow for high yields of mussels in a small area of the water. The Rías Baixas are on the -northern end of the Canary current and are in a major upwelling zone. Upwelling, which brings - -colder, nutrient-rich water up from the bottom of the ocean, typically occurs in this area -between April and October. Much of the mussel production in the Rías Baixas occurs during -this time, as the mollusks filter feed on nutrients and plentiful phytoplankton supported -by upwelling. Spain is the top mussel producing country in the world. Rías de Arousa alone -contains over 2,400 mussel rafts, producing about 40 percent of Europe’s mussels. NASA Earth - -Observatory image by Wanmei Liang, using Landsat data from the U.S. Geological Survey. Story -by Emily Cassidy.View this area in EO ExplorerThe estuarine inlets of Spain’s Galicia coast -are some of the most productive places to grow mussels.Image of the Day for September 19, -2023 Image of the Day Water Human Presence View more Images of the Day: Dust and Haze This -image shows Tropical Cyclones Eric and Fanele near Madagascar on January 19, 2009. Atmosphere - -Water Severe Storms This natural-color image shows Saharan dust forming an S-shaped curve -off the western coast of Africa, and passing directly over Cape Verde. Atmosphere Land Dust -and Haze Acquired March 8, 2010, this true-color image shows two icebergs, Iceberg B-09B and -an iceberg recently broken off the Mertz Glacier, floating in the Southern Ocean, just off -the George V Coast. Water Snow and Ice Sea and Lake Ice May 18, 2023JPEGSeptember 7, 2023JPEGMay - -18, 2023September 7, 2023May 18, 2023JPEGSeptember 7, 2023JPEGSeptember 7, 2023JPEGAfter going -dry in 2018, Laguna de Aculeo has begun to refill. NASA satellites began to detect water pooling -in the parched lake in late-August, after an intense winter storm dropped as much as 370 millimeters -(15 inches) of rain on some parts of central Chile. The storm was fueled by an atmospheric -river and exacerbated by the rugged terrain in central Chile.When the Operational Land Imager-2 - -(OLI-2) on Landsat 9 acquired this image (right) on September 7, 2023, Laguna de Aculeo covered -about 5 square kilometers (2 square miles) to a depth of roughly 1 meter (3 feet). The other -image (left) shows the dried water body on May 18, 2023, before the wet winter weather arrived. -Although it has refilled somewhat, water spans only half the area it did up to 2010 and contains -a quarter of the water volume, explained René Garreaud, an Earth scientist at the University - -of Chile. Seasonal changes and the influx of water have led to widespread greening of the -landscape around the lake.Researchers have assessed that ongoing development and water use -in the nearby community of Paine, increasing water use by farmers and in homes and pools, -as well as several years of drought, likely contributed to the drawdown of the lake. Annual -rainfall deficits that averaged 38 percent between 2010 and 2018 likely played a large role, - -according to one analysis from a team of researchers from the University of Chile.Before 2010, -the shallow water body was a popular haven for boaters, swimmers, and water skiers, but the -water hasn’t yet pooled up enough for swimmers or boaters to return. It is also unclear how -long the new water in Aculeo will persist. “Atmospheric rivers in June and August delivered -substantial precipitation along the high terrain and foothills that have giv­­en us a welcome - -interruption to the drought,” Garreaud said. “But Aculeo is a small, shallow lagoon that can -fill up rapidly, and it's only partly filled. Bigger reservoirs and aquifers will take much -longer to recover.”NASA Earth Observatory images by Lauren Dauphin, using Landsat data from -the U.S. Geological Survey. Story by Adam Voiland.View this area in EO ExplorerThe drought -in Chile isn’t over, but recent late-winter rains provided enough moisture for water to start - -pooling up again.Image of the Day for September 16, 2023 Image of the Day Life Water View -more Images of the Day:Data from winter 2022-2023 show the greatest net gain of water in nearly -22 years, but groundwater levels still suffer from years of drought. Image of the Day Land -Water As a persistent drought drags on, water levels are dropping at a key reservoir that -supplies Santiago. Image of the Day Land Water A new web tool designed by NASA applied scientists - -could help the tribe anticipate and respond to drought. Image of the Day Water Human Presence -Remote Sensing For more than 100 years, groups in the western United States have fought over -water. During the 1880s, sheep ranchers and cattle ranchers argued over drinking water for -their livestock on the high plains. In 1913, the city of Los Angeles began to draw water away -from small agricultural communities in Owen Valley, leaving a dusty dry lake bed. In the late - -1950s, construction of the Glen Canyon Dam catalyzed the American environmental movement. -Today, farmers are fighting fishermen, environmentalists, and Native American tribes over -the water in the Upper Klamath River Basin. The Landsat 7 satellite, launched by NASA and -operated by the U.S. Geological Survey, documented an extreme drought in the area along the -California/Oregon border in the spring of 2001. Image of the Day Land Life September 16, 2023JPEGSeptember - -10, 2021JPEGSeptember 16, 2023September 10, 2021September 16, 2023JPEGSeptember 10, 2021JPEGSeptember -10, 2021JPEGMonths of excessive heat and drought parched the Mississippi River in the summer -and early fall of 2023. In September, low water levels limited barge shipments downriver and -threatened drinking water supplies in some Louisiana communities, according to the Associated -Press.Water levels were especially low near Memphis, Tennessee. The images above show the - -Mississippi River near Memphis on September 16, 2023 (left), compared to September 10, 2021 -(right). The river was significantly slimmed down in 2023, exposing some of the river bottom.This -is the second year in a row drought has caused the river to fall to near-record lows at many -gauges. On September 26, 2023, the river level at a gauge in Memphis was -10.26 feet, close -to the record low level, -10.81 feet, measured at the same place on October 21, 2022. That - -was the lowest level recorded there since the start of National Weather Service records in -1954. Water levels, or “gauge heights,” do not indicate the depth of a stream; rather, they -are measured with respect to a chosen reference point. That is why some gauge height measurements -are negative.Farther upstream, water levels at New Madrid, Missouri, have been around -5 feet—near -the minimum operating level—since early September 2023. Water levels on the Mississippi normally - -decline in the fall and winter, and in 2022, the river did not get that low until mid-October. -September 26, 2023JPEGA hot, dry summer is the main reason water levels dropped so low in -2023. Across the globe, temperatures in summer 2023 were 1.2°C (2.1°F) warmer than average. -In the U.S., Louisiana and Mississippi experienced their hottest Augusts on record, according -to NOAA.The U.S. Drought Monitor map above—the product of a partnership between the U.S. Department - -of Agriculture, the National Oceanic and Atmospheric Administration, and the University of -Nebraska-Lincoln—shows conditions during the week of September 20-26, 2023. The map depicts -drought intensity in progressive shades of orange to red. It is based on an analysis of climate, -soil, and water condition measurements from more than 350 federal, state, and local observers -around the country. NASA contributes measurements and models that aid the drought monitoring - -effort.During that week, about 38 percent of the contiguous U.S. was experiencing drought. -Lack of precipitation and high temperatures over several months severely dried out soils in -states along the Mississippi River Valley. The Drought Monitor reported that 80 percent of -soils in Louisiana were dry (short or very short on water) as of September 24. And for most -states in the river valley, over 50 percent of topsoil was dry or very dry.Shallow conditions - -along the river interrupted normal shipments of goods. According to the Associated Press, -barge companies reduced the weight carried in many shipments in September because the river -was not deep enough to accommodate their normal weight. Much of U.S. grain exports are transported -down the Mississippi, and according to AP, the cost of these shipments from St. Louis southward -has risen 77 percent above the three-year average. The lack of freshwater flowing into the - -Gulf of Mexico has also allowed saltwater to make its way up the river and into some water -treatment plants in southern Louisiana, according to the Associated Press. Some parts of Plaquemines -Parish are under drinking water advisories and have relied on bottled water for cooking and -drinking since June.Significant rainfall would be needed to flush out saltwater in the river -in Plaquemines. According to the National Weather Service’s Lower Mississippi River Forecast - -Center, the forecast does not look promising. If enough rainfall doesn’t arrive before mid-to-late -October, saltwater could make its way to New Orleans.NASA Earth Observatory images by Lauren -Dauphin, using Landsat data from the U.S. Geological Survey and data from the United States -Drought Monitor at the University of Nebraska-Lincoln. Story by Emily Cassidy.View this area -in EO ExplorerIn September, low water levels made it more challenging to ship goods down the - -river and allowed a wedge of saltwater to move upstream.Image of the Day for October 1, 2023 -Image of the Day Water Drought View more Images of the Day:Persistent dry conditions can affect -water resources, ecosystems, and agriculture.Severe drought is reducing the number of daily -passages on the transoceanic shipping route. Image of the Day Water Human Presence Prolonged -drought in Kansas set the stage for what may be one of the state’s smallest wheat harvests - -in decades. Image of the Day Land Water Drought The most severe drought in 70 years of record -keeping threatens the Horn of Africa with famine. Image of the Day Land Water Drought Low -water levels are making it difficult to ship goods down the river and allowing a wedge of -saltwater to move upstream. Image of the Day Land Water Human Presence Remote Sensing September -25, 2023JPEGLake Winnipeg, the world’s 10th largest freshwater lake by surface area, has experienced - -algae blooms at a regular occurrence at least since the 1990s. A bloom of blue-green algae -once again covered parts of the lake in September 2023. Located in Manitoba, Canada, the long -lake has a watershed that spans one million square kilometers (386,000 square miles), draining -some of Canada’s agricultural land. The lake consists of a large, deep north basin and a smaller, -comparatively shallow south basin. Swirls of algae filled the south basin of the lake on September - -25, 2023, when the OLI-2 (Operational Land Imager-2) on Landsat 9 acquired this image. Around -this time, satellite observations analyzed by Environment and Climate Change Canada indicated -that algae covered about 8,400 square kilometers (3,200 square miles), or about a third of -the lake’s area.Blue-green algae, also known as cyanobacteria, are single-celled organisms -that rely on photosynthesis to turn sunlight into food. The bacteria grow swiftly when nutrients - -like phosphorus and nitrogen are abundant in still water. The bloom pictured here may contain -blue-green algae, as well as other types of phytoplankton; only a surface sample can confirm -the exact composition of a bloom. Some cyanobacteria produce microcystin—a potent toxin that -can irritate the skin and cause liver and kidney damage.While algae are part of a natural -freshwater ecosystem, excess algae, particularly cyanobacteria, can be a nuisance to residents - -and tourists using the lake and its beaches for fishing, swimming, and recreation. Beaches -in the south basin of Lake Winnipeg can get as many as 30,000 visitors a day during the summer -months. Water samples taken at Winnipeg Beach on the west shore found that cyanobacteria levels -were elevated in August, and visitors were advised to avoid swimming and fishing if green -scum was visible. The health of Lake Winnipeg has been in decline in recent decades. Between - -1990 and 2000, phosphorous concentrations in the lake almost doubled and algae blooms proliferated, -both in terms of occurrence and extent. The major contributors to the influx of phosphorous -to the lake were increased agricultural activities in the watershed and a higher frequency -of flooding, which has increased runoff into the lake.Phosphorus concentrations are almost -three times higher in the south basin of Lake Winnipeg, compared to the north basin. A 2019 - -study using data from the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument -on NASA’s Terra satellite found that the chlorophyll-a concentrations, which are used as a -measure of phytoplankton biomass, were on average more than twice as high in the south basin, -compared to the north. NASA Earth Observatory images by Wanmei Liang, using Landsat data from -the U.S. Geological Survey. Story by Emily Cassidy.View this area in EO ExplorerAn influx - -of nutrients in recent decades has contributed to the proliferation of algae in the large -Canadian lake.Image of the Day for October 6, 2023 Image of the Day Water Water Color View -more Images of the Day:Floating, plant-like organisms reproduce abundantly when there are -sufficient nutrients, sunlight, and water conditions. Extreme blooms of certain species can -become harmful to marine animals and humans.Cyanobacteria covered over half of the surface - -of Florida’s largest freshwater lake in mid-June 2023. Image of the Day Life Water Water Color -Nearly half of the lake was covered with blue-green algae in early July 2022. Image of the -Day Water Remote Sensing Water Color More than 40 years after the explosive eruption of Mount -St. Helens, relics from the blast continue to haunt a nearby lake. Image of the Day Water -Venezuela’s Lake Maracaibo is choking with oil slicks and algae. Image of the Day Life Water - -Human Presence Remote Sensing January 22 - July 26, 2023JPEGOne of the wettest wet seasons -in northern Australia transformed large areas of the country’s desert landscape over the course -of many months in 2023. A string of major rainfall events that dropped 690 millimeters (27 -inches) between October 2022 and April 2023 made it the sixth-wettest season on record since -1900–1901.This series of false-color images illustrates the rainfall’s months-long effects - -downstream in the Lake Eyre Basin. Water appears in shades of blue, vegetation is green, and -bare land is brown. The images were acquired by the Moderate Resolution Imaging Spectroradiometer -(MODIS) on NASA’s Terra satellite between January and July 2023.In the January 22 image (left), -water was coursing through seasonally dry channels of the Georgina River and Eyre Creek following -weeks of heavy rains in northern Queensland. By April 21 (middle), floodwaters had reached - -further downstream after another intense period of precipitation in March. This scene shows -that water had filled in some of the north-northwest trending ridges that are part of a vast -fossil landscape of wind-formed dunes, while vegetation had emerged in wet soil upstream. -Then by July 26 (right), the riverbed had filled with even more vegetation.The Georgina River -and Eyre Creek drain approximately 210,000 square kilometers (81,000 square miles), nearly - -the area of the United Kingdom. Visible in the lower part of the images, the lake gets refreshed -about every three years; when it reaches especially high levels, it may take 18 months to -2 years to dry up. Two smaller neighboring lakes flood seasonally. These three lakes and surrounding -floodplains support hundreds of thousands of waterbirds and are designated as an Important -Bird Area.Seasonal flooding is a regular occurrence in these desert river systems. However, - -the events of the 2022-2023 rainy season stood out in several ways. They occurred while La -Niña conditions were in place over the tropical Pacific Ocean. (The wettest seasons in northern -Australia have all occurred during La Niña years, according to Australia’s Bureau of Meteorology.) -In addition, major rains occurring in succession, as was the case with the January and March -events, have the overall effect of prolonging floods. That’s because vegetation that grows - -after the first event slows down the pulse of water that comes through in the next rain event.The -high water has affected both local communities and ecosystems. Floods have inundated cattle -farms and isolated towns on temporary islands. At the same time, they are a natural feature -of the “boom-and-bust” ecology of Channel Country, providing habitat and nutrients that support -biodiversity.NASA Earth Observatory image by Wanmei Liang, using MODIS data from NASA EOSDIS - -LANCE and GIBS/Worldview. Story by Lindsey Doermann.View this area in EO ExplorerRepeated -heavy rains in Australia set off waves of new growth across Channel Country.Image of the Day -for August 7, 2023 Image of the Day Land Water View more Images of the Day: Floods The waves -off the coast of Teahupo’o can heave a crushing amount of water toward the shore and onto -unlucky surfers. Image of the Day Water Waves of heavy rainfall left towns and farmland under - -water in October 2022. Image of the Day Water Floods Acquired February 26, 2011, and February -5, 2011, these false-color images show the impact of heavy rains in marshy areas southeast -of Georgetown, Guyana. Land Floods August 25, 2023JPEGSeptember 18, 2023JPEGAugust 25, 2023September -18, 2023August 25, 2023JPEGSeptember 18, 2023JPEGSeptember 18, 2023JPEGHeavy rain from a cyclone -in the Mediterranean inundated cities along the northeastern coast of Libya in early September - -2023, causing thousands of deaths. The port city of Derna (Darnah), home to about 90,000 people, -was one of the worst hit by the storm and suffered extensive flooding and damage. On September -10 and 11, over 100 millimeters (4 inches) of rain fell on Derna. The city lies at the end -of a long, narrow valley, called a wadi, which is dry except during the rainy season. Floods -triggered two dams along the wadi to collapse. The failure of the second dam, located just - -one kilometer inland of Derna, unleashed 3- to 7-meter-high floodwater that tore through the -city. According to news reports, the flash floods destroyed roads and swept entire neighborhoods -out to sea. The images above show the city before and after the storm. The image on the right, -acquired by the Operational Land Imager-2 (OLI-2) on Landsat 9 on September 18, shows eroded -banks of Wadi Derna near where it meets the Mediterranean. Water just off the coast appears - -muddier than in the image on the left, which shows the same area on August 25 and was acquired -by Landsat 8. Preliminary estimates by the United Nations Satellite Center (UNOSAT) indicate -that 3,100 buildings in Derna were damaged by rushing water. According to the UN International -Organization for Migration (IOM), about 40,000 people in the country were displaced by the -storm, and 30,000 of those were displaced from Derna. Tropical-like cyclones in the Mediterranean, - -or “medicanes,” develop only once or twice a year, according to NOAA, and typically form in -autumn. According to meteorologists at Yale Climate Connections, this storm was the deadliest -in Africa’s recorded history. A recent assessment by scientists at World Weather Attribution -estimated that precipitation received by the region was a one-in-300 to one-in-600-year event. -NASA Earth Observatory images by Lauren Dauphin, using Landsat data from the U.S. Geological - -Survey. Story by Emily Cassidy.View this area in EO ExplorerFlash floods in the port city -destroyed roads and swept neighborhoods out to sea.Image of the Day for September 21, 2023 -Image of the Day Land Water Floods Human Presence View more Images of the Day:The melting -of frozen rivers and snowpack, and the heavy rains of late spring and summer, can send rivers -out of their banks.A Mediterranean cyclone contributed to deadly flooding along the country’s - -coastline. Image of the Day Land Water Floods Record rainfall inundated towns and farmland -in the country’s Thessaly region. Image of the Day Water Floods Human Presence A stalled storm -dropped three feet of rain over four days on the Thessaly region, triggering extensive flooding. -Image of the Day Atmosphere Floods An isolated low-pressure system produced torrential downpours -in Spain and carried Saharan dust along its path. Image of the Day Atmosphere Land Floods - -Human Presence July 2002 - June 2022JPEGThe deep-blue sea is turning a touch greener. While -that may not seem as consequential as, say, record warm sea surface temperatures, the color -of the ocean surface is indicative of the ecosystem that lies beneath. Communities of phytoplankton, -microscopic photosynthesizing organisms, abound in near-surface waters and are foundational -to the aquatic food web and carbon cycle. This shift in the water’s hue confirms a trend expected - -under climate change and signals changes to ecosystems within the global ocean, which covers -70 percent of Earth’s surface. Researchers led by B. B. Cael, a principal scientist at the -U.K.’s National Oceanography Centre, revealed that 56 percent of the global sea surface has -undergone a significant change in color in the past 20 years. After analyzing ocean color -data from the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument on NASA’s Aqua - -satellite, they found that much of the change stems from the ocean turning more green. The -map above highlights the areas where ocean surface color changed between 2002 and 2022, with -darker shades of green representing more-significant differences (higher signal-to-noise ratio). -By extension, said Cael, “these are places we can detect a change in the ocean ecosystem in -the last 20 years.” The study focused on tropical and subtropical regions, excluding higher - -latitudes, which are dark for part of the year, and coastal waters, where the data are naturally -very noisy. The black dots on the map indicate the area, covering 12 percent of the ocean’s -surface, where chlorophyll levels also changed over the study period. Chlorophyll has been -the go-to measurement for remote sensing scientists to gauge phytoplankton abundance and productivity. -However, those estimates use only a few colors in the visible light spectrum. The values shown - -in green are based on the whole gamut of colors and therefore capture more information about -the ecosystem as a whole. A long time series from a single sensor is relatively rare in the -remote sensing world. As the Aqua satellite was celebrating its 20th year in orbit in 2022—far -exceeding its design life of 6 years—Cael wondered what long term trends could be discovered -in the data. In particular, he was curious what might have been missed in all the ocean color - -information it had collected. “There’s more encoded in the data than we actually make use -of,” he said. By going big with the data, the team discerned an ocean color trend that had -been predicted by climate modeling, but one that was expected to take 30-40 years of data -to detect using satellite-based chlorophyll estimates. That’s because the natural variability -in chlorophyll is high relative to the climate change trend. The new method, incorporating - -all visible light, was robust enough to confirm the trend in 20 years. At this stage, it is -difficult to say what exact ecological changes are responsible for the new hues. However, -the authors posit, they could result from different assemblages of plankton, more detrital -particles, or other organisms such as zooplankton. It is unlikely the color changes come from -materials such as plastics or other pollutants, said Cael, since they are not widespread enough - -to register at large scales. “What we do know is that in the last 20 years, the ocean has -become more stratified,” he said. Surface waters have absorbed excess heat from the warming -climate, and as a result, they are less prone to mixing with deeper, more nutrient-rich layers. -This scenario would favor plankton adapted to a nutrient-poor environment. The areas of ocean -color change align well with where the sea has become more stratified, said Cael, but there - -is no such overlap with sea surface temperature changes. More insights into Earth’s aquatic -ecosystems may soon be on the way. NASA’s PACE (Plankton, Aerosol, Cloud, ocean Ecosystem) -satellite, set to launch in 2024, will return observations in finer color resolution. The -new data will enable researchers to infer more information about ocean ecology, such as the -diversity of phytoplankton species and the rates of phytoplankton growth. NASA Earth Observatory - -image by Wanmei Liang, using data from Cael, B. B., et al. (2023). Story by Lindsey Doermann.Two -decades of satellite measurements show that the sea surface is shading toward green.Image -of the Day for October 2, 2023 Image of the Day Life Water View more Images of the Day:Datasets -from the Sentinel-6 Michael Freilich satellite will build upon three decades of sea level -measurements. Image of the Day Heat Water Remote Sensing Image of the Day Life Water Image - -of the Day Water The use of plastic on farms has become so common in recent decades that there -there’s a term for it—plasticulture. Image of the Day Human Presence August 16, 2023JPEGThe -Canary Islands were at the center of a mélange of natural events in summer 2023. The Moderate -Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this assemblage -of phenomena off the coast of Africa on August 16, 2023.In the center of the scene, smoke - -is seen rising from a wildfire burning on Tenerife in the Canary Islands. The blaze started -amid hot and dry conditions on August 15 in forests surrounding the Teide Volcano. Authorities -issued evacuation orders to five villages, and responders focused on containing the fire’s -spread and protecting residential areas near the coast, according to news reports. Other fires -have burned on the Canary Islands this summer, including on La Palma in July.To the west, - -a swirling cloud moves across the Atlantic. Cloud vortices appear routinely downwind of the -Canary Islands—sometimes in great abundance—and are produced when the tall volcanic peaks -disrupt the air flowing past them.Elsewhere in the atmosphere, dust from the Sahara Desert -was lofted out over the ocean. The river of dust crossing the Atlantic was more pronounced -in previous days, when it reached islands in the Caribbean. Traveling on the Saharan Air Layer, - -dust sometimes makes it even further west toward Central America and the U.S. states of Florida -and Texas.To round out the list, the patch of bright blue off the Moroccan coast is most likely -a bloom of phytoplankton. While the exact cause and composition of the bloom cannot be determined -from this image, mineral-rich desert dust has been shown to set off bursts of phytoplankton -growth.In addition to the Earth’s processes seen here, one remote sensing artifact is present. - -A diagonal streak of sunglint makes part of this scene appear washed out. Sunglint, an effect -that occurs when sunlight reflects off the surface of the water at the same angle that a satellite -sensor views it, is also the reason for the light-colored streaks trailing off the islands.NASA -Earth Observatory image by Wanmei Liang, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview. -Story by Lindsey Doermann.View this area in EO ExplorerAn assortment of natural phenomena - -visible from space appeared together in one image.Image of the Day for August 17, 2023 Image -of the Day Atmosphere Land Water View more Images of the Day:Flights were grounded as visibility -was severely hampered by a Calima event. Image of the Day Atmosphere Land Dust and Haze Human -Presence In one frame International Space Station astronauts were able to capture the evolution -of fringing reefs to atolls. As with the Hawaiian Islands, these volcanic hot spot islands - -become progressively older to the northwest. As these islands move away from their magma sources -they erode and subside. Image of the Day Land Water The dry, volcanic terrain of this Canary -Island is suitable for lichen and crops … and for training astronauts. Image of the Day Land -The event, known locally as “la calima,” turned skies orange and degraded air quality in Gran -Canaria and neighboring islands. Image of the Day Atmosphere Land Dust and Haze July 17, 2023JPEGFour - -funnel-shaped estuarine inlets, collectively known as Rías Baixas, line the coast of Galicia, -in northwest Spain. The nutrient-rich water in these inlets supports a wealth of marine life, -making the Galicia coast one of the most productive places for aquaculture.On July 17, 2023, -the Operational Land Imager-2 (OLI-2) on Landsat 9, acquired this image of the Rías de Arousa -(Arousa estuary), the largest and northernmost of the inlets. Small dots skirt the coasts - -of the embayment. In most cases, these dots are rectangular rafts designed for raising bivalves -like mussels. Buoys keep the lattice mussel rafts afloat on the surface of the water, and -hundreds of ropes are suspended into the water column from each structure. Mussels attach -to the ropes and filter feed on phytoplankton and other suspended organic particles. The rafts -allow for high yields of mussels in a small area of the water. The Rías Baixas are on the - -northern end of the Canary current and are in a major upwelling zone. Upwelling, which brings -colder, nutrient-rich water up from the bottom of the ocean, typically occurs in this area -between April and October. Much of the mussel production in the Rías Baixas occurs during -this time, as the mollusks filter feed on nutrients and plentiful phytoplankton supported -by upwelling. Spain is the top mussel producing country in the world. Rías de Arousa alone - -contains over 2,400 mussel rafts, producing about 40 percent of Europe’s mussels. NASA Earth -Observatory image by Wanmei Liang, using Landsat data from the U.S. Geological Survey. Story -by Emily Cassidy. Buoys keep the lattice mussel rafts afloat on the surface of the water, -and hundreds of ropes are suspended into the water column from each structure. Mussels attach -to the ropes and filter feed on phytoplankton and other suspended organic particles. The rafts - -allow for high yields of mussels in a small area of the water. The Rías Baixas are on the -northern end of the Canary current and are in a major upwelling zone. Upwelling, which brings -colder, nutrient-rich water up from the bottom of the ocean, typically occurs in this area -between April and October. Much of the mussel production in the Rías Baixas occurs during -this time, as the mollusks filter feed on nutrients and plentiful phytoplankton supported - -by upwelling. Spain is the top mussel producing country in the world. Rías de Arousa alone -contains over 2,400 mussel rafts, producing about 40 percent of Europe’s mussels. NASA Earth -Observatory image by Wanmei Liang, using Landsat data from the U.S. Geological Survey. Story -by Emily Cassidy.View this area in EO ExplorerThe estuarine inlets of Spain’s Galicia coast -are some of the most productive places to grow mussels.Image of the Day for September 19, - -2023 Image of the Day Water Human Presence View more Images of the Day: Dust and Haze This -image shows Tropical Cyclones Eric and Fanele near Madagascar on January 19, 2009. Atmosphere -Water Severe Storms This natural-color image shows Saharan dust forming an S-shaped curve -off the western coast of Africa, and passing directly over Cape Verde. Atmosphere Land Dust -and Haze Acquired March 8, 2010, this true-color image shows two icebergs, Iceberg B-09B and - -an iceberg recently broken off the Mertz Glacier, floating in the Southern Ocean, just off -the George V Coast. Water Snow and Ice Sea and Lake Ice May 18, 2023JPEGSeptember 7, 2023JPEGMay -18, 2023September 7, 2023May 18, 2023JPEGSeptember 7, 2023JPEGSeptember 7, 2023JPEGAfter going -dry in 2018, Laguna de Aculeo has begun to refill. NASA satellites began to detect water pooling -in the parched lake in late-August, after an intense winter storm dropped as much as 370 millimeters - -(15 inches) of rain on some parts of central Chile. The storm was fueled by an atmospheric -river and exacerbated by the rugged terrain in central Chile.When the Operational Land Imager-2 -(OLI-2) on Landsat 9 acquired this image (right) on September 7, 2023, Laguna de Aculeo covered -about 5 square kilometers (2 square miles) to a depth of roughly 1 meter (3 feet). The other -image (left) shows the dried water body on May 18, 2023, before the wet winter weather arrived. - -Although it has refilled somewhat, water spans only half the area it did up to 2010 and contains -a quarter of the water volume, explained René Garreaud, an Earth scientist at the University -of Chile. Seasonal changes and the influx of water have led to widespread greening of the -landscape around the lake.Researchers have assessed that ongoing development and water use -in the nearby community of Paine, increasing water use by farmers and in homes and pools, - -as well as several years of drought, likely contributed to the drawdown of the lake. Annual -rainfall deficits that averaged 38 percent between 2010 and 2018 likely played a large role, -according to one analysis from a team of researchers from the University of Chile.Before 2010, -the shallow water body was a popular haven for boaters, swimmers, and water skiers, but the -water hasn’t yet pooled up enough for swimmers or boaters to return. It is also unclear how - -long the new water in Aculeo will persist. “Atmospheric rivers in June and August delivered -substantial precipitation along the high terrain and foothills that have giv­­en us a welcome -interruption to the drought,” Garreaud said. “But Aculeo is a small, shallow lagoon that can -fill up rapidly, and it's only partly filled. Bigger reservoirs and aquifers will take much -longer to recover.”NASA Earth Observatory images by Lauren Dauphin, using Landsat data from - -the U.S. Geological Survey. Story by Adam Voiland.View this area in EO ExplorerThe drought -in Chile isn’t over, but recent late-winter rains provided enough moisture for water to start -pooling up again.Image of the Day for September 16, 2023 Image of the Day Life Water View -more Images of the Day:Data from winter 2022-2023 show the greatest net gain of water in nearly -22 years, but groundwater levels still suffer from years of drought. Image of the Day Land - -Water As a persistent drought drags on, water levels are dropping at a key reservoir that -supplies Santiago. Image of the Day Land Water A new web tool designed by NASA applied scientists -could help the tribe anticipate and respond to drought. Image of the Day Water Human Presence -Remote Sensing For more than 100 years, groups in the western United States have fought over -water. During the 1880s, sheep ranchers and cattle ranchers argued over drinking water for - -their livestock on the high plains. In 1913, the city of Los Angeles began to draw water away -from small agricultural communities in Owen Valley, leaving a dusty dry lake bed. In the late -1950s, construction of the Glen Canyon Dam catalyzed the American environmental movement. -Today, farmers are fighting fishermen, environmentalists, and Native American tribes over -the water in the Upper Klamath River Basin. The Landsat 7 satellite, launched by NASA and - -operated by the U.S. Geological Survey, documented an extreme drought in the area along the -California/Oregon border in the spring of 2001. Image of the Day Land Life September 16, 2023JPEGSeptember -10, 2021JPEGSeptember 16, 2023September 10, 2021September 16, 2023JPEGSeptember 10, 2021JPEGSeptember -10, 2021JPEGMonths of excessive heat and drought parched the Mississippi River in the summer -and early fall of 2023. In September, low water levels limited barge shipments downriver and - -threatened drinking water supplies in some Louisiana communities, according to the Associated -Press.Water levels were especially low near Memphis, Tennessee. The images above show the -Mississippi River near Memphis on September 16, 2023 (left), compared to September 10, 2021 -(right). The river was significantly slimmed down in 2023, exposing some of the river bottom.This -is the second year in a row drought has caused the river to fall to near-record lows at many - -gauges. On September 26, 2023, the river level at a gauge in Memphis was -10.26 feet, close -to the record low level, -10.81 feet, measured at the same place on October 21, 2022. That -was the lowest level recorded there since the start of National Weather Service records in -1954. Water levels, or “gauge heights,” do not indicate the depth of a stream; rather, they -are measured with respect to a chosen reference point. That is why some gauge height measurements - -are negative.Farther upstream, water levels at New Madrid, Missouri, have been around -5 feet—near -the minimum operating level—since early September 2023. Water levels on the Mississippi normally -decline in the fall and winter, and in 2022, the river did not get that low until mid-October. -September 26, 2023JPEGA hot, dry summer is the main reason water levels dropped so low in -2023. Across the globe, temperatures in summer 2023 were 1.2°C (2.1°F) warmer than average. - -In the U.S., Louisiana and Mississippi experienced their hottest Augusts on record, according -to NOAA.The U.S. Drought Monitor map above—the product of a partnership between the U.S. Department -of Agriculture, the National Oceanic and Atmospheric Administration, and the University of -Nebraska-Lincoln—shows conditions during the week of September 20-26, 2023. The map depicts -drought intensity in progressive shades of orange to red. It is based on an analysis of climate, - -soil, and water condition measurements from more than 350 federal, state, and local observers -around the country. NASA contributes measurements and models that aid the drought monitoring -effort.During that week, about 38 percent of the contiguous U.S. was experiencing drought. -Lack of precipitation and high temperatures over several months severely dried out soils in -states along the Mississippi River Valley. The Drought Monitor reported that 80 percent of - -soils in Louisiana were dry (short or very short on water) as of September 24. And for most -states in the river valley, over 50 percent of topsoil was dry or very dry.Shallow conditions -along the river interrupted normal shipments of goods. According to the Associated Press, -barge companies reduced the weight carried in many shipments in September because the river -was not deep enough to accommodate their normal weight. Much of U.S. grain exports are transported - -down the Mississippi, and according to AP, the cost of these shipments from St. Louis southward -has risen 77 percent above the three-year average. The lack of freshwater flowing into the -Gulf of Mexico has also allowed saltwater to make its way up the river and into some water -treatment plants in southern Louisiana, according to the Associated Press. Some parts of Plaquemines -Parish are under drinking water advisories and have relied on bottled water for cooking and - -drinking since June.Significant rainfall would be needed to flush out saltwater in the river -in Plaquemines. According to the National Weather Service’s Lower Mississippi River Forecast -Center, the forecast does not look promising. If enough rainfall doesn’t arrive before mid-to-late -October, saltwater could make its way to New Orleans.NASA Earth Observatory images by Lauren -Dauphin, using Landsat data from the U.S. Geological Survey and data from the United States - -Drought Monitor at the University of Nebraska-Lincoln. Story by Emily Cassidy.View this area -in EO ExplorerIn September, low water levels made it more challenging to ship goods down the -river and allowed a wedge of saltwater to move upstream.Image of the Day for October 1, 2023 -Image of the Day Water Drought View more Images of the Day:Persistent dry conditions can affect -water resources, ecosystems, and agriculture.Severe drought is reducing the number of daily - -passages on the transoceanic shipping route. Image of the Day Water Human Presence Prolonged -drought in Kansas set the stage for what may be one of the state’s smallest wheat harvests -in decades. Image of the Day Land Water Drought The most severe drought in 70 years of record -keeping threatens the Horn of Africa with famine. Image of the Day Land Water Drought Low -water levels are making it difficult to ship goods down the river and allowing a wedge of - -saltwater to move upstream. Image of the Day Land Water Human Presence Remote Sensing September -25, 2023JPEGLake Winnipeg, the world’s 10th largest freshwater lake by surface area, has experienced -algae blooms at a regular occurrence at least since the 1990s. A bloom of blue-green algae -once again covered parts of the lake in September 2023. Located in Manitoba, Canada, the long -lake has a watershed that spans one million square kilometers (386,000 square miles), draining - -some of Canada’s agricultural land. The lake consists of a large, deep north basin and a smaller, -comparatively shallow south basin. Swirls of algae filled the south basin of the lake on September -25, 2023, when the OLI-2 (Operational Land Imager-2) on Landsat 9 acquired this image. Around -this time, satellite observations analyzed by Environment and Climate Change Canada indicated -that algae covered about 8,400 square kilometers (3,200 square miles), or about a third of - -the lake’s area.Blue-green algae, also known as cyanobacteria, are single-celled organisms -that rely on photosynthesis to turn sunlight into food. The bacteria grow swiftly when nutrients -like phosphorus and nitrogen are abundant in still water. The bloom pictured here may contain -blue-green algae, as well as other types of phytoplankton; only a surface sample can confirm -the exact composition of a bloom. Some cyanobacteria produce microcystin—a potent toxin that - -can irritate the skin and cause liver and kidney damage.While algae are part of a natural -freshwater ecosystem, excess algae, particularly cyanobacteria, can be a nuisance to residents -and tourists using the lake and its beaches for fishing, swimming, and recreation. Beaches -in the south basin of Lake Winnipeg can get as many as 30,000 visitors a day during the summer -months. Water samples taken at Winnipeg Beach on the west shore found that cyanobacteria levels - -were elevated in August, and visitors were advised to avoid swimming and fishing if green -scum was visible. The health of Lake Winnipeg has been in decline in recent decades. Between -1990 and 2000, phosphorous concentrations in the lake almost doubled and algae blooms proliferated, -both in terms of occurrence and extent. The major contributors to the influx of phosphorous -to the lake were increased agricultural activities in the watershed and a higher frequency - -of flooding, which has increased runoff into the lake.Phosphorus concentrations are almost -three times higher in the south basin of Lake Winnipeg, compared to the north basin. A 2019 -study using data from the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument -on NASA’s Terra satellite found that the chlorophyll-a concentrations, which are used as a -measure of phytoplankton biomass, were on average more than twice as high in the south basin, - -compared to the north. NASA Earth Observatory images by Wanmei Liang, using Landsat data from -the U.S. Geological Survey. Story by Emily Cassidy.View this area in EO ExplorerAn influx -of nutrients in recent decades has contributed to the proliferation of algae in the large -Canadian lake.Image of the Day for October 6, 2023 Image of the Day Water Water Color View -more Images of the Day:Floating, plant-like organisms reproduce abundantly when there are - -sufficient nutrients, sunlight, and water conditions. Extreme blooms of certain species can -become harmful to marine animals and humans.Cyanobacteria covered over half of the surface -of Florida’s largest freshwater lake in mid-June 2023. Image of the Day Life Water Water Color -Nearly half of the lake was covered with blue-green algae in early July 2022. Image of the -Day Water Remote Sensing Water Color More than 40 years after the explosive eruption of Mount - -St. Helens, relics from the blast continue to haunt a nearby lake. Image of the Day Water -Venezuela’s Lake Maracaibo is choking with oil slicks and algae. Image of the Day Life Water -Human Presence Remote Sensing October 8, 2022JPEGOctober 3, 2023JPEGOctober 8, 2022October -3, 2023October 8, 2022JPEGOctober 3, 2023JPEGOctober 3, 2023JPEGJuly through October fall -within the dry season in the western and northern Amazon rainforest, but a particularly acute - -lack of rain during this period in 2023 has pushed the region into a severe drought.The OLI -(Operational Land Imager) instrument on Landsat 8 captured this image (right) of the parched -Rio Negro in the Brazilian province of Amazonas near the city of Manaus on October 3, 2023. -On that date, the level of the river, the largest tributary of the Amazon River, had dropped -to 15.14 meters (50.52 feet), according to data collected by the Port of Manaus. For comparison, - -the image on the left shows the same area on October 8, 2022, when the water level was 19.59 -meters, a more typical level for October. Rio Negro water levels continued to drop in the -days after the image was collected, reaching a record low of 13.49 meters on October 17, 2023.Some -areas in the Amazon River’s watershed have received less rain between July and September than -any year since 1980, Reuters reported. The drought has been particularly severe in the Rio - -Negro watershed in northern Amazonas, as well as parts of southern Venezuela and southern -Colombia.“Overall, this is a pretty unusual and extreme situation,” said René Garreaud, an -atmospheric scientist at the University of Chile. “The primary culprit exacerbating the drought -appears to be El Niño.” This cyclical warming of surface waters in the central-eastern Pacific -functions somewhat like a boulder in the middle of a stream, disrupting atmospheric circulation - -patterns in ways that lead to wetter conditions over the equatorial Pacific and drier conditions -over the Amazon Basin.According to news outlets, the low river water levels on the Rio Negro -and other nearby rivers have disrupted drinking water supplies in hundreds of communities, -slowed commercial navigation, and led to fish and dolphin die-offs.Manaus, the capital and -largest city of the Brazilian state of Amazonas, is the primary transportation hub for the - -upper Amazon, serving as an important transit point for soap, beef, and animal hides. Other -industries with a presence in the city of two million people include chemical, ship, and electrical -equipment manufacturing.NASA Earth Observatory images by Wanmei Liang, using Landsat data -from the U.S. Geological Survey. Story by Adam Voiland.View this area in EO ExplorerThe water -level of the largest tributary of the Amazon River has hit a record low.Image of the Day for - -October 18, 2023 Image of the Day Water Human Presence View more Images of the Day:The impact -of severe drought on the Negro River, a tributary of the Amazon River, and other rivers in -the basin is dramatically evident in this pair of images, which show that every body of water -has shrunk in 2010 compared to 2008. Image of the Day Atmosphere Land The volume of water -in New Mexico’s largest reservoir has dropped to historic lows due to drought and persistent - -demand. Image of the Day Water Human Presence Acquired June 25, 2011, and June 22, 2010, these -false-color images compare conditions along the Souris River, which reached a historic crest -at Minot, North Dakota in June 2011. Land Floods Acquired May 11, 2011, and April 21, 2007, -these false-color images show the Mississippi River near Natchez, Mississippi. The image from -May 2011 shows flooded conditions. Land Floods January 22 - July 26, 2023JPEGOne of the wettest - -wet seasons in northern Australia transformed large areas of the country’s desert landscape -over the course of many months in 2023. A string of major rainfall events that dropped 690 -millimeters (27 inches) between October 2022 and April 2023 made it the sixth-wettest season -on record since 1900–1901.This series of false-color images illustrates the rainfall’s months-long -effects downstream in the Lake Eyre Basin. Water appears in shades of blue, vegetation is - -green, and bare land is brown. The images were acquired by the Moderate Resolution Imaging -Spectroradiometer (MODIS) on NASA’s Terra satellite between January and July 2023.In the January -22 image (left), water was coursing through seasonally dry channels of the Georgina River -and Eyre Creek following weeks of heavy rains in northern Queensland. By April 21 (middle), -floodwaters had reached further downstream after another intense period of precipitation in - -March. This scene shows that water had filled in some of the north-northwest trending ridges -that are part of a vast fossil landscape of wind-formed dunes, while vegetation had emerged -in wet soil upstream. Then by July 26 (right), the riverbed had filled with even more vegetation.The -Georgina River and Eyre Creek drain approximately 210,000 square kilometers (81,000 square -miles), nearly the area of the United Kingdom. Visible in the lower part of the images, the - -lake gets refreshed about every three years; when it reaches especially high levels, it may -take 18 months to 2 years to dry up. Two smaller neighboring lakes flood seasonally. These -three lakes and surrounding floodplains support hundreds of thousands of waterbirds and are -designated as an Important Bird Area.Seasonal flooding is a regular occurrence in these desert -river systems. However, the events of the 2022-2023 rainy season stood out in several ways. - -They occurred while La Niña conditions were in place over the tropical Pacific Ocean. (The -wettest seasons in northern Australia have all occurred during La Niña years, according to -Australia’s Bureau of Meteorology.) In addition, major rains occurring in succession, as was -the case with the January and March events, have the overall effect of prolonging floods. -That’s because vegetation that grows after the first event slows down the pulse of water that - -comes through in the next rain event.The high water has affected both local communities and -ecosystems. Floods have inundated cattle farms and isolated towns on temporary islands. At -the same time, they are a natural feature of the “boom-and-bust” ecology of Channel Country, -providing habitat and nutrients that support biodiversity.NASA Earth Observatory image by -Wanmei Liang, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview. Story by Lindsey - -Doermann.View this area in EO ExplorerRepeated heavy rains in Australia set off waves of new -growth across Channel Country.Image of the Day for August 7, 2023 Image of the Day Land Water -View more Images of the Day: Floods The waves off the coast of Teahupo’o can heave a crushing -amount of water toward the shore and onto unlucky surfers. Image of the Day Water Waves of -heavy rainfall left towns and farmland under water in October 2022. Image of the Day Water - -Floods Acquired February 26, 2011, and February 5, 2011, these false-color images show the -impact of heavy rains in marshy areas southeast of Georgetown, Guyana. Land Floods August -25, 2023JPEGSeptember 18, 2023JPEGAugust 25, 2023September 18, 2023August 25, 2023JPEGSeptember -18, 2023JPEGSeptember 18, 2023JPEGHeavy rain from a cyclone in the Mediterranean inundated -cities along the northeastern coast of Libya in early September 2023, causing thousands of - -deaths. The port city of Derna (Darnah), home to about 90,000 people, was one of the worst -hit by the storm and suffered extensive flooding and damage. On September 10 and 11, over -100 millimeters (4 inches) of rain fell on Derna. The city lies at the end of a long, narrow -valley, called a wadi, which is dry except during the rainy season. Floods triggered two dams -along the wadi to collapse. The failure of the second dam, located just one kilometer inland - -of Derna, unleashed 3- to 7-meter-high floodwater that tore through the city. According to -news reports, the flash floods destroyed roads and swept entire neighborhoods out to sea. -The images above show the city before and after the storm. The image on the right, acquired -by the Operational Land Imager-2 (OLI-2) on Landsat 9 on September 18, shows eroded banks -of Wadi Derna near where it meets the Mediterranean. Water just off the coast appears muddier - -than in the image on the left, which shows the same area on August 25 and was acquired by -Landsat 8. Preliminary estimates by the United Nations Satellite Center (UNOSAT) indicate -that 3,100 buildings in Derna were damaged by rushing water. According to the UN International -Organization for Migration (IOM), about 40,000 people in the country were displaced by the -storm, and 30,000 of those were displaced from Derna. Tropical-like cyclones in the Mediterranean, - -or “medicanes,” develop only once or twice a year, according to NOAA, and typically form in -autumn. According to meteorologists at Yale Climate Connections, this storm was the deadliest -in Africa’s recorded history. A recent assessment by scientists at World Weather Attribution -estimated that precipitation received by the region was a one-in-300 to one-in-600-year event. -NASA Earth Observatory images by Lauren Dauphin, using Landsat data from the U.S. Geological - -Survey. Story by Emily Cassidy.View this area in EO ExplorerFlash floods in the port city -destroyed roads and swept neighborhoods out to sea.Image of the Day for September 21, 2023 -Image of the Day Land Water Floods Human Presence View more Images of the Day:The melting -of frozen rivers and snowpack, and the heavy rains of late spring and summer, can send rivers -out of their banks.A Mediterranean cyclone contributed to deadly flooding along the country’s - -coastline. Image of the Day Land Water Floods Record rainfall inundated towns and farmland -in the country’s Thessaly region. Image of the Day Water Floods Human Presence A stalled storm -dropped three feet of rain over four days on the Thessaly region, triggering extensive flooding. -Image of the Day Atmosphere Floods An isolated low-pressure system produced torrential downpours -in Spain and carried Saharan dust along its path. Image of the Day Atmosphere Land Floods - -Human Presence July 2002 - June 2022JPEGThe deep-blue sea is turning a touch greener. While -that may not seem as consequential as, say, record warm sea surface temperatures, the color -of the ocean surface is indicative of the ecosystem that lies beneath. Communities of phytoplankton, -microscopic photosynthesizing organisms, abound in near-surface waters and are foundational -to the aquatic food web and carbon cycle. This shift in the water’s hue confirms a trend expected - -under climate change and signals changes to ecosystems within the global ocean, which covers -70 percent of Earth’s surface. Researchers led by B. B. Cael, a principal scientist at the -U.K.’s National Oceanography Centre, revealed that 56 percent of the global sea surface has -undergone a significant change in color in the past 20 years. After analyzing ocean color -data from the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument on NASA’s Aqua - -satellite, they found that much of the change stems from the ocean turning more green. The -map above highlights the areas where ocean surface color changed between 2002 and 2022, with -darker shades of green representing more-significant differences (higher signal-to-noise ratio). -By extension, said Cael, “these are places we can detect a change in the ocean ecosystem in -the last 20 years.” The study focused on tropical and subtropical regions, excluding higher - -latitudes, which are dark for part of the year, and coastal waters, where the data are naturally -very noisy. The black dots on the map indicate the area, covering 12 percent of the ocean’s -surface, where chlorophyll levels also changed over the study period. Chlorophyll has been -the go-to measurement for remote sensing scientists to gauge phytoplankton abundance and productivity. -However, those estimates use only a few colors in the visible light spectrum. The values shown - -in green are based on the whole gamut of colors and therefore capture more information about -the ecosystem as a whole. A long time series from a single sensor is relatively rare in the -remote sensing world. As the Aqua satellite was celebrating its 20th year in orbit in 2022—far -exceeding its design life of 6 years—Cael wondered what long term trends could be discovered -in the data. In particular, he was curious what might have been missed in all the ocean color - -information it had collected. “There’s more encoded in the data than we actually make use -of,” he said. By going big with the data, the team discerned an ocean color trend that had -been predicted by climate modeling, but one that was expected to take 30-40 years of data -to detect using satellite-based chlorophyll estimates. That’s because the natural variability -in chlorophyll is high relative to the climate change trend. The new method, incorporating - -all visible light, was robust enough to confirm the trend in 20 years. At this stage, it is -difficult to say what exact ecological changes are responsible for the new hues. However, -the authors posit, they could result from different assemblages of plankton, more detrital -particles, or other organisms such as zooplankton. It is unlikely the color changes come from -materials such as plastics or other pollutants, said Cael, since they are not widespread enough - -to register at large scales. “What we do know is that in the last 20 years, the ocean has -become more stratified,” he said. Surface waters have absorbed excess heat from the warming -climate, and as a result, they are less prone to mixing with deeper, more nutrient-rich layers. -This scenario would favor plankton adapted to a nutrient-poor environment. The areas of ocean -color change align well with where the sea has become more stratified, said Cael, but there - -is no such overlap with sea surface temperature changes. More insights into Earth’s aquatic -ecosystems may soon be on the way. NASA’s PACE (Plankton, Aerosol, Cloud, ocean Ecosystem) -satellite, set to launch in 2024, will return observations in finer color resolution. The -new data will enable researchers to infer more information about ocean ecology, such as the -diversity of phytoplankton species and the rates of phytoplankton growth. NASA Earth Observatory - -image by Wanmei Liang, using data from Cael, B. B., et al. (2023). Story by Lindsey Doermann.Two -decades of satellite measurements show that the sea surface is shading toward green.Image -of the Day for October 2, 2023 Image of the Day Life Water View more Images of the Day:Datasets -from the Sentinel-6 Michael Freilich satellite will build upon three decades of sea level -measurements. Image of the Day Heat Water Remote Sensing Image of the Day Life Water Image - -of the Day Water The use of plastic on farms has become so common in recent decades that there -there’s a term for it—plasticulture. Image of the Day Human Presence August 16, 2023JPEGThe -Canary Islands were at the center of a mélange of natural events in summer 2023. The Moderate -Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this assemblage -of phenomena off the coast of Africa on August 16, 2023.In the center of the scene, smoke - -is seen rising from a wildfire burning on Tenerife in the Canary Islands. The blaze started -amid hot and dry conditions on August 15 in forests surrounding the Teide Volcano. Authorities -issued evacuation orders to five villages, and responders focused on containing the fire’s -spread and protecting residential areas near the coast, according to news reports. Other fires -have burned on the Canary Islands this summer, including on La Palma in July.To the west, - -a swirling cloud moves across the Atlantic. Cloud vortices appear routinely downwind of the -Canary Islands—sometimes in great abundance—and are produced when the tall volcanic peaks -disrupt the air flowing past them.Elsewhere in the atmosphere, dust from the Sahara Desert -was lofted out over the ocean. The river of dust crossing the Atlantic was more pronounced -in previous days, when it reached islands in the Caribbean. Traveling on the Saharan Air Layer, - -dust sometimes makes it even further west toward Central America and the U.S. states of Florida -and Texas.To round out the list, the patch of bright blue off the Moroccan coast is most likely -a bloom of phytoplankton. While the exact cause and composition of the bloom cannot be determined -from this image, mineral-rich desert dust has been shown to set off bursts of phytoplankton -growth.In addition to the Earth’s processes seen here, one remote sensing artifact is present. - -A diagonal streak of sunglint makes part of this scene appear washed out. Sunglint, an effect -that occurs when sunlight reflects off the surface of the water at the same angle that a satellite -sensor views it, is also the reason for the light-colored streaks trailing off the islands.NASA -Earth Observatory image by Wanmei Liang, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview. -Story by Lindsey Doermann.View this area in EO ExplorerAn assortment of natural phenomena - -visible from space appeared together in one image.Image of the Day for August 17, 2023 Image -of the Day Atmosphere Land Water View more Images of the Day:Flights were grounded as visibility -was severely hampered by a Calima event. Image of the Day Atmosphere Land Dust and Haze Human -Presence In one frame International Space Station astronauts were able to capture the evolution -of fringing reefs to atolls. As with the Hawaiian Islands, these volcanic hot spot islands - -become progressively older to the northwest. As these islands move away from their magma sources -they erode and subside. Image of the Day Land Water The dry, volcanic terrain of this Canary -Island is suitable for lichen and crops … and for training astronauts. Image of the Day Land -The event, known locally as “la calima,” turned skies orange and degraded air quality in Gran -Canaria and neighboring islands. Image of the Day Atmosphere Land Dust and Haze July 17, 2023JPEGFour - -funnel-shaped estuarine inlets, collectively known as Rías Baixas, line the coast of Galicia, -in northwest Spain. The nutrient-rich water in these inlets supports a wealth of marine life, -making the Galicia coast one of the most productive places for aquaculture.On July 17, 2023, -the Operational Land Imager-2 (OLI-2) on Landsat 9, acquired this image of the Rías de Arousa -(Arousa estuary), the largest and northernmost of the inlets. Small dots skirt the coasts - -of the embayment. In most cases, these dots are rectangular rafts designed for raising bivalves -like mussels. Buoys keep the lattice mussel rafts afloat on the surface of the water, and -hundreds of ropes are suspended into the water column from each structure. Mussels attach -to the ropes and filter feed on phytoplankton and other suspended organic particles. The rafts -allow for high yields of mussels in a small area of the water. The Rías Baixas are on the - -northern end of the Canary current and are in a major upwelling zone. Upwelling, which brings -colder, nutrient-rich water up from the bottom of the ocean, typically occurs in this area -between April and October. Much of the mussel production in the Rías Baixas occurs during -this time, as the mollusks filter feed on nutrients and plentiful phytoplankton supported -by upwelling. Spain is the top mussel producing country in the world. Rías de Arousa alone - -contains over 2,400 mussel rafts, producing about 40 percent of Europe’s mussels. NASA Earth -Observatory image by Wanmei Liang, using Landsat data from the U.S. Geological Survey. Story -by Emily Cassidy. Buoys keep the lattice mussel rafts afloat on the surface of the water, -and hundreds of ropes are suspended into the water column from each structure. Mussels attach -to the ropes and filter feed on phytoplankton and other suspended organic particles. The rafts - -allow for high yields of mussels in a small area of the water. The Rías Baixas are on the -northern end of the Canary current and are in a major upwelling zone. Upwelling, which brings -colder, nutrient-rich water up from the bottom of the ocean, typically occurs in this area -between April and October. Much of the mussel production in the Rías Baixas occurs during -this time, as the mollusks filter feed on nutrients and plentiful phytoplankton supported - -by upwelling. Spain is the top mussel producing country in the world. Rías de Arousa alone -contains over 2,400 mussel rafts, producing about 40 percent of Europe’s mussels. NASA Earth -Observatory image by Wanmei Liang, using Landsat data from the U.S. Geological Survey. Story -by Emily Cassidy.View this area in EO ExplorerThe estuarine inlets of Spain’s Galicia coast -are some of the most productive places to grow mussels.Image of the Day for September 19, - -2023 Image of the Day Water Human Presence View more Images of the Day: Dust and Haze This -image shows Tropical Cyclones Eric and Fanele near Madagascar on January 19, 2009. Atmosphere -Water Severe Storms This natural-color image shows Saharan dust forming an S-shaped curve -off the western coast of Africa, and passing directly over Cape Verde. Atmosphere Land Dust -and Haze Acquired March 8, 2010, this true-color image shows two icebergs, Iceberg B-09B and - -an iceberg recently broken off the Mertz Glacier, floating in the Southern Ocean, just off -the George V Coast. Water Snow and Ice Sea and Lake Ice May 18, 2023JPEGSeptember 7, 2023JPEGMay -18, 2023September 7, 2023May 18, 2023JPEGSeptember 7, 2023JPEGSeptember 7, 2023JPEGAfter going -dry in 2018, Laguna de Aculeo has begun to refill. NASA satellites began to detect water pooling -in the parched lake in late-August, after an intense winter storm dropped as much as 370 millimeters - -(15 inches) of rain on some parts of central Chile. The storm was fueled by an atmospheric -river and exacerbated by the rugged terrain in central Chile.When the Operational Land Imager-2 -(OLI-2) on Landsat 9 acquired this image (right) on September 7, 2023, Laguna de Aculeo covered -about 5 square kilometers (2 square miles) to a depth of roughly 1 meter (3 feet). The other -image (left) shows the dried water body on May 18, 2023, before the wet winter weather arrived. - -Although it has refilled somewhat, water spans only half the area it did up to 2010 and contains -a quarter of the water volume, explained René Garreaud, an Earth scientist at the University -of Chile. Seasonal changes and the influx of water have led to widespread greening of the -landscape around the lake.Researchers have assessed that ongoing development and water use -in the nearby community of Paine, increasing water use by farmers and in homes and pools, - -as well as several years of drought, likely contributed to the drawdown of the lake. Annual -rainfall deficits that averaged 38 percent between 2010 and 2018 likely played a large role, -according to one analysis from a team of researchers from the University of Chile.Before 2010, -the shallow water body was a popular haven for boaters, swimmers, and water skiers, but the -water hasn’t yet pooled up enough for swimmers or boaters to return. It is also unclear how - -long the new water in Aculeo will persist. “Atmospheric rivers in June and August delivered -substantial precipitation along the high terrain and foothills that have giv­­en us a welcome -interruption to the drought,” Garreaud said. “But Aculeo is a small, shallow lagoon that can -fill up rapidly, and it's only partly filled. Bigger reservoirs and aquifers will take much -longer to recover.”NASA Earth Observatory images by Lauren Dauphin, using Landsat data from - -the U.S. Geological Survey. Story by Adam Voiland.View this area in EO ExplorerThe drought -in Chile isn’t over, but recent late-winter rains provided enough moisture for water to start -pooling up again.Image of the Day for September 16, 2023 Image of the Day Life Water View -more Images of the Day:Data from winter 2022-2023 show the greatest net gain of water in nearly -22 years, but groundwater levels still suffer from years of drought. Image of the Day Land - -Water As a persistent drought drags on, water levels are dropping at a key reservoir that -supplies Santiago. Image of the Day Land Water A new web tool designed by NASA applied scientists -could help the tribe anticipate and respond to drought. Image of the Day Water Human Presence -Remote Sensing For more than 100 years, groups in the western United States have fought over -water. During the 1880s, sheep ranchers and cattle ranchers argued over drinking water for - -their livestock on the high plains. In 1913, the city of Los Angeles began to draw water away -from small agricultural communities in Owen Valley, leaving a dusty dry lake bed. In the late -1950s, construction of the Glen Canyon Dam catalyzed the American environmental movement. -Today, farmers are fighting fishermen, environmentalists, and Native American tribes over -the water in the Upper Klamath River Basin. The Landsat 7 satellite, launched by NASA and - -operated by the U.S. Geological Survey, documented an extreme drought in the area along the -California/Oregon border in the spring of 2001. Image of the Day Land Life September 16, 2023JPEGSeptember -10, 2021JPEGSeptember 16, 2023September 10, 2021September 16, 2023JPEGSeptember 10, 2021JPEGSeptember -10, 2021JPEGMonths of excessive heat and drought parched the Mississippi River in the summer -and early fall of 2023. In September, low water levels limited barge shipments downriver and - -threatened drinking water supplies in some Louisiana communities, according to the Associated -Press.Water levels were especially low near Memphis, Tennessee. The images above show the -Mississippi River near Memphis on September 16, 2023 (left), compared to September 10, 2021 -(right). The river was significantly slimmed down in 2023, exposing some of the river bottom.This -is the second year in a row drought has caused the river to fall to near-record lows at many - -gauges. On September 26, 2023, the river level at a gauge in Memphis was -10.26 feet, close -to the record low level, -10.81 feet, measured at the same place on October 21, 2022. That -was the lowest level recorded there since the start of National Weather Service records in -1954. Water levels, or “gauge heights,” do not indicate the depth of a stream; rather, they -are measured with respect to a chosen reference point. That is why some gauge height measurements - -are negative.Farther upstream, water levels at New Madrid, Missouri, have been around -5 feet—near -the minimum operating level—since early September 2023. Water levels on the Mississippi normally -decline in the fall and winter, and in 2022, the river did not get that low until mid-October. -September 26, 2023JPEGA hot, dry summer is the main reason water levels dropped so low in -2023. Across the globe, temperatures in summer 2023 were 1.2°C (2.1°F) warmer than average. - -In the U.S., Louisiana and Mississippi experienced their hottest Augusts on record, according -to NOAA.The U.S. Drought Monitor map above—the product of a partnership between the U.S. Department -of Agriculture, the National Oceanic and Atmospheric Administration, and the University of -Nebraska-Lincoln—shows conditions during the week of September 20-26, 2023. The map depicts -drought intensity in progressive shades of orange to red. It is based on an analysis of climate, - -soil, and water condition measurements from more than 350 federal, state, and local observers -around the country. NASA contributes measurements and models that aid the drought monitoring -effort.During that week, about 38 percent of the contiguous U.S. was experiencing drought. -Lack of precipitation and high temperatures over several months severely dried out soils in -states along the Mississippi River Valley. The Drought Monitor reported that 80 percent of - -soils in Louisiana were dry (short or very short on water) as of September 24. And for most -states in the river valley, over 50 percent of topsoil was dry or very dry.Shallow conditions -along the river interrupted normal shipments of goods. According to the Associated Press, -barge companies reduced the weight carried in many shipments in September because the river -was not deep enough to accommodate their normal weight. Much of U.S. grain exports are transported - -down the Mississippi, and according to AP, the cost of these shipments from St. Louis southward -has risen 77 percent above the three-year average. The lack of freshwater flowing into the -Gulf of Mexico has also allowed saltwater to make its way up the river and into some water -treatment plants in southern Louisiana, according to the Associated Press. Some parts of Plaquemines -Parish are under drinking water advisories and have relied on bottled water for cooking and - -drinking since June.Significant rainfall would be needed to flush out saltwater in the river -in Plaquemines. According to the National Weather Service’s Lower Mississippi River Forecast -Center, the forecast does not look promising. If enough rainfall doesn’t arrive before mid-to-late -October, saltwater could make its way to New Orleans.NASA Earth Observatory images by Lauren -Dauphin, using Landsat data from the U.S. Geological Survey and data from the United States - -Drought Monitor at the University of Nebraska-Lincoln. Story by Emily Cassidy.View this area -in EO ExplorerIn September, low water levels made it more challenging to ship goods down the -river and allowed a wedge of saltwater to move upstream.Image of the Day for October 1, 2023 -Image of the Day Water Drought View more Images of the Day:Persistent dry conditions can affect -water resources, ecosystems, and agriculture.Severe drought is reducing the number of daily - -passages on the transoceanic shipping route. Image of the Day Water Human Presence Prolonged -drought in Kansas set the stage for what may be one of the state’s smallest wheat harvests -in decades. Image of the Day Land Water Drought The most severe drought in 70 years of record -keeping threatens the Horn of Africa with famine. Image of the Day Land Water Drought Low -water levels are making it difficult to ship goods down the river and allowing a wedge of - -saltwater to move upstream. Image of the Day Land Water Human Presence Remote Sensing September -25, 2023JPEGLake Winnipeg, the world’s 10th largest freshwater lake by surface area, has experienced -algae blooms at a regular occurrence at least since the 1990s. A bloom of blue-green algae -once again covered parts of the lake in September 2023. Located in Manitoba, Canada, the long -lake has a watershed that spans one million square kilometers (386,000 square miles), draining - -some of Canada’s agricultural land. The lake consists of a large, deep north basin and a smaller, -comparatively shallow south basin. Swirls of algae filled the south basin of the lake on September -25, 2023, when the OLI-2 (Operational Land Imager-2) on Landsat 9 acquired this image. Around -this time, satellite observations analyzed by Environment and Climate Change Canada indicated -that algae covered about 8,400 square kilometers (3,200 square miles), or about a third of - -the lake’s area.Blue-green algae, also known as cyanobacteria, are single-celled organisms -that rely on photosynthesis to turn sunlight into food. The bacteria grow swiftly when nutrients -like phosphorus and nitrogen are abundant in still water. The bloom pictured here may contain -blue-green algae, as well as other types of phytoplankton; only a surface sample can confirm -the exact composition of a bloom. Some cyanobacteria produce microcystin—a potent toxin that - -can irritate the skin and cause liver and kidney damage.While algae are part of a natural -freshwater ecosystem, excess algae, particularly cyanobacteria, can be a nuisance to residents -and tourists using the lake and its beaches for fishing, swimming, and recreation. Beaches -in the south basin of Lake Winnipeg can get as many as 30,000 visitors a day during the summer -months. Water samples taken at Winnipeg Beach on the west shore found that cyanobacteria levels - -were elevated in August, and visitors were advised to avoid swimming and fishing if green -scum was visible. The health of Lake Winnipeg has been in decline in recent decades. Between -1990 and 2000, phosphorous concentrations in the lake almost doubled and algae blooms proliferated, -both in terms of occurrence and extent. The major contributors to the influx of phosphorous -to the lake were increased agricultural activities in the watershed and a higher frequency - -of flooding, which has increased runoff into the lake.Phosphorus concentrations are almost -three times higher in the south basin of Lake Winnipeg, compared to the north basin. A 2019 -study using data from the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument -on NASA’s Terra satellite found that the chlorophyll-a concentrations, which are used as a -measure of phytoplankton biomass, were on average more than twice as high in the south basin, - -compared to the north. NASA Earth Observatory images by Wanmei Liang, using Landsat data from -the U.S. Geological Survey. Story by Emily Cassidy.View this area in EO ExplorerAn influx -of nutrients in recent decades has contributed to the proliferation of algae in the large -Canadian lake.Image of the Day for October 6, 2023 Image of the Day Water Water Color View -more Images of the Day:Floating, plant-like organisms reproduce abundantly when there are - -sufficient nutrients, sunlight, and water conditions. Extreme blooms of certain species can -become harmful to marine animals and humans.Cyanobacteria covered over half of the surface -of Florida’s largest freshwater lake in mid-June 2023. Image of the Day Life Water Water Color -Nearly half of the lake was covered with blue-green algae in early July 2022. Image of the -Day Water Remote Sensing Water Color More than 40 years after the explosive eruption of Mount - -St. Helens, relics from the blast continue to haunt a nearby lake. Image of the Day Water -Venezuela’s Lake Maracaibo is choking with oil slicks and algae. Image of the Day Life Water -Human Presence Remote Sensing October 8, 2022JPEGOctober 3, 2023JPEGOctober 8, 2022October -3, 2023October 8, 2022JPEGOctober 3, 2023JPEGOctober 3, 2023JPEGJuly through October fall -within the dry season in the western and northern Amazon rainforest, but a particularly acute - -lack of rain during this period in 2023 has pushed the region into a severe drought.The OLI -(Operational Land Imager) instrument on Landsat 8 captured this image (right) of the parched -Rio Negro in the Brazilian province of Amazonas near the city of Manaus on October 3, 2023. -On that date, the level of the river, the largest tributary of the Amazon River, had dropped -to 15.14 meters (50.52 feet), according to data collected by the Port of Manaus. For comparison, - -the image on the left shows the same area on October 8, 2022, when the water level was 19.59 -meters, a more typical level for October. Rio Negro water levels continued to drop in the -days after the image was collected, reaching a record low of 13.49 meters on October 17, 2023.Some -areas in the Amazon River’s watershed have received less rain between July and September than -any year since 1980, Reuters reported. The drought has been particularly severe in the Rio - -Negro watershed in northern Amazonas, as well as parts of southern Venezuela and southern -Colombia.“Overall, this is a pretty unusual and extreme situation,” said René Garreaud, an -atmospheric scientist at the University of Chile. “The primary culprit exacerbating the drought -appears to be El Niño.” This cyclical warming of surface waters in the central-eastern Pacific -functions somewhat like a boulder in the middle of a stream, disrupting atmospheric circulation - -patterns in ways that lead to wetter conditions over the equatorial Pacific and drier conditions -over the Amazon Basin.According to news outlets, the low river water levels on the Rio Negro -and other nearby rivers have disrupted drinking water supplies in hundreds of communities, -slowed commercial navigation, and led to fish and dolphin die-offs.Manaus, the capital and -largest city of the Brazilian state of Amazonas, is the primary transportation hub for the - -upper Amazon, serving as an important transit point for soap, beef, and animal hides. Other -industries with a presence in the city of two million people include chemical, ship, and electrical -equipment manufacturing.NASA Earth Observatory images by Wanmei Liang, using Landsat data -from the U.S. Geological Survey. Story by Adam Voiland.View this area in EO ExplorerThe water -level of the largest tributary of the Amazon River has hit a record low.Image of the Day for - -October 18, 2023 Image of the Day Water Human Presence View more Images of the Day:The impact -of severe drought on the Negro River, a tributary of the Amazon River, and other rivers in -the basin is dramatically evident in this pair of images, which show that every body of water -has shrunk in 2010 compared to 2008. Image of the Day Atmosphere Land The volume of water -in New Mexico’s largest reservoir has dropped to historic lows due to drought and persistent - -demand. Image of the Day Water Human Presence Acquired June 25, 2011, and June 22, 2010, these -false-color images compare conditions along the Souris River, which reached a historic crest -at Minot, North Dakota in June 2011. Land Floods Acquired May 11, 2011, and April 21, 2007, -these false-color images show the Mississippi River near Natchez, Mississippi. The image from -May 2011 shows flooded conditions. Land Floods September 6, 2020JPEGSeptember 7, 2023JPEGSeptember - -6, 2020September 7, 2023September 6, 2020JPEGSeptember 7, 2023JPEGSeptember 7, 2023JPEGAfter -rapidly growing in volume just a few years earlier, northwest Iran’s Lake Urmia nearly dried -out in autumn 2023. The largest lake in the Middle East and one of the largest hypersaline -lakes on Earth at its greatest extent, Lake Urmia has for the most part transformed into a -vast, dry salt flat. On September 7, 2023, the OLI-2 (Operational Land Imager-2) on Landsat - -9 captured this image (right) of the desiccated lakebed. It stands in contrast to the image -from three years earlier (left), acquired by the OLI on Landsat 8 on September 8, 2020, when -water filled most of the basin and salt deposits were only visible around the perimeter of -the lake. The replenishment followed a period of above-average precipitation that sent a surge -of freshwater into the basin, expanding its watery footprint. Drier conditions have since - -brought levels back down. The longer-term trend for Urmia has been one toward drying. In 1995, -Lake Urmia reached a high-water mark; then in the ensuing two decades, the lake level dropped -more than 7 meters (23 feet) and lost approximately 90 percent of its area. Consecutive droughts, -agricultural water use, and dam construction on rivers feeding the lake have contributed to -the decline. A shrinking Lake Urmia has implications for ecological and human health. The - -lake, its islands, and surrounding wetlands comprise valuable habitat and are recognized as -a UNESCO Biosphere Reserve, Ramsar site, and national park. The area provides breeding grounds -for waterbirds such as flamingos, white pelicans, and white-headed ducks, as well as a stopover -for migratory species. However, with low lake levels, what water remains becomes more saline -and taxes the populations of brine shrimp and other food sources for larger animals. A shrinking - -lake also increases the likelihood of dust from the exposed lakebed becoming swept up by winds -and degrading air quality. Recent studies have linked the low water levels in Lake Urmia with -respiratory health impacts among the local population.The relative effects of climate, water -usage, and dams on Lake Urmia’s water level is a topic of debate. The lake did see some recovery -during a 10-year restoration program beginning in 2013. However, the efficacy of that effort - -has been difficult to parse since strong rains also fell during that period. Some research -has concluded that climatic factors were primarily responsible for the recovery. NASA Earth -Observatory images by Lauren Dauphin, using Landsat data from the U.S. Geological Survey. -Story by Lindsey Doermann.View this area in EO ExplorerA few years after a fresh influx of -water raised its levels, the large lake has nearly gone dry.Image of the Day for October 10, - -2023 Image of the Day Land Water View more Images of the Day:Water levels are at their lowest -since 1937. Image of the Day Water Drought Fires Long and short. Deep and shallow. Salty and -fresh. Blue and brown. These are Africa’s Lake Tanganyika and Lake Rukwa. Image of the Day -Land Water In May 2016, the reservoir behind Hoover Dam reached its lowest level since the -1930s. Image of the Day Water When the water gets saltier in Iran’s largest lake, the microscopic - -inhabitants can turn the water dark red. Image of the Day Water Water Color January 22 - July -26, 2023JPEGOne of the wettest wet seasons in northern Australia transformed large areas of -the country’s desert landscape over the course of many months in 2023. A string of major rainfall -events that dropped 690 millimeters (27 inches) between October 2022 and April 2023 made it -the sixth-wettest season on record since 1900–1901.This series of false-color images illustrates - -the rainfall’s months-long effects downstream in the Lake Eyre Basin. Water appears in shades -of blue, vegetation is green, and bare land is brown. The images were acquired by the Moderate -Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite between January and -July 2023.In the January 22 image (left), water was coursing through seasonally dry channels -of the Georgina River and Eyre Creek following weeks of heavy rains in northern Queensland. - -By April 21 (middle), floodwaters had reached further downstream after another intense period -of precipitation in March. This scene shows that water had filled in some of the north-northwest -trending ridges that are part of a vast fossil landscape of wind-formed dunes, while vegetation -had emerged in wet soil upstream. Then by July 26 (right), the riverbed had filled with even -more vegetation.The Georgina River and Eyre Creek drain approximately 210,000 square kilometers - -(81,000 square miles), nearly the area of the United Kingdom. Visible in the lower part of -the images, the lake gets refreshed about every three years; when it reaches especially high -levels, it may take 18 months to 2 years to dry up. Two smaller neighboring lakes flood seasonally. -These three lakes and surrounding floodplains support hundreds of thousands of waterbirds -and are designated as an Important Bird Area.Seasonal flooding is a regular occurrence in - -these desert river systems. However, the events of the 2022-2023 rainy season stood out in -several ways. They occurred while La Niña conditions were in place over the tropical Pacific -Ocean. (The wettest seasons in northern Australia have all occurred during La Niña years, -according to Australia’s Bureau of Meteorology.) In addition, major rains occurring in succession, -as was the case with the January and March events, have the overall effect of prolonging floods. - -That’s because vegetation that grows after the first event slows down the pulse of water that -comes through in the next rain event.The high water has affected both local communities and -ecosystems. Floods have inundated cattle farms and isolated towns on temporary islands. At -the same time, they are a natural feature of the “boom-and-bust” ecology of Channel Country, -providing habitat and nutrients that support biodiversity.NASA Earth Observatory image by - -Wanmei Liang, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview. Story by Lindsey -Doermann.View this area in EO ExplorerRepeated heavy rains in Australia set off waves of new -growth across Channel Country.Image of the Day for August 7, 2023 Image of the Day Land Water -View more Images of the Day: Floods The waves off the coast of Teahupo’o can heave a crushing -amount of water toward the shore and onto unlucky surfers. Image of the Day Water Waves of - -heavy rainfall left towns and farmland under water in October 2022. Image of the Day Water -Floods Acquired February 26, 2011, and February 5, 2011, these false-color images show the -impact of heavy rains in marshy areas southeast of Georgetown, Guyana. Land Floods August -25, 2023JPEGSeptember 18, 2023JPEGAugust 25, 2023September 18, 2023August 25, 2023JPEGSeptember -18, 2023JPEGSeptember 18, 2023JPEGHeavy rain from a cyclone in the Mediterranean inundated - -cities along the northeastern coast of Libya in early September 2023, causing thousands of -deaths. The port city of Derna (Darnah), home to about 90,000 people, was one of the worst -hit by the storm and suffered extensive flooding and damage. On September 10 and 11, over -100 millimeters (4 inches) of rain fell on Derna. The city lies at the end of a long, narrow -valley, called a wadi, which is dry except during the rainy season. Floods triggered two dams - -along the wadi to collapse. The failure of the second dam, located just one kilometer inland -of Derna, unleashed 3- to 7-meter-high floodwater that tore through the city. According to -news reports, the flash floods destroyed roads and swept entire neighborhoods out to sea. -The images above show the city before and after the storm. The image on the right, acquired -by the Operational Land Imager-2 (OLI-2) on Landsat 9 on September 18, shows eroded banks - -of Wadi Derna near where it meets the Mediterranean. Water just off the coast appears muddier -than in the image on the left, which shows the same area on August 25 and was acquired by -Landsat 8. Preliminary estimates by the United Nations Satellite Center (UNOSAT) indicate -that 3,100 buildings in Derna were damaged by rushing water. According to the UN International -Organization for Migration (IOM), about 40,000 people in the country were displaced by the - -storm, and 30,000 of those were displaced from Derna. Tropical-like cyclones in the Mediterranean, -or “medicanes,” develop only once or twice a year, according to NOAA, and typically form in -autumn. According to meteorologists at Yale Climate Connections, this storm was the deadliest -in Africa’s recorded history. A recent assessment by scientists at World Weather Attribution -estimated that precipitation received by the region was a one-in-300 to one-in-600-year event. - -NASA Earth Observatory images by Lauren Dauphin, using Landsat data from the U.S. Geological -Survey. Story by Emily Cassidy.View this area in EO ExplorerFlash floods in the port city -destroyed roads and swept neighborhoods out to sea.Image of the Day for September 21, 2023 -Image of the Day Land Water Floods Human Presence View more Images of the Day:The melting -of frozen rivers and snowpack, and the heavy rains of late spring and summer, can send rivers - -out of their banks.A Mediterranean cyclone contributed to deadly flooding along the country’s -coastline. Image of the Day Land Water Floods Record rainfall inundated towns and farmland -in the country’s Thessaly region. Image of the Day Water Floods Human Presence A stalled storm -dropped three feet of rain over four days on the Thessaly region, triggering extensive flooding. -Image of the Day Atmosphere Floods An isolated low-pressure system produced torrential downpours - -in Spain and carried Saharan dust along its path. Image of the Day Atmosphere Land Floods -Human Presence July 2002 - June 2022JPEGThe deep-blue sea is turning a touch greener. While -that may not seem as consequential as, say, record warm sea surface temperatures, the color -of the ocean surface is indicative of the ecosystem that lies beneath. Communities of phytoplankton, -microscopic photosynthesizing organisms, abound in near-surface waters and are foundational - -to the aquatic food web and carbon cycle. This shift in the water’s hue confirms a trend expected -under climate change and signals changes to ecosystems within the global ocean, which covers -70 percent of Earth’s surface. Researchers led by B. B. Cael, a principal scientist at the -U.K.’s National Oceanography Centre, revealed that 56 percent of the global sea surface has -undergone a significant change in color in the past 20 years. After analyzing ocean color - -data from the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument on NASA’s Aqua -satellite, they found that much of the change stems from the ocean turning more green. The -map above highlights the areas where ocean surface color changed between 2002 and 2022, with -darker shades of green representing more-significant differences (higher signal-to-noise ratio). -By extension, said Cael, “these are places we can detect a change in the ocean ecosystem in - -the last 20 years.” The study focused on tropical and subtropical regions, excluding higher -latitudes, which are dark for part of the year, and coastal waters, where the data are naturally -very noisy. The black dots on the map indicate the area, covering 12 percent of the ocean’s -surface, where chlorophyll levels also changed over the study period. Chlorophyll has been -the go-to measurement for remote sensing scientists to gauge phytoplankton abundance and productivity. - -However, those estimates use only a few colors in the visible light spectrum. The values shown -in green are based on the whole gamut of colors and therefore capture more information about -the ecosystem as a whole. A long time series from a single sensor is relatively rare in the -remote sensing world. As the Aqua satellite was celebrating its 20th year in orbit in 2022—far -exceeding its design life of 6 years—Cael wondered what long term trends could be discovered - -in the data. In particular, he was curious what might have been missed in all the ocean color -information it had collected. “There’s more encoded in the data than we actually make use -of,” he said. By going big with the data, the team discerned an ocean color trend that had -been predicted by climate modeling, but one that was expected to take 30-40 years of data -to detect using satellite-based chlorophyll estimates. That’s because the natural variability - -in chlorophyll is high relative to the climate change trend. The new method, incorporating -all visible light, was robust enough to confirm the trend in 20 years. At this stage, it is -difficult to say what exact ecological changes are responsible for the new hues. However, -the authors posit, they could result from different assemblages of plankton, more detrital -particles, or other organisms such as zooplankton. It is unlikely the color changes come from - -materials such as plastics or other pollutants, said Cael, since they are not widespread enough -to register at large scales. “What we do know is that in the last 20 years, the ocean has -become more stratified,” he said. Surface waters have absorbed excess heat from the warming -climate, and as a result, they are less prone to mixing with deeper, more nutrient-rich layers. -This scenario would favor plankton adapted to a nutrient-poor environment. The areas of ocean - -color change align well with where the sea has become more stratified, said Cael, but there -is no such overlap with sea surface temperature changes. More insights into Earth’s aquatic -ecosystems may soon be on the way. NASA’s PACE (Plankton, Aerosol, Cloud, ocean Ecosystem) -satellite, set to launch in 2024, will return observations in finer color resolution. The -new data will enable researchers to infer more information about ocean ecology, such as the - -diversity of phytoplankton species and the rates of phytoplankton growth. NASA Earth Observatory -image by Wanmei Liang, using data from Cael, B. B., et al. (2023). Story by Lindsey Doermann.Two -decades of satellite measurements show that the sea surface is shading toward green.Image -of the Day for October 2, 2023 Image of the Day Life Water View more Images of the Day:Datasets -from the Sentinel-6 Michael Freilich satellite will build upon three decades of sea level - -measurements. Image of the Day Heat Water Remote Sensing Image of the Day Life Water Image -of the Day Water The use of plastic on farms has become so common in recent decades that there -there’s a term for it—plasticulture. Image of the Day Human Presence August 16, 2023JPEGThe -Canary Islands were at the center of a mélange of natural events in summer 2023. The Moderate -Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this assemblage - -of phenomena off the coast of Africa on August 16, 2023.In the center of the scene, smoke -is seen rising from a wildfire burning on Tenerife in the Canary Islands. The blaze started -amid hot and dry conditions on August 15 in forests surrounding the Teide Volcano. Authorities -issued evacuation orders to five villages, and responders focused on containing the fire’s -spread and protecting residential areas near the coast, according to news reports. Other fires - -have burned on the Canary Islands this summer, including on La Palma in July.To the west, -a swirling cloud moves across the Atlantic. Cloud vortices appear routinely downwind of the -Canary Islands—sometimes in great abundance—and are produced when the tall volcanic peaks -disrupt the air flowing past them.Elsewhere in the atmosphere, dust from the Sahara Desert -was lofted out over the ocean. The river of dust crossing the Atlantic was more pronounced - -in previous days, when it reached islands in the Caribbean. Traveling on the Saharan Air Layer, -dust sometimes makes it even further west toward Central America and the U.S. states of Florida -and Texas.To round out the list, the patch of bright blue off the Moroccan coast is most likely -a bloom of phytoplankton. While the exact cause and composition of the bloom cannot be determined -from this image, mineral-rich desert dust has been shown to set off bursts of phytoplankton - -growth.In addition to the Earth’s processes seen here, one remote sensing artifact is present. -A diagonal streak of sunglint makes part of this scene appear washed out. Sunglint, an effect -that occurs when sunlight reflects off the surface of the water at the same angle that a satellite -sensor views it, is also the reason for the light-colored streaks trailing off the islands.NASA -Earth Observatory image by Wanmei Liang, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview. - -Story by Lindsey Doermann.View this area in EO ExplorerAn assortment of natural phenomena -visible from space appeared together in one image.Image of the Day for August 17, 2023 Image -of the Day Atmosphere Land Water View more Images of the Day:Flights were grounded as visibility -was severely hampered by a Calima event. Image of the Day Atmosphere Land Dust and Haze Human -Presence In one frame International Space Station astronauts were able to capture the evolution - -of fringing reefs to atolls. As with the Hawaiian Islands, these volcanic hot spot islands -become progressively older to the northwest. As these islands move away from their magma sources -they erode and subside. Image of the Day Land Water The dry, volcanic terrain of this Canary -Island is suitable for lichen and crops … and for training astronauts. Image of the Day Land -The event, known locally as “la calima,” turned skies orange and degraded air quality in Gran - -Canaria and neighboring islands. Image of the Day Atmosphere Land Dust and Haze July 17, 2023JPEGFour -funnel-shaped estuarine inlets, collectively known as Rías Baixas, line the coast of Galicia, -in northwest Spain. The nutrient-rich water in these inlets supports a wealth of marine life, -making the Galicia coast one of the most productive places for aquaculture.On July 17, 2023, -the Operational Land Imager-2 (OLI-2) on Landsat 9, acquired this image of the Rías de Arousa - -(Arousa estuary), the largest and northernmost of the inlets. Small dots skirt the coasts -of the embayment. In most cases, these dots are rectangular rafts designed for raising bivalves -like mussels. Buoys keep the lattice mussel rafts afloat on the surface of the water, and -hundreds of ropes are suspended into the water column from each structure. Mussels attach -to the ropes and filter feed on phytoplankton and other suspended organic particles. The rafts - -allow for high yields of mussels in a small area of the water. The Rías Baixas are on the -northern end of the Canary current and are in a major upwelling zone. Upwelling, which brings -colder, nutrient-rich water up from the bottom of the ocean, typically occurs in this area -between April and October. Much of the mussel production in the Rías Baixas occurs during -this time, as the mollusks filter feed on nutrients and plentiful phytoplankton supported - -by upwelling. Spain is the top mussel producing country in the world. Rías de Arousa alone -contains over 2,400 mussel rafts, producing about 40 percent of Europe’s mussels. NASA Earth -Observatory image by Wanmei Liang, using Landsat data from the U.S. Geological Survey. Story -by Emily Cassidy. Buoys keep the lattice mussel rafts afloat on the surface of the water, -and hundreds of ropes are suspended into the water column from each structure. Mussels attach - -to the ropes and filter feed on phytoplankton and other suspended organic particles. The rafts -allow for high yields of mussels in a small area of the water. The Rías Baixas are on the -northern end of the Canary current and are in a major upwelling zone. Upwelling, which brings -colder, nutrient-rich water up from the bottom of the ocean, typically occurs in this area -between April and October. Much of the mussel production in the Rías Baixas occurs during - -this time, as the mollusks filter feed on nutrients and plentiful phytoplankton supported -by upwelling. Spain is the top mussel producing country in the world. Rías de Arousa alone -contains over 2,400 mussel rafts, producing about 40 percent of Europe’s mussels. NASA Earth -Observatory image by Wanmei Liang, using Landsat data from the U.S. Geological Survey. Story -by Emily Cassidy.View this area in EO ExplorerThe estuarine inlets of Spain’s Galicia coast - -are some of the most productive places to grow mussels.Image of the Day for September 19, -2023 Image of the Day Water Human Presence View more Images of the Day: Dust and Haze This -image shows Tropical Cyclones Eric and Fanele near Madagascar on January 19, 2009. Atmosphere -Water Severe Storms This natural-color image shows Saharan dust forming an S-shaped curve -off the western coast of Africa, and passing directly over Cape Verde. Atmosphere Land Dust - -and Haze Acquired March 8, 2010, this true-color image shows two icebergs, Iceberg B-09B and -an iceberg recently broken off the Mertz Glacier, floating in the Southern Ocean, just off -the George V Coast. Water Snow and Ice Sea and Lake Ice May 18, 2023JPEGSeptember 7, 2023JPEGMay -18, 2023September 7, 2023May 18, 2023JPEGSeptember 7, 2023JPEGSeptember 7, 2023JPEGAfter going -dry in 2018, Laguna de Aculeo has begun to refill. NASA satellites began to detect water pooling - -in the parched lake in late-August, after an intense winter storm dropped as much as 370 millimeters -(15 inches) of rain on some parts of central Chile. The storm was fueled by an atmospheric -river and exacerbated by the rugged terrain in central Chile.When the Operational Land Imager-2 -(OLI-2) on Landsat 9 acquired this image (right) on September 7, 2023, Laguna de Aculeo covered -about 5 square kilometers (2 square miles) to a depth of roughly 1 meter (3 feet). The other - -image (left) shows the dried water body on May 18, 2023, before the wet winter weather arrived. -Although it has refilled somewhat, water spans only half the area it did up to 2010 and contains -a quarter of the water volume, explained René Garreaud, an Earth scientist at the University -of Chile. Seasonal changes and the influx of water have led to widespread greening of the -landscape around the lake.Researchers have assessed that ongoing development and water use - -in the nearby community of Paine, increasing water use by farmers and in homes and pools, -as well as several years of drought, likely contributed to the drawdown of the lake. Annual -rainfall deficits that averaged 38 percent between 2010 and 2018 likely played a large role, -according to one analysis from a team of researchers from the University of Chile.Before 2010, -the shallow water body was a popular haven for boaters, swimmers, and water skiers, but the - -water hasn’t yet pooled up enough for swimmers or boaters to return. It is also unclear how -long the new water in Aculeo will persist. “Atmospheric rivers in June and August delivered -substantial precipitation along the high terrain and foothills that have giv­­en us a welcome -interruption to the drought,” Garreaud said. “But Aculeo is a small, shallow lagoon that can -fill up rapidly, and it's only partly filled. Bigger reservoirs and aquifers will take much - -longer to recover.”NASA Earth Observatory images by Lauren Dauphin, using Landsat data from -the U.S. Geological Survey. Story by Adam Voiland.View this area in EO ExplorerThe drought -in Chile isn’t over, but recent late-winter rains provided enough moisture for water to start -pooling up again.Image of the Day for September 16, 2023 Image of the Day Life Water View -more Images of the Day:Data from winter 2022-2023 show the greatest net gain of water in nearly - -22 years, but groundwater levels still suffer from years of drought. Image of the Day Land -Water As a persistent drought drags on, water levels are dropping at a key reservoir that -supplies Santiago. Image of the Day Land Water A new web tool designed by NASA applied scientists -could help the tribe anticipate and respond to drought. Image of the Day Water Human Presence -Remote Sensing For more than 100 years, groups in the western United States have fought over - -water. During the 1880s, sheep ranchers and cattle ranchers argued over drinking water for -their livestock on the high plains. In 1913, the city of Los Angeles began to draw water away -from small agricultural communities in Owen Valley, leaving a dusty dry lake bed. In the late -1950s, construction of the Glen Canyon Dam catalyzed the American environmental movement. -Today, farmers are fighting fishermen, environmentalists, and Native American tribes over - -the water in the Upper Klamath River Basin. The Landsat 7 satellite, launched by NASA and -operated by the U.S. Geological Survey, documented an extreme drought in the area along the -California/Oregon border in the spring of 2001. Image of the Day Land Life September 16, 2023JPEGSeptember -10, 2021JPEGSeptember 16, 2023September 10, 2021September 16, 2023JPEGSeptember 10, 2021JPEGSeptember -10, 2021JPEGMonths of excessive heat and drought parched the Mississippi River in the summer - -and early fall of 2023. In September, low water levels limited barge shipments downriver and -threatened drinking water supplies in some Louisiana communities, according to the Associated -Press.Water levels were especially low near Memphis, Tennessee. The images above show the -Mississippi River near Memphis on September 16, 2023 (left), compared to September 10, 2021 -(right). The river was significantly slimmed down in 2023, exposing some of the river bottom.This - -is the second year in a row drought has caused the river to fall to near-record lows at many -gauges. On September 26, 2023, the river level at a gauge in Memphis was -10.26 feet, close -to the record low level, -10.81 feet, measured at the same place on October 21, 2022. That -was the lowest level recorded there since the start of National Weather Service records in -1954. Water levels, or “gauge heights,” do not indicate the depth of a stream; rather, they - -are measured with respect to a chosen reference point. That is why some gauge height measurements -are negative.Farther upstream, water levels at New Madrid, Missouri, have been around -5 feet—near -the minimum operating level—since early September 2023. Water levels on the Mississippi normally -decline in the fall and winter, and in 2022, the river did not get that low until mid-October. -September 26, 2023JPEGA hot, dry summer is the main reason water levels dropped so low in - -2023. Across the globe, temperatures in summer 2023 were 1.2°C (2.1°F) warmer than average. -In the U.S., Louisiana and Mississippi experienced their hottest Augusts on record, according -to NOAA.The U.S. Drought Monitor map above—the product of a partnership between the U.S. Department -of Agriculture, the National Oceanic and Atmospheric Administration, and the University of -Nebraska-Lincoln—shows conditions during the week of September 20-26, 2023. The map depicts - -drought intensity in progressive shades of orange to red. It is based on an analysis of climate, -soil, and water condition measurements from more than 350 federal, state, and local observers -around the country. NASA contributes measurements and models that aid the drought monitoring -effort.During that week, about 38 percent of the contiguous U.S. was experiencing drought. -Lack of precipitation and high temperatures over several months severely dried out soils in - -states along the Mississippi River Valley. The Drought Monitor reported that 80 percent of -soils in Louisiana were dry (short or very short on water) as of September 24. And for most -states in the river valley, over 50 percent of topsoil was dry or very dry.Shallow conditions -along the river interrupted normal shipments of goods. According to the Associated Press, -barge companies reduced the weight carried in many shipments in September because the river - -was not deep enough to accommodate their normal weight. Much of U.S. grain exports are transported -down the Mississippi, and according to AP, the cost of these shipments from St. Louis southward -has risen 77 percent above the three-year average. The lack of freshwater flowing into the -Gulf of Mexico has also allowed saltwater to make its way up the river and into some water -treatment plants in southern Louisiana, according to the Associated Press. Some parts of Plaquemines - -Parish are under drinking water advisories and have relied on bottled water for cooking and -drinking since June.Significant rainfall would be needed to flush out saltwater in the river -in Plaquemines. According to the National Weather Service’s Lower Mississippi River Forecast -Center, the forecast does not look promising. If enough rainfall doesn’t arrive before mid-to-late -October, saltwater could make its way to New Orleans.NASA Earth Observatory images by Lauren - -Dauphin, using Landsat data from the U.S. Geological Survey and data from the United States -Drought Monitor at the University of Nebraska-Lincoln. Story by Emily Cassidy.View this area -in EO ExplorerIn September, low water levels made it more challenging to ship goods down the -river and allowed a wedge of saltwater to move upstream.Image of the Day for October 1, 2023 -Image of the Day Water Drought View more Images of the Day:Persistent dry conditions can affect - -water resources, ecosystems, and agriculture.Severe drought is reducing the number of daily -passages on the transoceanic shipping route. Image of the Day Water Human Presence Prolonged -drought in Kansas set the stage for what may be one of the state’s smallest wheat harvests -in decades. Image of the Day Land Water Drought The most severe drought in 70 years of record -keeping threatens the Horn of Africa with famine. Image of the Day Land Water Drought Low - -water levels are making it difficult to ship goods down the river and allowing a wedge of -saltwater to move upstream. Image of the Day Land Water Human Presence Remote Sensing September -25, 2023JPEGLake Winnipeg, the world’s 10th largest freshwater lake by surface area, has experienced -algae blooms at a regular occurrence at least since the 1990s. A bloom of blue-green algae -once again covered parts of the lake in September 2023. Located in Manitoba, Canada, the long - -lake has a watershed that spans one million square kilometers (386,000 square miles), draining -some of Canada’s agricultural land. The lake consists of a large, deep north basin and a smaller, -comparatively shallow south basin. Swirls of algae filled the south basin of the lake on September -25, 2023, when the OLI-2 (Operational Land Imager-2) on Landsat 9 acquired this image. Around -this time, satellite observations analyzed by Environment and Climate Change Canada indicated - -that algae covered about 8,400 square kilometers (3,200 square miles), or about a third of -the lake’s area.Blue-green algae, also known as cyanobacteria, are single-celled organisms -that rely on photosynthesis to turn sunlight into food. The bacteria grow swiftly when nutrients -like phosphorus and nitrogen are abundant in still water. The bloom pictured here may contain -blue-green algae, as well as other types of phytoplankton; only a surface sample can confirm - -the exact composition of a bloom. Some cyanobacteria produce microcystin—a potent toxin that -can irritate the skin and cause liver and kidney damage.While algae are part of a natural -freshwater ecosystem, excess algae, particularly cyanobacteria, can be a nuisance to residents -and tourists using the lake and its beaches for fishing, swimming, and recreation. Beaches -in the south basin of Lake Winnipeg can get as many as 30,000 visitors a day during the summer - -months. Water samples taken at Winnipeg Beach on the west shore found that cyanobacteria levels -were elevated in August, and visitors were advised to avoid swimming and fishing if green -scum was visible. The health of Lake Winnipeg has been in decline in recent decades. Between -1990 and 2000, phosphorous concentrations in the lake almost doubled and algae blooms proliferated, -both in terms of occurrence and extent. The major contributors to the influx of phosphorous - -to the lake were increased agricultural activities in the watershed and a higher frequency -of flooding, which has increased runoff into the lake.Phosphorus concentrations are almost -three times higher in the south basin of Lake Winnipeg, compared to the north basin. A 2019 -study using data from the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument -on NASA’s Terra satellite found that the chlorophyll-a concentrations, which are used as a - -measure of phytoplankton biomass, were on average more than twice as high in the south basin, -compared to the north. NASA Earth Observatory images by Wanmei Liang, using Landsat data from -the U.S. Geological Survey. Story by Emily Cassidy.View this area in EO ExplorerAn influx -of nutrients in recent decades has contributed to the proliferation of algae in the large -Canadian lake.Image of the Day for October 6, 2023 Image of the Day Water Water Color View - -more Images of the Day:Floating, plant-like organisms reproduce abundantly when there are -sufficient nutrients, sunlight, and water conditions. Extreme blooms of certain species can -become harmful to marine animals and humans.Cyanobacteria covered over half of the surface -of Florida’s largest freshwater lake in mid-June 2023. Image of the Day Life Water Water Color -Nearly half of the lake was covered with blue-green algae in early July 2022. Image of the - -Day Water Remote Sensing Water Color More than 40 years after the explosive eruption of Mount -St. Helens, relics from the blast continue to haunt a nearby lake. Image of the Day Water -Venezuela’s Lake Maracaibo is choking with oil slicks and algae. Image of the Day Life Water -Human Presence Remote Sensing October 8, 2022JPEGOctober 3, 2023JPEGOctober 8, 2022October -3, 2023October 8, 2022JPEGOctober 3, 2023JPEGOctober 3, 2023JPEGJuly through October fall - -within the dry season in the western and northern Amazon rainforest, but a particularly acute -lack of rain during this period in 2023 has pushed the region into a severe drought.The OLI -(Operational Land Imager) instrument on Landsat 8 captured this image (right) of the parched -Rio Negro in the Brazilian province of Amazonas near the city of Manaus on October 3, 2023. -On that date, the level of the river, the largest tributary of the Amazon River, had dropped - -to 15.14 meters (50.52 feet), according to data collected by the Port of Manaus. For comparison, -the image on the left shows the same area on October 8, 2022, when the water level was 19.59 -meters, a more typical level for October. Rio Negro water levels continued to drop in the -days after the image was collected, reaching a record low of 13.49 meters on October 17, 2023.Some -areas in the Amazon River’s watershed have received less rain between July and September than - -any year since 1980, Reuters reported. The drought has been particularly severe in the Rio -Negro watershed in northern Amazonas, as well as parts of southern Venezuela and southern -Colombia.“Overall, this is a pretty unusual and extreme situation,” said René Garreaud, an -atmospheric scientist at the University of Chile. “The primary culprit exacerbating the drought -appears to be El Niño.” This cyclical warming of surface waters in the central-eastern Pacific - -functions somewhat like a boulder in the middle of a stream, disrupting atmospheric circulation -patterns in ways that lead to wetter conditions over the equatorial Pacific and drier conditions -over the Amazon Basin.According to news outlets, the low river water levels on the Rio Negro -and other nearby rivers have disrupted drinking water supplies in hundreds of communities, -slowed commercial navigation, and led to fish and dolphin die-offs.Manaus, the capital and - -largest city of the Brazilian state of Amazonas, is the primary transportation hub for the -upper Amazon, serving as an important transit point for soap, beef, and animal hides. Other -industries with a presence in the city of two million people include chemical, ship, and electrical -equipment manufacturing.NASA Earth Observatory images by Wanmei Liang, using Landsat data -from the U.S. Geological Survey. Story by Adam Voiland.View this area in EO ExplorerThe water - -level of the largest tributary of the Amazon River has hit a record low.Image of the Day for -October 18, 2023 Image of the Day Water Human Presence View more Images of the Day:The impact -of severe drought on the Negro River, a tributary of the Amazon River, and other rivers in -the basin is dramatically evident in this pair of images, which show that every body of water -has shrunk in 2010 compared to 2008. Image of the Day Atmosphere Land The volume of water - -in New Mexico’s largest reservoir has dropped to historic lows due to drought and persistent -demand. Image of the Day Water Human Presence Acquired June 25, 2011, and June 22, 2010, these -false-color images compare conditions along the Souris River, which reached a historic crest -at Minot, North Dakota in June 2011. Land Floods Acquired May 11, 2011, and April 21, 2007, -these false-color images show the Mississippi River near Natchez, Mississippi. The image from - -May 2011 shows flooded conditions. Land Floods September 6, 2020JPEGSeptember 7, 2023JPEGSeptember -6, 2020September 7, 2023September 6, 2020JPEGSeptember 7, 2023JPEGSeptember 7, 2023JPEGAfter -rapidly growing in volume just a few years earlier, northwest Iran’s Lake Urmia nearly dried -out in autumn 2023. The largest lake in the Middle East and one of the largest hypersaline -lakes on Earth at its greatest extent, Lake Urmia has for the most part transformed into a - -vast, dry salt flat. On September 7, 2023, the OLI-2 (Operational Land Imager-2) on Landsat -9 captured this image (right) of the desiccated lakebed. It stands in contrast to the image -from three years earlier (left), acquired by the OLI on Landsat 8 on September 8, 2020, when -water filled most of the basin and salt deposits were only visible around the perimeter of -the lake. The replenishment followed a period of above-average precipitation that sent a surge - -of freshwater into the basin, expanding its watery footprint. Drier conditions have since -brought levels back down. The longer-term trend for Urmia has been one toward drying. In 1995, -Lake Urmia reached a high-water mark; then in the ensuing two decades, the lake level dropped -more than 7 meters (23 feet) and lost approximately 90 percent of its area. Consecutive droughts, -agricultural water use, and dam construction on rivers feeding the lake have contributed to - -the decline. A shrinking Lake Urmia has implications for ecological and human health. The -lake, its islands, and surrounding wetlands comprise valuable habitat and are recognized as -a UNESCO Biosphere Reserve, Ramsar site, and national park. The area provides breeding grounds -for waterbirds such as flamingos, white pelicans, and white-headed ducks, as well as a stopover -for migratory species. However, with low lake levels, what water remains becomes more saline - -and taxes the populations of brine shrimp and other food sources for larger animals. A shrinking -lake also increases the likelihood of dust from the exposed lakebed becoming swept up by winds -and degrading air quality. Recent studies have linked the low water levels in Lake Urmia with -respiratory health impacts among the local population.The relative effects of climate, water -usage, and dams on Lake Urmia’s water level is a topic of debate. The lake did see some recovery - -during a 10-year restoration program beginning in 2013. However, the efficacy of that effort -has been difficult to parse since strong rains also fell during that period. Some research -has concluded that climatic factors were primarily responsible for the recovery. NASA Earth -Observatory images by Lauren Dauphin, using Landsat data from the U.S. Geological Survey. -Story by Lindsey Doermann.View this area in EO ExplorerA few years after a fresh influx of - -water raised its levels, the large lake has nearly gone dry.Image of the Day for October 10, -2023 Image of the Day Land Water View more Images of the Day:Water levels are at their lowest -since 1937. Image of the Day Water Drought Fires Long and short. Deep and shallow. Salty and -fresh. Blue and brown. These are Africa’s Lake Tanganyika and Lake Rukwa. Image of the Day -Land Water In May 2016, the reservoir behind Hoover Dam reached its lowest level since the - -1930s. Image of the Day Water When the water gets saltier in Iran’s largest lake, the microscopic -inhabitants can turn the water dark red. Image of the Day Water Water Color July 1 - September -30, 2023MPEG For several months in 2023, global sea surface temperatures reached record-high -levels, fueled by decades of human-caused climate warming and a recent boost from the natural -climate phenomenon El Niño. Some areas—including the seas around Florida, Cuba, and the Bahamas—saw - -particularly high temperatures, with implications for the health of coral reefs.Corals thrive -within a small range of temperatures and become stressed when water is too hot or cold. Bleaching -occurs when stressed corals expel the algae that live inside them, stripping corals of their -color. Extreme bleaching can leave a reef susceptible to starvation, disease, and even death. -Observations made by divers in the Florida Keys found that the marine heatwave in summer 2023 - -caused widespread bleaching.Stress on corals can also be detected using data from satellites. -This animation shows the evolution of accumulated heat stress from July through September -2023. The colors depict “degree heating weeks” (°C-weeks)—a measure that provides an estimate -of the severity and duration of thermal stress. Data for the product are compiled by NOAA’s -Coral Reef Watch, which blends observations from polar orbiting satellites such as the NASA-NOAA - -Suomi NPP, and from geostationary satellites such as GOES, with computer models.Observations -have shown that when the accumulated heat stress reaches a value of 4, significant coral bleaching -can result. At values of 8, coral bleaching and widespread mortality are likely. By midway -through this animation, in August, heat stress across much of the region already soared well -above both of those thresholds. According to NOAA, cumulative heat stress by late September - -2023 hit 22°C-weeks (40°F-weeks), nearly triple the previous record for the region.Bleaching -was already observed in some areas as early as July. Notice that areas of coral reef (gray) -near the Florida Keys, Cuba, and the Bahamas, are among the first areas to show high cumulative -heat stress. Hurricane Idalia in late August helped cool surface waters somewhat, but only -temporarily.Nearing mid-October, waters around the Florida Keys were under a bleaching watch. - -Further south, waters around parts of Cuba and the Bahamas remained at bleaching alert level -2, the highest level of the scale, signifying that severe bleaching and mortality are likely.NASA -Earth Observatory animation by Wanmei Liang, using Daily 5km Degree Heating Weeks data from -Coral Reef Watch. Coral reef data from UNEP-WCMC, WorldFish Centre, WRI, TNC. Story by Kathryn -Hansen.View this area in EO ExplorerThe seas around Florida, Cuba, and the Bahamas saw large - -accumulations of heat stress beginning in summer 2023, with implications for the health of -coral reefs.Image of the Day for October 16, 2023 Image of the Day Water Temperature Extremes -View more Images of the Day:Warmer-than-average temperatures are showing up locally and globally, -with consequences for people, landscapes, and ecosystems. Image of the Day Water Image of -the Day Life Water Image of the Day Heat Life Water Studying corals from above could help - -scientists understand how these critical ecosystems will weather a changing climate. Image -of the Day Land Life Water January 22 - July 26, 2023JPEGOne of the wettest wet seasons in -northern Australia transformed large areas of the country’s desert landscape over the course -of many months in 2023. A string of major rainfall events that dropped 690 millimeters (27 -inches) between October 2022 and April 2023 made it the sixth-wettest season on record since - -1900–1901.This series of false-color images illustrates the rainfall’s months-long effects -downstream in the Lake Eyre Basin. Water appears in shades of blue, vegetation is green, and -bare land is brown. The images were acquired by the Moderate Resolution Imaging Spectroradiometer -(MODIS) on NASA’s Terra satellite between January and July 2023.In the January 22 image (left), -water was coursing through seasonally dry channels of the Georgina River and Eyre Creek following - -weeks of heavy rains in northern Queensland. By April 21 (middle), floodwaters had reached -further downstream after another intense period of precipitation in March. This scene shows -that water had filled in some of the north-northwest trending ridges that are part of a vast -fossil landscape of wind-formed dunes, while vegetation had emerged in wet soil upstream. -Then by July 26 (right), the riverbed had filled with even more vegetation.The Georgina River - -and Eyre Creek drain approximately 210,000 square kilometers (81,000 square miles), nearly -the area of the United Kingdom. Visible in the lower part of the images, the lake gets refreshed -about every three years; when it reaches especially high levels, it may take 18 months to -2 years to dry up. Two smaller neighboring lakes flood seasonally. These three lakes and surrounding -floodplains support hundreds of thousands of waterbirds and are designated as an Important - -Bird Area.Seasonal flooding is a regular occurrence in these desert river systems. However, -the events of the 2022-2023 rainy season stood out in several ways. They occurred while La -Niña conditions were in place over the tropical Pacific Ocean. (The wettest seasons in northern -Australia have all occurred during La Niña years, according to Australia’s Bureau of Meteorology.) -In addition, major rains occurring in succession, as was the case with the January and March - -events, have the overall effect of prolonging floods. That’s because vegetation that grows -after the first event slows down the pulse of water that comes through in the next rain event.The -high water has affected both local communities and ecosystems. Floods have inundated cattle -farms and isolated towns on temporary islands. At the same time, they are a natural feature -of the “boom-and-bust” ecology of Channel Country, providing habitat and nutrients that support - -biodiversity.NASA Earth Observatory image by Wanmei Liang, using MODIS data from NASA EOSDIS -LANCE and GIBS/Worldview. Story by Lindsey Doermann.View this area in EO ExplorerRepeated -heavy rains in Australia set off waves of new growth across Channel Country.Image of the Day -for August 7, 2023 Image of the Day Land Water View more Images of the Day: Floods The waves -off the coast of Teahupo’o can heave a crushing amount of water toward the shore and onto - -unlucky surfers. Image of the Day Water Waves of heavy rainfall left towns and farmland under -water in October 2022. Image of the Day Water Floods Acquired February 26, 2011, and February -5, 2011, these false-color images show the impact of heavy rains in marshy areas southeast -of Georgetown, Guyana. Land Floods August 25, 2023JPEGSeptember 18, 2023JPEGAugust 25, 2023September -18, 2023August 25, 2023JPEGSeptember 18, 2023JPEGSeptember 18, 2023JPEGHeavy rain from a cyclone - -in the Mediterranean inundated cities along the northeastern coast of Libya in early September -2023, causing thousands of deaths. The port city of Derna (Darnah), home to about 90,000 people, -was one of the worst hit by the storm and suffered extensive flooding and damage. On September -10 and 11, over 100 millimeters (4 inches) of rain fell on Derna. The city lies at the end -of a long, narrow valley, called a wadi, which is dry except during the rainy season. Floods - -triggered two dams along the wadi to collapse. The failure of the second dam, located just -one kilometer inland of Derna, unleashed 3- to 7-meter-high floodwater that tore through the -city. According to news reports, the flash floods destroyed roads and swept entire neighborhoods -out to sea. The images above show the city before and after the storm. The image on the right, -acquired by the Operational Land Imager-2 (OLI-2) on Landsat 9 on September 18, shows eroded - -banks of Wadi Derna near where it meets the Mediterranean. Water just off the coast appears -muddier than in the image on the left, which shows the same area on August 25 and was acquired -by Landsat 8. Preliminary estimates by the United Nations Satellite Center (UNOSAT) indicate -that 3,100 buildings in Derna were damaged by rushing water. According to the UN International -Organization for Migration (IOM), about 40,000 people in the country were displaced by the - -storm, and 30,000 of those were displaced from Derna. Tropical-like cyclones in the Mediterranean, -or “medicanes,” develop only once or twice a year, according to NOAA, and typically form in -autumn. According to meteorologists at Yale Climate Connections, this storm was the deadliest -in Africa’s recorded history. A recent assessment by scientists at World Weather Attribution -estimated that precipitation received by the region was a one-in-300 to one-in-600-year event. - -NASA Earth Observatory images by Lauren Dauphin, using Landsat data from the U.S. Geological -Survey. Story by Emily Cassidy.View this area in EO ExplorerFlash floods in the port city -destroyed roads and swept neighborhoods out to sea.Image of the Day for September 21, 2023 -Image of the Day Land Water Floods Human Presence View more Images of the Day:The melting -of frozen rivers and snowpack, and the heavy rains of late spring and summer, can send rivers - -out of their banks.A Mediterranean cyclone contributed to deadly flooding along the country’s -coastline. Image of the Day Land Water Floods Record rainfall inundated towns and farmland -in the country’s Thessaly region. Image of the Day Water Floods Human Presence A stalled storm -dropped three feet of rain over four days on the Thessaly region, triggering extensive flooding. -Image of the Day Atmosphere Floods An isolated low-pressure system produced torrential downpours - -in Spain and carried Saharan dust along its path. Image of the Day Atmosphere Land Floods -Human Presence July 2002 - June 2022JPEGThe deep-blue sea is turning a touch greener. While -that may not seem as consequential as, say, record warm sea surface temperatures, the color -of the ocean surface is indicative of the ecosystem that lies beneath. Communities of phytoplankton, -microscopic photosynthesizing organisms, abound in near-surface waters and are foundational - -to the aquatic food web and carbon cycle. This shift in the water’s hue confirms a trend expected -under climate change and signals changes to ecosystems within the global ocean, which covers -70 percent of Earth’s surface. Researchers led by B. B. Cael, a principal scientist at the -U.K.’s National Oceanography Centre, revealed that 56 percent of the global sea surface has -undergone a significant change in color in the past 20 years. After analyzing ocean color - -data from the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument on NASA’s Aqua -satellite, they found that much of the change stems from the ocean turning more green. The -map above highlights the areas where ocean surface color changed between 2002 and 2022, with -darker shades of green representing more-significant differences (higher signal-to-noise ratio). -By extension, said Cael, “these are places we can detect a change in the ocean ecosystem in - -the last 20 years.” The study focused on tropical and subtropical regions, excluding higher -latitudes, which are dark for part of the year, and coastal waters, where the data are naturally -very noisy. The black dots on the map indicate the area, covering 12 percent of the ocean’s -surface, where chlorophyll levels also changed over the study period. Chlorophyll has been -the go-to measurement for remote sensing scientists to gauge phytoplankton abundance and productivity. - -However, those estimates use only a few colors in the visible light spectrum. The values shown -in green are based on the whole gamut of colors and therefore capture more information about -the ecosystem as a whole. A long time series from a single sensor is relatively rare in the -remote sensing world. As the Aqua satellite was celebrating its 20th year in orbit in 2022—far -exceeding its design life of 6 years—Cael wondered what long term trends could be discovered - -in the data. In particular, he was curious what might have been missed in all the ocean color -information it had collected. “There’s more encoded in the data than we actually make use -of,” he said. By going big with the data, the team discerned an ocean color trend that had -been predicted by climate modeling, but one that was expected to take 30-40 years of data -to detect using satellite-based chlorophyll estimates. That’s because the natural variability - -in chlorophyll is high relative to the climate change trend. The new method, incorporating -all visible light, was robust enough to confirm the trend in 20 years. At this stage, it is -difficult to say what exact ecological changes are responsible for the new hues. However, -the authors posit, they could result from different assemblages of plankton, more detrital -particles, or other organisms such as zooplankton. It is unlikely the color changes come from - -materials such as plastics or other pollutants, said Cael, since they are not widespread enough -to register at large scales. “What we do know is that in the last 20 years, the ocean has -become more stratified,” he said. Surface waters have absorbed excess heat from the warming -climate, and as a result, they are less prone to mixing with deeper, more nutrient-rich layers. -This scenario would favor plankton adapted to a nutrient-poor environment. The areas of ocean - -color change align well with where the sea has become more stratified, said Cael, but there -is no such overlap with sea surface temperature changes. More insights into Earth’s aquatic -ecosystems may soon be on the way. NASA’s PACE (Plankton, Aerosol, Cloud, ocean Ecosystem) -satellite, set to launch in 2024, will return observations in finer color resolution. The -new data will enable researchers to infer more information about ocean ecology, such as the - -diversity of phytoplankton species and the rates of phytoplankton growth. NASA Earth Observatory -image by Wanmei Liang, using data from Cael, B. B., et al. (2023). Story by Lindsey Doermann.Two -decades of satellite measurements show that the sea surface is shading toward green.Image -of the Day for October 2, 2023 Image of the Day Life Water View more Images of the Day:Datasets -from the Sentinel-6 Michael Freilich satellite will build upon three decades of sea level - -measurements. Image of the Day Heat Water Remote Sensing Image of the Day Life Water Image -of the Day Water The use of plastic on farms has become so common in recent decades that there -there’s a term for it—plasticulture. Image of the Day Human Presence August 16, 2023JPEGThe -Canary Islands were at the center of a mélange of natural events in summer 2023. The Moderate -Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this assemblage - -of phenomena off the coast of Africa on August 16, 2023.In the center of the scene, smoke -is seen rising from a wildfire burning on Tenerife in the Canary Islands. The blaze started -amid hot and dry conditions on August 15 in forests surrounding the Teide Volcano. Authorities -issued evacuation orders to five villages, and responders focused on containing the fire’s -spread and protecting residential areas near the coast, according to news reports. Other fires - -have burned on the Canary Islands this summer, including on La Palma in July.To the west, -a swirling cloud moves across the Atlantic. Cloud vortices appear routinely downwind of the -Canary Islands—sometimes in great abundance—and are produced when the tall volcanic peaks -disrupt the air flowing past them.Elsewhere in the atmosphere, dust from the Sahara Desert -was lofted out over the ocean. The river of dust crossing the Atlantic was more pronounced - -in previous days, when it reached islands in the Caribbean. Traveling on the Saharan Air Layer, -dust sometimes makes it even further west toward Central America and the U.S. states of Florida -and Texas.To round out the list, the patch of bright blue off the Moroccan coast is most likely -a bloom of phytoplankton. While the exact cause and composition of the bloom cannot be determined -from this image, mineral-rich desert dust has been shown to set off bursts of phytoplankton - -growth.In addition to the Earth’s processes seen here, one remote sensing artifact is present. -A diagonal streak of sunglint makes part of this scene appear washed out. Sunglint, an effect -that occurs when sunlight reflects off the surface of the water at the same angle that a satellite -sensor views it, is also the reason for the light-colored streaks trailing off the islands.NASA -Earth Observatory image by Wanmei Liang, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview. - -Story by Lindsey Doermann.View this area in EO ExplorerAn assortment of natural phenomena -visible from space appeared together in one image.Image of the Day for August 17, 2023 Image -of the Day Atmosphere Land Water View more Images of the Day:Flights were grounded as visibility -was severely hampered by a Calima event. Image of the Day Atmosphere Land Dust and Haze Human -Presence In one frame International Space Station astronauts were able to capture the evolution - -of fringing reefs to atolls. As with the Hawaiian Islands, these volcanic hot spot islands -become progressively older to the northwest. As these islands move away from their magma sources -they erode and subside. Image of the Day Land Water The dry, volcanic terrain of this Canary -Island is suitable for lichen and crops … and for training astronauts. Image of the Day Land -The event, known locally as “la calima,” turned skies orange and degraded air quality in Gran - -Canaria and neighboring islands. Image of the Day Atmosphere Land Dust and Haze July 17, 2023JPEGFour -funnel-shaped estuarine inlets, collectively known as Rías Baixas, line the coast of Galicia, -in northwest Spain. The nutrient-rich water in these inlets supports a wealth of marine life, -making the Galicia coast one of the most productive places for aquaculture.On July 17, 2023, -the Operational Land Imager-2 (OLI-2) on Landsat 9, acquired this image of the Rías de Arousa - -(Arousa estuary), the largest and northernmost of the inlets. Small dots skirt the coasts -of the embayment. In most cases, these dots are rectangular rafts designed for raising bivalves -like mussels. Buoys keep the lattice mussel rafts afloat on the surface of the water, and -hundreds of ropes are suspended into the water column from each structure. Mussels attach -to the ropes and filter feed on phytoplankton and other suspended organic particles. The rafts - -allow for high yields of mussels in a small area of the water. The Rías Baixas are on the -northern end of the Canary current and are in a major upwelling zone. Upwelling, which brings -colder, nutrient-rich water up from the bottom of the ocean, typically occurs in this area -between April and October. Much of the mussel production in the Rías Baixas occurs during -this time, as the mollusks filter feed on nutrients and plentiful phytoplankton supported - -by upwelling. Spain is the top mussel producing country in the world. Rías de Arousa alone -contains over 2,400 mussel rafts, producing about 40 percent of Europe’s mussels. NASA Earth -Observatory image by Wanmei Liang, using Landsat data from the U.S. Geological Survey. Story -by Emily Cassidy. Buoys keep the lattice mussel rafts afloat on the surface of the water, -and hundreds of ropes are suspended into the water column from each structure. Mussels attach - -to the ropes and filter feed on phytoplankton and other suspended organic particles. The rafts -allow for high yields of mussels in a small area of the water. The Rías Baixas are on the -northern end of the Canary current and are in a major upwelling zone. Upwelling, which brings -colder, nutrient-rich water up from the bottom of the ocean, typically occurs in this area -between April and October. Much of the mussel production in the Rías Baixas occurs during - -this time, as the mollusks filter feed on nutrients and plentiful phytoplankton supported -by upwelling. Spain is the top mussel producing country in the world. Rías de Arousa alone -contains over 2,400 mussel rafts, producing about 40 percent of Europe’s mussels. NASA Earth -Observatory image by Wanmei Liang, using Landsat data from the U.S. Geological Survey. Story -by Emily Cassidy.View this area in EO ExplorerThe estuarine inlets of Spain’s Galicia coast - -are some of the most productive places to grow mussels.Image of the Day for September 19, -2023 Image of the Day Water Human Presence View more Images of the Day: Dust and Haze This -image shows Tropical Cyclones Eric and Fanele near Madagascar on January 19, 2009. Atmosphere -Water Severe Storms This natural-color image shows Saharan dust forming an S-shaped curve -off the western coast of Africa, and passing directly over Cape Verde. Atmosphere Land Dust - -and Haze Acquired March 8, 2010, this true-color image shows two icebergs, Iceberg B-09B and -an iceberg recently broken off the Mertz Glacier, floating in the Southern Ocean, just off -the George V Coast. Water Snow and Ice Sea and Lake Ice May 18, 2023JPEGSeptember 7, 2023JPEGMay -18, 2023September 7, 2023May 18, 2023JPEGSeptember 7, 2023JPEGSeptember 7, 2023JPEGAfter going -dry in 2018, Laguna de Aculeo has begun to refill. NASA satellites began to detect water pooling - -in the parched lake in late-August, after an intense winter storm dropped as much as 370 millimeters -(15 inches) of rain on some parts of central Chile. The storm was fueled by an atmospheric -river and exacerbated by the rugged terrain in central Chile.When the Operational Land Imager-2 -(OLI-2) on Landsat 9 acquired this image (right) on September 7, 2023, Laguna de Aculeo covered -about 5 square kilometers (2 square miles) to a depth of roughly 1 meter (3 feet). The other - -image (left) shows the dried water body on May 18, 2023, before the wet winter weather arrived. -Although it has refilled somewhat, water spans only half the area it did up to 2010 and contains -a quarter of the water volume, explained René Garreaud, an Earth scientist at the University -of Chile. Seasonal changes and the influx of water have led to widespread greening of the -landscape around the lake.Researchers have assessed that ongoing development and water use - -in the nearby community of Paine, increasing water use by farmers and in homes and pools, -as well as several years of drought, likely contributed to the drawdown of the lake. Annual -rainfall deficits that averaged 38 percent between 2010 and 2018 likely played a large role, -according to one analysis from a team of researchers from the University of Chile.Before 2010, -the shallow water body was a popular haven for boaters, swimmers, and water skiers, but the - -water hasn’t yet pooled up enough for swimmers or boaters to return. It is also unclear how -long the new water in Aculeo will persist. “Atmospheric rivers in June and August delivered -substantial precipitation along the high terrain and foothills that have giv­­en us a welcome -interruption to the drought,” Garreaud said. “But Aculeo is a small, shallow lagoon that can -fill up rapidly, and it's only partly filled. Bigger reservoirs and aquifers will take much - -longer to recover.”NASA Earth Observatory images by Lauren Dauphin, using Landsat data from -the U.S. Geological Survey. Story by Adam Voiland.View this area in EO ExplorerThe drought -in Chile isn’t over, but recent late-winter rains provided enough moisture for water to start -pooling up again.Image of the Day for September 16, 2023 Image of the Day Life Water View -more Images of the Day:Data from winter 2022-2023 show the greatest net gain of water in nearly - -22 years, but groundwater levels still suffer from years of drought. Image of the Day Land -Water As a persistent drought drags on, water levels are dropping at a key reservoir that -supplies Santiago. Image of the Day Land Water A new web tool designed by NASA applied scientists -could help the tribe anticipate and respond to drought. Image of the Day Water Human Presence -Remote Sensing For more than 100 years, groups in the western United States have fought over - -water. During the 1880s, sheep ranchers and cattle ranchers argued over drinking water for -their livestock on the high plains. In 1913, the city of Los Angeles began to draw water away -from small agricultural communities in Owen Valley, leaving a dusty dry lake bed. In the late -1950s, construction of the Glen Canyon Dam catalyzed the American environmental movement. -Today, farmers are fighting fishermen, environmentalists, and Native American tribes over - -the water in the Upper Klamath River Basin. The Landsat 7 satellite, launched by NASA and -operated by the U.S. Geological Survey, documented an extreme drought in the area along the -California/Oregon border in the spring of 2001. Image of the Day Land Life September 16, 2023JPEGSeptember -10, 2021JPEGSeptember 16, 2023September 10, 2021September 16, 2023JPEGSeptember 10, 2021JPEGSeptember -10, 2021JPEGMonths of excessive heat and drought parched the Mississippi River in the summer - -and early fall of 2023. In September, low water levels limited barge shipments downriver and -threatened drinking water supplies in some Louisiana communities, according to the Associated -Press.Water levels were especially low near Memphis, Tennessee. The images above show the -Mississippi River near Memphis on September 16, 2023 (left), compared to September 10, 2021 -(right). The river was significantly slimmed down in 2023, exposing some of the river bottom.This - -is the second year in a row drought has caused the river to fall to near-record lows at many -gauges. On September 26, 2023, the river level at a gauge in Memphis was -10.26 feet, close -to the record low level, -10.81 feet, measured at the same place on October 21, 2022. That -was the lowest level recorded there since the start of National Weather Service records in -1954. Water levels, or “gauge heights,” do not indicate the depth of a stream; rather, they - -are measured with respect to a chosen reference point. That is why some gauge height measurements -are negative.Farther upstream, water levels at New Madrid, Missouri, have been around -5 feet—near -the minimum operating level—since early September 2023. Water levels on the Mississippi normally -decline in the fall and winter, and in 2022, the river did not get that low until mid-October. -September 26, 2023JPEGA hot, dry summer is the main reason water levels dropped so low in - -2023. Across the globe, temperatures in summer 2023 were 1.2°C (2.1°F) warmer than average. -In the U.S., Louisiana and Mississippi experienced their hottest Augusts on record, according -to NOAA.The U.S. Drought Monitor map above—the product of a partnership between the U.S. Department -of Agriculture, the National Oceanic and Atmospheric Administration, and the University of -Nebraska-Lincoln—shows conditions during the week of September 20-26, 2023. The map depicts - -drought intensity in progressive shades of orange to red. It is based on an analysis of climate, -soil, and water condition measurements from more than 350 federal, state, and local observers -around the country. NASA contributes measurements and models that aid the drought monitoring -effort.During that week, about 38 percent of the contiguous U.S. was experiencing drought. -Lack of precipitation and high temperatures over several months severely dried out soils in - -states along the Mississippi River Valley. The Drought Monitor reported that 80 percent of -soils in Louisiana were dry (short or very short on water) as of September 24. And for most -states in the river valley, over 50 percent of topsoil was dry or very dry.Shallow conditions -along the river interrupted normal shipments of goods. According to the Associated Press, -barge companies reduced the weight carried in many shipments in September because the river - -was not deep enough to accommodate their normal weight. Much of U.S. grain exports are transported -down the Mississippi, and according to AP, the cost of these shipments from St. Louis southward -has risen 77 percent above the three-year average. The lack of freshwater flowing into the -Gulf of Mexico has also allowed saltwater to make its way up the river and into some water -treatment plants in southern Louisiana, according to the Associated Press. Some parts of Plaquemines - -Parish are under drinking water advisories and have relied on bottled water for cooking and -drinking since June.Significant rainfall would be needed to flush out saltwater in the river -in Plaquemines. According to the National Weather Service’s Lower Mississippi River Forecast -Center, the forecast does not look promising. If enough rainfall doesn’t arrive before mid-to-late -October, saltwater could make its way to New Orleans.NASA Earth Observatory images by Lauren - -Dauphin, using Landsat data from the U.S. Geological Survey and data from the United States -Drought Monitor at the University of Nebraska-Lincoln. Story by Emily Cassidy.View this area -in EO ExplorerIn September, low water levels made it more challenging to ship goods down the -river and allowed a wedge of saltwater to move upstream.Image of the Day for October 1, 2023 -Image of the Day Water Drought View more Images of the Day:Persistent dry conditions can affect - -water resources, ecosystems, and agriculture.Severe drought is reducing the number of daily -passages on the transoceanic shipping route. Image of the Day Water Human Presence Prolonged -drought in Kansas set the stage for what may be one of the state’s smallest wheat harvests -in decades. Image of the Day Land Water Drought The most severe drought in 70 years of record -keeping threatens the Horn of Africa with famine. Image of the Day Land Water Drought Low - -water levels are making it difficult to ship goods down the river and allowing a wedge of -saltwater to move upstream. Image of the Day Land Water Human Presence Remote Sensing September -25, 2023JPEGLake Winnipeg, the world’s 10th largest freshwater lake by surface area, has experienced -algae blooms at a regular occurrence at least since the 1990s. A bloom of blue-green algae -once again covered parts of the lake in September 2023. Located in Manitoba, Canada, the long - -lake has a watershed that spans one million square kilometers (386,000 square miles), draining -some of Canada’s agricultural land. The lake consists of a large, deep north basin and a smaller, -comparatively shallow south basin. Swirls of algae filled the south basin of the lake on September -25, 2023, when the OLI-2 (Operational Land Imager-2) on Landsat 9 acquired this image. Around -this time, satellite observations analyzed by Environment and Climate Change Canada indicated - -that algae covered about 8,400 square kilometers (3,200 square miles), or about a third of -the lake’s area.Blue-green algae, also known as cyanobacteria, are single-celled organisms -that rely on photosynthesis to turn sunlight into food. The bacteria grow swiftly when nutrients -like phosphorus and nitrogen are abundant in still water. The bloom pictured here may contain -blue-green algae, as well as other types of phytoplankton; only a surface sample can confirm - -the exact composition of a bloom. Some cyanobacteria produce microcystin—a potent toxin that -can irritate the skin and cause liver and kidney damage.While algae are part of a natural -freshwater ecosystem, excess algae, particularly cyanobacteria, can be a nuisance to residents -and tourists using the lake and its beaches for fishing, swimming, and recreation. Beaches -in the south basin of Lake Winnipeg can get as many as 30,000 visitors a day during the summer - -months. Water samples taken at Winnipeg Beach on the west shore found that cyanobacteria levels -were elevated in August, and visitors were advised to avoid swimming and fishing if green -scum was visible. The health of Lake Winnipeg has been in decline in recent decades. Between -1990 and 2000, phosphorous concentrations in the lake almost doubled and algae blooms proliferated, -both in terms of occurrence and extent. The major contributors to the influx of phosphorous - -to the lake were increased agricultural activities in the watershed and a higher frequency -of flooding, which has increased runoff into the lake.Phosphorus concentrations are almost -three times higher in the south basin of Lake Winnipeg, compared to the north basin. A 2019 -study using data from the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument -on NASA’s Terra satellite found that the chlorophyll-a concentrations, which are used as a - -measure of phytoplankton biomass, were on average more than twice as high in the south basin, -compared to the north. NASA Earth Observatory images by Wanmei Liang, using Landsat data from -the U.S. Geological Survey. Story by Emily Cassidy.View this area in EO ExplorerAn influx -of nutrients in recent decades has contributed to the proliferation of algae in the large -Canadian lake.Image of the Day for October 6, 2023 Image of the Day Water Water Color View - -more Images of the Day:Floating, plant-like organisms reproduce abundantly when there are -sufficient nutrients, sunlight, and water conditions. Extreme blooms of certain species can -become harmful to marine animals and humans.Cyanobacteria covered over half of the surface -of Florida’s largest freshwater lake in mid-June 2023. Image of the Day Life Water Water Color -Nearly half of the lake was covered with blue-green algae in early July 2022. Image of the - -Day Water Remote Sensing Water Color More than 40 years after the explosive eruption of Mount -St. Helens, relics from the blast continue to haunt a nearby lake. Image of the Day Water -Venezuela’s Lake Maracaibo is choking with oil slicks and algae. Image of the Day Life Water -Human Presence Remote Sensing October 8, 2022JPEGOctober 3, 2023JPEGOctober 8, 2022October -3, 2023October 8, 2022JPEGOctober 3, 2023JPEGOctober 3, 2023JPEGJuly through October fall - -within the dry season in the western and northern Amazon rainforest, but a particularly acute -lack of rain during this period in 2023 has pushed the region into a severe drought.The OLI -(Operational Land Imager) instrument on Landsat 8 captured this image (right) of the parched -Rio Negro in the Brazilian province of Amazonas near the city of Manaus on October 3, 2023. -On that date, the level of the river, the largest tributary of the Amazon River, had dropped - -to 15.14 meters (50.52 feet), according to data collected by the Port of Manaus. For comparison, -the image on the left shows the same area on October 8, 2022, when the water level was 19.59 -meters, a more typical level for October. Rio Negro water levels continued to drop in the -days after the image was collected, reaching a record low of 13.49 meters on October 17, 2023.Some -areas in the Amazon River’s watershed have received less rain between July and September than - -any year since 1980, Reuters reported. The drought has been particularly severe in the Rio -Negro watershed in northern Amazonas, as well as parts of southern Venezuela and southern -Colombia.“Overall, this is a pretty unusual and extreme situation,” said René Garreaud, an -atmospheric scientist at the University of Chile. “The primary culprit exacerbating the drought -appears to be El Niño.” This cyclical warming of surface waters in the central-eastern Pacific - -functions somewhat like a boulder in the middle of a stream, disrupting atmospheric circulation -patterns in ways that lead to wetter conditions over the equatorial Pacific and drier conditions -over the Amazon Basin.According to news outlets, the low river water levels on the Rio Negro -and other nearby rivers have disrupted drinking water supplies in hundreds of communities, -slowed commercial navigation, and led to fish and dolphin die-offs.Manaus, the capital and - -largest city of the Brazilian state of Amazonas, is the primary transportation hub for the -upper Amazon, serving as an important transit point for soap, beef, and animal hides. Other -industries with a presence in the city of two million people include chemical, ship, and electrical -equipment manufacturing.NASA Earth Observatory images by Wanmei Liang, using Landsat data -from the U.S. Geological Survey. Story by Adam Voiland.View this area in EO ExplorerThe water - -level of the largest tributary of the Amazon River has hit a record low.Image of the Day for -October 18, 2023 Image of the Day Water Human Presence View more Images of the Day:The impact -of severe drought on the Negro River, a tributary of the Amazon River, and other rivers in -the basin is dramatically evident in this pair of images, which show that every body of water -has shrunk in 2010 compared to 2008. Image of the Day Atmosphere Land The volume of water - -in New Mexico’s largest reservoir has dropped to historic lows due to drought and persistent -demand. Image of the Day Water Human Presence Acquired June 25, 2011, and June 22, 2010, these -false-color images compare conditions along the Souris River, which reached a historic crest -at Minot, North Dakota in June 2011. Land Floods Acquired May 11, 2011, and April 21, 2007, -these false-color images show the Mississippi River near Natchez, Mississippi. The image from - -May 2011 shows flooded conditions. Land Floods September 6, 2020JPEGSeptember 7, 2023JPEGSeptember -6, 2020September 7, 2023September 6, 2020JPEGSeptember 7, 2023JPEGSeptember 7, 2023JPEGAfter -rapidly growing in volume just a few years earlier, northwest Iran’s Lake Urmia nearly dried -out in autumn 2023. The largest lake in the Middle East and one of the largest hypersaline -lakes on Earth at its greatest extent, Lake Urmia has for the most part transformed into a - -vast, dry salt flat. On September 7, 2023, the OLI-2 (Operational Land Imager-2) on Landsat -9 captured this image (right) of the desiccated lakebed. It stands in contrast to the image -from three years earlier (left), acquired by the OLI on Landsat 8 on September 8, 2020, when -water filled most of the basin and salt deposits were only visible around the perimeter of -the lake. The replenishment followed a period of above-average precipitation that sent a surge - -of freshwater into the basin, expanding its watery footprint. Drier conditions have since -brought levels back down. The longer-term trend for Urmia has been one toward drying. In 1995, -Lake Urmia reached a high-water mark; then in the ensuing two decades, the lake level dropped -more than 7 meters (23 feet) and lost approximately 90 percent of its area. Consecutive droughts, -agricultural water use, and dam construction on rivers feeding the lake have contributed to - -the decline. A shrinking Lake Urmia has implications for ecological and human health. The -lake, its islands, and surrounding wetlands comprise valuable habitat and are recognized as -a UNESCO Biosphere Reserve, Ramsar site, and national park. The area provides breeding grounds -for waterbirds such as flamingos, white pelicans, and white-headed ducks, as well as a stopover -for migratory species. However, with low lake levels, what water remains becomes more saline - -and taxes the populations of brine shrimp and other food sources for larger animals. A shrinking -lake also increases the likelihood of dust from the exposed lakebed becoming swept up by winds -and degrading air quality. Recent studies have linked the low water levels in Lake Urmia with -respiratory health impacts among the local population.The relative effects of climate, water -usage, and dams on Lake Urmia’s water level is a topic of debate. The lake did see some recovery - -during a 10-year restoration program beginning in 2013. However, the efficacy of that effort -has been difficult to parse since strong rains also fell during that period. Some research -has concluded that climatic factors were primarily responsible for the recovery. NASA Earth -Observatory images by Lauren Dauphin, using Landsat data from the U.S. Geological Survey. -Story by Lindsey Doermann.View this area in EO ExplorerA few years after a fresh influx of - -water raised its levels, the large lake has nearly gone dry.Image of the Day for October 10, -2023 Image of the Day Land Water View more Images of the Day:Water levels are at their lowest -since 1937. Image of the Day Water Drought Fires Long and short. Deep and shallow. Salty and -fresh. Blue and brown. These are Africa’s Lake Tanganyika and Lake Rukwa. Image of the Day -Land Water In May 2016, the reservoir behind Hoover Dam reached its lowest level since the - -1930s. Image of the Day Water When the water gets saltier in Iran’s largest lake, the microscopic -inhabitants can turn the water dark red. Image of the Day Water Water Color July 1 - September -30, 2023MPEG For several months in 2023, global sea surface temperatures reached record-high -levels, fueled by decades of human-caused climate warming and a recent boost from the natural -climate phenomenon El Niño. Some areas—including the seas around Florida, Cuba, and the Bahamas—saw - -particularly high temperatures, with implications for the health of coral reefs.Corals thrive -within a small range of temperatures and become stressed when water is too hot or cold. Bleaching -occurs when stressed corals expel the algae that live inside them, stripping corals of their -color. Extreme bleaching can leave a reef susceptible to starvation, disease, and even death. -Observations made by divers in the Florida Keys found that the marine heatwave in summer 2023 - -caused widespread bleaching.Stress on corals can also be detected using data from satellites. -This animation shows the evolution of accumulated heat stress from July through September -2023. The colors depict “degree heating weeks” (°C-weeks)—a measure that provides an estimate -of the severity and duration of thermal stress. Data for the product are compiled by NOAA’s -Coral Reef Watch, which blends observations from polar orbiting satellites such as the NASA-NOAA - -Suomi NPP, and from geostationary satellites such as GOES, with computer models.Observations -have shown that when the accumulated heat stress reaches a value of 4, significant coral bleaching -can result. At values of 8, coral bleaching and widespread mortality are likely. By midway -through this animation, in August, heat stress across much of the region already soared well -above both of those thresholds. According to NOAA, cumulative heat stress by late September - -2023 hit 22°C-weeks (40°F-weeks), nearly triple the previous record for the region.Bleaching -was already observed in some areas as early as July. Notice that areas of coral reef (gray) -near the Florida Keys, Cuba, and the Bahamas, are among the first areas to show high cumulative -heat stress. Hurricane Idalia in late August helped cool surface waters somewhat, but only -temporarily.Nearing mid-October, waters around the Florida Keys were under a bleaching watch. - -Further south, waters around parts of Cuba and the Bahamas remained at bleaching alert level -2, the highest level of the scale, signifying that severe bleaching and mortality are likely.NASA -Earth Observatory animation by Wanmei Liang, using Daily 5km Degree Heating Weeks data from -Coral Reef Watch. Coral reef data from UNEP-WCMC, WorldFish Centre, WRI, TNC. Story by Kathryn -Hansen.View this area in EO ExplorerThe seas around Florida, Cuba, and the Bahamas saw large - -accumulations of heat stress beginning in summer 2023, with implications for the health of -coral reefs.Image of the Day for October 16, 2023 Image of the Day Water Temperature Extremes -View more Images of the Day:Warmer-than-average temperatures are showing up locally and globally, -with consequences for people, landscapes, and ecosystems. Image of the Day Water Image of -the Day Life Water Image of the Day Heat Life Water Studying corals from above could help - -scientists understand how these critical ecosystems will weather a changing climate. Image -of the Day Land Life Water Thank you for visiting nature.com. You are using a browser version -with limited support for CSS. To obtain the best experience, we recommend you use a more up -to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to -ensure continued support, we are displaying the site without styles and JavaScript.Advertisement - -Scientific Data volume 7, Article number: 112 (2020) Cite this article 30k Accesses126 Citations88 -AltmetricMetrics detailsRemotely sensed biomass carbon density maps are widely used for myriad -scientific and policy applications, but all remain limited in scope. They often only represent -a single vegetation type and rarely account for carbon stocks in belowground biomass. To date, -no global product integrates these disparate estimates into an all-encompassing map at a scale - -appropriate for many modelling or decision-making applications. We developed an approach for -harmonizing vegetation-specific maps of both above and belowground biomass into a single, -comprehensive representation of each. We overlaid input maps and allocated their estimates -in proportion to the relative spatial extent of each vegetation type using ancillary maps -of percent tree cover and landcover, and a rule-based decision schema. The resulting maps - -consistently and seamlessly report biomass carbon density estimates across a wide range of -vegetation types in 2010 with quantified uncertainty. They do so for the globe at an unprecedented -300-meter spatial resolution and can be used to more holistically account for diverse vegetation -carbon stocks in global analyses and greenhouse gas inventories.Measurement(s)biomass carbon -densityTechnology Type(s)digital curationFactor Type(s)climatic zone • above or below ground - -• land coverSample Characteristic - Environmentorganic materialSample Characteristic - LocationEarth -(planet)Machine-accessible metadata file describing the reported data: https://doi.org/10.6084/m9.figshare.11872383Terrestrial -ecosystems store vast quantities of carbon (C) in aboveground and belowground biomass1. At -any point in time, these stocks represent a dynamic balance between the C gains of growth -and C losses from death, decay and combustion. Maps of biomass are routinely used for benchmarking - -biophysical models2,3,4, estimating C cycle effects of disturbance5,6,7, and assessing biogeographical -patterns and ecosystem services8,9,10,11. They are also critical for assessing climate change -drivers, impacts, and solutions, and factor prominently in policies like Reducing Emissions -from Deforestation and Forest Degradation (REDD+) and C offset schemes12,13,14. Numerous methods -have been used to map biomass C stocks but their derivatives often remain limited in either - -scope or extent12,15. There thus remains a critical need for a globally harmonized, integrative -map that comprehensively reports biomass C across a wide range of vegetation types.Most existing -maps of aboveground biomass (AGB) and the carbon it contains (AGBC) are produced from statistical -or data-driven methods relating field-measured or field-estimated biomass densities and spaceborne -optical and/or radar imagery12,15,16. They largely focus on the AGB of trees, particularly - -those in tropical landscapes where forests store the majority of the region’s biotic C in -aboveground plant matter. Land cover maps are often used to isolate forests from other landcover -types where the predictive model may not be appropriate such that forest AGB maps intentionally -omit AGB stocks in non-forest vegetation like shrublands, grasslands, and croplands, as well -as the AGB of trees located within the mapped extent of these excluded landcovers17. Non-forest - -AGB has also been mapped to some extent using similar approaches but these maps are also routinely -masked to the geographic extent of their focal landcover18,19,20,21. To date, there has been -no rigorous attempt to harmonize and integrate these landcover-specific, remotely sensed products -into a single comprehensive and temporally consistent map of C in all living biomass.Maps -of belowground biomass (BGB) and carbon density (BGBC) are far less common than those of AGB - -because BGB cannot be readily observed from space or airborne sensors. Consequently, BGB is -often inferred from taxa-, region-, and/or climate-specific “root-to-shoot” ratios that relate -the quantity of BGB to that of AGB22,23,24. These ratios can be used to map BGB by spatially -applying them to AGB estimates using maps of their respective strata5. In recent years, more -sophisticated regression-based methods have been developed to predict root-to-shoot ratios - -of some landcover types based on covariance with other biophysical and/or ecological factors25,26. -When applied spatially, these methods can allow for more continuous estimates of local BGB5,27. -Like AGBC, though, few attempts have been made to comprehensively map BGBC for the globe.Despite -the myriad of emerging mapping methods and products, to date, the Intergovernmental Panel -on Climate Change (IPCC) Tier-1 maps by Ruesch and Gibbs28 remains the primary source of global - -AGBC and BGBC estimates that transcend individual landcover types. These maps, which represents -the year 2000, were produced prior to the relatively recent explosion of satellite-based AGB -maps and they therefore rely on an alternative mapping technique called “stratify and multiply”15, -which assigns landcover-specific biomass estimates or “defaults” (often derived from field -measurements or literature reviews) to the corresponding classified grid cells of a chosen - -landcover map12. While this approach yields a comprehensive wall-to-wall product, it can fail -to capture finer-scale spatial patterns often evident in the field and in many satellite-based -products12,15. The accuracy of these maps is also tightly coupled to the quality and availability -of field measurements29 and the thematic accuracy and discontinuity of the chosen landcover -map.Given the wealth of landcover-specific satellite based AGB maps, a new harmonization method - -akin to “stratify and multiply” is needed to merge the validated spatial detail of landcover-specific -remotely sensed biomass maps into a single, globally harmonized product. We developed such -an approach by which we (i) overlay distinct satellite-based biomass maps and (ii) proportionately -allocate their estimates to each grid cell (“overlay and allocate”). Specifically, we overlay -continental-to-global scale remotely sensed maps of landcover-specific biomass C density and - -then allocate fractional contributions of each to a given grid cell using additional maps -of percent tree cover, thematic landcover and a rule-based decision tree. We implement the -new approach here using temporally consistent maps of AGBC as well as matching derived maps -of BGBC to generate separate harmonized maps of AGBC and BGBC densities. In addition, we generate -associated uncertainty layers by propagating the prediction error of each input dataset. The - -resulting global maps consistently represent biomass C and associated uncertainty across a -broad range of vegetation in the year 2010 at an unprecedented 300 meter (m) spatial resolution.Our -harmonization approach (Fig. 1) relies on independent, landcover-specific biomass maps and -ancillary layers, which we compiled from the published literature (Table 1). When published -maps did not represent our epoch of interest (i.e. grasslands and croplands) or did not completely - -cover the necessary spatial extent (i.e. tundra vegetation), we used the predictive model -reported with the respective map to generate an updated version that met our spatial and temporal -requirements. We then used landcover specific root-to-shoot relationships to generate matching -BGBC maps for each of the input AGBC maps before implementing the harmonization procedure. -Below we describe, in detail, the methodologies used for mapping AGBC and BGBC of each landcover - -type and the procedure used to integrate them.Generalized, three-step workflow used to create -harmonized global biomass maps. In step one, woody AGB maps are prepared, combined, converted -to AGBC density and used to create separate but complementary maps of BGBC. In step two, a -similar workflow is used to generate matching maps of AGBC and BGBC for tundra vegetation, -grasses, and annual crops. In step three, all maps are combined using a rule-based decision - -tree detailed in Fig. 3 to generate comprehensive, harmonized global maps. All input data -sources are listed and described in Table 1.Since the first remotely sensed woody AGB maps -were published in the early 1990s, the number of available products has grown at an extraordinary -pace16 and it can thus be challenging to determine which product is best suited for a given -application. For our purposes, we relied on the GlobBiomass AGB density map30 as our primary - -source of woody AGB estimates due to its precision, timestamp, spatial resolution, and error -quantification. It was produced using a combination of spaceborne optical and synthetic aperture -radar (SAR) imagery and represents the year 2010 at a 100 m spatial resolution – making it -the most contemporary global woody AGB currently available and the only such map available -for that year. Moreover, GlobBiomass aims to minimize prediction uncertainty to less than - -30% and a recent study suggests that it has high fidelity for fine-scale applications31.The -GlobBiomass product was produced by first mapping the growing stock volume (GSV; i.e. stem -volume) of living trees, defined following Food and Agriculture Organization (FAO) guidelines32 -as those having a diameter at breast height (DBH) greater than 10 centimeters (cm). AGB density -was then determined from GSV by applying spatialized biomass expansion factors (BEFs) and - -wood density estimates. These factors were mapped using machine learning methods trained from -a suite of plant morphological databases that compile thousands of field measurements from -around the globe33. The resulting AGB estimates represent biomass in the living structures -(stems, branches, bark, twigs) of trees with a DBH greater than 10 cm. This definition may -thereby overlook AGB of smaller trees and/or shrubs common to many global regions. Unlike - -other maps, though, the GlobBiomass product employs a subpixel masking procedure that retains -AGB estimates in 100 m grid cells in which any amount of tree cover was detected in finer -resolution (30 m) imagery34. This unique procedure retains AGB estimates in tree-sparse regions -like savannahs, grasslands, croplands, and agroforestry systems where AGB is often overlooked17, -as well as in forest plantations. The GlobBiomass product is the only global map that also - -includes a dedicated uncertainty layer reporting the standard error of prediction. We used -this layer to propagate uncertainty when converting AGB to AGBC density, modelling BGBC, and -integrating with C density estimates of other vegetation types.Bouvet et al.35 – some of whom -were also participants of the GlobBiomass project – independently produced a separate AGB -density map for African savannahs, shrublands and dry woodlands circa 2010 at 25 m spatial - -resolution35 (hereafter “Bouvet map”), which we included in our harmonized product to begin -to address the GlobBiomass map’s potential omission of small trees and shrubs that do not -meet the FAO definition of woody AGB. This continental map of Africa is based on a predictive -model that directly relates spaceborne L-band SAR imagery – an indirect measure of vegetation -structure that is sensitive to low biomass densities36 – with region-specific, field-measured - -AGB. Field measurements (n = 144 sites) were compiled from 7 different sampling campaigns -– each specifically seeking training data for biomass remote sensing – that encompassed 8 -different countries35. The resulting map is not constrained by the FAO tree definition and -is masked to exclude grid cells in which predicted AGB exceeds 85 megagrams dry mater per -hectare (Mg ha−1) – the threshold at which the SAR-biomass relationship saturates. To avoid - -extraneous prediction, it further excludes areas identified as “broadleaved evergreen closed-to-open -forest”, “flooded forests”, “urban areas” and “water bodies” by the European Space Agency’s -Climate Change Initiative (CCI) Landcover 2010 map37 and as “bare areas” in the Global Land -Cover (GLC) 2000 map38. While the Bouvet map is not natively accompanied by an uncertainty -layer, its authors provided us with an analytic expression of its uncertainty (SE; standard - -error of prediction) as a function of estimated AGB (Eq. 1) which we used to generate an uncertainty -layer for subsequent error propagation.We combined the GlobBiomass and Bouvet products to -generate a single woody biomass map by first upscaling each map separately to a matching 300 -m spatial resolution using an area-weighted average to aggregate grid cells, and then assigning -the Bouvet estimate to all overlapping grid cells, except those identified by the CCI Landcover - -2010 map as closed or flooded forest types (Online-only Table 1) which were not within the -dryland domain of the Bouvet map. While more complex harmonization procedures based on various -averaging techniques have been used by others39,40, their fidelity remains unclear since they -fail to explicitly identify and reconcile the underlying source of the inputs’ discrepancies41. -We thus opted to use a more transparent ruled-based approach when combining these two woody - -biomass maps, which allows users to easily identify the source of a grid cell’s woody biomass -estimate. Given the local specificity of the training data used to produce the Bouvet map, -we chose to prioritize its predictions over those of the GlobBiomass product when within its -domain. In areas of overlap, the Bouvet map values tend to be lower in moist regions and higher -in dryer regions (Fig. 2), though, where used, these differences rarely exceed ±25 megagrams - -C per hectare (MgC ha−1).Difference between underlying woody aboveground biomass maps in Africa. -Maps considered are the GlobBiomass30 global map and the Bouvet35 map of Africa. Both maps -were aggregated to a 300 m spatial resolution and converted to C density prior to comparison -using the same schema. The difference map was subsequently aggregated to a 3 km spatial resolution -and reprojected for visualization. Negative values denote lower estimates by Bouvet et al.35, - -while positive values denote higher estimates.We then converted all woody AGB estimates to -AGBC by mapping climate and phylogeny-specific biomass C concentrations from Martin et al.42. -Climate zones were delineated by aggregating classes of the Köppen-Gieger classification43 -(Table 2) to match those of Martin et al.42. Phylogenetic classes (angiosperm, gymnosperm -and mixed/ambiguous) were subsequently delineated within each of these zones using aggregated - -classes of the CCI Landcover 2010 map (Online-only Table 1). Martin et al.42 only report values -for angiosperms and gymnosperms so grid cells with a mixed or ambiguous phylogeny were assigned -the average of the angiosperm and gymnosperm values and the standard error of this value was -calculated from their pooled variance. Due to residual classification error in the aggregated -phylogenetic classes, we weighted the phylogeny-specific C concentration within each climate - -zone by the binary probability of correctly mapping that phylogeny (i.e. user’s accuracy)44 -using Eq. 2where, within each climate zone, μc is the mean probability-weighted C concentration -of the most probable phylogeny, μm is the mean C concentration of that phylogeny from Martin -et al.42, pm is the user’s accuracy of that phylogeny’s classification (Table 3), and μn and -μo are the mean C concentrations of the remain phylogenetic classes from Martin et al.42. - -Standard error estimates for these C concentrations were similarly weighted using summation -in quadrature (Eq. 3)where \({\sigma }_{c}\) is the probability-weighted standard error of -the most probable phylogeny’s C concentration and \({\sigma }_{m}\), \({\sigma }_{n}\) and -\({\sigma }_{o}\) are the standard errors of the respective phylogeny-specific C concentrations -from Martin et al.42. Probability-weighted C concentrations used are reported in Table 4.Mapped, - -probability-weighted C estimates were then arithmetically applied to AGB estimates. Uncertainty -associated with this correction was propagated using summation in quadrature of the general -form (Eq. 4)where \({\mu }_{f}=f(i,j,\ldots ,k)\), \({\sigma }_{f}\) is the uncertainty of -μf, and \({\sigma }_{i},{\sigma }_{j},\ldots ,{\sigma }_{k}\), are the respective uncertainty -estimates of the dependent parameters (standard error unless otherwise noted). Here, μf, is - -the estimated AGBC of a given grid cell, and is the product of its woody AGB estimate, and -its corresponding C concentration.The tundra and portions of the boreal biome are characterized -by sparse trees and dwarf woody shrubs as well as herbaceous cover that are not included in -the GlobBiomass definition of biomass. AGB density of these classes has been collectively -mapped by Berner et al.18,45 for the North Slope of Alaska from annual Landsat imagery composites - -of the normalized difference vegetation index (NDVI) and a non-linear regression-based model -trained from field measurements of peak AGB that were collected from the published literature -(n = 28 sites). Berner et al.18 note that while these field measurements did not constitute -a random or systematic sample, they did encompass a broad range of tundra plant communities. -In the absence of a global map and due the sparsity of high quality Landsat imagery at high - -latitudes, we extended this model to the pan-Arctic and circumboreal regions using NDVI composites -created from daily 250 m MODIS Aqua and Terra surface reflectance images46,47 that were cloud -masked and numerically calibrated to Landsat ETM reflectance – upon which the tundra model -is based – using globally derived conversion coefficients48. We generated six separate 80th -percentile NDVI composites circa 2010 – one for each of the MODIS missions (Aqua and Terra) - -in 2009, 2010 and 2011 – following Berner et al.18. We chose to use three years of imagery -(circa 2010) rather than just one (2010) to account for the potential influence that cloud -masking may exert upon estimates of the 80th NDVI percentile in a single year. We then applied -the tundra AGB model to each composite, converted AGB estimates to AGBC by assuming a biomass -C fraction of 49.2% (SE = 0.8%)42 and generated error layers for each composite from the reported - -errors of the AGB regression coefficients and the biomass C conversion factor using summation -in quadrature as generally described above (Eq. 4). A single composite of tundra AGBC circa -2010 was then created as the pixelwise mean of all six composites. We also generated a complementary -uncertainty layer representing the cumulative standard error of prediction, calculated as -the pixelwise root mean of the squared error images in accordance with summation in quadrature. - -Both maps were upscaled from their native 250 m spatial resolution to a 300 m spatial resolution -using an area weighted aggregation procedure, whereby pixels of the 300 m biomass layer was -calculated as the area weighted average of contained 250 m grid cells, and the uncertainty -layer was calculated – using summation in quadrature – as the root area-weighted average of -the contained grid cells squared.Grassland AGBC density was modelled directly from maximum - -annual NDVI composites using a non-linear regression-based model developed by Xia et al.19 -for mapping at the global scale. This model was trained by relating maximum annual NDVI as -measured by the spaceborne Advanced Very High-Resolution Radiometer (AVHRR) sensor to globally -distributed field measurements of grassland AGBC that were compiled from the published literature -(81 sites for a total of 158 site-years). Like the tundra biomass training data, these samples - -did not constitute a random or systematic sample but do encompass a comprehensive range of -global grassland communities. Given the inevitable co-occurrence of trees in the AVHRR sensor’s -8 km resolution pixels upon which the model is trained, it’s predictions of grassland AGBC -are relatively insensitive to the effects of co-occurring tree cover. We thereby assume that -its predictions for grid cells containing partial tree cover represent the expected herbaceous - -AGBC density in the absence of those trees. Maximum model predicted AGBC (NDVI = 1) is 2.3 -MgC ha−1 which is comparable to the upper quartile of herbaceous AGBC estimates from global -grasslands49 and suggests that our assumption will not lead to an exaggerated estimation. -For partially wooded grid cells, we used modelled grassland AGBC density to represent that -associated with the herbaceous fraction of the grid cell in a manner similar to Zomer et al.17 - -as described below (See “Harmonizing Biomass Carbon Maps”).We applied the grassland AGBC model -to all grid cells of maximum annual NDVI composites produced from finer resolution 16-day -(250 m) MODIS NDVI imagery composites circa 201050,51. Here again, three years of imagery -were used to account for potential idiosyncrasies in a single year’s NDVI composites resulting -from annual data availability and quality. As with AGB of tundra vegetation, annual composites - -(2009–2011) were constructed separately from cloud-masked imagery collected by both MODIS -missions (Aqua and Terra; n = 6) and then numerically calibrated to AVHRR reflectance using -globally derived conversion coefficients specific to areas of herbaceous cover52. We then -applied the AGBC model to each of these composites and estimated error for each composite -from both the AVHRR calibration (standard deviation approximated from the 95% confidence interval - -of the calibration scalar) and the AGBC model (relative RMSE) using summation in quadrature. -A single map of grassland AGBC circa 2010 was then created as the pixelwise mean of all six -composites and an associated error layer was created as the pixelwise root mean of the squared -error images. Both maps were aggregated from their original 250 m resolution to 300 m to facilitate -harmonization using the area-weighted procedure described previously for woody and tundra - -vegetation (see section 1.2).Prior to harvest, cropland biomass can also represent a sizable -terrestrial C stock. In annually harvested cropping systems, the maximum standing biomass -of these crops can be inferred from annual net primary productivity (ANPP). While spaceborne -ANPP products exist, they generally perform poorly in croplands53,54. Instead, cropland ANPP -is more commonly derived from crop yields20,21,53. We used globally gridded, crop-specific - -yields of 70 annually harvested herbaceous commodity crops circa 2000 by Monfreda et al.20 -– the only year in which these data were available. These maps were produced by spatially -disaggregating crop-yield statistics for thousands of globally distributed administrative -units throughout the full extent of a satellite-based cropland map20. These maps were combined -with crop-specific parameters (Online-only Table 2) to globally map AGBC as aboveground ANPP - -for each crop following the method of Wolf et al.21. This method can be simplified as (Eq. -5)where y is the crop’s yield (Mg ha−1), ω is the dry matter fraction of its harvested biomass, -h is its harvest index (fraction of total AGB collected at harvest) and c is the carbon content -fraction of its harvested dry mass. This simplification assumes, following Wolf et al.21, -that 2.5% of all harvested biomass is lost between the field and farmgate and that unharvested - -residue and root mass is 44% C.Total cropland AGBC density was then calculated as the harvested-area-weighted -average of all crop-specific AGBC estimates within a given grid cell. Since multiple harvests -in a single year can confound inference of maximum AGBC from ANPP, we further determined the -harvest frequency (f) of each grid cell by dividing a cell’s total harvested area (sum of -the harvested area of each crop reported within a given grid cell) by its absolute cropland - -extent as reported in a complementary map by Ramankutty et al.55. If f was greater than one, -multiple harvests were assumed to have occurred and AGBC was divided by f to ensure that AGBC -estimates did not exceed the maximum standing biomass density.Since the yields of many crops -and, by association, their biomass have changed considerably since 200056,57, we calibrated -our circa 2000 AGBC estimates to the year 2010 using local rates of annual ANPP change (MgC - -ha−1 yr−1) derived as the Theil-Sen slope estimator – a non-parametric estimator that is relatively -insensitive to outliers – of the full MODIS Terra ANPP timeseries (2000–2015)58. Total ANPP -change between 2000 and 2010 for each grid cell was calculated as ten times this annual rate -of change. Since MODIS ANPP represents C gains in both AGB and BGB, we proportionately allocated -aboveground ANPP to AGBC using the total root-to-shoot ratio derived from the circa 2000 total - -crop AGBC and BGBC maps (described below). Since error estimates were not available for the -yield maps or the crop-specific parameters used to generate the circa 2000 AGBC map, estimated -error of the circa 2010 crop AGBC map was exclusively based on that of the 2000–2010 correction. -The error of this correction was calculated as the pixel-wise standard deviation of bootstrapped -simulations (n = 1000) in which a random subset of years was omitted from the slope estimator - -in each iteration. The 8 km resolution circa 2000 AGBC map and error layer were resampled -to 1 km to match the resolution of MODIS ANPP using the bilinear method prior to ANPP correction -and then further resampled to 300 m to facilitate harmonization.Woody crops like fruit, nut, -and palm oil plantations were not captured using the procedure just described and their biomass -was instead assumed to be captured by the previously described woody biomass products which - -retained biomass estimates in all pixels where any amount of tree cover was detected at the -sub-pixel level (see section 1.1).Matching maps of BGBC and associated uncertainty were subsequently -produced for each of the landcover-specific AGBC maps using published empirical relationships.With -the exception of savannah and shrubland areas, woody BGBC was modelled from AGBC using a multiple -regression model by Reich et al.25 that considers the phylogeny, mean annual temperature (MAT), - -and regenerative origin of each wooded grid cell and that was applied spatially using maps -of each covariate in a fashion similar to other studies5,27. Tree phylogeny (angiosperm or -gymnosperm) was determined from aggregated classes of the CCI Landcover 2010 map37 (Online-only -Table 1) with phylogenetically mixed or ambiguous classes assumed to be composed of 50% of -each. MAT was taken from version 2 of the WorldClim bioclimatic variables dataset (1970–2000) - -at 1 km resolution59 and resampled to 300 m using the bilinear method. Since there is not -a single global data product mapping forest management, we determined tree origin – whether -naturally propagated or planted – by combining multiple data sources. These data included -(i) a global map of “Intact Forest Landscapes” (IFL) in the year 201360 (a conservative proxy -of primary, naturally regenerating forests defined as large contiguous areas with minimal - -human impact), (ii) a Spatial Database of Planted Trees (SDPT) with partial global coverage61, -(iii) national statistics reported by the FAO Global Forest Resources Assessment (FRA) on -the extent of both naturally regenerating and planted forests and woodlands within each country -in the year 201062, and (iv) national statistics reported by the FAOSTAT database (http://www.fao.org/faostat) -on the planted area of plantation crops in 2010. Within each country, we assumed that the - -total area of natural and planted trees was equal to the corresponding FRA estimates. If the -FAOSTAT-reported area of tree crops exceeded FRA-reported planted area, the difference was -added to FRA planted total. All areas mapped as IFL were assumed to be of natural origin and -BGB was modelled as such. Likewise, besides the exceptions noted below, all tree plantations -mapped by the SDPT were assumed to be of planted origin. In countries where the extent of - -the IFL or SDPT maps fell short of the FRA/FAOSTAT reported areas of natural or planted forests, -respectively, we estimated BGBC in the remaining, unknown-origin forest grid cells of that -country (BGBCu), as the probability-weighted average of the planted and natural origin estimates -using Eq. 6where \(BGB{C}_{p}\) and \(BGB{C}_{n}\) are the respective BGBC estimates for a -grid cell assuming entirely planted and natural origin, respectively, and \({\Delta }_{p}\) - -and \({\Delta }_{n}\) are the respective differences between (i) the FRA/FAOSTAT and (ii) -mapped extent of planted and natural forest within the given grid cell’s country. While the -mapped extent of IFL forests within a given country never exceeded that country’s FRA reported -natural forest extent, there were infrequent cases (n = 22 of 257) in which the mapped extent -of tree plantations exceeded the corresponding FRA/FAOSTAT estimate of planted forest area. - -In these cases, we down-weighted the BGB estimates of SDPT forests in a similar fashion such -that the weight of their planted estimate (\({\omega }_{p}\)) was equal to the quotient of -(i) the FRA/FAOSTAT planted area and (ii) the SDPT extent within the country, and the weight -of the natural origin estimate applied to the SDPT extent (\({\omega }_{n}\)) was equal to -\(1-{\omega }_{p}\).A BGBC error layer was then produced using summation in quadrature from - -the standard error estimates of the model coefficients, the AGBC error layer, the relative -RMSE of MAT (27%), and the derived global uncertainty of the phylogeny layer. Phylogeny error -was calculated as the Bernoulli standard deviation (δ) of the binary probability (p) of correct -classification (i.e. “area weighted user’s accuracy”44; Table 3) using Eq. 7.Since savannahs -and shrublands are underrepresented in the regression-based model25, their BGBC was instead - -estimated using static root-to-shoot ratios reported by Mokany et al.22, which are somewhat -conservative in comparison to the IPCC Tier-1 defaults23,24 put favoured for consistency with -methods used for grasslands (see below). Error was subsequently mapped from that of the AGBC -estimates and the root-to-shoot ratios applied (Table 5).BGBC of tundra vegetation was mapped -from AGBC using a univariate regression model derived by Wang et al.26 that predicts root-to-shoot - -ratio as a function of MAT. We applied the model using the WorldClim version 2 MAT map59 and -propagated error from the AGBC estimates, the relative RMSE of MAT and the standard error -of regression coefficients. Where tundra AGB exceeded 25 Mg ha−1 – the maximum field-measured -shrub biomass reported by Berner et al.18 – vegetation was considered to include trees and -the Reich et al.25 method described earlier for woody vegetation was used instead.In the absence - -of a continuous predictor of grassland root-to-shoot ratios, we applied climate specific root-to-shoot -ratios from Mokany et al.22 to the corresponding climate regions of the Köppen-Gieger classification43 -(Table 2). Here, again, these ratios vary slightly from the IPCC Tier-1 defaults23,24 but -were chosen for their greater sample size and specificity. Grassland BGBC error was mapped -from the error of the AGBC estimates and the respective root-to-shoot ratios.Cropland BGBC - -was again estimated from crop-specific yields and morphological parameters (Online-only Table -2) following Wolf et al.21 and Eq. 8where y is the crop’s yield (Mg ha−1), r is the root-to-shoot -ratio of the crop, and h is its harvest index. Here again we assume that 2.5% of all harvested -biomass is lost between the field and farmgate and that root biomass is 44% C, following Wolf -et al.21. BGBC error was mapped from the error of the 2000-to-2010 ANPP correction for BGBC - -allocation as described above for cropland AGBC.The AGBC and BGBC maps were harmonized separately -following the same general schema (Fig. 3). Given that our harmonized woody biomass map contains -biomass estimates for grid cells in which any amount of tree cover was detected at the subpixel -level (see section 1.1), we conserved its estimates regardless of the landcover reported by -the 2010 CCI map in order to more fully account for woody biomass in non-forested areas17. - -We then used the MODIS continuous vegetation fields percent tree cover map for 201063 to allocate -additional biomass density associated with the most probable herbaceous cover (grass or crop) -to each grid cell in quantities complementary to that of the grid cell’s fractional tree cover -estimate (Eq. 9)where μT is the total biomass estimate of a grid cell, μw is the woody biomass -estimate for the grid cell, μh is its herbaceous biomass estimate, and q is the MODIS fractional - -tree cover of the grid cell. Since MODIS tree cover estimates saturate at around 80%64, we -linearly stretched values such that 80% was treated as complete tree cover (100%). Moreover, -we acknowledge that percent cover can realistically exceed 100% when understory cover is considered -but we were unable to reasonably determine the extent of underlying cover from satellite imagery. -As such, our approach may underestimate the contribution of herbaceous C stocks in densely - -forested grid cells. The most likely herbaceous cover type was determined from the CCI Landcover -2010 map, which we aggregated into two “likely herbaceous cover” classes – grass or crop – -based on the assumed likelihood of cropland in each CCI class (Online-only Table 1). However, -due to inherent classification error in the native CCI Landcover map, when determining the -herbaceous biomass contribution we weighted the relative allocation of crop and grass biomass - -to a given grid cell based on the probability of correct classification by the CCI map (i.e. -“user’s accuracy”, Table 6) of the most probable herbaceous class (\({p}_{i}\)) such that -μh can be further expressed as (Eq. 10)where μi is the predicted biomass of the most probable -herbaceous class, and μj is that of the less probable class.Decision tree used to allocate -landcover-specific biomass estimates to each grid cell of our harmonized global products.The - -uncertainty of a grid cell’s total AGBC or BGBC estimate (\({\sigma }_{T}\)) was determined -and mapped from that of its components (\({\mu }_{w}\,{\rm{and}}\,{\mu }_{h}\)) by summation -in quadrature which can be simplified as (Eq. 11)where \({\sigma }_{w}\) is the error of the -grid cell’s estimated μw, \({\sigma }_{h}\) is the error of its estimated μh, and \({\sigma -}_{q}\) is the error of its q. Here, \({\sigma }_{h}\) can be further decomposed and expressed - -as Eq. 12 to account for the accuracy weighted allocation procedure expressed previously (Eq. -10)where \({\sigma }_{i}\) is the error of the estimated biomass density of the most probable -herbaceous class, \({\delta }_{i}\) is the estimated standard deviation of that class’s Bernoulli -probability (p; Eq. 7), and \({\sigma }_{j}\) is the error of the estimated biomass density -of the less probable herbaceous subclass.Exceptions to the above schema were made in the tundra - -and boreal biomes – as delineated by the RESOLVE Ecoregions 2017 biome polygons65 – where -thematic overlap was likely between the woody and tundra plant biomass maps. A separate set -of decision rules (Fig. 3) was used to determine whether grid cells in these biomes were to -be exclusively allocated the estimate of the tundra plant map or that of the fractional allocation -procedure described above. In general, any land in these biomes identified as sparse landcover - -by the CCI landcover map (Online-only Table 1) was assigned the tundra vegetation estimate. -In addition, lands north of 60° latitude with less than 10% tree cover or where the tundra -AGBC estimate exceeded that of the woody AGBC estimate were also exclusively assigned the -tundra vegetation estimate. Lands north of 60° latitude not meeting these criteria were assigned -the woody value with the additional contribution of grass.Subtle numerical artefacts emerged - -from the divergent methodologies employed north and south of 60°N latitude. These were eliminated -by distance weighting grid cells within 1° of 60°N based on their linear proximity to 60°N -and then averaging estimates such that values at or north of 61°N were exclusively based on -the northern methodology, those at 60°N were the arithmetic average of the two methodologies -and those at or south of 59°N were exclusively based on the southern methodology. This produced - -a seamless, globally harmonized product that integrates the best remotely sensed estimates -of landcover-specific C density. Water bodies identified as class “210” of the CCI 2010 landcover -map were then masked from our final products.Data layers (n = 4, Table 7) for the maps of -AGBC and BGBC density (Fig. 4) as well as their associated uncertainty maps which represent -the combined standard error of prediction (Fig. 5) are available as individual 16-bit integer - -rasters in GeoTiff format. All layers are natively in a WGS84 Mercator projection with a spatial -resolution of approximately 300 m at the equator and match that of the ESA CCI Landcover Maps37. -Raster values are in units megagrams C per hectare (MgC ha−1) and have been scaled by a factor -of ten to reduce file size. These data are accessible through the Oak Ridge National Laboratory -(ORNL) DAAC data repository (https://doi.org/10.3334/ORNLDAAC/1763)66. In addition, updated - -and/or derived vegetation-specific layers that were used to create our harmonized 2010 maps -are available as supplemental data on figshare67.Globally harmonized maps of above and belowground -living biomass carbon densities. (a) Aboveground biomass carbon density (AGBC) and (b) belowground -biomass carbon density (BGBC) are shown separately. Maps have been aggregated to a 5 km spatial -resolution and reprojected here for visualization.Uncertainty of grid cell level above and - -belowground biomass carbon density estimates. Uncertainty is shown here as the coefficient -of variation (%; standard error layer divided by mean estimate layer) of estimated AGBC (a) -and BGBC (b) densities after harmonization. Maps have been aggregated to a 5 km spatial resolution -and projected for visualization.Our harmonized products rely almost exclusively upon maps -and models that have been rigorously validated by their original producers and were often - -accompanied by constrained uncertainty estimates. Throughout our harmonization procedure, -we strived to conserve the validity of each of these products by minimizing the introduction -of additional error and by tracking any introductions, as described above, such that the final -error layers represent the cumulative uncertainty of the inputs used. Ground truth AGB and -BGB data are almost always collected for individual landcover types. Consequently, we are - -unable to directly assess the validity of our integrated estimates beyond their relationships -to individual landcover-specific estimates and the extents to which they were modified from -their original, previously-validated form prior to and during our harmonization procedure.Temporal -and spatial updates made to existing landcover-specific maps of non-tree AGB resulted in relatively -small changes to their predictions. For example, we used numerically calibrated MODIS imagery - -to extend the Landsat-based tundra plant AGB model beyond its native extent (the North Slope -of Alaska) to the pan-Arctic region since neither a comparable model nor a consistent Landsat -time series were available for this extent. We assessed the effects of these assumptions by -comparing our predictions for the North Slope with those of the original map18 (Fig. 6a). -Both positive and negative discrepancies exist between ours and the original, though these - -rarely exceed ±2 MgC ha−1 and no discernibly systematic bias was evident.Differences between -landcover-specific AGBC estimates from the original published maps and the modified versions -used as inputs to create the 2010 harmonized global maps. Tundra vegetation AGBC (a) is compared -to the Landsat-based map of Berner et al.45 for the north slope of Alaska after converting -it to units MgC ha−1. Here, the comparison map was subsequently aggregated to a 1 km resolution - -and reprojected for visualization. Grassland AGBC (b) is compared to the AVHRR-based map of -Xia et al.19 which represents the average estimate between 1982–2006. For visualization, the -map was aggregated to a 5 km resolution and subsequently reprojected after being masked to -MODIS IGBP grasslands in the year 200685 following Xia et al.19. As such, this map does not -necessarily represent the spatial distribution of grid cells in which grassland estimates - -were used. Cropland AGBC (c) is compared to the original circa 2000 estimates to assess the -effects of the 2000-to-2010 correction. The map is masked to the native extent of the combined -yield maps and aggregated to a 5 km resolution for visualization. For all maps, negative values -indicate that our circa 2010 estimates are lower than those of the earlier maps while positive -values indicate higher estimates.Our updated map of grassland biomass carbon in the year 2010 - -was similarly made by applying the original AVHRR-based model to calibrated MODIS imagery. -This too resulted in only subtle changes to the original biomass map (Fig. 6b) that were rarely -in excess of 0.5 MgC ha−1. In most areas, our estimates were higher than those of Xia et al.19 -who mapped the mean AGBC density between 1986 and 2006. Most of these elevated estimates corresponded -with areas in which significant NDVI increases (“greening”) have been reported while notably - -lower estimates in the Argentine Monte and Patagonian steppe biomes of southern South America, -likewise, correspond with areas of reported “browning”68,69. Both greening and browning trends -are well documented phenomena and have been linked to climatic changes70. Moreover, we further -compared AGBC estimates from both the original Xia et al.19 map and our 2010 update to AGBC -field measurements coordinated by the Nutrient Network that were collected from 48 sites around - -the world between 2007 and 200949. The RMSE (0.68 MgC ha−1) of our updated map was 10% less -that of the Xia et al. map for sites with less than 40% tree cover. Likewise, our 2010 estimates -were virtually unbiased (bias = −0.01 MgC ha−1) in comparison to the Xia map (bias = 0.25 -MgC ha−1). While still noisy, these results suggest that our temporal update improved the -overall accuracy of estimated grassland AGBC.Finally, cropland biomass carbon maps were also - -updated from their native epoch (2000) to 2010 using pixel-wise rates of MODIS ANPP change -over a ten-year period. While MODIS ANPP may be a poor snapshot of crop biomass in a single -year, we assumed that its relative change over time reflects real physiological shifts affecting -the cropland C cycle. This correction also resulted in only small differences that rarely -exceeded ±2 MgC ha−1 and that, spatially, correspond well with observed declines in the yields - -of select crops that have been linked to climate change71,72 (Fig. 6c). Nonetheless, updated -global yield maps comparable to those available for 2000 would greatly improve our understanding -of the interactions between climate change, crop yields, and C dynamics.Belowground biomass -is notoriously difficult to measure, model, and also to validate. We accounted for the reported -uncertainty of nearly every variable considered when estimating belowground biomass and pixel-level - -uncertainty, but we were unable to perform an independent validation of our harmonized estimates -at the pixel level due to a paucity of globally consistent field data. To complete such a -task, a globally orchestrated effort to collect more BGB samples data across all vegetation -types is needed.Given this lack of data, we instead compared the estimated uncertainty of -our BGBC maps to that of our AGBC estimates to infer the sources of any divergence (Fig. 5). - -As expected, our cumulative BGBC uncertainty layer generally reveals greater overall uncertainty -than our AGBC estimates, with BGBC uncertainty roughly twice that of AGBC throughout most -of the globe. The highest absolute uncertainty was found in biomass rich forests. Arid woodlands, -especially those of the Sahel and eastern Namibia, generally had the greatest relative BGBC -uncertainty, though their absolute uncertainty was quite small (generally less than 3 MgC - -ha−1). Here, biomass estimates of sparse woody vegetation were primarily responsible for heightened -relative uncertainty. High relative and absolute BGBC uncertainty were also associated with -predictions in select mountainous forests (e.g. east central Chile) as well as forested areas -in and around cities. These patterns were largely driven by AGB uncertainty in the GlobBiomass -product.The GlobBiomass global woody AGB map produced by Santoro et al.30 comprises the backbone - -of our integrated products and, with few exceptions, remains largely unchanged in our final -AGBC map. The native version of the GlobBiomass map is accompanied by an error layer describing -the uncertainty of each pixel’s biomass estimate and this too forms the core of our integrated -uncertainty layers. In areas with tree cover, the global average error of GlobBiomass estimates -is 39 Mg ha−1 or 50% with greater relative uncertainty in densely forested areas, along the - -margins of forested expanses like farm fields and cities, and in similar areas with sparse -tree cover.Adding additional grass or crop biomass in complementary proportion to a grid cell’s -tree cover often did not exceed the estimated error of the original GlobBiomass map (Fig. -7). Grid cells exceeding GlobBiomass’s native uncertainty comprise less than 40% of its total -extent. Exceptions were primarily found in grassland and cropland dominated regions where - -tree cover was generally sparse, and, consequently, the herbaceous biomass contribution was -relatively high. Even so, the absolute magnitude of these additions remains somewhat small -(less than 2.3 MgC ha−1 for grassland and 15 MgC ha−1 for cropland).Differences between the -final harmonized AGBC map and GlobBiomass AGBC. GlobBiomass AGB was aggregated to a 300 m -spatial resolution and converted to C density prior to comparison. Negative values indicate - -areas where the new map reports lower values than GlobBiomass while positive value denote -higher estimates.Larger deviations from GlobBiomass were also present in areas of both dryland -Africa and the Arctic tundra biome, where we used independent layers to estimate woody biomass. -In African drylands, GlobBiomass likely underestimates woody biomass by adopting the conservative -FAO definition (DBH > 10 cm), which implicitly omits the relatively small trees and shrubs - -that are common to the region. The Bouvet map of Africa that we used to supplement these estimates -is not bound by this constraint, was developed from region-specific data, and predicts substantially -higher AGB density throughout much of its extent with comparatively high accuracy (RMSE = -17.1 Mg ha−1)35.GlobBiomass also included sporadic biomass estimates throughout much of the -Arctic tundra biome. Trees are generally scarce throughout this biome, which is instead dominated - -by dwarf shrubs and herbaceous forbs and graminoids, so given GlobBiomass’s adherence to FAO -guidelines, its predictions here may be spurious. We thus prioritized the estimates of the -independent model developed specifically to collectively predict biomass of both woody and -herbaceous tundra vegetation. These estimates were generally higher than GlobBiomass but agreed -well with independent validation data from North America (RMSE = 2.9 Mg ha−1)18.While far - -from a perfect comparison, the only other map to comprehensively report global biomass carbon -density for all landcover types is the IPCC Tier-1 map for the year 2000 by Ruesch and Gibbs28. -As previously described, this map was produced using an entirely different method (“stratify -and multiply”) and distinct data sources23 and represents an earlier epoch. However, the map -is widely used for myriad applications, and it may thus be informative to assess notable differences - -between it and our new products.Ruesch and Gibbs28 report total living C stocks of 345 petagrams -(PgC) in AGBC and 133 PgC in BGBC for a total of 478 PgC, globally. Our estimates are lower -at 287 PgC and 122 PgC in global AGBC and BGBC, respectively, for a total of 409 PgC in living -global vegetation biomass. Herbaceous biomass in our maps comprised 9.1 and 28.3 PgC of total -AGBC and BGBC, respectively. Half of all herbaceous AGBC (4.5 PgC) and roughly 6% of all herbaceous - -BGBC (1.7 PgC) was found in croplands. Moreover, we mapped 22.3 and 6.1 PgC, respectively, -in the AGB and BGB of trees located within the cropland extent. These trees constituted roughly -7% of all global biomass C and are likely overlooked by both the Ruesch and Gibbs map28 and -by remotely sensed forest C maps that are masked to forested areas. Zomer et al.17 first highlighted -this potential discrepancy in the Ruesch and Gibbs map28 when they produced a remarkably similar - -estimate of 34.2 Pg of overlooked C in cropland trees using Tier-1 defaults. However, their -estimates were assumed to be in addition to the 474 PgC originally mapped by Ruesch and Gibbs28. -Here, we suggest that the 28.4 PgC we mapped in cropland trees is already factored into our -409 PgC total.Our AGBC product predicts substantially less biomass C than Ruesch and Gibbs28 -throughout most of the pantropical region and, to a lesser extent, southern temperate forests - -(Fig. 8a). This pattern has been noted by others comparing the Ruesch and Gibbs map28 to other -satellite-based biomass maps73 and may suggest that the IPCC default values used to create -it23 are spatially biased. In addition, well-defined areas of high disagreement emerge in -Africa that directly correspond with the FAO boundaries of the “tropical moist deciduous forest” -ecofloristic zone and suggest that this area, in particular, may merit critical review. Moreover, - -the opposite pattern is observed in this same ecofloristic zone throughout South America. -Our map also predicts greater AGBC throughout much of the boreal forest as well as in African -shrublands and the steppes of South America.Differences between the 2010 harmonized global -maps of above and belowground biomass carbon density and those of the IPCC Tier-1 product -by Ruesch and Gibbs for 2000. Comparisons of AGBC (a) and BGBC (b) maps are shown separately. - -Negative values indicate that the circa 2010 estimates are comparatively lower while positive -values indicate higher estimates.We observed similar, though less pronounced discrepancies, -when comparing BGBC maps (Fig. 8b). Notably, our map predicts substantially more BGBC throughout -the tundra biome – a previously underappreciated C stock that has recently risen to prominance74 -– the boreal forest, African shrublands and most of South America and Australia. However, - -we predict less BGBC in nearly all rainforests (Temperate and Tropical). These differences -and their distinct spatial patterns correspond with the vegetation strata used to make the -IPCC Tier-1 map28 and suggest that the accuracy of the “stratify and multiply” method depends -heavily upon the quality of the referenced and spatial data considered. Inaccuracies in these -data may, in turn, lead to false geographies. Integrating, continuous spatial estimates that - -better capture local and regional variation, as we have done, may thus greatly improve our -understanding of global carbon geographies and their role in the earth system.The error and -variance between our woody biomass estimates – when aggregated to the country level – and -comparable totals reported in the FRA were less for comparisons made against FRA estimates -generated using higher tier IPCC methodologies than for those based on Tier-1 approaches (Fig. - -9). Across the board for AGBC, BGBC, and total C comparisons, the relative RMSE (RMSECV) of -our estimates, when compared to estimates generated using high tier methods, was roughly half -of that obtained from comparisons with Tier-1 estimates (Table 8). Likewise, the coefficient -of determination (R2) was greatest for comparisons with Tier-3 estimates. For each pool-specific -comparison (AGBC, BGBC, and total C), the slopes of the relationships between Tier-1, 2, and - -3 estimates were neither significantly different from a 1:1 relationship nor from one another -(p > 0.05; ANCOVA). Combined, these results suggest that our maps lead to C stock estimates -congruent with those attained from independent, higher-tier reporting methodologies.Comparison -of woody biomass density estimates to corresponding estimates of the FAO’s FRA and the USFS’s -FIA. National woody AGBC totals derived from the woody components of our harmonized maps are - -compared to national totals reported in the 2015 FRA62 (a) in relation to the IPCC inventory -methodology used by each country. Likewise, we derived woody AGBC totals for US states and -compared them to the corresponding totals reported by the 2014 FIA75 (b), a Tier-3 inventory. -We also show the additional effect of considering non-woody C – as is reported in our harmonized -maps – in light green. Similar comparisons were made between our woody BGBC estimates and - -the corresponding estimates of both the FRA (c) and FIA (d). We further summed our woody AGBC -and BGBC estimates and compared them to the total woody C stocks reported by both the FRA -(e) and FIA (f).To explore this association at a finer regional scale, we also compared our -woody C estimates to the United States Forest Service’s Forest Inventory Analysis75 (FIA) -and found similarly strong congruence for AGBC and Total C stocks but subtle overestimates - -for BGBC (Fig. 9). The FIA is a Tier-3 inventory of woody forest biomass C stocks that is -based on extensive and statistically rigorous field sampling and subsequent upscaling, We -used data available at the state level for the year 2014 – again, the only year in which we -could obtain data partitioned by AGBC and BGBC. Like our FRA comparison, we found a tight -relationship between our woody AGBC totals and those reported by the FIA (Fig. 9b; RMSECV - -= 25.7%, R2 = 0.960, slope = 1.10, n = 48). Our woody BGBC estimates, though, were systematically -greater than those reported by the FIA (Fig. 9d; RMSECV = 86.4%, R2 = 0.95, slope = 1.51, -n = 48). This trend has been noted by others27 and suggests that the global model that we -used to estimate woody BGBC may not be appropriate for some finer scale applications as is -foretold by the elevated uncertainty reported in our corresponding uncertainty layer (Fig. - -5b). Our total woody C (AGBC + BGBC) estimates (Fig. 9f), however, agreed well with the FIA -(RMSECV = 34.1%, R2 = 0.961, slope = 1.17, n = 48) and thus reflect the outsized contribution -of AGBC to the total woody C stock. When the contribution of herbaceous C stocks is further -added to these comparisons, our stock estimates intuitively increase in rough proportion to -a state’s proportional extent of herbaceous cover. The effect of this addition is particularly - -pronounced for BGBC estimates due to the large root-to-shoot ratios of grassland vegetation.The -relative congruence of our results with higher-tier stock estimates suggests that our maps -could be used to facilitate broader adoption of higher-tier methods among countries currently -lacking the requisite data and those seeking to better account for C in non-woody biomass. -This congruence spans a comprehensive range of biophysical conditions and spatial scales ranging - -from small states to large nations. Moreover, a recent study suggests that the fidelity of -the underlying GlobBiomass AGB map may extend to even finer scales31. While our BGBC estimates -may differ from some fine-scale estimates (Fig. 9d), their tight agreement with high tier -BGBC totals at the national level (Fig. 9c) suggests that they may still be well suited for -many national-scale C inventories – especially for countries lacking requisite high tier data. - -Use of our maps is unlikely to introduce error in excess of that currently implicit in Tier-1 -estimates. Credence, though, should be given to the associated uncertainty estimates. To facilitate -wider adoption of higher-tier methodologies, our maps could be used to derive new, region-specific -default values for use in Tier-2 frameworks76 or to either represent or calibrate 2010 baseline -conditions in Tier-3 frameworks. In so doing, inventories and studies alike could more accurately - -account for the nuanced global geographies of biomass C.These maps are intended for global -applications in which continuous spatial estimates of live AGBC and/or BGBC density are needed -that span a broad range of vegetation types and/or require estimates circa 2010. They are -loosely based upon and share the spatial resolution of the ESA CCI Landcover 2010 map37, which -can be used to extract landcover specific C totals. However, our products notably do not account - -for C stored in non-living C pools like litter or coarse woody debris, nor soil organic matter, -though these both represent large, additional ecosystem C stocks77,78,79. Our maps are explicitly -intended for global scale applications seeking to consider C in the collective living biomass -of multiple vegetation types. For global scale applications focused exclusively on the C stocks -of a single vegetation type, we strongly encourage users to instead use the respective input - -map or model referenced in Table 1 to avoid potential errors that may have been introduced -by our harmonization procedure. For AGB applications over smaller extents, users should further -consider whether locally specific products are available. If such maps are not available and -our maps are considered instead, credence should be given to their pixel-level uncertainty -estimates. As mentioned above, the biomass of shrublands was only explicitly accounted for - -in Africa and the Arctic tundra, since neither broad-scale maps nor models generalizable to -other areas were available in the existing literature. 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We are also grateful to the thoughtful feedback of three anonymous reviewers - -whose suggestions greatly improved the quality of our products and the clarity of our manuscript. -Funding for this project was generously provided by the David and Lucile Packard Foundation -and the National Wildlife Federation.Department of Geography, University of Wisconsin-Madison, -Madison, WI, USASeth A. Spawn, Clare C. Sullivan & Holly K. GibbsCenter for Sustainability -and the Global Environment (SAGE), Nelson Institute for Environmental Studies, University - -of Wisconsin-Madison, Madison, WI, USASeth A. Spawn, Clare C. Sullivan, Tyler J. Lark & Holly -K. GibbsYou can also search for this author in PubMed Google ScholarYou can also search for -this author in PubMed Google ScholarYou can also search for this author in PubMed Google ScholarYou -can also search for this author in PubMed Google ScholarS.A.S. designed the harmonization -procedure, compiled and standardized individual biomass layers, conducted all mapping, and - -led manuscript development. C.C.S., T.J.L. and H.K.G. assisted with conceptualization, and -manuscript development.Correspondence to Seth A. Spawn.The authors declare no competing interests.Publisher’s -note Springer Nature remains neutral with regard to jurisdictional claims in published maps -and institutional affiliations.Open Access This article is licensed under a Creative Commons -Attribution 4.0 International License, which permits use, sharing, adaptation, distribution - -and reproduction in any medium or format, as long as you give appropriate credit to the original -author(s) and the source, provide a link to the Creative Commons license, and indicate if -changes were made. The images or other third party material in this article are included in -the article’s Creative Commons license, unless indicated otherwise in a credit line to the -material. If material is not included in the article’s Creative Commons license and your intended - -use is not permitted by statutory regulation or exceeds the permitted use, you will need to -obtain permission directly from the copyright holder. To view a copy of this license, visit -http://creativecommons.org/licenses/by/4.0/.The Creative Commons Public Domain Dedication -waiver http://creativecommons.org/publicdomain/zero/1.0/ applies to the metadata files associated -with this article.Reprints and PermissionsSpawn, S.A., Sullivan, C.C., Lark, T.J. et al. Harmonized - -global maps of above and belowground biomass carbon density in the year 2010. Sci Data 7, -112 (2020). https://doi.org/10.1038/s41597-020-0444-4Download citationReceived: 03 July 2019Accepted: -14 February 2020Published: 06 April 2020DOI: https://doi.org/10.1038/s41597-020-0444-4Anyone -you share the following link with will be able to read this content:Sorry, a shareable link -is not currently available for this article. Provided by the Springer Nature SharedIt content-sharing - -initiative Nature Water (2023)Nature Plants (2023)Nature Communications (2023)Scientific Data -(2023)Nature Communications (2023)Advertisement Scientific Data (Sci Data) ISSN 2052-4463 -(online) © 2023 Springer Nature LimitedSign up for the Nature Briefing newsletter — what matters -in science, free to your inbox daily. January 22 - July 26, 2023JPEGOne of the wettest wet -seasons in northern Australia transformed large areas of the country’s desert landscape over - -the course of many months in 2023. A string of major rainfall events that dropped 690 millimeters -(27 inches) between October 2022 and April 2023 made it the sixth-wettest season on record -since 1900–1901.This series of false-color images illustrates the rainfall’s months-long effects -downstream in the Lake Eyre Basin. Water appears in shades of blue, vegetation is green, and -bare land is brown. The images were acquired by the Moderate Resolution Imaging Spectroradiometer - -(MODIS) on NASA’s Terra satellite between January and July 2023.In the January 22 image (left), -water was coursing through seasonally dry channels of the Georgina River and Eyre Creek following -weeks of heavy rains in northern Queensland. By April 21 (middle), floodwaters had reached -further downstream after another intense period of precipitation in March. This scene shows -that water had filled in some of the north-northwest trending ridges that are part of a vast - -fossil landscape of wind-formed dunes, while vegetation had emerged in wet soil upstream. -Then by July 26 (right), the riverbed had filled with even more vegetation.The Georgina River -and Eyre Creek drain approximately 210,000 square kilometers (81,000 square miles), nearly -the area of the United Kingdom. Visible in the lower part of the images, the lake gets refreshed -about every three years; when it reaches especially high levels, it may take 18 months to - -2 years to dry up. Two smaller neighboring lakes flood seasonally. These three lakes and surrounding -floodplains support hundreds of thousands of waterbirds and are designated as an Important -Bird Area.Seasonal flooding is a regular occurrence in these desert river systems. However, -the events of the 2022-2023 rainy season stood out in several ways. They occurred while La -Niña conditions were in place over the tropical Pacific Ocean. (The wettest seasons in northern - -Australia have all occurred during La Niña years, according to Australia’s Bureau of Meteorology.) -In addition, major rains occurring in succession, as was the case with the January and March -events, have the overall effect of prolonging floods. That’s because vegetation that grows -after the first event slows down the pulse of water that comes through in the next rain event.The -high water has affected both local communities and ecosystems. Floods have inundated cattle - -farms and isolated towns on temporary islands. At the same time, they are a natural feature -of the “boom-and-bust” ecology of Channel Country, providing habitat and nutrients that support -biodiversity.NASA Earth Observatory image by Wanmei Liang, using MODIS data from NASA EOSDIS -LANCE and GIBS/Worldview. Story by Lindsey Doermann.View this area in EO ExplorerRepeated -heavy rains in Australia set off waves of new growth across Channel Country.Image of the Day - -for August 7, 2023 Image of the Day Land Water View more Images of the Day: Floods The waves -off the coast of Teahupo’o can heave a crushing amount of water toward the shore and onto -unlucky surfers. Image of the Day Water Waves of heavy rainfall left towns and farmland under -water in October 2022. Image of the Day Water Floods Acquired February 26, 2011, and February -5, 2011, these false-color images show the impact of heavy rains in marshy areas southeast - -of Georgetown, Guyana. Land Floods August 25, 2023JPEGSeptember 18, 2023JPEGAugust 25, 2023September -18, 2023August 25, 2023JPEGSeptember 18, 2023JPEGSeptember 18, 2023JPEGHeavy rain from a cyclone -in the Mediterranean inundated cities along the northeastern coast of Libya in early September -2023, causing thousands of deaths. The port city of Derna (Darnah), home to about 90,000 people, -was one of the worst hit by the storm and suffered extensive flooding and damage. On September - -10 and 11, over 100 millimeters (4 inches) of rain fell on Derna. The city lies at the end -of a long, narrow valley, called a wadi, which is dry except during the rainy season. Floods -triggered two dams along the wadi to collapse. The failure of the second dam, located just -one kilometer inland of Derna, unleashed 3- to 7-meter-high floodwater that tore through the -city. According to news reports, the flash floods destroyed roads and swept entire neighborhoods - -out to sea. The images above show the city before and after the storm. The image on the right, -acquired by the Operational Land Imager-2 (OLI-2) on Landsat 9 on September 18, shows eroded -banks of Wadi Derna near where it meets the Mediterranean. Water just off the coast appears -muddier than in the image on the left, which shows the same area on August 25 and was acquired -by Landsat 8. Preliminary estimates by the United Nations Satellite Center (UNOSAT) indicate - -that 3,100 buildings in Derna were damaged by rushing water. According to the UN International -Organization for Migration (IOM), about 40,000 people in the country were displaced by the -storm, and 30,000 of those were displaced from Derna. Tropical-like cyclones in the Mediterranean, -or “medicanes,” develop only once or twice a year, according to NOAA, and typically form in -autumn. According to meteorologists at Yale Climate Connections, this storm was the deadliest - -in Africa’s recorded history. A recent assessment by scientists at World Weather Attribution -estimated that precipitation received by the region was a one-in-300 to one-in-600-year event. -NASA Earth Observatory images by Lauren Dauphin, using Landsat data from the U.S. Geological -Survey. Story by Emily Cassidy.View this area in EO ExplorerFlash floods in the port city -destroyed roads and swept neighborhoods out to sea.Image of the Day for September 21, 2023 - -Image of the Day Land Water Floods Human Presence View more Images of the Day:The melting -of frozen rivers and snowpack, and the heavy rains of late spring and summer, can send rivers -out of their banks.A Mediterranean cyclone contributed to deadly flooding along the country’s -coastline. Image of the Day Land Water Floods Record rainfall inundated towns and farmland -in the country’s Thessaly region. Image of the Day Water Floods Human Presence A stalled storm - -dropped three feet of rain over four days on the Thessaly region, triggering extensive flooding. -Image of the Day Atmosphere Floods An isolated low-pressure system produced torrential downpours -in Spain and carried Saharan dust along its path. Image of the Day Atmosphere Land Floods -Human Presence July 2002 - June 2022JPEGThe deep-blue sea is turning a touch greener. While -that may not seem as consequential as, say, record warm sea surface temperatures, the color - -of the ocean surface is indicative of the ecosystem that lies beneath. Communities of phytoplankton, -microscopic photosynthesizing organisms, abound in near-surface waters and are foundational -to the aquatic food web and carbon cycle. This shift in the water’s hue confirms a trend expected -under climate change and signals changes to ecosystems within the global ocean, which covers -70 percent of Earth’s surface. Researchers led by B. B. Cael, a principal scientist at the - -U.K.’s National Oceanography Centre, revealed that 56 percent of the global sea surface has -undergone a significant change in color in the past 20 years. After analyzing ocean color -data from the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument on NASA’s Aqua -satellite, they found that much of the change stems from the ocean turning more green. The -map above highlights the areas where ocean surface color changed between 2002 and 2022, with - -darker shades of green representing more-significant differences (higher signal-to-noise ratio). -By extension, said Cael, “these are places we can detect a change in the ocean ecosystem in -the last 20 years.” The study focused on tropical and subtropical regions, excluding higher -latitudes, which are dark for part of the year, and coastal waters, where the data are naturally -very noisy. The black dots on the map indicate the area, covering 12 percent of the ocean’s - -surface, where chlorophyll levels also changed over the study period. Chlorophyll has been -the go-to measurement for remote sensing scientists to gauge phytoplankton abundance and productivity. -However, those estimates use only a few colors in the visible light spectrum. The values shown -in green are based on the whole gamut of colors and therefore capture more information about -the ecosystem as a whole. A long time series from a single sensor is relatively rare in the - -remote sensing world. As the Aqua satellite was celebrating its 20th year in orbit in 2022—far -exceeding its design life of 6 years—Cael wondered what long term trends could be discovered -in the data. In particular, he was curious what might have been missed in all the ocean color -information it had collected. “There’s more encoded in the data than we actually make use -of,” he said. By going big with the data, the team discerned an ocean color trend that had - -been predicted by climate modeling, but one that was expected to take 30-40 years of data -to detect using satellite-based chlorophyll estimates. That’s because the natural variability -in chlorophyll is high relative to the climate change trend. The new method, incorporating -all visible light, was robust enough to confirm the trend in 20 years. At this stage, it is -difficult to say what exact ecological changes are responsible for the new hues. However, - -the authors posit, they could result from different assemblages of plankton, more detrital -particles, or other organisms such as zooplankton. It is unlikely the color changes come from -materials such as plastics or other pollutants, said Cael, since they are not widespread enough -to register at large scales. “What we do know is that in the last 20 years, the ocean has -become more stratified,” he said. Surface waters have absorbed excess heat from the warming - -climate, and as a result, they are less prone to mixing with deeper, more nutrient-rich layers. -This scenario would favor plankton adapted to a nutrient-poor environment. The areas of ocean -color change align well with where the sea has become more stratified, said Cael, but there -is no such overlap with sea surface temperature changes. More insights into Earth’s aquatic -ecosystems may soon be on the way. NASA’s PACE (Plankton, Aerosol, Cloud, ocean Ecosystem) - -satellite, set to launch in 2024, will return observations in finer color resolution. The -new data will enable researchers to infer more information about ocean ecology, such as the -diversity of phytoplankton species and the rates of phytoplankton growth. NASA Earth Observatory -image by Wanmei Liang, using data from Cael, B. B., et al. (2023). Story by Lindsey Doermann.Two -decades of satellite measurements show that the sea surface is shading toward green.Image - -of the Day for October 2, 2023 Image of the Day Life Water View more Images of the Day:Datasets -from the Sentinel-6 Michael Freilich satellite will build upon three decades of sea level -measurements. Image of the Day Heat Water Remote Sensing Image of the Day Life Water Image -of the Day Water The use of plastic on farms has become so common in recent decades that there -there’s a term for it—plasticulture. Image of the Day Human Presence August 16, 2023JPEGThe - -Canary Islands were at the center of a mélange of natural events in summer 2023. The Moderate -Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this assemblage -of phenomena off the coast of Africa on August 16, 2023.In the center of the scene, smoke -is seen rising from a wildfire burning on Tenerife in the Canary Islands. The blaze started -amid hot and dry conditions on August 15 in forests surrounding the Teide Volcano. Authorities - -issued evacuation orders to five villages, and responders focused on containing the fire’s -spread and protecting residential areas near the coast, according to news reports. Other fires -have burned on the Canary Islands this summer, including on La Palma in July.To the west, -a swirling cloud moves across the Atlantic. Cloud vortices appear routinely downwind of the -Canary Islands—sometimes in great abundance—and are produced when the tall volcanic peaks - -disrupt the air flowing past them.Elsewhere in the atmosphere, dust from the Sahara Desert -was lofted out over the ocean. The river of dust crossing the Atlantic was more pronounced -in previous days, when it reached islands in the Caribbean. Traveling on the Saharan Air Layer, -dust sometimes makes it even further west toward Central America and the U.S. states of Florida -and Texas.To round out the list, the patch of bright blue off the Moroccan coast is most likely - -a bloom of phytoplankton. While the exact cause and composition of the bloom cannot be determined -from this image, mineral-rich desert dust has been shown to set off bursts of phytoplankton -growth.In addition to the Earth’s processes seen here, one remote sensing artifact is present. -A diagonal streak of sunglint makes part of this scene appear washed out. Sunglint, an effect -that occurs when sunlight reflects off the surface of the water at the same angle that a satellite - -sensor views it, is also the reason for the light-colored streaks trailing off the islands.NASA -Earth Observatory image by Wanmei Liang, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview. -Story by Lindsey Doermann.View this area in EO ExplorerAn assortment of natural phenomena -visible from space appeared together in one image.Image of the Day for August 17, 2023 Image -of the Day Atmosphere Land Water View more Images of the Day:Flights were grounded as visibility - -was severely hampered by a Calima event. Image of the Day Atmosphere Land Dust and Haze Human -Presence In one frame International Space Station astronauts were able to capture the evolution -of fringing reefs to atolls. As with the Hawaiian Islands, these volcanic hot spot islands -become progressively older to the northwest. As these islands move away from their magma sources -they erode and subside. Image of the Day Land Water The dry, volcanic terrain of this Canary - -Island is suitable for lichen and crops … and for training astronauts. Image of the Day Land -The event, known locally as “la calima,” turned skies orange and degraded air quality in Gran -Canaria and neighboring islands. Image of the Day Atmosphere Land Dust and Haze July 17, 2023JPEGFour -funnel-shaped estuarine inlets, collectively known as Rías Baixas, line the coast of Galicia, -in northwest Spain. The nutrient-rich water in these inlets supports a wealth of marine life, - -making the Galicia coast one of the most productive places for aquaculture.On July 17, 2023, -the Operational Land Imager-2 (OLI-2) on Landsat 9, acquired this image of the Rías de Arousa -(Arousa estuary), the largest and northernmost of the inlets. Small dots skirt the coasts -of the embayment. In most cases, these dots are rectangular rafts designed for raising bivalves -like mussels. Buoys keep the lattice mussel rafts afloat on the surface of the water, and - -hundreds of ropes are suspended into the water column from each structure. Mussels attach -to the ropes and filter feed on phytoplankton and other suspended organic particles. The rafts -allow for high yields of mussels in a small area of the water. The Rías Baixas are on the -northern end of the Canary current and are in a major upwelling zone. Upwelling, which brings -colder, nutrient-rich water up from the bottom of the ocean, typically occurs in this area - -between April and October. Much of the mussel production in the Rías Baixas occurs during -this time, as the mollusks filter feed on nutrients and plentiful phytoplankton supported -by upwelling. Spain is the top mussel producing country in the world. Rías de Arousa alone -contains over 2,400 mussel rafts, producing about 40 percent of Europe’s mussels. NASA Earth -Observatory image by Wanmei Liang, using Landsat data from the U.S. Geological Survey. Story - -by Emily Cassidy. Buoys keep the lattice mussel rafts afloat on the surface of the water, -and hundreds of ropes are suspended into the water column from each structure. Mussels attach -to the ropes and filter feed on phytoplankton and other suspended organic particles. The rafts -allow for high yields of mussels in a small area of the water. The Rías Baixas are on the -northern end of the Canary current and are in a major upwelling zone. Upwelling, which brings - -colder, nutrient-rich water up from the bottom of the ocean, typically occurs in this area -between April and October. Much of the mussel production in the Rías Baixas occurs during -this time, as the mollusks filter feed on nutrients and plentiful phytoplankton supported -by upwelling. Spain is the top mussel producing country in the world. Rías de Arousa alone -contains over 2,400 mussel rafts, producing about 40 percent of Europe’s mussels. NASA Earth - -Observatory image by Wanmei Liang, using Landsat data from the U.S. Geological Survey. Story -by Emily Cassidy.View this area in EO ExplorerThe estuarine inlets of Spain’s Galicia coast -are some of the most productive places to grow mussels.Image of the Day for September 19, -2023 Image of the Day Water Human Presence View more Images of the Day: Dust and Haze This -image shows Tropical Cyclones Eric and Fanele near Madagascar on January 19, 2009. Atmosphere - -Water Severe Storms This natural-color image shows Saharan dust forming an S-shaped curve -off the western coast of Africa, and passing directly over Cape Verde. Atmosphere Land Dust -and Haze Acquired March 8, 2010, this true-color image shows two icebergs, Iceberg B-09B and -an iceberg recently broken off the Mertz Glacier, floating in the Southern Ocean, just off -the George V Coast. Water Snow and Ice Sea and Lake Ice May 18, 2023JPEGSeptember 7, 2023JPEGMay - -18, 2023September 7, 2023May 18, 2023JPEGSeptember 7, 2023JPEGSeptember 7, 2023JPEGAfter going -dry in 2018, Laguna de Aculeo has begun to refill. NASA satellites began to detect water pooling -in the parched lake in late-August, after an intense winter storm dropped as much as 370 millimeters -(15 inches) of rain on some parts of central Chile. The storm was fueled by an atmospheric -river and exacerbated by the rugged terrain in central Chile.When the Operational Land Imager-2 - -(OLI-2) on Landsat 9 acquired this image (right) on September 7, 2023, Laguna de Aculeo covered -about 5 square kilometers (2 square miles) to a depth of roughly 1 meter (3 feet). The other -image (left) shows the dried water body on May 18, 2023, before the wet winter weather arrived. -Although it has refilled somewhat, water spans only half the area it did up to 2010 and contains -a quarter of the water volume, explained René Garreaud, an Earth scientist at the University - -of Chile. Seasonal changes and the influx of water have led to widespread greening of the -landscape around the lake.Researchers have assessed that ongoing development and water use -in the nearby community of Paine, increasing water use by farmers and in homes and pools, -as well as several years of drought, likely contributed to the drawdown of the lake. Annual -rainfall deficits that averaged 38 percent between 2010 and 2018 likely played a large role, - -according to one analysis from a team of researchers from the University of Chile.Before 2010, -the shallow water body was a popular haven for boaters, swimmers, and water skiers, but the -water hasn’t yet pooled up enough for swimmers or boaters to return. It is also unclear how -long the new water in Aculeo will persist. “Atmospheric rivers in June and August delivered -substantial precipitation along the high terrain and foothills that have giv­­en us a welcome - -interruption to the drought,” Garreaud said. “But Aculeo is a small, shallow lagoon that can -fill up rapidly, and it's only partly filled. Bigger reservoirs and aquifers will take much -longer to recover.”NASA Earth Observatory images by Lauren Dauphin, using Landsat data from -the U.S. Geological Survey. Story by Adam Voiland.View this area in EO ExplorerThe drought -in Chile isn’t over, but recent late-winter rains provided enough moisture for water to start - -pooling up again.Image of the Day for September 16, 2023 Image of the Day Life Water View -more Images of the Day:Data from winter 2022-2023 show the greatest net gain of water in nearly -22 years, but groundwater levels still suffer from years of drought. Image of the Day Land -Water As a persistent drought drags on, water levels are dropping at a key reservoir that -supplies Santiago. Image of the Day Land Water A new web tool designed by NASA applied scientists - -could help the tribe anticipate and respond to drought. Image of the Day Water Human Presence -Remote Sensing For more than 100 years, groups in the western United States have fought over -water. During the 1880s, sheep ranchers and cattle ranchers argued over drinking water for -their livestock on the high plains. In 1913, the city of Los Angeles began to draw water away -from small agricultural communities in Owen Valley, leaving a dusty dry lake bed. In the late - -1950s, construction of the Glen Canyon Dam catalyzed the American environmental movement. -Today, farmers are fighting fishermen, environmentalists, and Native American tribes over -the water in the Upper Klamath River Basin. The Landsat 7 satellite, launched by NASA and -operated by the U.S. Geological Survey, documented an extreme drought in the area along the -California/Oregon border in the spring of 2001. Image of the Day Land Life September 16, 2023JPEGSeptember - -10, 2021JPEGSeptember 16, 2023September 10, 2021September 16, 2023JPEGSeptember 10, 2021JPEGSeptember -10, 2021JPEGMonths of excessive heat and drought parched the Mississippi River in the summer -and early fall of 2023. In September, low water levels limited barge shipments downriver and -threatened drinking water supplies in some Louisiana communities, according to the Associated -Press.Water levels were especially low near Memphis, Tennessee. The images above show the - -Mississippi River near Memphis on September 16, 2023 (left), compared to September 10, 2021 -(right). The river was significantly slimmed down in 2023, exposing some of the river bottom.This -is the second year in a row drought has caused the river to fall to near-record lows at many -gauges. On September 26, 2023, the river level at a gauge in Memphis was -10.26 feet, close -to the record low level, -10.81 feet, measured at the same place on October 21, 2022. That - -was the lowest level recorded there since the start of National Weather Service records in -1954. Water levels, or “gauge heights,” do not indicate the depth of a stream; rather, they -are measured with respect to a chosen reference point. That is why some gauge height measurements -are negative.Farther upstream, water levels at New Madrid, Missouri, have been around -5 feet—near -the minimum operating level—since early September 2023. Water levels on the Mississippi normally - -decline in the fall and winter, and in 2022, the river did not get that low until mid-October. -September 26, 2023JPEGA hot, dry summer is the main reason water levels dropped so low in -2023. Across the globe, temperatures in summer 2023 were 1.2°C (2.1°F) warmer than average. -In the U.S., Louisiana and Mississippi experienced their hottest Augusts on record, according -to NOAA.The U.S. Drought Monitor map above—the product of a partnership between the U.S. Department - -of Agriculture, the National Oceanic and Atmospheric Administration, and the University of -Nebraska-Lincoln—shows conditions during the week of September 20-26, 2023. The map depicts -drought intensity in progressive shades of orange to red. It is based on an analysis of climate, -soil, and water condition measurements from more than 350 federal, state, and local observers -around the country. NASA contributes measurements and models that aid the drought monitoring - -effort.During that week, about 38 percent of the contiguous U.S. was experiencing drought. -Lack of precipitation and high temperatures over several months severely dried out soils in -states along the Mississippi River Valley. The Drought Monitor reported that 80 percent of -soils in Louisiana were dry (short or very short on water) as of September 24. And for most -states in the river valley, over 50 percent of topsoil was dry or very dry.Shallow conditions - -along the river interrupted normal shipments of goods. According to the Associated Press, -barge companies reduced the weight carried in many shipments in September because the river -was not deep enough to accommodate their normal weight. Much of U.S. grain exports are transported -down the Mississippi, and according to AP, the cost of these shipments from St. Louis southward -has risen 77 percent above the three-year average. The lack of freshwater flowing into the - -Gulf of Mexico has also allowed saltwater to make its way up the river and into some water -treatment plants in southern Louisiana, according to the Associated Press. Some parts of Plaquemines -Parish are under drinking water advisories and have relied on bottled water for cooking and -drinking since June.Significant rainfall would be needed to flush out saltwater in the river -in Plaquemines. According to the National Weather Service’s Lower Mississippi River Forecast - -Center, the forecast does not look promising. If enough rainfall doesn’t arrive before mid-to-late -October, saltwater could make its way to New Orleans.NASA Earth Observatory images by Lauren -Dauphin, using Landsat data from the U.S. Geological Survey and data from the United States -Drought Monitor at the University of Nebraska-Lincoln. Story by Emily Cassidy.View this area -in EO ExplorerIn September, low water levels made it more challenging to ship goods down the - -river and allowed a wedge of saltwater to move upstream.Image of the Day for October 1, 2023 -Image of the Day Water Drought View more Images of the Day:Persistent dry conditions can affect -water resources, ecosystems, and agriculture.Severe drought is reducing the number of daily -passages on the transoceanic shipping route. Image of the Day Water Human Presence Prolonged -drought in Kansas set the stage for what may be one of the state’s smallest wheat harvests - -in decades. Image of the Day Land Water Drought The most severe drought in 70 years of record -keeping threatens the Horn of Africa with famine. Image of the Day Land Water Drought Low -water levels are making it difficult to ship goods down the river and allowing a wedge of -saltwater to move upstream. Image of the Day Land Water Human Presence Remote Sensing September -25, 2023JPEGLake Winnipeg, the world’s 10th largest freshwater lake by surface area, has experienced - -algae blooms at a regular occurrence at least since the 1990s. A bloom of blue-green algae -once again covered parts of the lake in September 2023. Located in Manitoba, Canada, the long -lake has a watershed that spans one million square kilometers (386,000 square miles), draining -some of Canada’s agricultural land. The lake consists of a large, deep north basin and a smaller, -comparatively shallow south basin. Swirls of algae filled the south basin of the lake on September - -25, 2023, when the OLI-2 (Operational Land Imager-2) on Landsat 9 acquired this image. Around -this time, satellite observations analyzed by Environment and Climate Change Canada indicated -that algae covered about 8,400 square kilometers (3,200 square miles), or about a third of -the lake’s area.Blue-green algae, also known as cyanobacteria, are single-celled organisms -that rely on photosynthesis to turn sunlight into food. The bacteria grow swiftly when nutrients - -like phosphorus and nitrogen are abundant in still water. The bloom pictured here may contain -blue-green algae, as well as other types of phytoplankton; only a surface sample can confirm -the exact composition of a bloom. Some cyanobacteria produce microcystin—a potent toxin that -can irritate the skin and cause liver and kidney damage.While algae are part of a natural -freshwater ecosystem, excess algae, particularly cyanobacteria, can be a nuisance to residents - -and tourists using the lake and its beaches for fishing, swimming, and recreation. Beaches -in the south basin of Lake Winnipeg can get as many as 30,000 visitors a day during the summer -months. Water samples taken at Winnipeg Beach on the west shore found that cyanobacteria levels -were elevated in August, and visitors were advised to avoid swimming and fishing if green -scum was visible. The health of Lake Winnipeg has been in decline in recent decades. Between - -1990 and 2000, phosphorous concentrations in the lake almost doubled and algae blooms proliferated, -both in terms of occurrence and extent. The major contributors to the influx of phosphorous -to the lake were increased agricultural activities in the watershed and a higher frequency -of flooding, which has increased runoff into the lake.Phosphorus concentrations are almost -three times higher in the south basin of Lake Winnipeg, compared to the north basin. A 2019 - -study using data from the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument -on NASA’s Terra satellite found that the chlorophyll-a concentrations, which are used as a -measure of phytoplankton biomass, were on average more than twice as high in the south basin, -compared to the north. NASA Earth Observatory images by Wanmei Liang, using Landsat data from -the U.S. Geological Survey. Story by Emily Cassidy.View this area in EO ExplorerAn influx - -of nutrients in recent decades has contributed to the proliferation of algae in the large -Canadian lake.Image of the Day for October 6, 2023 Image of the Day Water Water Color View -more Images of the Day:Floating, plant-like organisms reproduce abundantly when there are -sufficient nutrients, sunlight, and water conditions. Extreme blooms of certain species can -become harmful to marine animals and humans.Cyanobacteria covered over half of the surface - -of Florida’s largest freshwater lake in mid-June 2023. Image of the Day Life Water Water Color -Nearly half of the lake was covered with blue-green algae in early July 2022. Image of the -Day Water Remote Sensing Water Color More than 40 years after the explosive eruption of Mount -St. Helens, relics from the blast continue to haunt a nearby lake. Image of the Day Water -Venezuela’s Lake Maracaibo is choking with oil slicks and algae. Image of the Day Life Water - -Human Presence Remote Sensing October 8, 2022JPEGOctober 3, 2023JPEGOctober 8, 2022October -3, 2023October 8, 2022JPEGOctober 3, 2023JPEGOctober 3, 2023JPEGJuly through October fall -within the dry season in the western and northern Amazon rainforest, but a particularly acute -lack of rain during this period in 2023 has pushed the region into a severe drought.The OLI -(Operational Land Imager) instrument on Landsat 8 captured this image (right) of the parched - -Rio Negro in the Brazilian province of Amazonas near the city of Manaus on October 3, 2023. -On that date, the level of the river, the largest tributary of the Amazon River, had dropped -to 15.14 meters (50.52 feet), according to data collected by the Port of Manaus. For comparison, -the image on the left shows the same area on October 8, 2022, when the water level was 19.59 -meters, a more typical level for October. Rio Negro water levels continued to drop in the - -days after the image was collected, reaching a record low of 13.49 meters on October 17, 2023.Some -areas in the Amazon River’s watershed have received less rain between July and September than -any year since 1980, Reuters reported. The drought has been particularly severe in the Rio -Negro watershed in northern Amazonas, as well as parts of southern Venezuela and southern -Colombia.“Overall, this is a pretty unusual and extreme situation,” said René Garreaud, an - -atmospheric scientist at the University of Chile. “The primary culprit exacerbating the drought -appears to be El Niño.” This cyclical warming of surface waters in the central-eastern Pacific -functions somewhat like a boulder in the middle of a stream, disrupting atmospheric circulation -patterns in ways that lead to wetter conditions over the equatorial Pacific and drier conditions -over the Amazon Basin.According to news outlets, the low river water levels on the Rio Negro - -and other nearby rivers have disrupted drinking water supplies in hundreds of communities, -slowed commercial navigation, and led to fish and dolphin die-offs.Manaus, the capital and -largest city of the Brazilian state of Amazonas, is the primary transportation hub for the -upper Amazon, serving as an important transit point for soap, beef, and animal hides. Other -industries with a presence in the city of two million people include chemical, ship, and electrical - -equipment manufacturing.NASA Earth Observatory images by Wanmei Liang, using Landsat data -from the U.S. Geological Survey. Story by Adam Voiland.View this area in EO ExplorerThe water -level of the largest tributary of the Amazon River has hit a record low.Image of the Day for -October 18, 2023 Image of the Day Water Human Presence View more Images of the Day:The impact -of severe drought on the Negro River, a tributary of the Amazon River, and other rivers in - -the basin is dramatically evident in this pair of images, which show that every body of water -has shrunk in 2010 compared to 2008. Image of the Day Atmosphere Land The volume of water -in New Mexico’s largest reservoir has dropped to historic lows due to drought and persistent -demand. Image of the Day Water Human Presence Acquired June 25, 2011, and June 22, 2010, these -false-color images compare conditions along the Souris River, which reached a historic crest - -at Minot, North Dakota in June 2011. Land Floods Acquired May 11, 2011, and April 21, 2007, -these false-color images show the Mississippi River near Natchez, Mississippi. The image from -May 2011 shows flooded conditions. Land Floods September 6, 2020JPEGSeptember 7, 2023JPEGSeptember -6, 2020September 7, 2023September 6, 2020JPEGSeptember 7, 2023JPEGSeptember 7, 2023JPEGAfter -rapidly growing in volume just a few years earlier, northwest Iran’s Lake Urmia nearly dried - -out in autumn 2023. The largest lake in the Middle East and one of the largest hypersaline -lakes on Earth at its greatest extent, Lake Urmia has for the most part transformed into a -vast, dry salt flat. On September 7, 2023, the OLI-2 (Operational Land Imager-2) on Landsat -9 captured this image (right) of the desiccated lakebed. It stands in contrast to the image -from three years earlier (left), acquired by the OLI on Landsat 8 on September 8, 2020, when - -water filled most of the basin and salt deposits were only visible around the perimeter of -the lake. The replenishment followed a period of above-average precipitation that sent a surge -of freshwater into the basin, expanding its watery footprint. Drier conditions have since -brought levels back down. The longer-term trend for Urmia has been one toward drying. In 1995, -Lake Urmia reached a high-water mark; then in the ensuing two decades, the lake level dropped - -more than 7 meters (23 feet) and lost approximately 90 percent of its area. Consecutive droughts, -agricultural water use, and dam construction on rivers feeding the lake have contributed to -the decline. A shrinking Lake Urmia has implications for ecological and human health. The -lake, its islands, and surrounding wetlands comprise valuable habitat and are recognized as -a UNESCO Biosphere Reserve, Ramsar site, and national park. The area provides breeding grounds - -for waterbirds such as flamingos, white pelicans, and white-headed ducks, as well as a stopover -for migratory species. However, with low lake levels, what water remains becomes more saline -and taxes the populations of brine shrimp and other food sources for larger animals. A shrinking -lake also increases the likelihood of dust from the exposed lakebed becoming swept up by winds -and degrading air quality. Recent studies have linked the low water levels in Lake Urmia with - -respiratory health impacts among the local population.The relative effects of climate, water -usage, and dams on Lake Urmia’s water level is a topic of debate. The lake did see some recovery -during a 10-year restoration program beginning in 2013. However, the efficacy of that effort -has been difficult to parse since strong rains also fell during that period. Some research -has concluded that climatic factors were primarily responsible for the recovery. NASA Earth - -Observatory images by Lauren Dauphin, using Landsat data from the U.S. Geological Survey. -Story by Lindsey Doermann.View this area in EO ExplorerA few years after a fresh influx of -water raised its levels, the large lake has nearly gone dry.Image of the Day for October 10, -2023 Image of the Day Land Water View more Images of the Day:Water levels are at their lowest -since 1937. Image of the Day Water Drought Fires Long and short. Deep and shallow. Salty and - -fresh. Blue and brown. These are Africa’s Lake Tanganyika and Lake Rukwa. Image of the Day -Land Water In May 2016, the reservoir behind Hoover Dam reached its lowest level since the -1930s. Image of the Day Water When the water gets saltier in Iran’s largest lake, the microscopic -inhabitants can turn the water dark red. Image of the Day Water Water Color July 1 - September -30, 2023MPEG For several months in 2023, global sea surface temperatures reached record-high - -levels, fueled by decades of human-caused climate warming and a recent boost from the natural -climate phenomenon El Niño. Some areas—including the seas around Florida, Cuba, and the Bahamas—saw -particularly high temperatures, with implications for the health of coral reefs.Corals thrive -within a small range of temperatures and become stressed when water is too hot or cold. Bleaching -occurs when stressed corals expel the algae that live inside them, stripping corals of their - -color. Extreme bleaching can leave a reef susceptible to starvation, disease, and even death. -Observations made by divers in the Florida Keys found that the marine heatwave in summer 2023 -caused widespread bleaching.Stress on corals can also be detected using data from satellites. -This animation shows the evolution of accumulated heat stress from July through September -2023. The colors depict “degree heating weeks” (°C-weeks)—a measure that provides an estimate - -of the severity and duration of thermal stress. Data for the product are compiled by NOAA’s -Coral Reef Watch, which blends observations from polar orbiting satellites such as the NASA-NOAA -Suomi NPP, and from geostationary satellites such as GOES, with computer models.Observations -have shown that when the accumulated heat stress reaches a value of 4, significant coral bleaching -can result. At values of 8, coral bleaching and widespread mortality are likely. By midway - -through this animation, in August, heat stress across much of the region already soared well -above both of those thresholds. According to NOAA, cumulative heat stress by late September -2023 hit 22°C-weeks (40°F-weeks), nearly triple the previous record for the region.Bleaching -was already observed in some areas as early as July. Notice that areas of coral reef (gray) -near the Florida Keys, Cuba, and the Bahamas, are among the first areas to show high cumulative - -heat stress. Hurricane Idalia in late August helped cool surface waters somewhat, but only -temporarily.Nearing mid-October, waters around the Florida Keys were under a bleaching watch. -Further south, waters around parts of Cuba and the Bahamas remained at bleaching alert level -2, the highest level of the scale, signifying that severe bleaching and mortality are likely.NASA -Earth Observatory animation by Wanmei Liang, using Daily 5km Degree Heating Weeks data from - -Coral Reef Watch. Coral reef data from UNEP-WCMC, WorldFish Centre, WRI, TNC. Story by Kathryn -Hansen.View this area in EO ExplorerThe seas around Florida, Cuba, and the Bahamas saw large -accumulations of heat stress beginning in summer 2023, with implications for the health of -coral reefs.Image of the Day for October 16, 2023 Image of the Day Water Temperature Extremes -View more Images of the Day:Warmer-than-average temperatures are showing up locally and globally, - -with consequences for people, landscapes, and ecosystems. Image of the Day Water Image of -the Day Life Water Image of the Day Heat Life Water Studying corals from above could help -scientists understand how these critical ecosystems will weather a changing climate. Image -of the Day Land Life Water Thank you for visiting nature.com. You are using a browser version -with limited support for CSS. To obtain the best experience, we recommend you use a more up - -to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to -ensure continued support, we are displaying the site without styles and JavaScript.Advertisement -Scientific Data volume 7, Article number: 112 (2020) Cite this article 30k Accesses126 Citations88 -AltmetricMetrics detailsRemotely sensed biomass carbon density maps are widely used for myriad -scientific and policy applications, but all remain limited in scope. They often only represent - -a single vegetation type and rarely account for carbon stocks in belowground biomass. To date, -no global product integrates these disparate estimates into an all-encompassing map at a scale -appropriate for many modelling or decision-making applications. We developed an approach for -harmonizing vegetation-specific maps of both above and belowground biomass into a single, -comprehensive representation of each. We overlaid input maps and allocated their estimates - -in proportion to the relative spatial extent of each vegetation type using ancillary maps -of percent tree cover and landcover, and a rule-based decision schema. The resulting maps -consistently and seamlessly report biomass carbon density estimates across a wide range of -vegetation types in 2010 with quantified uncertainty. They do so for the globe at an unprecedented -300-meter spatial resolution and can be used to more holistically account for diverse vegetation - -carbon stocks in global analyses and greenhouse gas inventories.Measurement(s)biomass carbon -densityTechnology Type(s)digital curationFactor Type(s)climatic zone • above or below ground -• land coverSample Characteristic - Environmentorganic materialSample Characteristic - LocationEarth -(planet)Machine-accessible metadata file describing the reported data: https://doi.org/10.6084/m9.figshare.11872383Terrestrial -ecosystems store vast quantities of carbon (C) in aboveground and belowground biomass1. At - -any point in time, these stocks represent a dynamic balance between the C gains of growth -and C losses from death, decay and combustion. Maps of biomass are routinely used for benchmarking -biophysical models2,3,4, estimating C cycle effects of disturbance5,6,7, and assessing biogeographical -patterns and ecosystem services8,9,10,11. They are also critical for assessing climate change -drivers, impacts, and solutions, and factor prominently in policies like Reducing Emissions - -from Deforestation and Forest Degradation (REDD+) and C offset schemes12,13,14. Numerous methods -have been used to map biomass C stocks but their derivatives often remain limited in either -scope or extent12,15. There thus remains a critical need for a globally harmonized, integrative -map that comprehensively reports biomass C across a wide range of vegetation types.Most existing -maps of aboveground biomass (AGB) and the carbon it contains (AGBC) are produced from statistical - -or data-driven methods relating field-measured or field-estimated biomass densities and spaceborne -optical and/or radar imagery12,15,16. They largely focus on the AGB of trees, particularly -those in tropical landscapes where forests store the majority of the region’s biotic C in -aboveground plant matter. Land cover maps are often used to isolate forests from other landcover -types where the predictive model may not be appropriate such that forest AGB maps intentionally - -omit AGB stocks in non-forest vegetation like shrublands, grasslands, and croplands, as well -as the AGB of trees located within the mapped extent of these excluded landcovers17. Non-forest -AGB has also been mapped to some extent using similar approaches but these maps are also routinely -masked to the geographic extent of their focal landcover18,19,20,21. To date, there has been -no rigorous attempt to harmonize and integrate these landcover-specific, remotely sensed products - -into a single comprehensive and temporally consistent map of C in all living biomass.Maps -of belowground biomass (BGB) and carbon density (BGBC) are far less common than those of AGB -because BGB cannot be readily observed from space or airborne sensors. Consequently, BGB is -often inferred from taxa-, region-, and/or climate-specific “root-to-shoot” ratios that relate -the quantity of BGB to that of AGB22,23,24. These ratios can be used to map BGB by spatially - -applying them to AGB estimates using maps of their respective strata5. In recent years, more -sophisticated regression-based methods have been developed to predict root-to-shoot ratios -of some landcover types based on covariance with other biophysical and/or ecological factors25,26. -When applied spatially, these methods can allow for more continuous estimates of local BGB5,27. -Like AGBC, though, few attempts have been made to comprehensively map BGBC for the globe.Despite - -the myriad of emerging mapping methods and products, to date, the Intergovernmental Panel -on Climate Change (IPCC) Tier-1 maps by Ruesch and Gibbs28 remains the primary source of global -AGBC and BGBC estimates that transcend individual landcover types. These maps, which represents -the year 2000, were produced prior to the relatively recent explosion of satellite-based AGB -maps and they therefore rely on an alternative mapping technique called “stratify and multiply”15, - -which assigns landcover-specific biomass estimates or “defaults” (often derived from field -measurements or literature reviews) to the corresponding classified grid cells of a chosen -landcover map12. While this approach yields a comprehensive wall-to-wall product, it can fail -to capture finer-scale spatial patterns often evident in the field and in many satellite-based -products12,15. The accuracy of these maps is also tightly coupled to the quality and availability - -of field measurements29 and the thematic accuracy and discontinuity of the chosen landcover -map.Given the wealth of landcover-specific satellite based AGB maps, a new harmonization method -akin to “stratify and multiply” is needed to merge the validated spatial detail of landcover-specific -remotely sensed biomass maps into a single, globally harmonized product. We developed such -an approach by which we (i) overlay distinct satellite-based biomass maps and (ii) proportionately - -allocate their estimates to each grid cell (“overlay and allocate”). Specifically, we overlay -continental-to-global scale remotely sensed maps of landcover-specific biomass C density and -then allocate fractional contributions of each to a given grid cell using additional maps -of percent tree cover, thematic landcover and a rule-based decision tree. We implement the -new approach here using temporally consistent maps of AGBC as well as matching derived maps - -of BGBC to generate separate harmonized maps of AGBC and BGBC densities. In addition, we generate -associated uncertainty layers by propagating the prediction error of each input dataset. The -resulting global maps consistently represent biomass C and associated uncertainty across a -broad range of vegetation in the year 2010 at an unprecedented 300 meter (m) spatial resolution.Our -harmonization approach (Fig. 1) relies on independent, landcover-specific biomass maps and - -ancillary layers, which we compiled from the published literature (Table 1). When published -maps did not represent our epoch of interest (i.e. grasslands and croplands) or did not completely -cover the necessary spatial extent (i.e. tundra vegetation), we used the predictive model -reported with the respective map to generate an updated version that met our spatial and temporal -requirements. We then used landcover specific root-to-shoot relationships to generate matching - -BGBC maps for each of the input AGBC maps before implementing the harmonization procedure. -Below we describe, in detail, the methodologies used for mapping AGBC and BGBC of each landcover -type and the procedure used to integrate them.Generalized, three-step workflow used to create -harmonized global biomass maps. In step one, woody AGB maps are prepared, combined, converted -to AGBC density and used to create separate but complementary maps of BGBC. In step two, a - -similar workflow is used to generate matching maps of AGBC and BGBC for tundra vegetation, -grasses, and annual crops. In step three, all maps are combined using a rule-based decision -tree detailed in Fig. 3 to generate comprehensive, harmonized global maps. All input data -sources are listed and described in Table 1.Since the first remotely sensed woody AGB maps -were published in the early 1990s, the number of available products has grown at an extraordinary - -pace16 and it can thus be challenging to determine which product is best suited for a given -application. For our purposes, we relied on the GlobBiomass AGB density map30 as our primary -source of woody AGB estimates due to its precision, timestamp, spatial resolution, and error -quantification. It was produced using a combination of spaceborne optical and synthetic aperture -radar (SAR) imagery and represents the year 2010 at a 100 m spatial resolution – making it - -the most contemporary global woody AGB currently available and the only such map available -for that year. Moreover, GlobBiomass aims to minimize prediction uncertainty to less than -30% and a recent study suggests that it has high fidelity for fine-scale applications31.The -GlobBiomass product was produced by first mapping the growing stock volume (GSV; i.e. stem -volume) of living trees, defined following Food and Agriculture Organization (FAO) guidelines32 - -as those having a diameter at breast height (DBH) greater than 10 centimeters (cm). AGB density -was then determined from GSV by applying spatialized biomass expansion factors (BEFs) and -wood density estimates. These factors were mapped using machine learning methods trained from -a suite of plant morphological databases that compile thousands of field measurements from -around the globe33. The resulting AGB estimates represent biomass in the living structures - -(stems, branches, bark, twigs) of trees with a DBH greater than 10 cm. This definition may -thereby overlook AGB of smaller trees and/or shrubs common to many global regions. Unlike -other maps, though, the GlobBiomass product employs a subpixel masking procedure that retains -AGB estimates in 100 m grid cells in which any amount of tree cover was detected in finer -resolution (30 m) imagery34. This unique procedure retains AGB estimates in tree-sparse regions - -like savannahs, grasslands, croplands, and agroforestry systems where AGB is often overlooked17, -as well as in forest plantations. The GlobBiomass product is the only global map that also -includes a dedicated uncertainty layer reporting the standard error of prediction. We used -this layer to propagate uncertainty when converting AGB to AGBC density, modelling BGBC, and -integrating with C density estimates of other vegetation types.Bouvet et al.35 – some of whom - -were also participants of the GlobBiomass project – independently produced a separate AGB -density map for African savannahs, shrublands and dry woodlands circa 2010 at 25 m spatial -resolution35 (hereafter “Bouvet map”), which we included in our harmonized product to begin -to address the GlobBiomass map’s potential omission of small trees and shrubs that do not -meet the FAO definition of woody AGB. This continental map of Africa is based on a predictive - -model that directly relates spaceborne L-band SAR imagery – an indirect measure of vegetation -structure that is sensitive to low biomass densities36 – with region-specific, field-measured -AGB. Field measurements (n = 144 sites) were compiled from 7 different sampling campaigns -– each specifically seeking training data for biomass remote sensing – that encompassed 8 -different countries35. The resulting map is not constrained by the FAO tree definition and - -is masked to exclude grid cells in which predicted AGB exceeds 85 megagrams dry mater per -hectare (Mg ha−1) – the threshold at which the SAR-biomass relationship saturates. To avoid -extraneous prediction, it further excludes areas identified as “broadleaved evergreen closed-to-open -forest”, “flooded forests”, “urban areas” and “water bodies” by the European Space Agency’s -Climate Change Initiative (CCI) Landcover 2010 map37 and as “bare areas” in the Global Land - -Cover (GLC) 2000 map38. While the Bouvet map is not natively accompanied by an uncertainty -layer, its authors provided us with an analytic expression of its uncertainty (SE; standard -error of prediction) as a function of estimated AGB (Eq. 1) which we used to generate an uncertainty -layer for subsequent error propagation.We combined the GlobBiomass and Bouvet products to -generate a single woody biomass map by first upscaling each map separately to a matching 300 - -m spatial resolution using an area-weighted average to aggregate grid cells, and then assigning -the Bouvet estimate to all overlapping grid cells, except those identified by the CCI Landcover -2010 map as closed or flooded forest types (Online-only Table 1) which were not within the -dryland domain of the Bouvet map. While more complex harmonization procedures based on various -averaging techniques have been used by others39,40, their fidelity remains unclear since they - -fail to explicitly identify and reconcile the underlying source of the inputs’ discrepancies41. -We thus opted to use a more transparent ruled-based approach when combining these two woody -biomass maps, which allows users to easily identify the source of a grid cell’s woody biomass -estimate. Given the local specificity of the training data used to produce the Bouvet map, -we chose to prioritize its predictions over those of the GlobBiomass product when within its - -domain. In areas of overlap, the Bouvet map values tend to be lower in moist regions and higher -in dryer regions (Fig. 2), though, where used, these differences rarely exceed ±25 megagrams -C per hectare (MgC ha−1).Difference between underlying woody aboveground biomass maps in Africa. -Maps considered are the GlobBiomass30 global map and the Bouvet35 map of Africa. Both maps -were aggregated to a 300 m spatial resolution and converted to C density prior to comparison - -using the same schema. The difference map was subsequently aggregated to a 3 km spatial resolution -and reprojected for visualization. Negative values denote lower estimates by Bouvet et al.35, -while positive values denote higher estimates.We then converted all woody AGB estimates to -AGBC by mapping climate and phylogeny-specific biomass C concentrations from Martin et al.42. -Climate zones were delineated by aggregating classes of the Köppen-Gieger classification43 - -(Table 2) to match those of Martin et al.42. Phylogenetic classes (angiosperm, gymnosperm -and mixed/ambiguous) were subsequently delineated within each of these zones using aggregated -classes of the CCI Landcover 2010 map (Online-only Table 1). Martin et al.42 only report values -for angiosperms and gymnosperms so grid cells with a mixed or ambiguous phylogeny were assigned -the average of the angiosperm and gymnosperm values and the standard error of this value was - -calculated from their pooled variance. Due to residual classification error in the aggregated -phylogenetic classes, we weighted the phylogeny-specific C concentration within each climate -zone by the binary probability of correctly mapping that phylogeny (i.e. user’s accuracy)44 -using Eq. 2where, within each climate zone, μc is the mean probability-weighted C concentration -of the most probable phylogeny, μm is the mean C concentration of that phylogeny from Martin - -et al.42, pm is the user’s accuracy of that phylogeny’s classification (Table 3), and μn and -μo are the mean C concentrations of the remain phylogenetic classes from Martin et al.42. -Standard error estimates for these C concentrations were similarly weighted using summation -in quadrature (Eq. 3)where \({\sigma }_{c}\) is the probability-weighted standard error of -the most probable phylogeny’s C concentration and \({\sigma }_{m}\), \({\sigma }_{n}\) and - -\({\sigma }_{o}\) are the standard errors of the respective phylogeny-specific C concentrations -from Martin et al.42. Probability-weighted C concentrations used are reported in Table 4.Mapped, -probability-weighted C estimates were then arithmetically applied to AGB estimates. Uncertainty -associated with this correction was propagated using summation in quadrature of the general -form (Eq. 4)where \({\mu }_{f}=f(i,j,\ldots ,k)\), \({\sigma }_{f}\) is the uncertainty of - -μf, and \({\sigma }_{i},{\sigma }_{j},\ldots ,{\sigma }_{k}\), are the respective uncertainty -estimates of the dependent parameters (standard error unless otherwise noted). Here, μf, is -the estimated AGBC of a given grid cell, and is the product of its woody AGB estimate, and -its corresponding C concentration.The tundra and portions of the boreal biome are characterized -by sparse trees and dwarf woody shrubs as well as herbaceous cover that are not included in - -the GlobBiomass definition of biomass. AGB density of these classes has been collectively -mapped by Berner et al.18,45 for the North Slope of Alaska from annual Landsat imagery composites -of the normalized difference vegetation index (NDVI) and a non-linear regression-based model -trained from field measurements of peak AGB that were collected from the published literature -(n = 28 sites). Berner et al.18 note that while these field measurements did not constitute - -a random or systematic sample, they did encompass a broad range of tundra plant communities. -In the absence of a global map and due the sparsity of high quality Landsat imagery at high -latitudes, we extended this model to the pan-Arctic and circumboreal regions using NDVI composites -created from daily 250 m MODIS Aqua and Terra surface reflectance images46,47 that were cloud -masked and numerically calibrated to Landsat ETM reflectance – upon which the tundra model - -is based – using globally derived conversion coefficients48. We generated six separate 80th -percentile NDVI composites circa 2010 – one for each of the MODIS missions (Aqua and Terra) -in 2009, 2010 and 2011 – following Berner et al.18. We chose to use three years of imagery -(circa 2010) rather than just one (2010) to account for the potential influence that cloud -masking may exert upon estimates of the 80th NDVI percentile in a single year. We then applied - -the tundra AGB model to each composite, converted AGB estimates to AGBC by assuming a biomass -C fraction of 49.2% (SE = 0.8%)42 and generated error layers for each composite from the reported -errors of the AGB regression coefficients and the biomass C conversion factor using summation -in quadrature as generally described above (Eq. 4). A single composite of tundra AGBC circa -2010 was then created as the pixelwise mean of all six composites. We also generated a complementary - -uncertainty layer representing the cumulative standard error of prediction, calculated as -the pixelwise root mean of the squared error images in accordance with summation in quadrature. -Both maps were upscaled from their native 250 m spatial resolution to a 300 m spatial resolution -using an area weighted aggregation procedure, whereby pixels of the 300 m biomass layer was -calculated as the area weighted average of contained 250 m grid cells, and the uncertainty - -layer was calculated – using summation in quadrature – as the root area-weighted average of -the contained grid cells squared.Grassland AGBC density was modelled directly from maximum -annual NDVI composites using a non-linear regression-based model developed by Xia et al.19 -for mapping at the global scale. This model was trained by relating maximum annual NDVI as -measured by the spaceborne Advanced Very High-Resolution Radiometer (AVHRR) sensor to globally - -distributed field measurements of grassland AGBC that were compiled from the published literature -(81 sites for a total of 158 site-years). Like the tundra biomass training data, these samples -did not constitute a random or systematic sample but do encompass a comprehensive range of -global grassland communities. Given the inevitable co-occurrence of trees in the AVHRR sensor’s -8 km resolution pixels upon which the model is trained, it’s predictions of grassland AGBC - -are relatively insensitive to the effects of co-occurring tree cover. We thereby assume that -its predictions for grid cells containing partial tree cover represent the expected herbaceous -AGBC density in the absence of those trees. Maximum model predicted AGBC (NDVI = 1) is 2.3 -MgC ha−1 which is comparable to the upper quartile of herbaceous AGBC estimates from global -grasslands49 and suggests that our assumption will not lead to an exaggerated estimation. - -For partially wooded grid cells, we used modelled grassland AGBC density to represent that -associated with the herbaceous fraction of the grid cell in a manner similar to Zomer et al.17 -as described below (See “Harmonizing Biomass Carbon Maps”).We applied the grassland AGBC model -to all grid cells of maximum annual NDVI composites produced from finer resolution 16-day -(250 m) MODIS NDVI imagery composites circa 201050,51. Here again, three years of imagery - -were used to account for potential idiosyncrasies in a single year’s NDVI composites resulting -from annual data availability and quality. As with AGB of tundra vegetation, annual composites -(2009–2011) were constructed separately from cloud-masked imagery collected by both MODIS -missions (Aqua and Terra; n = 6) and then numerically calibrated to AVHRR reflectance using -globally derived conversion coefficients specific to areas of herbaceous cover52. We then - -applied the AGBC model to each of these composites and estimated error for each composite -from both the AVHRR calibration (standard deviation approximated from the 95% confidence interval -of the calibration scalar) and the AGBC model (relative RMSE) using summation in quadrature. -A single map of grassland AGBC circa 2010 was then created as the pixelwise mean of all six -composites and an associated error layer was created as the pixelwise root mean of the squared - -error images. Both maps were aggregated from their original 250 m resolution to 300 m to facilitate -harmonization using the area-weighted procedure described previously for woody and tundra -vegetation (see section 1.2).Prior to harvest, cropland biomass can also represent a sizable -terrestrial C stock. In annually harvested cropping systems, the maximum standing biomass -of these crops can be inferred from annual net primary productivity (ANPP). While spaceborne - -ANPP products exist, they generally perform poorly in croplands53,54. Instead, cropland ANPP -is more commonly derived from crop yields20,21,53. We used globally gridded, crop-specific -yields of 70 annually harvested herbaceous commodity crops circa 2000 by Monfreda et al.20 -– the only year in which these data were available. These maps were produced by spatially -disaggregating crop-yield statistics for thousands of globally distributed administrative - -units throughout the full extent of a satellite-based cropland map20. These maps were combined -with crop-specific parameters (Online-only Table 2) to globally map AGBC as aboveground ANPP -for each crop following the method of Wolf et al.21. This method can be simplified as (Eq. -5)where y is the crop’s yield (Mg ha−1), ω is the dry matter fraction of its harvested biomass, -h is its harvest index (fraction of total AGB collected at harvest) and c is the carbon content - -fraction of its harvested dry mass. This simplification assumes, following Wolf et al.21, -that 2.5% of all harvested biomass is lost between the field and farmgate and that unharvested -residue and root mass is 44% C.Total cropland AGBC density was then calculated as the harvested-area-weighted -average of all crop-specific AGBC estimates within a given grid cell. Since multiple harvests -in a single year can confound inference of maximum AGBC from ANPP, we further determined the - -harvest frequency (f) of each grid cell by dividing a cell’s total harvested area (sum of -the harvested area of each crop reported within a given grid cell) by its absolute cropland -extent as reported in a complementary map by Ramankutty et al.55. If f was greater than one, -multiple harvests were assumed to have occurred and AGBC was divided by f to ensure that AGBC -estimates did not exceed the maximum standing biomass density.Since the yields of many crops - -and, by association, their biomass have changed considerably since 200056,57, we calibrated -our circa 2000 AGBC estimates to the year 2010 using local rates of annual ANPP change (MgC -ha−1 yr−1) derived as the Theil-Sen slope estimator – a non-parametric estimator that is relatively -insensitive to outliers – of the full MODIS Terra ANPP timeseries (2000–2015)58. Total ANPP -change between 2000 and 2010 for each grid cell was calculated as ten times this annual rate - -of change. Since MODIS ANPP represents C gains in both AGB and BGB, we proportionately allocated -aboveground ANPP to AGBC using the total root-to-shoot ratio derived from the circa 2000 total -crop AGBC and BGBC maps (described below). Since error estimates were not available for the -yield maps or the crop-specific parameters used to generate the circa 2000 AGBC map, estimated -error of the circa 2010 crop AGBC map was exclusively based on that of the 2000–2010 correction. - -The error of this correction was calculated as the pixel-wise standard deviation of bootstrapped -simulations (n = 1000) in which a random subset of years was omitted from the slope estimator -in each iteration. The 8 km resolution circa 2000 AGBC map and error layer were resampled -to 1 km to match the resolution of MODIS ANPP using the bilinear method prior to ANPP correction -and then further resampled to 300 m to facilitate harmonization.Woody crops like fruit, nut, - -and palm oil plantations were not captured using the procedure just described and their biomass -was instead assumed to be captured by the previously described woody biomass products which -retained biomass estimates in all pixels where any amount of tree cover was detected at the -sub-pixel level (see section 1.1).Matching maps of BGBC and associated uncertainty were subsequently -produced for each of the landcover-specific AGBC maps using published empirical relationships.With - -the exception of savannah and shrubland areas, woody BGBC was modelled from AGBC using a multiple -regression model by Reich et al.25 that considers the phylogeny, mean annual temperature (MAT), -and regenerative origin of each wooded grid cell and that was applied spatially using maps -of each covariate in a fashion similar to other studies5,27. Tree phylogeny (angiosperm or -gymnosperm) was determined from aggregated classes of the CCI Landcover 2010 map37 (Online-only - -Table 1) with phylogenetically mixed or ambiguous classes assumed to be composed of 50% of -each. MAT was taken from version 2 of the WorldClim bioclimatic variables dataset (1970–2000) -at 1 km resolution59 and resampled to 300 m using the bilinear method. Since there is not -a single global data product mapping forest management, we determined tree origin – whether -naturally propagated or planted – by combining multiple data sources. These data included - -(i) a global map of “Intact Forest Landscapes” (IFL) in the year 201360 (a conservative proxy -of primary, naturally regenerating forests defined as large contiguous areas with minimal -human impact), (ii) a Spatial Database of Planted Trees (SDPT) with partial global coverage61, -(iii) national statistics reported by the FAO Global Forest Resources Assessment (FRA) on -the extent of both naturally regenerating and planted forests and woodlands within each country - -in the year 201062, and (iv) national statistics reported by the FAOSTAT database (http://www.fao.org/faostat) -on the planted area of plantation crops in 2010. Within each country, we assumed that the -total area of natural and planted trees was equal to the corresponding FRA estimates. If the -FAOSTAT-reported area of tree crops exceeded FRA-reported planted area, the difference was -added to FRA planted total. All areas mapped as IFL were assumed to be of natural origin and - -BGB was modelled as such. Likewise, besides the exceptions noted below, all tree plantations -mapped by the SDPT were assumed to be of planted origin. In countries where the extent of -the IFL or SDPT maps fell short of the FRA/FAOSTAT reported areas of natural or planted forests, -respectively, we estimated BGBC in the remaining, unknown-origin forest grid cells of that -country (BGBCu), as the probability-weighted average of the planted and natural origin estimates - -using Eq. 6where \(BGB{C}_{p}\) and \(BGB{C}_{n}\) are the respective BGBC estimates for a -grid cell assuming entirely planted and natural origin, respectively, and \({\Delta }_{p}\) -and \({\Delta }_{n}\) are the respective differences between (i) the FRA/FAOSTAT and (ii) -mapped extent of planted and natural forest within the given grid cell’s country. While the -mapped extent of IFL forests within a given country never exceeded that country’s FRA reported - -natural forest extent, there were infrequent cases (n = 22 of 257) in which the mapped extent -of tree plantations exceeded the corresponding FRA/FAOSTAT estimate of planted forest area. -In these cases, we down-weighted the BGB estimates of SDPT forests in a similar fashion such -that the weight of their planted estimate (\({\omega }_{p}\)) was equal to the quotient of -(i) the FRA/FAOSTAT planted area and (ii) the SDPT extent within the country, and the weight - -of the natural origin estimate applied to the SDPT extent (\({\omega }_{n}\)) was equal to -\(1-{\omega }_{p}\).A BGBC error layer was then produced using summation in quadrature from -the standard error estimates of the model coefficients, the AGBC error layer, the relative -RMSE of MAT (27%), and the derived global uncertainty of the phylogeny layer. Phylogeny error -was calculated as the Bernoulli standard deviation (δ) of the binary probability (p) of correct - -classification (i.e. “area weighted user’s accuracy”44; Table 3) using Eq. 7.Since savannahs -and shrublands are underrepresented in the regression-based model25, their BGBC was instead -estimated using static root-to-shoot ratios reported by Mokany et al.22, which are somewhat -conservative in comparison to the IPCC Tier-1 defaults23,24 put favoured for consistency with -methods used for grasslands (see below). Error was subsequently mapped from that of the AGBC - -estimates and the root-to-shoot ratios applied (Table 5).BGBC of tundra vegetation was mapped -from AGBC using a univariate regression model derived by Wang et al.26 that predicts root-to-shoot -ratio as a function of MAT. We applied the model using the WorldClim version 2 MAT map59 and -propagated error from the AGBC estimates, the relative RMSE of MAT and the standard error -of regression coefficients. Where tundra AGB exceeded 25 Mg ha−1 – the maximum field-measured - -shrub biomass reported by Berner et al.18 – vegetation was considered to include trees and -the Reich et al.25 method described earlier for woody vegetation was used instead.In the absence -of a continuous predictor of grassland root-to-shoot ratios, we applied climate specific root-to-shoot -ratios from Mokany et al.22 to the corresponding climate regions of the Köppen-Gieger classification43 -(Table 2). Here, again, these ratios vary slightly from the IPCC Tier-1 defaults23,24 but - -were chosen for their greater sample size and specificity. Grassland BGBC error was mapped -from the error of the AGBC estimates and the respective root-to-shoot ratios.Cropland BGBC -was again estimated from crop-specific yields and morphological parameters (Online-only Table -2) following Wolf et al.21 and Eq. 8where y is the crop’s yield (Mg ha−1), r is the root-to-shoot -ratio of the crop, and h is its harvest index. Here again we assume that 2.5% of all harvested - -biomass is lost between the field and farmgate and that root biomass is 44% C, following Wolf -et al.21. BGBC error was mapped from the error of the 2000-to-2010 ANPP correction for BGBC -allocation as described above for cropland AGBC.The AGBC and BGBC maps were harmonized separately -following the same general schema (Fig. 3). Given that our harmonized woody biomass map contains -biomass estimates for grid cells in which any amount of tree cover was detected at the subpixel - -level (see section 1.1), we conserved its estimates regardless of the landcover reported by -the 2010 CCI map in order to more fully account for woody biomass in non-forested areas17. -We then used the MODIS continuous vegetation fields percent tree cover map for 201063 to allocate -additional biomass density associated with the most probable herbaceous cover (grass or crop) -to each grid cell in quantities complementary to that of the grid cell’s fractional tree cover - -estimate (Eq. 9)where μT is the total biomass estimate of a grid cell, μw is the woody biomass -estimate for the grid cell, μh is its herbaceous biomass estimate, and q is the MODIS fractional -tree cover of the grid cell. Since MODIS tree cover estimates saturate at around 80%64, we -linearly stretched values such that 80% was treated as complete tree cover (100%). Moreover, -we acknowledge that percent cover can realistically exceed 100% when understory cover is considered - -but we were unable to reasonably determine the extent of underlying cover from satellite imagery. -As such, our approach may underestimate the contribution of herbaceous C stocks in densely -forested grid cells. The most likely herbaceous cover type was determined from the CCI Landcover -2010 map, which we aggregated into two “likely herbaceous cover” classes – grass or crop – -based on the assumed likelihood of cropland in each CCI class (Online-only Table 1). However, - -due to inherent classification error in the native CCI Landcover map, when determining the -herbaceous biomass contribution we weighted the relative allocation of crop and grass biomass -to a given grid cell based on the probability of correct classification by the CCI map (i.e. -“user’s accuracy”, Table 6) of the most probable herbaceous class (\({p}_{i}\)) such that -μh can be further expressed as (Eq. 10)where μi is the predicted biomass of the most probable - -herbaceous class, and μj is that of the less probable class.Decision tree used to allocate -landcover-specific biomass estimates to each grid cell of our harmonized global products.The -uncertainty of a grid cell’s total AGBC or BGBC estimate (\({\sigma }_{T}\)) was determined -and mapped from that of its components (\({\mu }_{w}\,{\rm{and}}\,{\mu }_{h}\)) by summation -in quadrature which can be simplified as (Eq. 11)where \({\sigma }_{w}\) is the error of the - -grid cell’s estimated μw, \({\sigma }_{h}\) is the error of its estimated μh, and \({\sigma -}_{q}\) is the error of its q. Here, \({\sigma }_{h}\) can be further decomposed and expressed -as Eq. 12 to account for the accuracy weighted allocation procedure expressed previously (Eq. -10)where \({\sigma }_{i}\) is the error of the estimated biomass density of the most probable -herbaceous class, \({\delta }_{i}\) is the estimated standard deviation of that class’s Bernoulli - -probability (p; Eq. 7), and \({\sigma }_{j}\) is the error of the estimated biomass density -of the less probable herbaceous subclass.Exceptions to the above schema were made in the tundra -and boreal biomes – as delineated by the RESOLVE Ecoregions 2017 biome polygons65 – where -thematic overlap was likely between the woody and tundra plant biomass maps. A separate set -of decision rules (Fig. 3) was used to determine whether grid cells in these biomes were to - -be exclusively allocated the estimate of the tundra plant map or that of the fractional allocation -procedure described above. In general, any land in these biomes identified as sparse landcover -by the CCI landcover map (Online-only Table 1) was assigned the tundra vegetation estimate. -In addition, lands north of 60° latitude with less than 10% tree cover or where the tundra -AGBC estimate exceeded that of the woody AGBC estimate were also exclusively assigned the - -tundra vegetation estimate. Lands north of 60° latitude not meeting these criteria were assigned -the woody value with the additional contribution of grass.Subtle numerical artefacts emerged -from the divergent methodologies employed north and south of 60°N latitude. These were eliminated -by distance weighting grid cells within 1° of 60°N based on their linear proximity to 60°N -and then averaging estimates such that values at or north of 61°N were exclusively based on - -the northern methodology, those at 60°N were the arithmetic average of the two methodologies -and those at or south of 59°N were exclusively based on the southern methodology. This produced -a seamless, globally harmonized product that integrates the best remotely sensed estimates -of landcover-specific C density. Water bodies identified as class “210” of the CCI 2010 landcover -map were then masked from our final products.Data layers (n = 4, Table 7) for the maps of - -AGBC and BGBC density (Fig. 4) as well as their associated uncertainty maps which represent -the combined standard error of prediction (Fig. 5) are available as individual 16-bit integer -rasters in GeoTiff format. All layers are natively in a WGS84 Mercator projection with a spatial -resolution of approximately 300 m at the equator and match that of the ESA CCI Landcover Maps37. -Raster values are in units megagrams C per hectare (MgC ha−1) and have been scaled by a factor - -of ten to reduce file size. These data are accessible through the Oak Ridge National Laboratory -(ORNL) DAAC data repository (https://doi.org/10.3334/ORNLDAAC/1763)66. In addition, updated -and/or derived vegetation-specific layers that were used to create our harmonized 2010 maps -are available as supplemental data on figshare67.Globally harmonized maps of above and belowground -living biomass carbon densities. (a) Aboveground biomass carbon density (AGBC) and (b) belowground - -biomass carbon density (BGBC) are shown separately. Maps have been aggregated to a 5 km spatial -resolution and reprojected here for visualization.Uncertainty of grid cell level above and -belowground biomass carbon density estimates. Uncertainty is shown here as the coefficient -of variation (%; standard error layer divided by mean estimate layer) of estimated AGBC (a) -and BGBC (b) densities after harmonization. Maps have been aggregated to a 5 km spatial resolution - -and projected for visualization.Our harmonized products rely almost exclusively upon maps -and models that have been rigorously validated by their original producers and were often -accompanied by constrained uncertainty estimates. Throughout our harmonization procedure, -we strived to conserve the validity of each of these products by minimizing the introduction -of additional error and by tracking any introductions, as described above, such that the final - -error layers represent the cumulative uncertainty of the inputs used. Ground truth AGB and -BGB data are almost always collected for individual landcover types. Consequently, we are -unable to directly assess the validity of our integrated estimates beyond their relationships -to individual landcover-specific estimates and the extents to which they were modified from -their original, previously-validated form prior to and during our harmonization procedure.Temporal - -and spatial updates made to existing landcover-specific maps of non-tree AGB resulted in relatively -small changes to their predictions. For example, we used numerically calibrated MODIS imagery -to extend the Landsat-based tundra plant AGB model beyond its native extent (the North Slope -of Alaska) to the pan-Arctic region since neither a comparable model nor a consistent Landsat -time series were available for this extent. We assessed the effects of these assumptions by - -comparing our predictions for the North Slope with those of the original map18 (Fig. 6a). -Both positive and negative discrepancies exist between ours and the original, though these -rarely exceed ±2 MgC ha−1 and no discernibly systematic bias was evident.Differences between -landcover-specific AGBC estimates from the original published maps and the modified versions -used as inputs to create the 2010 harmonized global maps. Tundra vegetation AGBC (a) is compared - -to the Landsat-based map of Berner et al.45 for the north slope of Alaska after converting -it to units MgC ha−1. Here, the comparison map was subsequently aggregated to a 1 km resolution -and reprojected for visualization. Grassland AGBC (b) is compared to the AVHRR-based map of -Xia et al.19 which represents the average estimate between 1982–2006. For visualization, the -map was aggregated to a 5 km resolution and subsequently reprojected after being masked to - -MODIS IGBP grasslands in the year 200685 following Xia et al.19. As such, this map does not -necessarily represent the spatial distribution of grid cells in which grassland estimates -were used. Cropland AGBC (c) is compared to the original circa 2000 estimates to assess the -effects of the 2000-to-2010 correction. The map is masked to the native extent of the combined -yield maps and aggregated to a 5 km resolution for visualization. For all maps, negative values - -indicate that our circa 2010 estimates are lower than those of the earlier maps while positive -values indicate higher estimates.Our updated map of grassland biomass carbon in the year 2010 -was similarly made by applying the original AVHRR-based model to calibrated MODIS imagery. -This too resulted in only subtle changes to the original biomass map (Fig. 6b) that were rarely -in excess of 0.5 MgC ha−1. In most areas, our estimates were higher than those of Xia et al.19 - -who mapped the mean AGBC density between 1986 and 2006. Most of these elevated estimates corresponded -with areas in which significant NDVI increases (“greening”) have been reported while notably -lower estimates in the Argentine Monte and Patagonian steppe biomes of southern South America, -likewise, correspond with areas of reported “browning”68,69. Both greening and browning trends -are well documented phenomena and have been linked to climatic changes70. Moreover, we further - -compared AGBC estimates from both the original Xia et al.19 map and our 2010 update to AGBC -field measurements coordinated by the Nutrient Network that were collected from 48 sites around -the world between 2007 and 200949. The RMSE (0.68 MgC ha−1) of our updated map was 10% less -that of the Xia et al. map for sites with less than 40% tree cover. Likewise, our 2010 estimates -were virtually unbiased (bias = −0.01 MgC ha−1) in comparison to the Xia map (bias = 0.25 - -MgC ha−1). While still noisy, these results suggest that our temporal update improved the -overall accuracy of estimated grassland AGBC.Finally, cropland biomass carbon maps were also -updated from their native epoch (2000) to 2010 using pixel-wise rates of MODIS ANPP change -over a ten-year period. While MODIS ANPP may be a poor snapshot of crop biomass in a single -year, we assumed that its relative change over time reflects real physiological shifts affecting - -the cropland C cycle. This correction also resulted in only small differences that rarely -exceeded ±2 MgC ha−1 and that, spatially, correspond well with observed declines in the yields -of select crops that have been linked to climate change71,72 (Fig. 6c). Nonetheless, updated -global yield maps comparable to those available for 2000 would greatly improve our understanding -of the interactions between climate change, crop yields, and C dynamics.Belowground biomass - -is notoriously difficult to measure, model, and also to validate. We accounted for the reported -uncertainty of nearly every variable considered when estimating belowground biomass and pixel-level -uncertainty, but we were unable to perform an independent validation of our harmonized estimates -at the pixel level due to a paucity of globally consistent field data. To complete such a -task, a globally orchestrated effort to collect more BGB samples data across all vegetation - -types is needed.Given this lack of data, we instead compared the estimated uncertainty of -our BGBC maps to that of our AGBC estimates to infer the sources of any divergence (Fig. 5). -As expected, our cumulative BGBC uncertainty layer generally reveals greater overall uncertainty -than our AGBC estimates, with BGBC uncertainty roughly twice that of AGBC throughout most -of the globe. The highest absolute uncertainty was found in biomass rich forests. Arid woodlands, - -especially those of the Sahel and eastern Namibia, generally had the greatest relative BGBC -uncertainty, though their absolute uncertainty was quite small (generally less than 3 MgC -ha−1). Here, biomass estimates of sparse woody vegetation were primarily responsible for heightened -relative uncertainty. High relative and absolute BGBC uncertainty were also associated with -predictions in select mountainous forests (e.g. east central Chile) as well as forested areas - -in and around cities. These patterns were largely driven by AGB uncertainty in the GlobBiomass -product.The GlobBiomass global woody AGB map produced by Santoro et al.30 comprises the backbone -of our integrated products and, with few exceptions, remains largely unchanged in our final -AGBC map. The native version of the GlobBiomass map is accompanied by an error layer describing -the uncertainty of each pixel’s biomass estimate and this too forms the core of our integrated - -uncertainty layers. In areas with tree cover, the global average error of GlobBiomass estimates -is 39 Mg ha−1 or 50% with greater relative uncertainty in densely forested areas, along the -margins of forested expanses like farm fields and cities, and in similar areas with sparse -tree cover.Adding additional grass or crop biomass in complementary proportion to a grid cell’s -tree cover often did not exceed the estimated error of the original GlobBiomass map (Fig. - -7). Grid cells exceeding GlobBiomass’s native uncertainty comprise less than 40% of its total -extent. Exceptions were primarily found in grassland and cropland dominated regions where -tree cover was generally sparse, and, consequently, the herbaceous biomass contribution was -relatively high. Even so, the absolute magnitude of these additions remains somewhat small -(less than 2.3 MgC ha−1 for grassland and 15 MgC ha−1 for cropland).Differences between the - -final harmonized AGBC map and GlobBiomass AGBC. GlobBiomass AGB was aggregated to a 300 m -spatial resolution and converted to C density prior to comparison. Negative values indicate -areas where the new map reports lower values than GlobBiomass while positive value denote -higher estimates.Larger deviations from GlobBiomass were also present in areas of both dryland -Africa and the Arctic tundra biome, where we used independent layers to estimate woody biomass. - -In African drylands, GlobBiomass likely underestimates woody biomass by adopting the conservative -FAO definition (DBH > 10 cm), which implicitly omits the relatively small trees and shrubs -that are common to the region. The Bouvet map of Africa that we used to supplement these estimates -is not bound by this constraint, was developed from region-specific data, and predicts substantially -higher AGB density throughout much of its extent with comparatively high accuracy (RMSE = - -17.1 Mg ha−1)35.GlobBiomass also included sporadic biomass estimates throughout much of the -Arctic tundra biome. Trees are generally scarce throughout this biome, which is instead dominated -by dwarf shrubs and herbaceous forbs and graminoids, so given GlobBiomass’s adherence to FAO -guidelines, its predictions here may be spurious. We thus prioritized the estimates of the -independent model developed specifically to collectively predict biomass of both woody and - -herbaceous tundra vegetation. These estimates were generally higher than GlobBiomass but agreed -well with independent validation data from North America (RMSE = 2.9 Mg ha−1)18.While far -from a perfect comparison, the only other map to comprehensively report global biomass carbon -density for all landcover types is the IPCC Tier-1 map for the year 2000 by Ruesch and Gibbs28. -As previously described, this map was produced using an entirely different method (“stratify - -and multiply”) and distinct data sources23 and represents an earlier epoch. However, the map -is widely used for myriad applications, and it may thus be informative to assess notable differences -between it and our new products.Ruesch and Gibbs28 report total living C stocks of 345 petagrams -(PgC) in AGBC and 133 PgC in BGBC for a total of 478 PgC, globally. Our estimates are lower -at 287 PgC and 122 PgC in global AGBC and BGBC, respectively, for a total of 409 PgC in living - -global vegetation biomass. Herbaceous biomass in our maps comprised 9.1 and 28.3 PgC of total -AGBC and BGBC, respectively. Half of all herbaceous AGBC (4.5 PgC) and roughly 6% of all herbaceous -BGBC (1.7 PgC) was found in croplands. Moreover, we mapped 22.3 and 6.1 PgC, respectively, -in the AGB and BGB of trees located within the cropland extent. These trees constituted roughly -7% of all global biomass C and are likely overlooked by both the Ruesch and Gibbs map28 and - -by remotely sensed forest C maps that are masked to forested areas. Zomer et al.17 first highlighted -this potential discrepancy in the Ruesch and Gibbs map28 when they produced a remarkably similar -estimate of 34.2 Pg of overlooked C in cropland trees using Tier-1 defaults. However, their -estimates were assumed to be in addition to the 474 PgC originally mapped by Ruesch and Gibbs28. -Here, we suggest that the 28.4 PgC we mapped in cropland trees is already factored into our - -409 PgC total.Our AGBC product predicts substantially less biomass C than Ruesch and Gibbs28 -throughout most of the pantropical region and, to a lesser extent, southern temperate forests -(Fig. 8a). This pattern has been noted by others comparing the Ruesch and Gibbs map28 to other -satellite-based biomass maps73 and may suggest that the IPCC default values used to create -it23 are spatially biased. In addition, well-defined areas of high disagreement emerge in - -Africa that directly correspond with the FAO boundaries of the “tropical moist deciduous forest” -ecofloristic zone and suggest that this area, in particular, may merit critical review. Moreover, -the opposite pattern is observed in this same ecofloristic zone throughout South America. -Our map also predicts greater AGBC throughout much of the boreal forest as well as in African -shrublands and the steppes of South America.Differences between the 2010 harmonized global - -maps of above and belowground biomass carbon density and those of the IPCC Tier-1 product -by Ruesch and Gibbs for 2000. Comparisons of AGBC (a) and BGBC (b) maps are shown separately. -Negative values indicate that the circa 2010 estimates are comparatively lower while positive -values indicate higher estimates.We observed similar, though less pronounced discrepancies, -when comparing BGBC maps (Fig. 8b). Notably, our map predicts substantially more BGBC throughout - -the tundra biome – a previously underappreciated C stock that has recently risen to prominance74 -– the boreal forest, African shrublands and most of South America and Australia. However, -we predict less BGBC in nearly all rainforests (Temperate and Tropical). These differences -and their distinct spatial patterns correspond with the vegetation strata used to make the -IPCC Tier-1 map28 and suggest that the accuracy of the “stratify and multiply” method depends - -heavily upon the quality of the referenced and spatial data considered. Inaccuracies in these -data may, in turn, lead to false geographies. Integrating, continuous spatial estimates that -better capture local and regional variation, as we have done, may thus greatly improve our -understanding of global carbon geographies and their role in the earth system.The error and -variance between our woody biomass estimates – when aggregated to the country level – and - -comparable totals reported in the FRA were less for comparisons made against FRA estimates -generated using higher tier IPCC methodologies than for those based on Tier-1 approaches (Fig. -9). Across the board for AGBC, BGBC, and total C comparisons, the relative RMSE (RMSECV) of -our estimates, when compared to estimates generated using high tier methods, was roughly half -of that obtained from comparisons with Tier-1 estimates (Table 8). Likewise, the coefficient - -of determination (R2) was greatest for comparisons with Tier-3 estimates. For each pool-specific -comparison (AGBC, BGBC, and total C), the slopes of the relationships between Tier-1, 2, and -3 estimates were neither significantly different from a 1:1 relationship nor from one another -(p > 0.05; ANCOVA). Combined, these results suggest that our maps lead to C stock estimates -congruent with those attained from independent, higher-tier reporting methodologies.Comparison - -of woody biomass density estimates to corresponding estimates of the FAO’s FRA and the USFS’s -FIA. National woody AGBC totals derived from the woody components of our harmonized maps are -compared to national totals reported in the 2015 FRA62 (a) in relation to the IPCC inventory -methodology used by each country. Likewise, we derived woody AGBC totals for US states and -compared them to the corresponding totals reported by the 2014 FIA75 (b), a Tier-3 inventory. - -We also show the additional effect of considering non-woody C – as is reported in our harmonized -maps – in light green. Similar comparisons were made between our woody BGBC estimates and -the corresponding estimates of both the FRA (c) and FIA (d). We further summed our woody AGBC -and BGBC estimates and compared them to the total woody C stocks reported by both the FRA -(e) and FIA (f).To explore this association at a finer regional scale, we also compared our - -woody C estimates to the United States Forest Service’s Forest Inventory Analysis75 (FIA) -and found similarly strong congruence for AGBC and Total C stocks but subtle overestimates -for BGBC (Fig. 9). The FIA is a Tier-3 inventory of woody forest biomass C stocks that is -based on extensive and statistically rigorous field sampling and subsequent upscaling, We -used data available at the state level for the year 2014 – again, the only year in which we - -could obtain data partitioned by AGBC and BGBC. Like our FRA comparison, we found a tight -relationship between our woody AGBC totals and those reported by the FIA (Fig. 9b; RMSECV -= 25.7%, R2 = 0.960, slope = 1.10, n = 48). Our woody BGBC estimates, though, were systematically -greater than those reported by the FIA (Fig. 9d; RMSECV = 86.4%, R2 = 0.95, slope = 1.51, -n = 48). This trend has been noted by others27 and suggests that the global model that we - -used to estimate woody BGBC may not be appropriate for some finer scale applications as is -foretold by the elevated uncertainty reported in our corresponding uncertainty layer (Fig. -5b). Our total woody C (AGBC + BGBC) estimates (Fig. 9f), however, agreed well with the FIA -(RMSECV = 34.1%, R2 = 0.961, slope = 1.17, n = 48) and thus reflect the outsized contribution -of AGBC to the total woody C stock. When the contribution of herbaceous C stocks is further - -added to these comparisons, our stock estimates intuitively increase in rough proportion to -a state’s proportional extent of herbaceous cover. The effect of this addition is particularly -pronounced for BGBC estimates due to the large root-to-shoot ratios of grassland vegetation.The -relative congruence of our results with higher-tier stock estimates suggests that our maps -could be used to facilitate broader adoption of higher-tier methods among countries currently - -lacking the requisite data and those seeking to better account for C in non-woody biomass. -This congruence spans a comprehensive range of biophysical conditions and spatial scales ranging -from small states to large nations. Moreover, a recent study suggests that the fidelity of -the underlying GlobBiomass AGB map may extend to even finer scales31. While our BGBC estimates -may differ from some fine-scale estimates (Fig. 9d), their tight agreement with high tier - -BGBC totals at the national level (Fig. 9c) suggests that they may still be well suited for -many national-scale C inventories – especially for countries lacking requisite high tier data. -Use of our maps is unlikely to introduce error in excess of that currently implicit in Tier-1 -estimates. Credence, though, should be given to the associated uncertainty estimates. To facilitate -wider adoption of higher-tier methodologies, our maps could be used to derive new, region-specific - -default values for use in Tier-2 frameworks76 or to either represent or calibrate 2010 baseline -conditions in Tier-3 frameworks. In so doing, inventories and studies alike could more accurately -account for the nuanced global geographies of biomass C.These maps are intended for global -applications in which continuous spatial estimates of live AGBC and/or BGBC density are needed -that span a broad range of vegetation types and/or require estimates circa 2010. They are - -loosely based upon and share the spatial resolution of the ESA CCI Landcover 2010 map37, which -can be used to extract landcover specific C totals. However, our products notably do not account -for C stored in non-living C pools like litter or coarse woody debris, nor soil organic matter, -though these both represent large, additional ecosystem C stocks77,78,79. Our maps are explicitly -intended for global scale applications seeking to consider C in the collective living biomass - -of multiple vegetation types. For global scale applications focused exclusively on the C stocks -of a single vegetation type, we strongly encourage users to instead use the respective input -map or model referenced in Table 1 to avoid potential errors that may have been introduced -by our harmonization procedure. For AGB applications over smaller extents, users should further -consider whether locally specific products are available. If such maps are not available and - -our maps are considered instead, credence should be given to their pixel-level uncertainty -estimates. As mentioned above, the biomass of shrublands was only explicitly accounted for -in Africa and the Arctic tundra, since neither broad-scale maps nor models generalizable to -other areas were available in the existing literature. 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We are also grateful to the thoughtful feedback of three anonymous reviewers -whose suggestions greatly improved the quality of our products and the clarity of our manuscript. -Funding for this project was generously provided by the David and Lucile Packard Foundation -and the National Wildlife Federation.Department of Geography, University of Wisconsin-Madison, - -Madison, WI, USASeth A. Spawn, Clare C. Sullivan & Holly K. GibbsCenter for Sustainability -and the Global Environment (SAGE), Nelson Institute for Environmental Studies, University -of Wisconsin-Madison, Madison, WI, USASeth A. Spawn, Clare C. Sullivan, Tyler J. Lark & Holly -K. GibbsYou can also search for this author in PubMed Google ScholarYou can also search for -this author in PubMed Google ScholarYou can also search for this author in PubMed Google ScholarYou - -can also search for this author in PubMed Google ScholarS.A.S. designed the harmonization -procedure, compiled and standardized individual biomass layers, conducted all mapping, and -led manuscript development. C.C.S., T.J.L. and H.K.G. assisted with conceptualization, and -manuscript development.Correspondence to Seth A. Spawn.The authors declare no competing interests.Publisher’s -note Springer Nature remains neutral with regard to jurisdictional claims in published maps - -and institutional affiliations.Open Access This article is licensed under a Creative Commons -Attribution 4.0 International License, which permits use, sharing, adaptation, distribution -and reproduction in any medium or format, as long as you give appropriate credit to the original -author(s) and the source, provide a link to the Creative Commons license, and indicate if -changes were made. The images or other third party material in this article are included in - -the article’s Creative Commons license, unless indicated otherwise in a credit line to the -material. If material is not included in the article’s Creative Commons license and your intended -use is not permitted by statutory regulation or exceeds the permitted use, you will need to -obtain permission directly from the copyright holder. To view a copy of this license, visit -http://creativecommons.org/licenses/by/4.0/.The Creative Commons Public Domain Dedication - -waiver http://creativecommons.org/publicdomain/zero/1.0/ applies to the metadata files associated -with this article.Reprints and PermissionsSpawn, S.A., Sullivan, C.C., Lark, T.J. et al. Harmonized -global maps of above and belowground biomass carbon density in the year 2010. Sci Data 7, -112 (2020). https://doi.org/10.1038/s41597-020-0444-4Download citationReceived: 03 July 2019Accepted: -14 February 2020Published: 06 April 2020DOI: https://doi.org/10.1038/s41597-020-0444-4Anyone - -you share the following link with will be able to read this content:Sorry, a shareable link -is not currently available for this article. 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It is critical for maintaining -species diversity, regulating climate, and providing numerous ecosystem functions.The cryosphere -encompasses the frozen parts of Earth, including glaciers and ice sheets, sea ice, and any -other frozen body of water. The cryosphere plays a critical role in regulating climate and -sea levels.The human dimensions discipline includes ways humans interact with the environment - -and how these interactions impact Earth’s systems. It also explores the vulnerability of human -communities to natural disasters and hazards.The land surface discipline includes research -into areas such as shrinking forests, warming land, and eroding soils. NASA data provide key -information on land surface parameters and the ecological state of our planet.This vast, critical -reservoir supports a diversity of life and helps regulate Earth’s climate.Processes occurring - -deep within Earth constantly are shaping landforms. Although originating from below the surface, -these processes can be analyzed from ground, air, or space-based measurements.The Sun influences -a variety of physical and chemical processes in Earth’s atmosphere. NASA continually monitors -solar radiation and its effect on the planet.The terrestrial hydrosphere includes water on -the land surface and underground in the form of lakes, rivers, and groundwater along with - -total water storage.Whether you are a scientist, an educator, a student, or are just interested -in learning more about NASA’s Earth science data and how to use them, we have the resources -to help. Get information and guides to help you find and use NASA Earth science data, services, -and tools.We provide a variety of ways for Earth scientists to collaborate with NASA.Making -NASA's free and open Earth science data interactive, interoperable, and accessible for research - -and societal benefit both today and tomorrow.Changes in the land surface can impact climate, -terrestrial ecosystems, and hydrology. Land surface-related data, including land cover type, -land surface temperature, and topography, are critical for monitoring agricultural practices -and water resource availability and for guiding interventions when necessary.Land surface -reflectance is a measure of the fraction of incoming solar radiation reflected from Earth's - -surface to a satellite-borne or aircraft-borne sensor. These data are useful because they -provide an estimate of the surface spectral reflectance as it would be measured at ground -level in the absence of atmospheric scattering or absorption, which is referred to as atmospheric -correction.Land surface reflectance data can be used for visualizing the surface as well as -for computing metrics and creating models that are useful for specific analysis. Agricultural - -production estimates must be restricted to crop-specific areas (e.g., corn, soybeans, etc.) -to avoid confusion with other crops, natural vegetation, and areas of no vegetation. This -allows specific crops to be observed over time using sustained land imaging and multi-spectral -high-resolution imagery.An asterisk (*) next to an entry indicating that near real-time (NRT) -data products are available through NASA's Land, Atmosphere Near real-time Capability for - -EOS (LANCE) within three hours from satellite observation. Imagery is generally available -3-5 hours after observation. While not intended for scientific research, NRT data are good -resources for monitoring ongoing or time-critical events.Sensor(s)/ Model NameObservation -or Model500 m, 1 km, 5,600 m2017-present15 m, 30 m, 60 mOLI/OLI-2: 9 bands ranging from 0.43 -µm to 1.38 µmETM+: 8 bands ranging from 0.45 µm to 12.5 µmTM: 7 bands ranging in wavelength - -from 0.45 µm to 2.35 µmOLI-2, OLI, ETM+, TMGeoTIFFOLI/OLI-2: 9 bands ranging from 0.43 µm -to 1.38 µmMSI: 12 bands ranging from 0.443 µm to 2.190 µmThe Advanced Spaceborne Thermal Emission -and Reflection Radiometer (ASTER) instrument is a cooperative effort between NASA and Japan's -Ministry of Economy, Trade and Industry (METI). ASTER Surface Reflectance data can be visualized -and interactively explored using NASA Worldview:Research quality ASTER data products are available - -through Earthdata Search:Back to the TableThe Enhanced Thematic Mapper (ETM+), the Operational -Land Imager (OLI) and OLI-2, and the Thermal Infrared Sensor-2 (TIRS-2) are aboard the joint -NASA/USGS Landsat series of satellites.OLI data can be visualized and interactively explored -using NASA Worldview:Research quality Landsat land surface reflectance data products can be -accessed directly using USGS EarthExplorer:Back to the TableHarmonized Landsat Sentinel-2 - -(HLS) data provide consistent global observation of Earth’s surface reflectance and top-of-atmosphere -(TOA) brightness data from the Landsat OLI and OLI-2 and the ESA (European Space Agency) Multi-Spectral -Instrument (MSI) aboard the Sentinel-1A/B satellites every 2-3 days with 30 meter spatial -resolution.HLS Surface Reflectance data can be visualized and interactively explored using -NASA Worldview:Research quality HLS data products can be accessed directly from Earthdata - -Search:The Application for Extracting and Exploring Analysis Ready Samples (AppEEARS) tool -offers a simple and efficient way to access, transform, and visualize geospatial data from -a variety of federal data archives, including USGS Landsat Analysis Ready Data (ARD) surface -reflectance products. Back to the TableModerate Resolution Imaging Spectroradiometer (MODIS) -Surface Reflectance products provide an estimate of the surface spectral reflectance as it - -would be measured at ground level in the absence of atmospheric scattering or absorption.MODIS -Surface Reflectance data can be visualized and interactively explored using NASA Worldview:Multiple -Geographic Information Systems (GIS) MODIS Surface Reflectance data layers with different -band combinations are available through Esri’s ArcGIS OnLine (AGOL). NASA GIS data may be -used with open-source GIS software such as Quantum GIS or Geographic Resources Analysis Support - -System (GRASS). Learn more about these tools in the Use the Data section below.Research quality -MODIS data products can be accessed directly from Earthdata Search:Near real-time (NRT) MODIS -Surface Reflectance data are available through NASA’s Land, Atmosphere Near real-time Capability -for EOS (LANCE) within 60 to 125 minutes after a satellite observation:Back to the TableThe -Visible Infrared Imaging Radiometer Suite (VIIRS) instrument is aboard the NASA/NOAA Suomi - -National Polar-orbiting Partnership (Suomi NPP) and NOAA-20 satellites. VIIRS/NPP Land Surface -Reflectance Data from Earthdata Search Data are available daily and 8-day at various spatial -resolutions.Near real-time (NRT) VIIRS Surface Reflectance data are available through LANCE -within 60 to 125 minutes after a satellite observation:Back to the TableLand Surface Temperature -(LST) describes processes such as the exchange of energy and water between the land surface - -and Earth's atmosphere. LST influences the rate and timing of plant growth and is affected -by the albedo, or reflectance, of a surface. These data can improve decision-making for water -use and irrigation strategies, and are also an indicator for crop health and water stress.An -asterisk (*) next to an entry indicating that near real-time (NRT) data products are available -through NASA's Land, Atmosphere Near real-time Capability for EOS (LANCE) within three hours - -from satellite observation. Imagery is generally available 3-5 hours after observation. While -not intended for scientific research, NRT data are good resources for monitoring ongoing or -time-critical events.1 km, 0.05°0.25°, 0.5°, 1° GeoTIFFMODIS LST data can be visualized and -interactively explored using NASA Worldview:MODIS LST data can be visualized in Giovanni:Research -quality LST data products can be accessed directly from Earthdata Search and also are available - -through the Data Pool at NASA’s Land Processes DAAC (LP DAAC).The AppEEARS tool and MODIS -subsetting tools can be used to quickly extract a subset of MODIS data for a region of interest.Near -real-time (NRT) MODIS LST data are available through LANCE within 60 to 125 minutes after -a satellite observation.Back to the TableResearch quality LST data from the Advanced Spaceborne -Thermal Emission and Reflection Radiometer (ASTER) are available in HDF-EOS format:Back to - -the TableA suite of MODIS LST and Emissivity (LST&E) products are available that combine MODIS -data with ASTER data to leverage the strengths from both sensors. These integrated LST data -can be visualized and interactively explored using NASA Worldview:Back to the TableThe ECOsystem -Spaceborne Thermal Radiometer Experiment on Space Station (ECOSTRESS) mission measures the -temperature of plants to better understand how much water plants need and how they respond - -to stress.The AppEEARS tool and MODIS subsetting tools can be used to quickly extract a subset -of ECOSTRESS data for a region of interest.Back to the TableThe Visible Infrared Imaging Radiometer -Suite (VIIRS) instrument is aboard the NASA/NOAA Suomi National Polar-orbiting Partnership -(Suomi NPP) and NOAA-20 satellites. Research quality LST data products from VIIRS: Near real-time -(NRT) VIRS LST data are available through LANCE within 60 to 125 minutes after a satellite - -observation:Back to the TableLST data are produced as part of the NASA/USGS Landsat series -of Earth observing missions.