nasa-gesdisc/es-publications-researchareas huggingface dataset:
Australian wildfire smoke in the stratosphere: the decay phase in 2020/2021 and impact on ozone depletion (2022)

Abstract. Record-breaking wildfires raged in southeastern Australia in late December 2019 and early January 2020. Rather strong pyrocumulonimbus (pyroCb) convection developed over the fire areas and lofted enormous amounts of biomass burning smoke into the tropopause region and caused the strongest wildfire-related stratospheric aerosol perturbation ever observed around the globe. We discuss the geometrical, optical, and microphysical properties of the stratospheric smoke layers and the decay of this major stratospheric perturbation. A multiwavelength polarization Raman lidar at Punta Arenas (53.2 S, 70.9 W), southern Chile, and an elastic backscatter Raman lidar at Rio Grande (53.8 S, 67.7 W) in southern Argentina, were operated to monitor the major record-breaking event until the end of 2021. These lidar measurements can be regarded as representative for mid to high latitudes in the Southern Hemisphere. A unique dynamical feature, an anticyclonic, smoke-filled vortex with 1000 km horizontal width and 5 km vertical extent, which ascended by about 500 m d1, was observed over the full last week of January 2020. The key results of the long-term study are as follows. The smoke layers extended, on average, from 9 to 24 km in height. The smoke partly ascended to more than 30 km height as a result of self-lofting processes. Clear signs of a smoke impact on the record-breaking ozone hole over Antarctica in SeptemberNovember 2020 were found. A slow decay of the stratospheric perturbation detected by means of the 532 nm aerosol optical thickness (AOT) yielded an e-folding decay time of 1920 months. The maximum smoke AOT was around 1.0 over Punta Arenas in January 2020 and thus 2 to 3 orders of magnitude above the stratospheric aerosol background of 0.005. After 2 months with strongly varying smoke conditions, the 532 nm AOT decreased to 0.03-0.06 from MarchDecember 2020 and to 0.0150.03 throughout 2021. The particle extinction coefficients at 532 nm were in the range of 1075 Mm1 in January 2020 and, later on, mostly between 1 and 5 Mm1. Combined lidarphotometer retrievals revealed typical smoke extinction-to-backscatter ratios of 69  19 sr (at 355 nm), 91  17 sr (at 532 nm), and 120  22 sr (at 1064 nm). An ozone reduction of 20 %25 % in the 1522 km height range was observed over Antarctica and New Zealand ozonesonde stations in the smoke-polluted air, with particle surface area concentrations of 15 m2 cm3.

Research areas: Wildfires
Improvements in SO2 pollution in India: role of technology and environmental regulations (2022)

India relies heavily on coal-based thermal power plants to meet its energy demands. Sulphur dioxide (SO2) emitted from these plants and industries is a major air pollutant. Analysis of spatial and temporal changes in SO2 using accurate and continuous observations is required to formulate mitigation strategies to curb the increasing air pollution in India. Here, we present the temporal changes in SO2 concentrations over India in the past four decades (19802020). Our analysis shows that the Central and East India, and Indo-Gangetic Plain (IGP) are the hotspots of SO2, as these regions house a cluster of thermal power plants, petroleum refineries, steel manufacturing units, and cement Industries. Thermal power plants (51%), and manufacturing and construction industries (29%) are the main sources of anthropogenic SO2 in India. Its concentration over India is higher in winter (DecemberFebruary) and lower in pre-monsoon (MarchMay) seasons. The temporal analyses reveal that SO2 concentrations in India increased between 1980 and 2010 due to high coal burning and lack of novel technology to contain the emissions during the period. However, SO2 shows a decreasing trend in recent decade (20102020) because of the environmental regulations and implementation of effective control technologies such as the flue gas desulphurisation (FGD) and scrubber. Since 2010, India's renewable energy production has also been increased substantially when India adopted a sustainable development policy. Therefore, the shift in energy production from conventional coal to renewable sources, solid environmental regulation, better inventory, and effective technology would help to curb SO2 pollution in India. Both economic growth and air pollution control can be performed hand-in-hand by adopting new technology to reduce SO2 and GHG emissions.

Research areas: Air Quality, Energy Production/Use
Relationship between surface dissolved iron inventories and net community production during a marine heatwave in the subarctic northeast Pacific (2022)

From winter 201314 to the end of 201516, a high pressure atmospheric system induced elevated sea surface temperatures in the offshore subarctic northeast Pacific, resulting in a marine heatwave. Increased stratification due to the heatwave resulted in shoaling of the winter mixed layer and a decrease in nutrient re-supply to the euphotic zone. Here, we investigate relationships between dissolved iron (dFe) and macronutrients, net community production (NCP), (micro)nutrient uptake ratios, and phytoplankton community composition in the winter and summer from 2012 to 2015 to gain insight into coupled biogeochemical responses to the heatwave. Our investigation highlights the importance of external dFe supply during marine heatwave events, as a more shallow mixed layer reduces the transport of essential (micro)macronutrients to the surface layer. We conclude that recycled dFe did not contribute to NCP in 2014, but rather the vertical displacement of dFe rich water unrelated to mixed layer deepening played a major role. In 2015, such transport was not detected, resulting in abnormally low dFe and shift toward higher biomass of pico- and nano-phytoplankton size-classes.

Research areas: Atmospheric/Ocean Indicators, Ecosystems
The multi-year comparisons of chlorophyll and sea ice in Greenland Sea and Barents Sea and their relationships with the North Atlantic Oscillation (2022)

The Arctic Ocean (AO) has experienced very significant warming in recent decades with clear impacts on the extent and depth of sea ice cover. Sea ice serves as a primary habitat and plays an important role in the AO marine food web. The surface distributions of chlorophyll_a (CHL), sea ice concentration (ICE), sea surface temperature (SST) and North Atlantic Oscillation (NAO) are analyzed in the study region (20W-50E, 70N-80N) over the decade (20032014). This region spans the Barents Sea (BS), Norwegian (NS) and Greenland Sea (GS). In general, the peak of spatial averaged CHL in the BS was about 60% higher than the GS. Due to elevated SST in the southern BS, CHL was much higher especially in 2010 and 2013. In 2011, there was a strong meridional gradient in CHL decreasing from south to north of the BS, and also a strong zonal gradient from the southern GS to the southern BS. The northern GS had higher CHL than the southern GS due to the increased ice melting and nutrient-enriched runoff from east Greenland glaciers to the northern and western coastal regions of the GS. Seasonal peaks of spatially averaged CHL occurred in April or May and were about two weeks earlier in the BS than the GS. Higher ice melt in the northern BS was the main reason for CHL blooms especially in 2010 and 2011. Earlier and more extensive ice melting and a persistent negative NAO index causing atmospheric circulation patterns that favoured ice loss were the possible drivers of enhanced phytoplankton blooms in 2010. A previous negative winter NAO is thought to be linked to an increase in ICE in the following spring. NAO is mostly negative during spring in the GS. Sea ice melt was positively correlated with CHL in the northern sector of the study region.

Research areas: Cryospheric Indicators, Ecosystems
Changes in Surface Water Bodies Associated With Madoi (China) Mw 7.3 Earthquake of May 21, 2021 Using Sentinel-1 Data (2022)

On May 21, 2021 (UTC), an Mw 7.3 earthquake occurred in Madoi County of Qinghai Province (China). There was no damage to buildings or loss of life; however, surface manifestation was observed in the epicentral areas. The analysis of synthetic aperture radar (SAR) and ground observation data shows changes in the section of the Yellow River and some lakes within the epicentral region associated with this strong earthquake. The changes in radar backscattering coefficient (BC) in water bodies are observed attributed to turbidity from the intense shaking of the earthquake. The liquefaction locations observed in the field within the epicentral region, which is also supported by the changes in the BC derived from Sentinel-1 data.

Research areas: Earthquakes
Smoke in the river: an Aerosols, Radiation and Clouds in southern Africa (AEROCLO-sA) case study (2022)

Abstract. The formation of a river of smoke crossing southern Africa was investigated during the Aerosols, Radiation and Clouds in southern Africa (AEROCLO-sA) campaign in September 2017. A complementary set of global and mesoscale numerical simulations as well as ground-based, airborne and space-borne observations of the dynamics, thermodynamics and composition of the atmosphere are used to characterize the river of smoke in terms of timing and vertical extent of the biomass burning aerosol (BBA) layer. The study area was under the synoptic influence of a coastal low rooted in a tropical easterly wave and a high-pressure system over the continent and westerly waves at mid latitudes, one of which had an embedded cut-off low (CoL). The coastal low interacted with the second of two approaching westerly waves and ultimately formed a mid-level tropical temperate trough (TTT). The TTT created the fast-moving air mass transported to the southwestern Indian Ocean as a river of smoke. The CoL, which developed and intensified in the upper levels associated with the first (easternmost) westerly wave, remained stationary above northern Namibia prior to the formation of the TTT and was responsible for the thickening of the BBA layer. This shows that the evolution of the river of smoke is very much tied to the evolution of the TTT, while its vertical extent is related to the presence of the CoL. The mechanisms by which the CoL, observed over Namibia in the entrance region of the river of smoke, influences the vertical structure of the BBA layer is mainly associated with the ascending motion above the BBA layer. In the presence of the CoL, the top of the BBA layer over northern Namibia reaches altitudes above 8 km. This is much higher than the average height of the top of the BBA layer over the regions where the smoke comes from (Angola, Zambia, Zimbabwe, Mozambique), which is 5 to 6 km. The results suggest that the interaction between the TTTs and the CoLs which form during the winter may have a role in promoting the transport of BBA from fire-prone regions in the tropical band to the temperate mid latitudes and the southwestern Indian Ocean.

Research areas: Environmental Impacts, Atmospheric/Ocean Indicators
Solar Energy Potential on Surfaces with Various Inclination Modes in Saudi Arabia: Performance of an Isotropic and an Anisotropic Model (2022)

The present work investigated the performance of an isotropic (LiuJordan, LJ) and an anisotropic (Hay) model in assessing the solar energy potential of Saudi Arabia. Three types of solar collectors were considered: with southward fixed-tilt (mode (i)), with fixed-tilt tracking the Sun (mode (ii)), and with varying-tilt tracking the Sun (mode (iii)). This was the first time such a study was conducted for Saudi Arabia. The average annual difference between anisotropic (Hay) and isotropic (LJ) estimates is least 38 kWhm2 year1 over Saudi Arabia for mode (i), and therefore, the LJ model can be used effectively. In modes (ii) and (iii), the difference is greater (197 and 226 kWhm2 year1, respectively). It is, then, up to the solar energy engineer to decide which model is to be used, but it is recommended that the Hay model be utilised for mode-(iii) solar collectors. These results fill a research gap about the suitability of models in practice. An interesting feature for the ratio of the annual mean solar energy yield of Hay over LJ as function of the latitude, , and the ground albedo, r, is the formation of a well for 29    31 and 1.15  r  1.

Research areas: Energy Production/Use, Sun-Earth Interactions
Total lipid and fatty acid composition of mesozooplankton functional group members in the NE Pacific over a range of productivity regimes (2022)

Fish, whales, and seabirds along the productive west coast of Vancouver Island (WCVI), NE Pacific, rely on copepod prey that are assumed to be rich in lipid. However, the total lipid (TL) and fatty acid content of most copepod species and other mesozooplankton in this region have not been measured. To assess the diets and quality of zooplankton prey off the WCVI, we investigated differences in lipid content and composition of mesozooplankton according to their taxonomic versus functional group identities. Copepods, chaetognaths, euphausiids, and amphipods, belonging to 3 different functional groups, were sampled on the WCVI during pre-, mid-, and post-bloom conditions. Compared to taxonomic classifications, the functional group approach was superior in its ability to discern statistical differences in TL among zooplankton and between seasons. Furthermore, multivariate analyses using zooplankton fatty acid composition from all oceanographic regimes produced 3 to 4 statistically different clusters of species that corroborated functional group designations. However, some trophic flexibility was observed in several copepod species, particularly Calanus marshallae, that may relate to food scarcity or the presence of potentially noxious prey. The omnivorous-herbivorous functional group frequently contained higher amounts of TL and masses of essential fatty acids than the carnivorous group. Euphausiids and C. marshallae contributed the most lipid (mg m-3) to the pelagic lipid pool, due to very high lipid content and high abundance, respectively. However, on the continental slope and shelf break, chaetognaths and Neocalanus spp. copepods contributed substantially to the lipid pool.

Research areas: Ecosystems
Variability and Source Characterization of Regional PM of Two Urban Areas Dominated by Biomass Burning and Anthropogenic Emission (2022)

ABSTRACT Identifying the sources and formation pathways of particulate matter (PM) and its components is important to determine the impact of atmospheric aerosols on human health and the warming of the global atmosphere. Here, we characterized the variability of the eleven-year concentration and the origin of PM2.5 in two urban regions (Metro Manila and Boracay) in the Philippines, a country in South East Asia (SEA) with high local anthropogenic emissions and frequently impacted by transboundary pollution. The surface concentration of PM2.5 was analyzed using simulated and reanalyzed satellite data (MERRAero), complemented, and validated with filter measurements for PM2.5 and black carbon (BC). The PM2.5 masses in Metro Manila (12.3  2.4 g m3) and Boracay (12.9  3.6 g m3) were comparable yet with varying concentrations of aerosol components Anthropogenic related components of PM (organic carbon, sulfate, and BC) were more enhanced in the metropolis region (4.9 g m3) than in the prime tourist spot (2.72 g m3). Sulfate formation impacted the aerosol mass in Metro Manila, with the photochemical oxidation of SO2 as the predominant production pathway of sulfates. Analysis of regional organic matter (OM) and BC in Boracay revealed extensive transboundary transport of biomass burning (BB) plumes from equatorial SEA countries. Also, the ratio of OM and SO4 was utilized as a quick proxy for source characterization. Metro Manila and Boracay reported 0.77  0.20 and 1.06  0.55, highlighting the evident impact of traffic emissions in the PM mass in the metropolis region. For Boracay, the mixed contributions of BB and vehicular activities influenced the formation of PM. Overall, the reanalysis of satellite data captured the long-term variability and origins of surface PM in two vital urban regions in the Philippines. The utilization of MERRAero will be an important procedure in making regulatory decisions on regional pollution control.

Research areas: Air Quality, Environmental Impacts
Trends in the types and absorption characteristics of ambient aerosols over the Indo-Gangetic Plain and North China Plain in last two decades (2022)

The sixth assessment report released by the Intergovernmental Panel on Climate Change (IPCC) in 2021 states that our inadequate understanding of magnitudes and trends of atmospheric aerosols, particularly over Asia, is a major source of uncertainty in climate change. In this study, the climatology and trends in different types of aerosols with focus on absorbing aerosols over Kanpur located in the Indo-Gangetic Plain (IGP) in South Asia and Beijing in the North China Plain (NCP) in East Asia are derived for the first time. We perform a first analysis of high-quality time series of columnar aerosols observations over a period of nearly two-decades, along with satellite observations to provide a broader regional perspective. The satellite retrieved aerosol Angstrom exponent (AE) values have increased (1020%) suggesting an increasing contribution of fine aerosols to aerosol optical depth (AOD) over Asia in last 2-decades. Among the three aerosol types [urban-industrial (UI), biomass burning (BB), and dust (DU)], only UI and BB aerosols are present over Kanpur throughout the year, while DU is present along with UI and BB aerosols only during pre-monsoon and monsoon. Overall, there is a positive trend in BB aerosols over both Kanpur and Beijing, a positive (negative) trend in UI aerosols over Kanpur (Beijing), and positive (negative) trend in dust over Beijing (Kanpur). However, only the positive trend in BB aerosol type over Kanpur is statistically significant. Further, among the three absorbing aerosol types [mostly black carbon (MBC), mostly dust (MDU), and mixed (MIX) containing BC and dust], only MBC and MIX are present in post-monsoon and winter over IGP, and MDU is present along with MBC and MIX only during pre-monsoon and monsoon, which is in agreement with aerosol types found. Trends in MBC, MIX and MDU over Kanpur in IGP and in MIX over Beijing are statistically significant. These trends are attributed mainly to the changes in anthropogenic aerosol emissions, and not to natural and climatic factors as their changes are relatively small. These findings on hitherto unavailable climatology and trends in aerosols and absorbing aerosols over two global aerosol hotspots and identified contrasts will be crucial in model simulations to better decipher the aerosol-climate interactions over Asia.

Research areas: Air Quality, Environmental Impacts
Aerosol emissions and gravity waves of Taal volcano (2022)

The Taal volcano (14.0 N, 121.0 E) in Philippines erupted in JanuaryFebruary 2020, with a part of aerosols drifted northward and detected by a lidar system at Kaohsiung city (22.37 N, 120.15 E), Taiwan. The aerosol observed on Feb 11 is special for its high-altitude distributions at 47 km with discrete structures which can be resolved into a sinusoidal oscillation of ~ 30 min period, suggesting a case of wave event caused by the eruptions. We report in this paper the gravity wave generated by the volcanic eruptions and its effects on aerosol emissions. By studying the temperature and pressure data in the Taal region using radiosonde data, we found atmospheric gravity waves with powers correlated with the optical thickness (AOD) at 550 nm measured by the Moderate Resolution Imaging Spectrometer (MODIS) satellite. This study presents the first observation of modulation of the aerosol emissions by the volcanic gravity waves and a case of coupling of dynamics and chemistry.

Research areas: Volcanic Eruptions
A Qualitative Assessment of the Trends, Distribution and Sources of Methane in South Africa (2022)

Methane (CH4) is the second most important greenhouse gas (GHG) in terms of its concentration and impact on the climate. In the present study, we investigate the trends, sources and distribution of CH4 in South Africa. The study uses satellite datasets from Sentinel-5P and the Atmospheric Infrared Sounder (AIRS). The study also uses credible datasets from the World Bank, Statistics South Africa and the Global Methane Initiative (GMI). The results show an increasing trend of CH4 from 19701989. A turning point is observed in 1989, where a decreasing trend is observed from 19892001. An increasing trend is then observed from 2001 to 2021. A high concentration of CH4 is observed in the northern and interior parts of South Africa. The results also show that CH4 concentration is influenced by seasonal variations. The SeptemberOctoberNovember (SON) season has the highest CH4 concentration distribution in South Africa. The World Bank, Statistics South Africa and the GMI CH4 indictors show that agricultural activities, i.e., involving livestock, are the greatest emitters of CH4 in South Africa, followed by landfill sites. From the livestock data, sheep are the highest emitters of CH4. The increasing CH4 trend is a concern and efforts need to be made to drastically reduce emissions, if South Africa is to meet the 1997 Kyoto Protocol, 2015 Paris Agreement, sustainable development goal 13 (SDG 13) and the COP26 outcome agreements.

Research areas: Greenhouse Gases, Agriculture
Analyzing the Characteristics of Cloud Condensation Nuclei (CCN) in Hebei, China Using Multi-Year Observation and Reanalysis Data (2022)

The study of the characteristics and variations of cloud condensation nuclei (CCN) plays an important role in understanding the effects of aerosolcloud interactions. This paper selected observation data in a city region of Shijiazhuang in North China from 2005 to 2007, along with the corresponding MERRA-2 and ERA5 data, to analyze the characteristics of CCN, sort the factors affecting the diurnal variation of CCN number concentration (NCCN) according to their importance, and build the relationship between NCCN and supersaturation (SS) in the heavily polluted region. The results show that there was a bimodal distribution of a daily time series for NCCN in Shijiazhuang, China. By calculating the correlation between CCN and pollutants observed in winter 2007, we identified that the dominant factor for peaks of NCCN is SO2 in the morning but NO2 in the evening. We also ranked the factors affecting the diurnal variation of NCCN by using observation and reanalysis data and found that the concentration of pollutants is the greatest impact factor in summer, but the atmospheric stability is the greatest factor in winter. Finally, we determined the relationship between NCCN and SS according to the Twomey formula (NCCN=cSSk) and found there was a reasonable value range (i.e., 0.5~0.7) for the parameter k in East and North China. Specifically, it is more reasonable for k to be 0.5 in summer and 0.7 in winter.

Research areas: Air Quality, Atmospheric/Ocean Indicators