Group for Earth Observation

No 74 - June 2022

Enrico Gobbetti captured this AHRPT image transmitted from Meteor M2 on May 11, 2022, six days
after the satellite lost attitude control. The limb of Earth shows clearly at the right of the image and theoutline of the Mediterranean Sea and surrounding regions are noticeably distorted.

Useful User Groups

GEO MANAGEMENT TEAM
General Information
John Tellick,email: information@geo-web.org.uk

GEO Newsletter Editor
Les Hamilton,
email: geoeditor@geo-web.org.uk

Technical Consultant (Hardware)David Simmons
email: tech@geo-web.org.uk

Webmaster and Website Matters

Weather Satellite Reports
This group provided weekly reports, updates and news
on the operational aspects of weather satellites.

https://groups.io/g/weather-satellite-reports

SatSignal
This end-user self help group is for users of David
Taylor’s Satellite Software Tools, including the orbit
predictor WXtrack, the file decoders GeoSatSignal and
SatSignal, the HRPT Reader program, the remapper
GroundMap, and the manager programs - MSG DataManager, GOES-ABI Manager, AVHRR Manager etc.

https://groups.io/g/SatSignal

Vacancye-mail: webmaster@geo-web.org.uk

Management TeamDavid Anderson
Rob Denton

MSG-1
This forum provides a dedicated area for sharing
information about hardware and software for receiving
and processing EUMETCast data.

https://groups.io/g/MSG-1

Nigel Evans: nigel.m0nde@gmail.com
Clive Finnis
Carol FinnisPeter GreenDavid SimmonsDavid Taylor

GEO-Subscribers
This is the official group is for subscribers of the Groupfor Earth Observation (GEO), aimed at enthusiasts
wishing to exchange information relating to either GEO
or Earth Observation satellites.

https://groups.io/g/GEO-Subscribers/www.geo-web.org.uk

2

Les HamiltonAs we head towards another northern hemisphere summer, events around theglobe keep reminding us of the need to address the problem of climate change.
Already this year an ice shelf in Antarctica has suddenly suffered total disintegration
while the extent of the sea ice around the continent fell to an all-time record low
since the satellite record commenced in 1979! In Australia, where drought held swayfrom 2017 to 2019, ﬂooding is now the problem, particularly in the east, where anational emergency was declared in early March. In Spain, some parts of the nation
have already experienced their hottest May since records began, as hot, dry air fromAfrica caused temperatures to soar into the 40s. And to top everything, for the seventh
successive year, NOAA are predicting above-average hurricane activity in the Atlanticbasin during 2022, forecasting with 70% certainty between 14 and 21 named storms(winds of 63 kph or higher), 6 to 10 of which could become hurricanes (winds of
120 kph or higher) and 3 to 6 of them in categories 3 to 5 (winds of 180 kph or more).

TA

his issue sees the completion of Ed Murashie’s trilogy of images dealing with
Landsat data. Here he provides an overview/tutorial on some new tools that can beused to download completely free data from these satellites.
nd on the topic of satellite data, Richard Osborne details use of the VISAN tool for
visualising EUMETSAT SAF satellite products.

Contents
Floodwaters Reach Australia’s Channel Country
Young Impact Crater Uncovered in Yilan
Sea Ice and Cloud Streets in the Labrador Sea
Record Low for Great Salt Lake
Low Cost Landsat Data
Wildfires in South Korea
Cloud Party in the PacificGreening in Mali
Lofoten, Norway
Ice Shelf Collapse in East Antarctica
DISCOVR and EPIC
Uyuni Salt Pan Drying Out
Antarctic Sea Ice Reaches Record Low
Flooding in Eastern Australia
Meteor M2 Attitude Problem
Great Barrier Reef
Yukon-Kuskokswim in Colourful Transition
Visualising EUMETCast SAF Products using the VISAN Tool
Lake Mead Drops to a Record Low
Sediment in the Caspian Sea
Satellite Status

MODIS Web Image of the Day
NASA Earth Observatory
MODIS Web Image of the Day
NASA Earth Observatory
Ed Murashie
NASA Earth Observatory
NASA Earth Observatory
MODIS Web Image of the Day
European Space Agency
NASA Earth Observatory
Les Hamilton
MODIS Web Image of the Day
NASA Earth Observatory
NASA Earth Observatory
Les Hamilton
MODIS Web Image of the Day
NASA Earth Observatory
Richard Osborne
NASA Earth Observatory
MODIS Web Image of the Day

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Floodwaters Reach Australia’s Channel Country
MODIS Web Image of the Day

Image Credit: MODIS Land Rapid Response Team, NASA GSFC

Torrential rains over eastern Australia brought severe
flooding to parts of Queensland and New South Wales inearly March 2022. Media reported that tens of thousandsof residents along the southeastern Australia coast
had been evacuated, with about 1,000 rescues in New
South Wales by March 1. According to AccuWeather,
the city of Brisbane received more than 610 mm of rain
between February 24-27, setting the record for its wettest
three-day period since weather data tracking begin in
1840. According to the Center for Disaster Philanthropy,
the Insurance Council of Australia extended the area
declared an insurance catastrophe from south-east
Queensland into northern New South Wales in order tohelp prioritise handling more than 15,000 claims alreadylodged by March 1.
While the floods were nothing short of catastrophic acrossthe coastal regions, the flooding has brought water
trickling inland, even to Australia’s Channel Country, an

area so named because of the dry river channels thatmark the arid interior. The region is also known for its
ephemeral lakes, which are dry (or nearly so) most of
the year. Channel Country flooding is a fairly common
occurrence at the end of summer, but this year’s massive
flooding has brought large amounts of water to the region.
On March 3, the Moderate Resolution Imaging
Spectroradiometer (MODIS) on board NASA’s Aqua
satellite acquired a false-colour image of flooding in
the Channel Country of southwestern Queensland.
This type of false-colour image is particularly useful toseparate out deep water (dark blue) and shallow wateror moist salt flats (light blue) from dry land (brown) andvegetation (bright green). This image shows water inLakes Machattie, Mipia and Koolivoo. The floodplainsof the Georgina River and Eyre Creek are flushed withgreen vegetation far northward, heading into the Northern
Territory.

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Young Impact Crater Uncovered in Yilan
NASA Earth Observatory
Story by Sara E. Pratt

NASA Earth Observatory image by Lauren Dauphin, using Landsat data from the U.S. Geological Survey.

Despite China’s large land area, only one impact crater(the relatively small Xiuyan crater in Liaoning province)
had been discovered there prior to 2020. Then, in 2021, ateam of geologists found another crater northwest of Yilan
in Heilongjiang Province. The crater was discovered in theheavily forested Lesser Xing’an mountain range, where
local residents knew it as ‘Quanshan’, or ‘circular mountainridge’.
The Yilan crater, slightly larger than Xiuyan, spans about
1.85 kilometres, making it the largest crater on Earthunder 100,000 years old. Carbon-14 dating of charcoaland organic lake sediments suggests the crater formed
between 46,000 and 53,000 years ago. Barringer Crater inArizona is also roughly 50,000 years old, but its diameteris rather less at 1.2 kilometres.
In this image, acquired by the Operational Land Imager(OLI) on Landsat 8 on October 8, 2021, the scalloped
northern rim of Yilan crater is highlighted by fall foliage.
The northern rim—which rises 150 metres above the crater
floor—is well-preserved, but the southern third of the craterrim is missing.

Although the asteroid that created this crater struck
relatively recently in geologic time, the granite rocks
it impacted were much older, having formed about
200 million years ago in the Early Jurassic Period. To
investigate the impact structure, the research team drilled
down 440 metres into the centre of the crater, where theyfound hundreds of metres of ancient lake sediments andshattered granite. The team also found unambiguous
evidence that the structure was indeed an impact crater.
The core revealed shocked quartz, melted granite, glass
containing holes formed by gas bubbles, and tear-drop
shaped glass fragments—all indicators of a high-intensity
impact event.
The researchers continue to investigate the cause of themissing southern rim. However, the presence of lake bed
sediments inside the crater suggests that the rim was
intact long enough for significant deposits to build up on
the lake bottom. Such deposits often produce rich, organic
soil and some farm fields can be seen inside the southernpart of the crater. The rest of the crater interior is covered
with swamps and forest wetlands.

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Sea Ice and Cloud Streets in the Labrador Sea
MODIS Web Image of the Day

Image Credit: MODIS Land Rapid Response Team, NASA GSFC

Ice and cloud combined to create a fanciful scene
over the Labrador Sea between Canada andGreenland in early March 2022. The Moderate
Resolution Imaging Spectroradiometer (MODIS) on
board NASA’s Terra satellite acquired this true-color
image on March 2.
Ice hugs the snow-covered coast of Newfoundlandand Labrador, Canada, where the frigid off-shore
winds chill the relatively fresh near-coast water,allowing the formation of floating sea ice. The wateris shallower and less saline than in the open sea,thus ice will form more easily here. The swirlingfiligrees at the sea ice edge are areas where the ice isthin and more easily moved by winds and currents.

To the east, a large bank of cloud lines up inparallel bands, a patter One of the most widespread is
volcanic ash. Satellite images collected in the days after
the eruption show the fine-grained shards of pulverised
rock covering several islands, turning land surfaces fromlush green to tan and gray. On January 25, 2022, theOperational Land Imager (OLI) on Landsat‑8 captured theimage opposite showing ash coating much of Tongatapu,
Tonga’s most populous island. Compare this with the preeruption image featured on the front cover. n known as
cloud streets. These are formed when strong winds
push a mass of cold and dry air across a relatively
warm and moist body of water. As the cold air mass
moves over the water, it quickly gains moisturenecessary to form clouds. The clouds line up inorganized rows parallel to the direction of the wind.

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Record Low for Great Salt Lake
NASA Earth Observatory
Story by Michael Carlowicz

In late July 2021, the Great Salt
Lake in Utah reached its lowest
water level on record and has
continued dropping since. On
July 23, the U.S. Geological
Survey (USGS) gauge at theSaltair boat harbour, at thesouthern end of the lake, recorded
the average daily level at 1277.5
metres above sea level, the lowest
mark since measurements began
in 1875. The previous low was set
in 1963.
The Operational Land Imager(OLI) on Landsat-8 acquired theseimages of the north end of theGreat Salt Lake on July 29, 2017,
and July 24, 2021. Orange-brownareas along the edges of the lakeindicate shallow water, while brighttan and white fringes suggest
newly exposed portions of thelake bed. Note, too, the depletionof water in Clyman Bay and Bear
River Bay.

Landsat-9 image of the north end of Great Salt Lake on July 29, 2017
NASA Earth Observatory image by Joshua Stevens, using Landsat data fromthe USGS and lake elevations from the National Water Information System.

According to USGS, water levelsin the southern part of the lake
are usually a bit higher than
the northern half because moretributaries flow into the southern
section. The lake is divided by acauseway for the Union PacificRailroad.
According to water elevation datafrom USGS (plotted opposite), theGreat Salt Lake stood at 1277.4
metres as of August 12, 2021.
When full to its historic averagelevel of 1280 metres, the lakespreads across 4,400 square
kilometres. At the time of thishistoric low, it spans about 2460
square kilometres, a 44 percent
loss of surface area.

Landsat-9 image of the north end of Great Salt Lake on July 24, 2021
NASA Earth Observatory image by Joshua Stevens, using Landsat data fromthe USGS and lake elevations from the National Water Information System.

The low lake levels are due torecent trends in precipitation andlong-term trends in consumption
by humans. Snowfall was modest

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This zoomed image of the north of Great Salt Lake emphasises how the lake has declined in recent years
Image: NASA / USGS

to deficient in many areas the previous winter, andrecent research showed that snow cover in themountains around the Great Salt Lake melts at leasta week earlier now than 20 years ago.
Like much of the American West, rainfall has also
been sparse here for the past two years. In its
August 12 report, the U.S. Drought Monitor notedthat 100% of Utah was experiencing at least severe
drought while 50% of the state was in exceptional
drought, the highest category.
‘Based on current trends and historical data,
the USGS anticipates water levels may decline
an additional 30 centimetres over the next
several months,’ USGS Utah Water Science
Center data chief Ryan Rowland said in a July
24 statement.
Due to the extreme drought, nearly two-thirds ofUtah’s river and stream gauges were reporting
below-normal flows.
The Great Salt Lake is the largest water body in the

United States after the Great Lakes. It is a terminal
basin, which means the water that pours into thelake from rivers and streams has no outlet otherthan by evaporation. This allows salts and minerals
to concentrate in the lake such that it is three to fivetimes saltier than the ocean.
For more than 150 years, humans have been
taking more water out of this closed basin—for
farming, industry, and human consumption—thanis flowing into it. Drought may have contributed to
the recent drop in the lake, as have higher-thannormal temperatures. But according to scientists,
there has not been a significant long-term change inprecipitation in the basin.
In a white paper released in 2016, scientists notedthat river flow into the basin—from the Bear, Jordan,
and Weber rivers—has dropped 39% since themiddle of the 19th century. The volume of water inGreat Salt Lake has shrunk by 48% and the lakelevel has fallen 3.4 meters since 1847.

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LANDSAT: Low Cost Landsat Data
Part 3 – Tools for Downloading Free Landsat Imagery
Ed Murashie
For the low cost of not $4000, not $2, but free, you candownload nearly fifty years of Landsat imagery from theUnited States Geological Survey (USGS) website. Oneof the original goals of Landsat was to make imagery
available for $2 per image but at its peak the cost
was closer to $4000, which significantly reduced thenumber of distributed images. In 2008 that all changed
when the USGS adapted an open data policy with norestrictions on download, usage or redistribution. The
only ask is to include an acknowledgement statement
acknowledging that the source of the data is the
USGS. Since 2008, the number of images downloaded
has risen exponentially each year, reaching over 100
million in 2020 and providing over $3.5 billion dollars ofinternational economic impact [1,2].
So how do you get your hands on this free Landsat
data? There are three USGS user tools available andwe will go through each one briefly so that you candecided which is your favourite.

Figure 1 - Exponential growth of downloads of Landsat Data

Global Visualization Viewer (GloVis)
GloVis has been around since 2001 and can be accessed athttps://glovis.usgs.gov/
Assuming you want to download images and data, and not just browse, you will need to register. Click on Login in theupper left of the screen and either click on Create New Account or Sign In if you already have an account. The sameaccount login with work for USGS EarthExplorer and LandsatLook 2.0. Once signed in take a quick tour by clicking on
Take Tour in the upper left of the screen.
To start exploring, click on the Launch GloVis in Full Screen Mode button and either a default satellite image or thelast image you searched for will be displayed. The screen interface is very user friendly with the ability to select satellite
data sets, date range and percentage cloud cover on the left side of the screen. At the bottom of the screen is a timeline,
ability to load the next or previous image, view the image metadata, and download the bands. The top of the screen has
a home icon to set the current image location as a default, a location icon to jump a map location including a manuallyentered latitude/longitude, and a settings menu to change the base map, layers and view shortcut keys.
Let’s go through an example where we want to find out when construction of Dubai’s larger coastal man-made landmass was completed and download the scene (see figures 2, 3 overleaf).

1 Either use the mouse to scroll around the map to find the land mass, or click on the location icon in the upper right,
click on Lat/Long, enter a latitude of 25.0072, a longitude of 54.9876, and then click Jump to Location.
2 Now select a data set, and for a hint the construction date was after Landsat 5 was operational, so click the toggle
next to Landsat 7.
3 Leave the default date range which spans the operational life of Landsat 7, and the default cloud cover percentages
which defaults to all available images.
4 Step through the chronological images by clicking on the Next button in lower right corner of the screen until you
start to see that construction was completed. A faster method is to change the Time Scale to Year at the bottom of
the screen, then click on different years. Fine tune using the Next and Previous buttons. The Timeline View shows
the completion date around 10 July 2007. You will note the stripping in the image as mentioned in Part 2 of thisarticle series.
5 To download the image, click on the Download button in the lower right corner of the screen and then select thequality of the image with or without georeferencing.

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Figure 2 - The GloVis launch screen showing Dubai’s man-made Islands

Figure 3 - GloVis showing Landsat Stripping and the answer to the example

A Level-1 GeoTIFF Data Product will be downloaded as a compressed tar.gz file which can be decompressed using freeprograms like 7-Zip. Once decompressed you will have a TIFF file of each band and a few ancillary files.
EarthExplorer
USGS EarthExplorer is a later improved tool with more capability, including a wider range of search criteria, a longer listof satellite and aerial imagery data sets, and the ability to bulk download data. To get started go tohttps://earthexplorer.usgs.gov/
If you tried GloVis, you will notice in the upper right of the screen you are already logged in. If not click on Login andeither sign in or click on Create New Account to do so.

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10All of the controls except zooming are located in a tabbed menu on the left side of the screen. The Search Criteria taballows you to search by feature, like the Grand Canyon, an address/place, a path/row number, by uploading either a
KML/KMZ or shapefile, using a map, or by entering coordinates of a single point, polygon, circle or predefined area. If
you know what you want, EarthExplorer has a way for you to find it. Also on the Search Criteria tab are the tools forselecting a date range and cloud cover percentage. The Data Sets tab allows you to select data sets ranging from aerial
imagery, digital elevation, to satellites including Landsat 1 though Landsat 9. The Additional Criteria tab allows you toselect applicable options like path/row, sensor, collection category and others for the data set you chose.
Mount Pinatubo is the largest volcano eruption since the Landsat program has been operational
https://thelistwire.usatoday.com/lists/12-of-the-most-powerful-volcanic-eruptions-in-history/

Figure 4 - EarthExplorer Home Screen

Let’s use EarthExplorer to see what the mountain looked like before and after the eruption on June 15, 1991.
On the Search Criteria and Geocoder tabs, make sure the default of Features is set, then click theWorld Features tab. Enter Mount Pinatubo for the Feature Name and then click Show. Mount Pinatubo should
show up under Placename, click on it to select.
1 Click the Date Range tab and enter a range of 01/01/1990 to 01/30/1992. With this wide range we can be sure tofind a cloud free image before and after the eruption.
2 Click the Cloud Cover tab and move the slider for a range of 0% to 20%.
3 Click on the Data Sets tab at the top of part of the screen.
4 Click the + sign next to Landsat to expand the selections. Landsat 5 was the newest satellite during the selected
date range and the thematic mapper sensor had the highest resolution. Collection 2 Level-2 has the highest
processing and therefore a higher mapping precision, so click on Landsat Collection 2 Level 2 Landsat 4-5 TM C2
L2. For more information on this collection go tohttps://www.usgs.gov/centers/eros/science/
usgs-eros-archive-landsat-archives-landsat-4-5-tm-collection-2-level-2-science.
5 Click either the Results tab or Results button and you will be presented with eight image thumbnails and options.
6 Scroll down the results to the last thumbnail dated 1990/01/20 since it looks to be one of the most cloud free
images. Click on the footprint icon next to the thumbnail to see the scene coverage on the map.
7 Click the download icon to the right of the footprint to download the data. Click the Product Options button to see alist of available TIF files. Click the file ending in SR_B2.TIF to download the single band 2 image then click Close.
8 To download multiple single images, or the entire scene dataset, click the shopping basket next to each band, or
Add All to Bulk, or the diskette and download arrow icon next to the thumbnail to make your selection. To download
your selection, click on Item Basket at the top right of the screen, then click Start Order, and Submit ProductSelections.
Text continues on page 13

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Figure 5 - Mount Pinatubo search results screen

Figure 6 - Pinatubo before the eruption
1990/JAN/20 Landsat 5 Thermatic Mapper Band 2

Figure 7 - Pinatubo after the eruption
1992/JAN/26 Landsat 5 Thermatic Mapper Band 2

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9 Repeat steps 7 and 8 to select and download the 1992/1/26 image as the after eruption image.
10 Load the images in your favourite image processing program to adjust the contrast, brightness, and sharpness toyour liking. Personally I use Irfan View.
LandsatLook 2.0
In the newest tool, the USGS took their Landsat data put it in the cloud and using cloud based tools processed it toconvert it to cloud optimized GeoTIFF format, making it faster to manipulate. No longer are you dealing with individual
scenes but instead a pixel mosaic. The reflectance data was also stored and can be used to remove highly reflective
pixels, for example from a cloud, and use another pixel from the same timeframe instead.
To start, go tohttps://landsatlook.usgs.gov/
which takes you to the welcome screen. From there you can click on About in the upper right corner to access aninstructional video or the user’s guide. If you are going to be downloading data you will need to login using the same
credentials as used for Earth Explorer, just click on the user icon. To start exploring simply click on Explore.

Figure 8 - The LandsatLook 2.0 ‘Explore’ Home Screen

The second bar down is the menu bar and the options are:Imagery | Scene
Allows either displaying the imagery or the Landsat scene information in path/row format.
Date
Allows either selecting a date range using a calendar format or manually inputting a date range. Depending on whichsatellite(s) are selected, you may get a date warning notifying you that the satellite(s) were non-operational during that
period. The selected date range will show up on the right side of the screen as a vertical timeline.
Cloud Coverage
Filters images with a range of percentage cloud coverage. Clouds or highly reflective pixels can be replaced with otherpixels in the same month if Filter pixels is enabled.
Satellites
Allows satellite selection and provides the date range they were operational.
Tiers
Allows filtering images by the amount of GEO processing and precision ranging from Real Time with little processing toTier 1 with maximum precision.

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BandsAllows selecting processing Presets like Natural Color, Custom 1 band for displaying one band like Red, or Custom
RGB where you can assign different bands to red green and blue. Or you can select Formulae and then predefine band
ratios like Enhanced Vegetation Index.
The icons on the left side of the screen let you type in a location of interest, zoom in or zoom out, select your location,or enable map labels. The Metadata button on the bottom of the screen lets you display the metadata of all the scenes
used to create the pixel mosaic and download each scene data if logged in. The Export button lets you export a timelapse GIF, the current pixel mosaic, the search metadata or metadata search code. The right side of the screen is avertical timeline with a picture box above it which when clicked will loaded the best image of the month for the date
range. It will turn into a play button and when click will animate the images.
Let’s run through an example
Let’s say you saw NASA’s Earth Observatory 24 May 2022 email
https://earthobservatory.nasa.gov/images/149857/cabo-de-gata-nijar-natural-parkand you were intrigued since the images were Landsat 9 OLI-2 images and you wanted to learn more about the Cabo deGata—Nijar Natural Park and surrounding area.
1 Click on the magnifying glass search icon and type in Almería Spain. With all of the menu defaults selected, thebest image of the south coast of Spain is displayed in natural colour.
2 Using the mouse to pan and its wheel to zoom in, you can get a similar image to NASA’s image. To appreciate theuse of single pixel mosaics, know that the image of Spain is comprised of four separate Landsat scenes, yet it looks
seamless.
3 To save the image, click on the Export button at the bottom of the screen, then click the download icon to the rightof Map View.
4 To download the scenes, click on the Metadata button and then either click on SR Bands for surface reflectancedata or ST Bands for surface temperature bands to the right of the scene of interest. Another window will open, click
the download icon to the right of the band of interest.
5 To appreciate the power of cloud computing, click on the picture above the vertical timeline. When the images havebeen loaded, the icon turns into a play button, click on it to play an animation of the best image from each month.
You may find months with no images, those appear as just a base map.

Figure 9 - Almería, Spain Pixel Mosaic Screen

I hope you found the article series informative and now have a new source for Landsat and other satellite images.
References to USGS Web Pages
1 https://www.usgs.gov/news/featured-story/landsat-seen-stunning-return-public-investment
2 https://www.usgs.gov/news/landsat-milestone-one-hundred-million-downloads

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Wildfires Char South Korea
NASA Earth Observatory
Story by Adam Voiland

Amid dry weather and strong
winds, thousands of firefighters
raced to put out fires that burned
through forests in coastal South
Korea in early March 2022.
In NASA satellite data, the firstsigns of the fires began to appear
on March 3-4, in the coastal
areas of Uljin and Samcheok.
The Moderate Resolution Imaging
Spectroradiometer (MODIS) on
NASA’s Aqua satellite captured thenatural-color image shown above

on March 5. At the time, strong
westerly winds sent smoke plumes
streaming toward southern
Japan. By March 7, the smoke
had thinned somewhat as winds
slackened and the weather turned
foggy, but the satellites continued
to detect fire activity.
The blazes have destroyed morethan 300 homes, forced morethan 7,000 people to evacuate andcharred nearly 17,000 hectares(170 square kilometres), according

to news reports. At times, flamesneared a nuclear power plantand gas facilities, but firefighters
succeeded in fending them off.
Around 18,000 people and dozensof helicopters were mobilised tofight the fires.
Most forest fires in South Korea(58 percent) occur in the springwhen forests tend to be the driest
and vegetation is primed to burn,according to research published in
Applied Sciences.

NASA Earth Observatory image by Lauren Dauphin, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview.

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Electro L3
Image from Enrico GobbettiThis full Earth image was received directly from the Elektro-L3 geostationary satellite at
AZ 108°, EL 08° by Enrico Gobbetti using a 150 cm dish with LNB, an Airspy Mini High
Performance SDR Receiver and Satdump software to record the data. Elektro L3 transmits
every 3 hours starting from UT 00.42, and I receive it at UT 09.42, 12.42 and 16.42.
The image was received at a frequency of 1691 MHz at 09.42 UT on March 22, 2022.

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Cloud Party in the PacificNASA Earth Observatory
Story by Adam Voiland, with information from Michael Garay(NASA Jet Propulsion Laboratory).

One of the first features thatscientists noticed in April 1960
after NASA launched TIROS-1,
the first weather satellite, were
peculiar hexagonal ‘cells’ thatappeared in clouds over the ocean.
With diameters ranging between
50 and 100 kilometers, the features
were sufficiently large never to havebeen recognised from the ground.
The phenomenon came to be called
mesoscale cellular convection (MCC).
Meteorologists soon grouped thesecloud systems into two main classes.
The centres of ‘closed’ cells wereclouded over, while ‘open’ cells
had clear centres. By the time
TIROS-5 was launched in 1962,
researchers had identified a thirdclass of MCC—an intermediate typewith a radial structure that looked
similar to flowers or wagon wheels.
They named them actinoform clouds,
derived from the Greek word aktinos,
meaning ‘ray.’NOAA 20 image captured on March 11, 2022
NASA Earth Observatory image by Lauren Dauphin, using VIIRS data from NASA
EOSDIS LANCE, GIBS/Worldview, and the Joint Polar Satellite System (JPSS).

Though actinoform clouds were
initially thought to be rare, satellite
observations collected in the past few
decades have made it clear that they
are fairly common. The clouds are
regularly spotted in imagery of theocean. They can last up to 72 hours
and often bring drizzling rain.
On March 11, 2022, the Visible
Infrared Imaging Radiometer Suite(VIIRS) on the NOAA-20 satellite
captured this image of two actinoform
clouds to the west of Alejandro
Selkirk and Robinson Crusoe islandsin the Pacific Ocean. The cloud
farther to the east has a classic
actinoform shape, while its partner
to the northwest has a more linear,diffuse form.
It is not clear why actinoform clouds
develop, but they show up wheremarine stratocumulus clouds occur—
typically in stable air along thewestern coasts of major landmasses.
Researchers suspect that ocean
currents and water temperatures may
play a role in their formation.

Close-up of the Actinoform Clouds

Other eye-catching clouds were also
on display on March 11. Faint rows ofvon Kármán vortices appear north of
the two islands. The spiraling cloud
patterns form when winds become
diverted around elevated areas, often
islands, rising from the ocean.
The two islands beneath the clouds
are volcanic mountains off the coastof Chile. Alejandro Selkirk island wasnamed after a Scottish sailor who
spent four years as a castaway on the

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neighbouring island after his captainabandoned him after an argument.
Alexander Selkirk’s ordeal served as
partial inspiration for the novel: ‘The
Life and Adventures of Robinson
Crusoe’. Once known as Más a Tierra,
the smaller of the islands was
renamed Robinson Crusoe Island in1966 in honour of the book. At thesame time, Alejandro Selkirk island,
formally known as Isla Más Afuera,
was given its name.

17

Greening in Mali
MODIS Web Image oif the Day

Image Credit: MODIS Land Rapid Response Team, NASA GSFC

Spanning an area a little larger than twice thesize of the state of Texas, the land-locked Africancountry of Mali sits on the edge of both the
Sahara Desert and the African Sahel. The hot,dry climate provides little arable land, especiallyin the desert north. The Sahel, located mostly inthe south, has a slightly gentler climate than thenorth, with the hot and dry season (February toJune) giving way to a warm rainy season (June toearly November) and then a cooler dry season.
The rainy season fills the Niger River, the Bani
River, and several streams, which all cometogether at the Inland Niger Delta, creatinga heartland of brilliant green in southern
Mali. During the dry season, the Inland Deltashrinks dramatically to roughly 3,900 square
kilometres. By November, the Delta can expand
to 20,000 square kilometres. This wealth of waterprovides a boon for people, and excellent habitat
for migrating birds and West African manatees.
As waters recede, the fertile floodplains provide
excellent agricultural land, ripe for rice or pasture.
On November 17, 2021, The Moderate Resolution
Imaging Spectroradiometer (MODIS) on board
NASA’s Terra satellite acquired this true-colour
image of the gorgeous greening of the Inland
Niger Delta. The complex arrangement of river
channels, lakes, and swamps is evident. The
tree-like, branching tan area is actually an areaof higher elevation, which remains dry. Whereverwater seeps, especially close to the rivers, thearid, tan land has burst forth in green. Away fromthe rivers, a faint wash of green sits atop the tansthat mark near-desert conditions, representing
the tenacity of plants to grow when given even alittle rain.

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18

Lofoten, Norway
European Space Agency
Extending around 175 kilometresfrom north to south, the Lofoten
archipelago comprises five mainislands (Austvågøya, Gimsøya,
Vestvågøya, Flakstadøya, andMoskenesøya), as well as manysmall islands and skerries. Lofoten
is known for its distinctive scenery,with dramatic mountains and peaks,
sweeping beaches, deep blue fjords
and sheltered bays.
Svolvær, the chief town and port of
the Lofoten island group, is located on
the southern coast of Austvågøya, theeasternmost island of the archipelago.
The economy largely depends on cod
fisheries, with the town’s population
swelling during the spawning season
as fishermen flock in. The fjordof Vestfjorden lies between thearchipelago and the mainland.
Although lying entirely within the Arctic
Circle, Lofoten experiences one of theworld’s largest elevated temperature
anomalies relative to its high latitude.
Due to a convergence of the Gulf
Stream with two underwater currents,
the North Atlantic Current and theNorwegian Current, the weather in
Lofoten remains anomalously warm.
The colours of this image, acquired on
24 November 2020, come from the
combination of two ‘polarisations’ fromthe Copernicus Sentinel-1 mission
which have been converted into asingle image. This remote sensing
technique allows us to detect where
differences between the polarisations
are higher. These differences arevisible in shades of blue in the image,such as the choppy Norwegian Sea,
wetlands and mires such as those on
the northern tip of Andøya and wetsnow on hilltops and in mountains(bottom-right corner of the image).
What appears in yellow indicateswhat has fewer differences between
polarisations, such as forests andother vegetated land, as well as builtup areas.
Sentinel-1 is a radar mission and,unlike optical cameras, the images

Image contains modified Copernicus Sentinel data (2020),
processed by ESA, CC BY-SA 3.0 IGO

are usually black and white when they
are received. By using a technologythat aligns the radar beams sent
and received by the instrument in
one orientation—either vertically or
horizontally—the resulting data can

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be processed in a way that produces
coloured images such as the one
featured here.
This technique allows scientists toanalyse Earth’s surface better.

19

Ice Shelf Collapse in East Antarctica
NASA Earth Observatory
Story by Kathryn Hansen

It is relatively common for ice
shelves in Antarctica to spawn
icebergs. It is less common
for an ice shelf to completely
disintegrate. In March 2022, an
ice shelf in East Antarctica did
both. The collapse has reshapeda part of the Antarctic landscapewhere coastal glacial ice was once
thought to be stable.
The change happened fast. At thestart of March the floating shelf
fed by the Glenzer and Conger
glaciers was still intact. By the
middle of that month, it had fallen
apart. Images acquired by the
Operational Land Imager (OLI) on
NASA’s Landsat‑8 satellite show
the shelf before (figure ) and after(figure 2) the shelf disintegrated.

An early March Landsat-8 image of the intact ice shelf
Image: NASA

‘The whole shelf collapsedin just around two weeks,’
said Christopher Shuman,a University of Maryland,
Baltimore County, glaciologist
based at NASA’s Goddard
Space Flight Center. The
icy remnants of both glacial
shelf ice and adjacent sea ice
dispersed from the waters
around Bowman Island withinweeks. ‘All of this took lessthan a month,’ Shuman said.
‘It was quite the blowout.’
The progression of the collapse
is visible in the image series
on the following page. Images
were acquired with theModerate Resolution Imaging
Spectroradiometer (MODIS) on
NASA’s Terra and Aqua satellites.
Figure 3 shows the ice shelf
floating on the Mawson Sea on
February 22, 2022, prior to thecollapse. Fast ice—a type of sea
ice that becomes ‘fastened’ to theedges of ice shelves, coastlines,
and icebergs—is also part of themix. For two years prior to thisimage, the shelf was already ina state of decline. According toCatherine Walker of the Woods

A mid March Landsat-8 image of the same region after the shelf disintegrated
Image: NASA

Hole Oceanographic Institution,
the shelf was losing ice at an
average rate of about one square
kilometre per day through thenatural process of iceberg calving.

substantial loss of ice meant thatthe shelf became disconnectedfrom Bowman Island. Note thatsome sea ice remained attached tothe island.

But in early March 2022, the shelfin front of the Glenzer Glaciercalved a substantial iceberg.
Named C-37, the berg initiallymeasured about 144 square
kilometres. A few pieces brokeoff, such that C-37 measured
about 81 square kilometres on
March 12 when MODIS acquired
the image shown in figure 4. The‘Without being supported by aland anchor, the ice shelf wasdestabilised and primed tocollapse,’ said Jonathan Wille,
a postdoctoral researcher at
the Université Grenoble Alpes.

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According to Wille, an atmosphericriver on March 15 appears to havetriggered the shelf’s final collapse.

20

Figure 3 - MODIS image of the floating ice shelf on
February 22, 2022, prior to the collapse.

Figure 4 - MODIS image showing iceberg C-37 floating awayfrom the ice shelf on March 12, 2022.

Figure 5 - MODIS image showing the final collapse of the ice
shelf on March 16, 2022.

Figure 6 - MODIS image showing how the crumbled ice shelf had
dispersed by March 21, 2022.

The weather system—which caused temperaturesin eastern Antarctica to soar 40 degrees Celsius
above normal—also enhanced ocean swells andamplified winds near the vulnerable shelf. This
most likely caused the ice in front of Conger
Glacier to break apart and quickly disperse.
Figure 5 shows the area on March 16 after the
final collapse. The event spawned Iceberg C-38,
which at the time measured about 415 square
kilometres. The final image in the series (figure 6)
shows the crumbled shelf ice and fast ice as it
dispersed in the sea on March 21.
The loss of an ice shelf is problematic
because it can indirectly contribute tosea level rise. ‘Ice shelves are essentiallythe ‘safety band’ holding up the rest of the
Antarctic Ice Sheet,’ explained Walker. Whenthey collapse, the ice behind them can flow

into the ocean more quickly. ‘And that iswhat raises sea levels.’
By Antarctic standards, the ice shelf and glaciersthat it held back are relatively small, so theimpacts from the collapse are expected to beminimal. Scientists are more concerned about
the location of the collapse.
‘All of the previous collapses have taken placein West Antarctica, not East Antarctica, which
until recently has been thought of as relatively
stable,’ stated Walker. ‘This is something likea dress rehearsal for what we could expectfrom other, more massive ice shelves if they
continue to melt and destabilise. Then we’ll
really be past the turnaround point in terms ofslowing sea level rise.’NASA Earth Observatory images by Lauren Dauphin, using
Landsat data from the U.S. Geological Survey and MODIS
data from NASA EOSDIS LANCE and GIBS/Worldview.

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21

DISCOVR and EPIC
Les Hamilton

The Deep Space Climate Observatory (DSCOVR)
is a joint satellite mission between NASA, NOAA, andthe US Air Force, located at the Earth-Sun Lagrange-1
point. This location lies directly between Earth and the
Sun and some 1.5 million kilometres from Earth, where
the gravitational attractions of Earth and Sun are in nearequilibrium (figure 1). As a consequence, only minimal
station-keeping manoeuvres are required to maintain asatellite’s position at the L1 point where it will orbit the sun
with the same period as Earth. In fact, the satellite actually
moves around this equilibrium point in a lissajous halo orbit
roughly orthogonal with the Earth-Sun line.
The Air Force’s role in this mission was to provide theSpaceX Falcon 9 rocket which launched DSCOVR,
NOAA’s first operational deep space satellite, from Cape
Canaveral in February 2015.

Figure 1 - Location of DISCOVR at Lagrange Point 1(Not to scale)NASA built the spacecraft and performed its on-orbit
checkout and now operates the two Earth-facing science
instruments, the Earth Polychromatic Imaging Camera(EPIC) and the National Institute of Standards andTechnology Advanced Radiometer (NISTAR).
Once in orbit, NOAA took over the operation of the
570 kilogram spacecraft and provides the solar windplasma and interplanetary magnetic field measurements
which are critical to maintaining the accuracy of lead times(up to 60 minutes) for space weather alerts and forecasts.
Space weather has the potential to seriously disrupt
power grids, telecommunications and GPS, and NOAA
supplies these geomagnetic storm warnings to support
key industries such as commercial airlines, electric powercompanies and GPS-related facilities.
From its vantage point, DSCOVR has a continuous view ofboth the Sun and of the sunlit side of the Earth, monitors
variable solar wind conditions, provides early warningof approaching coronal mass ejections and observes
phenomena on Earth, including changes in ozone,
aerosols, dust and volcanic ash, cloud height, vegetation
cover and climate.
NOAA operates DSCOVR from its Satellite and ProductOperations Facility in Suitland, Maryland and thespace data acquired is processed for accurate weather

Figure 2 - The Earthward side of the deployed DSCOVR spacecraft and its complement of components and sensors.
(Image credit: NASA)

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22

Figure 3 - EPIC captured this image of the Moon emerging from behing the and Earth on October 2, 2020
Image: NASA

forecasting purposes at the Space Weather Prediction
Center in Boulder, Colorado.

noon and is able to process them faster than other Earthobservation satellites.

EPIC
An important part of DISCOVR’s payload is NASA’s Earth
Polychromatic Imaging Camera (EPIC), which provides ten
narrow band images in of the entire sunlit face of Earth.

The instrument consists of a 30 centimetre aperture
Cassegrain telescope which focuses its images on a2048 x 2048 charge-coupled device (CCD), using two filter
wheels, and containing a set of 10 bands at ultraviolet(UV), visible, and near-infrared (NIR) wavelengths in therange 317 to 780 nanometres.

After the spacecraft entered its operational phase, NASA
began releasing near-real-time images of Earth throughthe EPIC instrument’s website
https://epic.gsfc.nasa.gov/galleries
As an Earth viewing instrument, EPIC has a unique view ofthe planet, taking between 13 and 21 images daily at local

DSCOVR’s spacecraft is giving EPIC a unique angularperspective that will be used in science applications tomeasure ozone, aerosols, cloud reflectivity, cloud height,
vegetation properties, and UV radiation estimates at
Earth’s surface.

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23

With Meteor LRPT inactive, many enthusiasts turned their attention to the NOAA APT data streams, including
André T’Kindt from Ronse in Belgium, who sent in this excellent NOAA 18 image acquired on May 16, 2022.

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24

Uyuni Salt Pan Drying Out
MODIS Web Image of the Day

Image Credit: MODIS Land Rapid Response Team, NASA GSFC

Seated on the high Altiplano of Bolivia, Salar de Uyuni
shimmers bright white in satellite imagery, thanks to
the thick, salt-rich mineral crust that spans roughly ten
thousand square kilometres. The Altiplano plateau wasformed during the uplift of the Andes Mountains, whichsurround the region. This plateau harbours fresh andsaltwater lakes as well as several salars (salt flats) but thelargest salar in all of Bolivia—and the largest on Earth—isSalar de Uyuni.
Most of the year, this enormous salt flat wears a thick,nearly unbroken, salty crust. During the rainy season,
however, water often collects in Salar de Uyuni, dissolving
some of the salt and expanding the size of the salt flat.
The expansion is always temporary, as the hot dry season
drives rapid evaporation that once again shrinks Salar de
Uyuni as well as the other salars of the Altiplano.
Abundant rainfall around the Altiplano in the 2021-2022
rainy season filled Salar de Uyuni beyond the brim.
According to an article published by NASA’s Earth
Observatory on February 19, 2022, hydrologist Jorge
Molina Carpio of the Universidad Mayor de San Andrés
explained that the extent of the filling of Salar de Uyuni thisyear is above normal. The rainy season started earlier thanin previous years (in November 2021), and rainfall waswell above average over the southern Altiplano. He stated:‘This was probably related to the onset of a significant
La Niña event. Strong La Niñas during the rainyseason are related to positive rainfall anomalies in thesouthern Altiplano.’
Despite the abundance of water in the Salar de Uyuni by
February 2022, the onset of the dry season has seen rapid
shrinking.
The Moderate Resolution Imaging Spectroradiometer(MODIS) on board NASA’s Aqua satellite acquired thistrue-colour image of the Salar de Uyuni on April 21, 2022.
Most of the salt flat appears bright white, indicating dry
conditions. A few gray and blue-gray areas mark remaining
moisture both in Salar de Uyuni and the smaller Salar deCoipas. This is in marked contrast to the conditions seen
on February 11, 2022, when the salt crust of the Salar deCoipas was almost entirely dissolved as that salt flat filledwith fresh rainwater. The salty crust of Salar de Uyuni wasstill present, especially in the western section, but it wasalso filled with water, colouring it with swirls of blue, gray,and brown.

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25

Antarctic Sea Ice Reaches Record Low
NASA Earth Observatory
Story by Kathryn Hansen

Figure 1 - Antarctic Sea Ice Minimum - February 2022

In February 2022, sea ice around Antarctica reachedthe lowest extent ever observed since the start of thesatellite record in 1979. It marks the first time thatthe ice was observed to shrink below two million
square kilometres.
Sea ice in southern polar waters reached its lowest
extent on February 25, 2022, at 1.92 million square
kilometres, 190,000 square kilometres below theprevious record-low reached on March 3, 2017.
Compared to the average minimum, the sea ice
this year is missing an area about twice the size ofCalifornia.
Figure 1 shows the ice extent on the day of its record
low. Extent is defined as the total area in which theice concentration is at least 15%. The yellow outline
shows the median sea ice extent for February from
1981–2010. A median is the middle value: that is,half of the extents were larger than the yellow line
and half were smaller.
The 2021-2022 melting season began earlier thanusual, after the ice reached its seasonal maximum
extent on September 1, 2021, and then quickly
declined through the austral spring and summer.
According to Walt Meier, a sea ice researcher at the
National Snow and Ice Data Center, winds were themain reason for the low ice conditions this year. He
explained that the winds around the continent were‘much stronger than normal,’ which quickly pushed
ice north into warmer waters where it melted. An
exception was in the Weddell Sea, where winds
pushed the ice edge south.
One month after the sea ice reached its annual
minimum, Meier said that the rate of growth looked
normal. Even the heatwave that sent Antarctica’s

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26

Figure 2 - Antarctic Daily Sea Ice Extent by Year (1978-2022)

air temperatures soaring in the third weekof March did not seem to have slowed thegrowth. ‘It is really the ocean temperaturesthat count,’ Meier said, ‘and a brief heatwave won’t affect things too much in thatregard.’It remains to be seen how much ice will
regrow this year. While it is common for
Antarctic sea ice to melt nearly all the way
back to the coastline during the australsummer, the ice grows unconstrained
through autumn and winter. After months ofgrowth (February to September), new sea ice
typically spans an area of ocean about twice
the size of the continental United States.
From year to year, Antarctic sea ice can behighly variable. Since 2013 it has reachedboth its highest high and its lowest low
since record keeping began. A surge of sea
ice growth in 2014 and 2015 enhanced asmall upward trend in the long-term record.
But over the past seven years, sea ice has
generally been at or below average, including
record-low minima in 2017 and 2022. The
long-term trend now appears flat and,because of the variability, is not considered
statistically significant.
In contrast, sea ice in the Arctic shows aclear downward trend. That means that
globally, the planet is losing sea ice. ‘Overall,
for the Arctic and Antarctic combined,’ Meiersaid, ‘the trend is definitely still downward’(figure 3).

Figure 3 - Antarctic Sea Ice Trends

NASA Earth Observatory images by Joshua Stevenswww.geo-web.org.uk
using data from the National Snow and Ice Data Center27

Flooding in Eastern Australia
NASA Earth Observatory
Story by Sara E. Pratt

Just over three months into
2022, Sydney, Australia, hasalready received a year’s worthof rain. The deluge brought more
flooding to the already rain-soaked
southern and central coasts of
New South Wales, prompting
evacuations.
On April 7, torrential downpoursbrought a month’s worth of
precipitation—more than 100
millimetres—to parts of the city.
The storm pushed rain gauges
past 1,223 millimetres, already, inearly April, 10 millimetres above
the annual mean.
The excessive rain began in late
2021 with the rainiest November
on record. It continued with morerain and flooding in February
and March 2022. On March 9,
Australia declared a national
emergency.
The ground was saturated andrivers were swollen when the
Operational Land Imager-2(OLI‑2) on Landsat 9 acquired
these images on April 4, 2022.
The ongoing impacts of flooding
can be seen in the muddy rivers,
inundated land, and sedimentplumes draining from rivers along
the coast.
Near the top of figure 1, northof Newcastle, a large lobe ofbrown floodwater has inundated
the Hunter Wetlands. A plumeof sediment can also be seendischarging from the mouth of the
Hunter River and flowing along
the beach in Worimi National
Park. Sydney and its harbour canbe seen at the bottom left of theimage. North of Sydney are thebrown, sediment-laden waters ofthe Hawkesbury River, which areseen in more detail in figure 2, on
the following page.
The Hawkesbury River originates
to the west, where the Colo andFigure 1 - Landsat-9 image showing flooding from Newcastle to Sydney
NASA Earth Observatory image by Joshua Stevens
using Landsat data from the U.S. Geological Survey

Nepean rivers join. Areas of the
Hawkesbury-Nepean Valley weresome of the hardest hit in the
March 2022 floods, which left
thousands of homes damaged anduninhabitable.
Several climate systems influence
Australia’s weather. The El Niño
Southern Oscillation (ENSO), a
coupled atmospheric and ocean
circulation pattern in the tropical
Pacific, is currently in its La Niña
phase, which typically brings morerain and cooler temperatures toeastern Australia. The Southern
Annular Mode (SAM) describes
the north or south movementof strong westerly winds in theSouthern Hemisphere. With thewinds farther south, the SAM
has recently been in a positive
phase, which increases rainfall in

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eastern Australia in the summer.
The interaction of the two climate
modes exacerbates the amountof moisture in the atmosphereavailable for precipitation,according to research by team at
Australian National University,
CSIRO, and the University of New
South Wales.
The extreme precipitation in
the summer of 2021–22 comes
after a three-decade period whensoutheastern Australia had seen
an overall decline in rainfall,according to Australia’s Bureauof Meteorology. However, thedistribution of rainfall throughout
the year has also changed, withsummer rains intensifying, winterrains decreasing, and the intensityof short-duration, heavy rainfall
increasing.

28

Figure 2 - This Landsat-9 image shows the sediment-laden waters of the Hawkesbury River
meandering their way towards the ocean north of Sydney
NASA Earth Observatory image by Joshua Stevens using Landsat data from the U.S. Geological Survey

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29

Meteor M N2 Attitude Problem
Les Hamilton

On May 5 this year, followers of theRussian Meteor M N2 oceanographic
satellite started to observe seriously
distorted imagery. It was clear that thesatellite, instead of pointing directly
downward towards Earth’s surface,
was presenting angled views that
included Earth’s limb framed by theblackness of space.
It was apparent that the satellite
was experiencing attitude control
problems, and the skewed pointing
started to show the Earth’s limb as in
the AHRPT image opposite, obtainedon May 9 by Enrico Gobbetti.
Two days into the problem, the
LRPT data stream was discontinued,
although readers like Enrico, whohave the equipment to receive
Meteor’s high resolution AHRPT data
continued to view images such as theone on the front cover of this issue,
which was received two days later
and another on May 13 (overleaf).
This was by no means an unfamiliar
scenario: such behaviour had beenrecorded several times previously,
but the satellite’s attitude had always
been rectified within just a few days:
but not this time.

In this high resolution AHRPT image from Meteor M N2 on May 9, 2022, a distorted
Mediterranean sea snakes round the exposed limb of Earth.
Image: Enrico Gobbetti

Meteor M N2 was launched in July
2014 with a projected lifetime offive years, which implies that it is
now operating almost three years
beyond that. With the launch failureof Meteor M N2-1, the accident toMeteor M N2-2, and the delayed
launches of Meteors M N2-3 andM N2-4, the ageing satellite is clearly
now starting to struggle.
As the days turned into weeks, manyobservers were fearing the worst, andthat the LRPT could not be restored—
until, fifteen days later, on May 20,
Meteor came to life again.
There are still no definite dates
for the delayed Meteors to launch.
Just maybe this latest unfortunate
episode may hasten the launch of
Meteor M N2-3. But don’t hold yourbreath.

Taken from the 07:29 UT pass on May 20, 2022, this is a section from the firstcohesive LRPT image received from Meteor M N2 following its recovery.

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30

This high resolution AHRPT image from Meteor M N2 dates from May 13, 2022 and still shows distortion due to the satellite’s loss of
attitude control. The Earth’s limb is prominent at the right of the image, with the Black Sea in particular, hugely distended.
Image: Enrico Gobbettiwww.geo-web.org.uk

31

Great Barrier Reef
MODIS Web Image of the Day
When viewed from space, Australia’s
Great Barrier Reef appears to bea string of precious gems strung
across the Coral Sea just off the
Queensland coast. When viewed
from Earth, the uniqueness of this
precious ecosystem becomes evenmore obvious. According to theUnited Nations Education, Science
and Cultural Organization (UNESCO)World Heritage Convention, the Great
Barrier Reef is a site of remarkablevariety and beauty. It contains theworld’s largest collection of coral
reefs, with 400 types of coral, 1,500
species of fish, and 4,000 types ofmollusc. It also holds great scientificinterest as the habitat of species
such as the dugong (‘sea cow’) andthe large green turtle, which arethreatened with extinction. Because
the diversity of species and habitats
and their unique interconnectivity
make the Great Barrier Reef one of
the richest and most complex natural
ecosystems on Earth, this naturalwonder was inscribed on the World
Heritage List in October 1981.
Despite the fact that no other World
Heritage property contains suchbiodiversity, the Great Barrier Reef isin trouble. In early March 2022, sea
temperatures across the reef spiked,
creating heatwave conditions. On
April 1, the Australian Government’s
Great Barrier Reef Marine Park
Authority confirmed that thesewarm temperatures had created amass bleaching event of the reef,
with bleaching observed at multiple
reefs in all four management areasof the Reef. This was considered
to be largely consistent with thespatial distribution of the heat stressexperienced over summer. This is the
fourth time in six years that the Great
Barrier Reef has been impacted bybleaching, and it the first time it has
occurred during La Niña conditions.
Typically, La Niña brings cooler
temperatures to local waters.
Bleaching is a stress responseby coral and does not necessarilymean that the coral has died. Corals
have a symbiotic relationship with

Image Credit: MODIS Land Rapid Response Team, NASA GSFC

a type of microscopic alga known
as zooxanthellae. The colourfulzooxanthellae live within the coral,
providing oxygen and helping thecoral to remove wastes. In turn,the coral provides the algae witha protected environment andthe compounds they need forphotosynthesis. The zooxanthellae
also provide the glorious colours
that we associate with coral. Whencoral become stressed—most often
by a rise in ocean temperature ofas little as 1°C—the corals expel
the algae, exposing the pale white‘skeleton’ of the coral. This bleaching
isn’t immediately fatal to the coral,
but it weakens them, opening themto disease, starvation, and death. If
conditions return to normal and thesymbiotic relationship is repaired,
coral may recover from a bleaching
event.
The Great Barrier Reef Marine
Park’s website stated on April
1 that water temperatures hadcooled since early March but notedthat most of the Marine Park wascontinuing to experience the effectsof significant heat stress. Localised
weather patterns will remain criticalin determining the overall extent

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and severity of coral bleaching. The
website also noted that the Reef
Authority is now working with its
partners to conduct in-water surveys
to complement aerial surveys of thereef. This will provide more detailed
information about bleaching intensity,
mortality and depth range of bleaching
impacts.
On March 31, 2022, the Moderate
Resolution Imaging Spectroradiometer(MODIS) on board NASA’s Terrasatellite acquired this true-colour
image of the Great Barrier Reef. The
reef remains sparkling with blue tones
throughout the length visible in thisimage.
The MODIS instrument is useful formeasuring Sea Surface Temperatures(SSTs), which are correlated withcoral bleaching events, but truecolour images do not usuallyshow substantial colour changes
in bleaching events, as coral sits
underneath water and thus reflectivity
may not change substantially.
Currently, airplane flights or inspection
by diving are more sensitive for
estimating the amount of bleachingon any given coral reef than mostsatellites.

32

Yukon-Kuskokswim in Colorful Transition
NASA EarthObservatory
Story by Kathryn Hansen

The Yukon-Kuskokswim Delta is one of the world’s largest deltas, and it stands as aremarkable example of how water and ice can shape the land. This image shows the delta’s
northern lobe, where the Yukon River spills into the Bering Sea along the west coast of Alaska.

Figure 1 - Landsat-8 captured this image of the delta of the Yukon River on May 29, 2021
NASA Earth Observatory image by Joshua Stevens, using Landsat data from the U.S. Geological Survey.

The Yukon Delta is an exceptionally vivid landscape,whether viewed from the ground, from the air, or from lowEarth orbit. The vivid landscape is captured in figure 1,
acquired with the Operational Land Imager (OLI) on
Landsat 8 on May 29, 2021. The image is a composite,
blending the natural-colour imagery of water with falsecolour image of the land.

In general, the green areas across the delta are tall willow
shrublands. They are especially apparent on either side of
the river channels in the detailed image above. The lightbrown areas are primarily moist sedge meadows whichappear brown because much of it is the dead remains oflast year’s growth. Away from the delta (right side of theimage) the vegetation is shrub-tussock tundra.

While the image could be considered a work of art, there
are some useful aspects to looking at the land in thisway. For example, you can easily distinguish areas of live
vegetation (green) from land that is bare or contains deadvegetation (light brown) from the network of sediment-richrivers and ponded flood water (dark brown). A sprinkling ofthermokarst lakes are also part of the scene.

‘To me, one of the interesting things about the delta isthat it is a highly transitional area, with some elementsof Arctic tundra and some of boreal forest,’ said
Gerald Frost, a scientist at ABR, Inc.—Environmental
Research and Services in Fairbanks, Alaska.
The delta also transitions with the seasons. At the time

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33

of this image, the signature of springflooding is written across the delta.
Melting snow and ice cause the rivers
to spill over their banks and by lateMay, many of the marshes are filledwith floodwater, which appears as darkbrown ponds.
According to Lawrence Vulis, a
graduate student at the Universityof California, Irvine, the delta would
have appeared much more inundated
immediately following the melting ofsnow and ice a few weeks prior to thisimage. Stream gauges and satellite
images suggest that the bulk of theflooding had already subsided. Still,
the flooding was recent enough thatplenty ponding remained on May 29.
As summer advances, the floodwater
will continue to recede and thewetlands will continue to green up withvegetation.
Also notice the colourful water where
the delta meets the Bering Sea.
This is a product of glacial runoff far
upstream, which carries a large amountof sediment toward the coast. This
sediment is also instrumental to theformation of tall levees on the sides of
the channels, deposited there whenfloodwaters spill over their banks.
These levees support stands of tall
willows—important habitat for moose.
‘Interestingly, tall shrubs have
expanded a lot on the delta inrecent decades, and the moose
have followed,’ Frost said. ‘Today,
the delta has one of the highest
moose densities in the state of
Alaska.’The delta did not always look this way.
Studies have shown that the modern
Yukon Delta is just a few thousand
years old. It’s young age “is incredible
to think about,” Vulis said. “We areused to thinking about relatively ancientlandscapes, but modern river deltas
have only formed in the last 10,000 to
8,000 years since global sea level has
stabilised.”
The delta could quite possibly lookdifferent in the future. ‘The Yukon
and other Arctic deltas are thought
to be particularly vulnerable toclimate change,’ Vulis noted, ‘due
to the roles of permafrost and ice
in shaping these deltas.’

Figure 2 - A wider view showing the Yukon River making its way towards the Bering Sea
NASA Earth Observatory image by Joshua Stevens
using Landsat data from the U.S. Geological Survey.

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34

Visualising EUMETCast SAF Products using the VISAN Tool
Richard Osborne

Figure 1 - VISAN 3D Globe image of LSA Land Surface Temperature derived from LST
data over EUMETCast and co-ordinates from LSA website.

In the recent thread on “NWC ‘Cloud Types’ on
EUMETCast” in the MSG-1 Groups website, Ernst
Lobsiger has alluded to my article on visualising SAF data
in Geo Newsletter No 72. Since submitting the piece, I
have continued to look for visualisation tools and methods
that I may have missed since that time. Recently, I cameupon the Atmospheric Toolbox
https://atmospherictoolbox.org
that provides tools for ingesting, processing, and analysing
atmospheric remote sensing data. This includes data from
Sentinel-5P and the GOME-2 instrument on MetOp.
The component of particular interest to me is called
VISAN which is the graphical front-end visualisation tool
for the toolbox. VISAN can display data on a number ofcommon 2D map projections and also a 3D globe.The
graphical visualisation element is fully interactive with theability to zoom and pan under mouse control and also torotate the 3D globe. Preparation of data and launchingof the graphical element is done through a Python driven
command line interface from a special VISAN development
environment. Note that VISAN can only be installed as a

CONDA environment and Python scripts must be launchedwithin the dedicated VISAN environment. This is because
VISAN is built on wxPython which is not present in thenormal Python environment.
Whilst the VISAN visualisation tool is primarily intended
to interact with another component of the toolbox called
HARP, it can also be supplied with low level data from any
source provided that it is in the correct format and this is
the feature that is of particular interest to me. The dataneeds to be supplied as three separate one dimensional(1D) Python Numpy arrays containing the data to bevisualised along with corresponding latitude and longitude
coordinates for each data point or pixel. In case thissounds like a daunting task, I found it surprisingly easy
to extract the required data in the correct format using
Python from both netCDF and HDF5 files that contained
full geo-referencing data. Also, in my article, I mentioned
the Land Surface data for the MSG full disk contained no
geo-referencing information and this needed to be suppliedin some form to allow the data to be projected onto a map.
The LSA website provides HDF5 files with the necessary
co-ordinate data. I was able to easily convert this into thewww.geo-web.org.uk

35required latitude and longitude Numpy arrays which
I submitted with the data in a Numpy array allowing
me to visualise the data on the 3D globe. An example
output of the Land Surface Temperature is shown in
Figure 1.
The NWC Cloud Type data file contains a reduced setof geo-location data and the end-user is expected to
extrapolate between those to provide a complete set,so that each pixel has a unique latitude and longitude
co-ordinate. VISAN cannot accept this data as it needs
full geo-referencing. However, the NWCSAF readersin Satpy provide this function allowing a complete
geo-referenced image to be produced as shown in
the MSG-1 Groups thread. By inserting only ten lines
of extra Python code into the Satpy NWC Cloud Typescript, I was able to produced three Numpy arrays withwhich to feed the VISAN tool. The result is shown in

Figure 2. The colours are not correct because I still
have work to do to produce the correct colour lookup
table for the Cloud Type products but the image gives
the idea. Management of the colour table is underdeveloped at present but I have had a short discussion
with the author and I am hopeful of improvement.
I am hoping to experiment with VISAN and Python in
combining certain files from the HSAF facility because
the the current file structure can cause unwanted
artifacts with Panoply, McIDAS-V etc. Incidentally, the
VISAN installation also has a simple browser that canbe used to investigate the data structure and values of
any netCDF or HDF5 file which is useful in identifying
the name of variables of interest.
P.S. For more information, please post a request on the
MSG-1 Groups website.

Figure 2 - VISAN 3D Globe image of NWC Cloud Type from METOP-B derived from data
provided by Satpy script (experimental so colours are incorrect).

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36

Lake Mead Drops to a Record Low
NASA Earth Observatory
Story by Michael Carlowicz and Kathryn Hansen

Lake Mead is the largest reservoir
in the United States and part ofa system that supplies water toat least 40 million people acrossseven states and northern Mexico.
It stands today at its lowest level
since Franklin Delano Roosevelt
was president. This means lesswater will be portioned out tosome states in the 2022 wateryear.
As of August 22, 2021, Lake
Mead was filled to just 35% of
its capacity. This low water level
comes at a time when 95% of theland in nine Western states isaffected by some level of drought(64% is extreme or worse). It
continues a 22-year megadroughtthat may be the region’s worst dry
spell in twelve centuries.
The natural-colour images onthese pages were acquired by
NASA’s Landsat‑7 and Landsat‑8
satellites in August 2000 andmost recently in August 2021. The
tan fringes along the shoreline in
2021 (figure 2) are areas of thelake bed that would have been
underwater when the reservoir
was filled closer to capacity. The
phenomenon is often referred toas a ‘bathtub ring’.

Figure 1 - Lake Mead on August 7, 2000
NASA Earth Observatory images by Lauren Dauphin, using
Landsat data from the U.S. Geological Survey

The lake elevation data in figure 3,
below, come from the US Bureau
of Reclamation, which manages
Lake Mead, Lake Powell, and otherportions of the Colorado River
watershed. At the end of July
2021, the water elevation at the
Hoover Dam was 325.4 metresabove sea level, its lowest sinceApril 1937 at a time when the lake
was still being filled. The elevation
at the end of July 2000, aroundthe time of the Landsat‑7 image infigure 1, was 365.8 metres.
At maximum capacity, Lake Meadreaches an elevation 372 metresnear the dam and would hold36 cubic kilometres of water. The
lake last approached full capacity

Figure 2 - Lake Mead on August 9, 2021
NASA Earth Observatory images by Lauren Dauphin, using
Landsat data from the U.S. Geological Survey

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37

in the summers of 1983 and 1999.
It has been dropping ever since.
In most years, about 10% of
the water in the lake comesfrom local precipitation andgroundwater, with the rest comingfrom snowmelt in the Rocky
Mountains that flows down torivers, travelling through Lake
Powell, Glen Canyon and theGrand Canyon on the way. The
Colorado River basin is managed
to provide water to millions ofpeople—most notably the cities of
San Diego, Las Vegas, Phoenix,and Los Angeles—and also toapproximately five million acres offarmland in the Southwest. The
river is allotted to states and to
Mexico through laws like the 1922
Colorado River Compact and by arecent drought contingency planannounced in 2019.

Figure 3 - Lake Mead water level - 2000 to 2021
Credit: Geological Survey and lake elevation data from the Bureau of Reclamation.

With the Lake Mead reservoir
at 35% of capacity, Lake Powellat 31%, and the entire Lower
Colorado system at 40%, theBureau of Reclamation announced
on August 16 that water
allocations would be cut over the
next year.
“The Upper [Colorado] Basinexperienced an exceptionally
dry spring in 2021, with April
to July runoff into Lake Powelltotalling just 26% of average
despite near-average snowfall
last winter,” the USBR
statement said. ”Given ongoinghistoric drought and low runoff
conditions in the Colorado
River Basin, downstream
releases from Glen Canyon
Dam and Hoover Dam will
be reduced in 2022 due todeclining reservoir levels. In
the Lower Basin the reductions
represent the first ‘shortage’
declaration—demonstrating theseverity of the drought and low
reservoir conditions.”
For the 2022 water year, which
begins on October 1, Mexico will
receive 80,000 fewer acre-feet,approximately 5% of the country’s
annual allotment and Nevada’s
take will be cut by 21,000 acrefeet (about 7% of the state’s

Figure 4 - These zoomed image segments compares the changes in water level in
the Overton Arm of Lake Mead between 2000 (left) and 2021.
Credit: NASA Earth Observatory images by Lauren Dauphin
using Landsat data from the U.S. Geological Survey

annual apportionment). The
biggest cuts will come to Arizona,which will receive 512,000 fewer
acre-feet, approximately 18% of
the state’s annual apportionment
and 8% of the state’s total wateruse (for agriculture and humanconsumption).

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Note
One acre-foot is equivalent to1.233 million litres and would be
sufficient water to supply one or
two households with their waterneeds during an entire year.

38

Sediment in the Caspian Sea
MODIS-Web Image of the Day

Image Credit: MODIS Land Rapid Response Team, NASA GSFC

The Caspian Sea wins the prize for being thelargest closed body of water on Earth, witha volume estimate at about 78,000 cubic
kilometres and spanning a surface area ofroughly 380,000 square kilometres: that’s anarea larger than the country of Germany.
The Caspian Sea is sometimes divided into threeparts, ecologically speaking. In the north, thesea is shallow, with a mean depth of only about
10 metres, while the central sea deepens to 788
metres. The deepest part of the Caspian Sea
reaches 1,025 metres in its southern section.
Despite the deep water, the southeastern
Caspian Sea just off the coast of Turkmenistan
hosts a wide area of marine shallows, where the
mud-covered bottom lies under a layer of waterthat remains less than 30 metres. This coastal
shelf stretches 200 kilometres from north tosouth and 120 kilometres from the shoreline into
the sea. Beyond this shelf, the sea floor takes a
deep plunge; however, the waters over the shelf
are perpetually turbid as the ever-active windstirs mud and sediment up from the shallows.
On May 23, 2022, the Moderate Resolution
Imaging Spectroradiometer (MODIS) on board
NASA’s Terra satellite acquired this true-colour
image of brightly-coloured sediment in the
Caspian Sea off of the coast of Turkmenistan. A
small region of the coast of Iran is also visibleat the bottom of the image. The gorgeous colour
lies almost entirely over the shelf of marine
shallows located in this section of the of the
Caspian Sea.

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