Group for Earth Observation

No 73 - March 2022

This image of Tonga, acquired by Landsat-8 in May 2021, shows the island as it was prior to the
explosion of the uninhabited volcanic island Hunga Tonga-Hunga Ha‘apai in mid-January 2022.

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 HamiltonW

hat a winter Europe has experienced since the December issue. Not so muchfreezing cold with drifting snow, but milder and very windy. In Scotland, where
I live, the combined actions of storms Alex, Corrie, Malik, Dudley and Eunice havecaused damage unheard of since that fateful 1953 storm. It is estimated that in excess
of eight million mature trees were felled and sawmills throughout Scotland are working
round the clock to process all the timber. Northeast Scotland was worst hit, losing overone million trees, some of which actually snapped in half rather than being uprooted!

Looking on the brighter side, we have some great articles for you. Ed Murashie
continues his series on the Landsat Earth Observation satellites and details how
their instrumentation has developed since the ﬁrst launch in 1962, exactly 50 years
ago. There is more to learn about processing the EUMETCast SAF products as Richard
Osborne completes his treatise by including products omitted last issue.

Early this year I was contacted by Ernst Lobsiger, a Swiss EUMETCast enthusiast.
Ernst is a physicist and mathematician, and was enthused by Richard Fairman’s
article in December on overlaying Bracknell MSLP charts on Meteor 2M GIS imagery.
He reasoned that it should be possible to digitise the Bracknell MSLP charts and modify
them by GIS, thus enabling them to be overlaid accurately on MeteorGIS images. Afterseveral weeks of testing the job was done. I’ve compiled a short note about this, withsome illustrations on page 11, and provide a link to a web page I have constructed
detailing the technique as I successfully followed Ernst’s instructions.

Contents
Larsen B Embayment Breaks Up
Island Nation Hit Hard by Eruption
Water in Lake Eyre
Russia’s Crater of Diamonds
Overlay Digitised Bracknell Charts on Meteor M2 Images
Namib Sand Sea
Tenerife, Canary Islands
LANDSAT: The Satellite That Might Save the Earth, part 2
Tidal Vortices in the Sea of Okhotsk
Lake Manicouagan
Seeing Suomi
Colorado Faces Winter Urban Firestorm
A View of Vesuvius
Visualising EUMETCast SAF products: part 2
BahamasLake Erie’s February Freeze
Garabogazköl Basin
Water in Uyuni Salt Pan
Iceberg B22A
Satellite Status

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

www.geo-web.org.uk

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Storm Eunice, imaged by NASA’s Aqua satellite at 12.45 UT on February 17, 2022 as it
approached England, bringing the threat of damaging winds of over 150 kilometres per hour.

www.geo-web.org.uk

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Larsen B Embayment Breaks Up
NASA Earth Observatory
Story by Kathryn Hansen

After more than a decade fastened
to the coastline, a large expanseof sea ice has broken away fromthe Antarctic Peninsula. The
ice, which had persisted in the
Larsen B embayment since 2011,
crumbled away over the span of afew days in January 2022, taking
with it a Philadelphia-sized pieceof the Scar Inlet Ice Shelf.
The Moderate Resolution Imaging
Spectroradiometer (MODIS) on
NASA’s Terra and Aqua satellites
acquired these natural-colour
images of the embayment and ice
shelf. The upper image shows theembayment on January 16, 2022,
prior to the break up. The lower
image shows the same area on
January 26, shortly after the sea
ice broke up.

The intact Larsen-B embayment, imaged on January 16, 2022.

Scientists are still investigating
the reason for the breakup, but
the early clearing of seasonal sea
ice along the Antarctic Peninsulasuggests that the austral summer
has been warm and wet. Scientist
Rajashree Tri Datta of Universityof Colorado, Boulder, noted thatföhn winds, influenced by alarge atmospheric river, helped
destabilise the ice pack.
The breakup is the latest in aseries of notable events in the
Larsen B embayment over the past
20 years. Prior to 2002, glacial
ice on the Antarctic Peninsula
flowed toward the sea and fed intoa vast floating ice shelf known
as Larsen B. The shelf helped tobuttress inland tributary glaciers,pushing back against them andslowing their seaward flow. But
in early 2002, the shelf abruptly
fractured. With 3,250 square
kilometres of ice suddenly gone,
the glaciers thinned and flowed
more quickly into the open water.
Following the collapse of Larsen B,
landfast sea ice grew atop theseawater each winter and melted
away entirely in most summers.

The same area, imaged on January 26, 2022 shortly after breaking up.

But the sea ice that started to
grow in late March 2011 stuckaround.
‘It was the first time since theearly 2002 shelf collapse that
the Larsen B embayment wasseen to freeze up and stayfrozen through multiple australsummers,’ said Christopher
Shuman, a NASA/UMBC
glaciologist.

www.geo-web.org.uk

The sea ice retreated slightly at
its edges during summers, andits surface occasionally became
coated with blue meltwater,
but the ice persisted until thisJanuary.
Satellite images of the oftencloudy region indicate thatthe breakup occurred between
January 19-21, 2022. Sea ice
splintered and floated away from5

This is a wider view of the Larsen B region shortly after breaking up.

the coast, along with icebergs from the fronts of
Crane Glacier and its neighbours to the north andsouth. Shuman thinks strong outflows of ice fromthe Flank and Leppard tributary glaciers most likely
widened a rift that led the Scar Inlet Ice Shelf—thesouthern remnant of the Larsen B Ice Shelf—to shedseveral large icebergs.
Compared to a massive ice shelf (like the original
Larsen B), sea ice adjacent to land is less effective
at holding back the seaward flow of glaciers, but it
still plays a role. This summer’s breakup of the sea
ice in the embayment is important because—unlike

the meltwater from an ice shelf, icebergs, and sea ice(already floating)—the meltwater from a glacier adds
to the ocean’s volume and contributes directly to sea
level rise.
With the sea ice now gone, ‘the likelihood is thatbackstress will be reduced on all glaciers in the
Larsen B Embayment and that additional inland
ice losses will be coming soon,’ Shuman said.

NASA Earth Observatory images by Joshua Stevens, using
MODIS data from NASA EOSDIS LANCE and GIBS/Worldview. .

www.geo-web.org.uk

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Island Nation Hit Hard by Eruption
NASA Earth Observatory
Story by Adam VoilandEver since the uninhabited volcanicisland Hunga Tonga-Hunga Ha‘apai
exploded in mid-January 2022, thepeople of Tonga have faced a gauntletof hazards.
One of the most widespread is
volcanic ash. Satellite images
collected in the days after the eruption
show the fine-grained shards ofpulverised rock covering several
islands, turning land surfaces fromlush green to tan and gray. On
January 25, 2022, the Operational
Land Imager (OLI) on Landsat‑8
captured the image opposite showing
ash coating much of Tongatapu,
Tonga’s most populous island.
Compare this with the pre-eruption
image featured on the front cover.
The close-up images below show thearea near Nuku‘alofa before and after
the eruption. (Note that the sea waterin each image has been masked out
in order to focus on land features.)Tongatapu, Tonga’s most populous island, imaged by Landsat-8 following the explosionof the Hunga Tonga-Hunga Ha‘apai volcano

Image: NASA

These two images highlight the area near Nuku‘alofa, the capital of Tonga, before and after the eruption

Images: NASA

www.geo-web.org.uk

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According to the United Nations,an average of two centimetres ofash coated surfaces in the island
nation’s capital city after the eruption.
While the extent of damage fromthe ashfall is still being assessed,
preliminary reports indicate that it
had contaminated drinking water,
disrupted transportation networks, andmost likely damaged crops.
Though it is rare for volcanoes togenerate tsunamis, the islands ofTonga were slammed by a seriesof destructive waves soon after the
eruption. Estimates vary, but the
Tongan government reported thatwaves as high as 15 metres may
have struck the west coasts of several
islands, including Tongatapu and‘Eua. The waves washed away cars
and buildings, flattened trees, anddamaged power lines on several
islands. The United Nations reported
that three people were killed andhundreds of buildings were destroyed
or damaged by the waves.
After major catastrophes, it’s not often
clear at first which areas are mostin need of aid. Damage proxy maps
like the one shown at the top of thispage can help governments and first
responders gauge where to deploy
resources by quickly offering a broad
view of possible damages.
The lower damage proxy map shows
areas on Tongatapu that were most
likely damaged by the eruption andtsunami. Dark red pixels represent themost severe damage, while orange
and yellow areas are moderately or
partially damaged. Each coloured
pixel represents an area of 30
meters by 30 meters (about the sizeof a baseball infield). Researchers
from the The Earth Observatoryof Singapore - Remote Sensing
Lab (EOS-RS) made the maps bycomparing a post-eruption satellite
radar image from January 22, 2022,with pre-eruption images from March
2019 and March 2020.
The technique showed an especiallysevere line of damage along
Tongatapu’s northern coast. Other
hard-hit areas included small islands
north of Tongatapu, including
Nomuka, Mango, and Fonoifua. Onedamage assessment from the United
Nations Office for the Coordinationof Humanitarian Affairs indicates that
100 houses have been damaged or
destroyed in Tongatapu.
The damage proxy maps were
derived from synthetic apertureradar (SAR) images acquired by the
Advanced Land Observing Satellite-2(ALOS-2) satellites, operated by theJapan Aerospace Exploration Agency(JAXA).
SAR instruments send pulses of
microwaves toward Earth’s surface
and observe the reflections of thosewaves. By comparing signals frombefore and after an event, researchers
can map changes in the land surface
and the built environment.
The techniques used for these maps
were developed by researchers in
the Advanced Rapid Imaging andAnalysis (ARIA) group at NASA’s Jet
Propulsion Laboratory, the California
Institute of Technology, and EOSRS. The ARIA team is supportedby NASA’s Earth Science Disasters
Program.

NASA Earth Observatory images by Joshua Stevens, using Landsat data from the U.S.
Geological Survey and ALOS-2 data from the Japan Aerospace Exploration Agency/
JAXA and the Earth Observatory of Singapore Remote Sensing Lab.

www.geo-web.org.uk

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Water in Lake Eyre
MODIS Web Image of the Day
https://modis.gsfc.nasa.gov/gallery/showall.php

Image Credit: MODIS Land Rapid Response Team, NASA GSFC

Lake Eyre, Australia’s largest saltpan, sits in the dry outback about
650 kilometres north of Adelaide in
the state of South Australia. Also
called Kati Thanda or Kati ThandaLake Eyre, the large lake lies
15 metres below sea level in one of
the biggest internal drainage systems
in the world. The Lake Eyre Basinstretches over southeastern Northern
Territory, southwestern Queensland,
northwestern New South Wales, andthe northeast of South Australia.
Normally the lake is nearly dry andcrusted with salt, but when heavy
rains fall anywhere across the basin,water often makes it way throughrivers and channels to bring atleast some moisture to Lake Eyre.
Flooding strong enough to fill thelake is rare, but some seasonal fillingis not uncommon, especially in the

monsoon season, which runs from
December through April in much of
the Lake Eyre Basin.
Flooding rains struck parts of theAustralia outback in late January2022, followed by heavy storms inSouth Australia in early February,
all adding up to record rainfalls
to some areas. While the storms
wreaked havoc, washing out roads
and flooding highways, the abundant
water began to trickle-down to theLake Eyre Basin.
On February 5, 2022, the Moderate
Resolution Imaging Spectroradiometer(MODIS) on board NASA’s Terrasatellite acquired this false-colour
image showing water filling Lake Eyreand the normally dry outback aroundthe lake. The false-colour image iscomposed from a combination ofwww.geo-web.org.uk

infrared and visible light (MODIS
bands 7-2-1), where water appears
dark and light blue; bare ground isbrown; and vegetation is bright green.
This band combination makes it
easier to see where water is present.
According to the National Parks andWildlife Service South Australia’s
web page, ‘each time the lake floods,
the salt crust which forms much ofits surface begins to dissolve until
the salt level in the water reaches
saturation point. When the lake starts
to fill, the surface water is fairly freshand drinkable because the heavier
salty water is close to the lake bottom.
From the air, water salinity variations
can be seen as remarkable swirlingcurrent patterns.’ Such swirling
patterns are visible, especially in thesouthern portion of Lake Eyre North.

9Russia’s Crater of Diamonds
NASA Earth Observatory
Story by Kasha Patel

About 36 million years ago, anasteroid slammed into northern
Siberia and created one of the largest
craters on Earth. Streaking in at an
estimated speed of 20 kilometres per
second, the asteroid made an impactthat ejected millions of metric tons ofmaterial into the air. The asteroid—
between 5 and 8 km wide—created acrater nearly 100 km in diameter.
Popigai crater is the fourth largest
verified impact crater on Earth, tying
with the Manicouagan Reservoir in
Canada. The three larger craters areeither buried (Chicxulub), deformed(Sudbury), or severely eroded anddeformed (Vredefort). Popigai has
only been slightly modified by erosion,leaving it as one of the most wellpreserved craters in the world.
The images on this page show
Popigai crater, named for a nearby
river. The images were createdusing Blue Marble data, a cloud-freecomposite of monthly observations
from NASA’s Moderate Resolution
Imaging Spectroradiometer (MODIS)
observations. The data were draped
over an ASTER-derived global digital
elevation model, which shows the
topography of the area.
Located about 100 km from theLaptev Sea coast, the round
depression dives about 150 to
200 metres below the surrounding
land. Geological mapping andfield observations show a central
depression at the bottom of thecrater, surrounded by a peak ring ofabout 45 km wide. The ring gradually
passes outwards into a ring-shaped
trough, which is surrounded by a flat
annular terrace.
The crater sits on the northeastern
margin of the Anabar shield, whichcontains a mix of graphite-bearing
rocks and sedimentary rocks. The
impact from the asteroid melted 1,750
cubic kilometres of rocks and instantly
transformed the flakes of graphite
into diamonds. Diamonds formed ina hemispherical shell about 1.6 km
Concluded on page 23

NASA Earth Observatory images by Joshua Stevens, using data from NASA/
METI/AIST/Japan Space Systems, and the U.S./Japan ASTER Science
Team, and Blue Marble data from NASA Earth Observatory

www.geo-web.org.uk

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Using Shapefiles toOverlay Digitised Bracknell Charts on Meteor M2 Images
Les Hamilton

This is a section of a Meteor M2 infrared image was captured at 18.09 UT on February 6 2022 and rendered in MeteorGIS
It is shown bearing the 1800 UTC Bracknell MSLP chart for that day.

Around mid December last year I received an email from
Ernst Lobsiger, a Swiss physicist and retired teacher, who
had taken a great interest in Richard Fairman’s article
on overlaying Bracknell MSLP charts [1] on Meteor M2
images. He pointed out, however, that the technique
was somewhat approximate as the two entities did notshare the same mapping projection. But he believed thathe might be able to provide totally accurate overlays bydeveloping shapefiles from the Bracknell charts which
the MeteorGIS software itself could then overlay on the
Meteor M2 images.
A shapefile [2] is a digital geospatial vector data format
for geographic information system (GIS) software,
which spatially describes points, lines, and polygons as
vector features. The MeteorGIS.exe software already uses
shapefiles every time it overlays coastlines, country
boundaries, the graticule and major cities on your
Meteor images. You will find these shapefiles inside theMeteorGIS subfolder with names such as ‘ne_50m_coastline’and ‘ne_110m_graticules_10’. They always exist as file triples
with endings .shp (coordinates), .shx (pointers) and .dbf
(attributes).

Ernst reasoned that, if he could digitise the full-sized
weather charts from www.weathercharts.org, it would bepossible to create a set of shapefiles that MeteorGIS could
draw upon to automatically add accurate MSLP Bracknell
charts to Meteor images.
As Ernst does not run a Windows MeteorGIS system (heruns EUMETCast receivers under GNU/Linux), I provided
him with a few Meteor M2 S-files with which to carry out
his experiments.
Unlike the situation with coastlines etc, which are constant
and where the same shapefiles can be used every time,the data contained in Bracknall charts is dynamic: itchanges every six hours from one chart to the next. Thismeans that the user requires a means to create a new setof Bracknell shapefiles daily, if not even for each Meteor
pass! This is achieved using QGIS, a Free and Open
Source Geographic Information System tool. Although it
takes some time to become fully familiar with all the steps
in the process, by the time you have memorised them,a new set of Bracknell Shapefiles can be created from adownloaded chart in no more than a couple of minutes.

https://leshamilton.co.uk/BracknellGIS.htm
www.geo-web.org.uk

11

Ernst has prepared an instruction/information PDF
document describing every detail of the process he has
devised, fully illustrated at each step. He has also provided
scripts that automatically download and prepare the latest
Bracknell charts.
These scripts are far too detailed to reproduce
here and, in any case, copying them accurately
would be a major undertaking. They can all be
downloaded from the following URL
https://leshamilton.co.uk/BracknellGIS.htm
where which I explain how to integrate Ernst Lobsiger’s
methodology into the MeteorGIS folder itself.

This web page explains my own experiences as I followed
Ernst Lobsiger’s instructions, and provides links fordownloading all the necessary software and scripts. It also
explains how to create Bracknell.bat and Bracknell.ini files tosimplify adding the Bracknell shapefiles to your images(and also a link to download them, ready prepared, if you
prefer).
References
1 Bracknell Charts
https://www.weathercharts.net/ukmo_mslp_analysis/ppva_fullsize.gif
2 Shapefile
https://en.wikipedia.org/wiki/Shapefile

This is a segment from a Meteor M2 infrared image captured at 08.23 UT on February 11, 2022.
It is shown bearing an overlay of the noon Bracknell MSLP chart for that day.

https://leshamilton.co.uk/BracknellGIS.htm
www.geo-web.org.uk

12Captured at 08.01 UT on the morning of February 27, 2022, this is the first decent visible image of the year from Meteor M2.
The Bracknell overlay shows high pressure advancing from France as a depression builds over Iceland.

Captured at 17.51 UT on the same day, this infrared image graphically illustrates the deep low pressure system.

www.geo-web.org.uk

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Namib Sand Sea
NASA Earth Observatory
Story by Kathryn Hansen

The Namib Desert in southwestern
Africa is considered the oldest
desert on Earth. It also gives rise
to some of the planet’s tallest
dunes.
Many of the highest dunes arefound within the Namib Sand
Sea, a section of the desert thatspans 34,000 square kilometresof coastal Namibia. The sandsea and its dunes are visible infigure 1, acquired on January 20,
2020, with the HawkEye [1,2]sensor on the SeaHawk CubeSat.
Most of the sand originated from
erosion processes that occur tothe south of this scene, near theOrange River valley. The Orange
River carries sandy sediment
into the Atlantic Ocean, and thennorthward flowing currents moveit along the coast and deposit italong the shore. Strong prevailingwinds out of the south also canpick up sand and deliver it to theSand Sea.
Sculpted by winds, the dunes
are visible throughout the Sand
Sea. Crescent dunes (barchans)appear closest to the shore andare shaped by onshore winds.
Farther inland, linear dunes
dominate, interrupted in places by
patches of star dunes shaped bywind blowing from all directions.
Dune 45, visible in figure 2 andthe photograph on page 15, is an
example of a star dune. Composedof 5-million-year-old sands,
Dune 45 towers 80 metres overthe desert floor on the eastern
flank of the Sand Sea.
Other large dunes—including theSand Sea’s tallest, a 325-meter
dune nicknamed ‘Big Daddy’—line the bed of the Tsauchab
River. The Tsauchab originatesin the Naukluft Mountains, thencuts across the Sand Sea before
coming to an end at Sossusvlei,
a salt and clay pan about 40
kilometres from the Sand Sea’s

Figure 1 - The Namib Desert imaged by SeaHawk on January 20, 2020.

Figure 2 - A zoom into the detailed panel above, highlighting Dune 45

NASA image by Alan Holmes/NASA’s Ocean Color Web, using data from SeaHawk/HawkEye.

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Figure 3 - Dune 45
Photo courtesy of pxfuel - https://www.pxfuel.com/

eastern flank. Like most rivers and streams in
the region, the Tsauchab is ephemeral. Water
tends to flow in the Tsauchab and pool up in
Sossusvlei every few years or so, generally after
a rare heavy rainstorm. In the 2020 view above,
the riverbed and clay pans are dry. White areas
are probably salt.
Still, life has found a unique way to survive, even
without much rain. Fog is the primary source ofwater for the Namib Sand Sea, which is the only

coastal desert in the world to contain large dune
fields influenced by fog. This moisture results
in relatively abundant and diverse vegetation,
particularly on the rocky hills or mountains(inselbergs) that rise above the desert.
References
1 Seahawk/Hawkeye
https://oceancolor.gsfc.nasa.gov/data/hawkeye/
2 The Seahawk 3U Cubesat
https://uncw.edu/socon/seahawk.html

www.geo-web.org.uk

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Tenerife, Canary Islands
European Space Agency

Located in the Atlantic Ocean,
opposite the northwest coast of Africa,
the Canary Islands consist of eightmain islands including Gran Canaria,
Lanzarote and La Palma, as well as
Tenerife and many small islands andislets.
Teide National Park, locatedin the centre of the island, is a
UNESCO World Heritage Site
and includes Mount Teide which
dominates Tenerife. Rising to around3718 metres above sea level, its
summit is the highest point on
Spanish soil. However, much of
the volcano’s height is hidden. If
measured from the ocean floor, its
height of 7500 m makes Teide thethird-highest volcano in the world.
Teide is an active volcano: its mostrecent eruption occurred in 1909
when a lava flow buried much of thetown and harbour of Garachico on thenorthern coast.
Owing to the island’s diverse
topography and unique climatic
factors, Tenerife has multiple
microclimates, which means that theweather can vary drastically from onepart of the island to another. Weather
and climate are heavily influenced
by the trade winds blowing fromthe northeast for most of the year,
bringing humidity and precipitation to
the north of the island, as well as tothe northern slopes of Mount Teide.
This effect can be clearly seen in
the dark green colours in the image,which show vegetation cover. Thisband of green generally follows theboundary of Corona Forestal Natural
Park, which covers a total area of
46 000 hectares.
Most of Tenerife’s inhabitants liveon the lower slopes, within a few
kilometres of the sea. Around half
the population lives is in or near thecosmopolitan capital of Santa Cruzde Tenerife, located on the southerncoast of the narrower northeast partof the island, and San Cristóbal dela Laguna, the former capital. Other

The island of Tenerife, imaged by Sentinel-2
Contains modified Copernicus Sentinel (2021), processed by ESA, CC BY-SA 3.0 IGO

Mount Teide in Tenerife
Photo: James Dawn / Creative Commons Attribution-Share Alike license 3.0

www.geo-web.org.uk

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inhabitants live on the intensively
cultivated slopes near the northerncoast, where the chief towns are La
Orotava, Los Realejos, and Puertode la Cruz. The south of Tenerife
is a popular destination where
holidaymakers enjoy time on thebeautiful beaches of Costa Adeje.
Tenerife is home to Teide Observatory,
located around 10 kilometres fromSanta Cruz de Tenerife on the Izaña
mountain, which is home to ESA’s
IZN-1 laser ranging station – the firstlaser ranging station to be madecommercially available. It is from herethat lasers are aimed into Earth’sskies, seeking out satellites—andsoon pieces of space junk—as wellas measuring their positions andtrajectories to prevent catastrophic
collisions.

Santa Cruz de Tenerife, capital city of the island.
Image ESA

ESA’s IZN-1 laser ranging station
Photo: ESA

ESA’s IZN-1 laser ranging station on
top of the Izaña mountain in Tenerife,
Spain, has recently undergone monthsof testing and commissioning, passing
its final tests with flying colours. As it
reached ‘station acceptance’, it washanded over to ESA by DiGOS, theGerman company contracted to build
it. The station is a technology test-bed
and a vital first step in making debris
mitigation widely accessible to all
space sectors with a say in the futureof our space environment.
Read more about ESA’s laser ranging
station athttps://www.esa.int/Safety_Security/
Space_Debris/New_laser_station_lights_the_way_to_debris_
reduction

Mount Teide National Park on Tenerife. The volcano is in the centre of this scene.
Image ESA

www.geo-web.org.uk

17

LANDSAT: The Satellite That Might Save the EarthPart 2 – The Imagers and Applications
Ed Murashie
Only Landsat images can show
how Las Vegas, Nevada, USA has
rapidly expanded over the past 50
years when viewed from space. Thisis because Landsat is the longest
running Earth resources satellite
program and has been in continuous
operation since 1972. That’s probably
why the USGS, the folks that run theLandsat program, chose ‘Science fora changing world’ as their slogan. But
with technology advancing as fast as
it has, how is comparing decades ofimagery even possible? This should
be like comparing a picture taken bya 1972 Kodak Instamatic film camera
with another taken by a modern
cellphone camera. The answer is, lotsof planning and an understanding of
the imager’s evolution.

Landsat Imager Evolution
Return Beam Vidicon: Landsat 1-3
Landsat 1, 2, and 3 carried two
imagers. The primary imager was
the gold standard analog return
beam vidicon (RBV) imager similar
to the one flown on the TIROS
and early Nimbus spacecraft. One
RBV limitation was that it was only
operated during daylight, but anadvantage was that the Earth scene
could be imaged instantaneously likea camera. The imagers’ characteristics
are shown diagrammatically on
page 19 and in detail in Table 1
overleaf.
Multispectral Scanner: Landsat 1-5
The secondary imager was a newexperimental digital multispectral
scanner (MSS) and was thefirst digital imager flown on any
spacecraft. Sunlight reflected fromthe Earth was in turn reflected by arotating mirror and focused on a setof filters and detectors with an opticaltelescope. The angled spinning mirror
caused a west-to-east scan of the
Earth, while the spacecraft’s orbital
motion caused a north-to-south scan.
This is the same technique used in
the NOAA weather satellite’s AVHRR
imager. Because the west-to-east
scanning is like a broom sweepingfrom side-to-side, this type of imager

Las Vegas as seen by Landsat-1 on Sept 13, 1972
Image courtesy of the U.S. Geological Survey

The same scene as Las Vegas was viewed from Landsat-8 on May 15, 2013
Image courtesy of the U.S. Geological Survey

is referred to as a ‘whiskbroom’
imager. There are two interesting
MSS facts to make note of. One isthat during Landsat 1’s 196th orbit,
the RBV power relay stuck in its‘on’ position and, instead of trying tocorrect the problem, the imager wasleft off since the MSS proved to be
the superior imager. The other fact isthat Landsat 1-3’s orbital altitude waswww.geo-web.org.uk

approximately 900 km, while that ofLandsats 4 and 5 were at 700 km.
And, because the program wanted
satellite data compatibility, they
redesigned Landsat 4 and 5’s MSS
optics to maintain the 79 m resolution.
As an experiment, Landsat 3’s RBV
was redesigned to just have one
channel with higher resolution than its
MSS imager.
contiued on page 20

18

Imager

RBVSpacecraft

Landsat 1-2
Landsat 3

MSS

TM

ETM+

Landsat 1-5

Landsat 4-5

Landsat 7

Swath
Width

183 km
183 km

185 km

185 km

183 kmChannelWavelength(um)Resolution
Fidelity(m)

10.48-0.5780

Analog2

0.58-0.6880Analog30.70-0.83

80

Analog10.505-0.75

40Analog1

0.5-0.679

6 bits Digital

Green

2

0.6-0.779

6 bits DigitalRed

3

0.7-0.879

6 bits Digital

Near infrared4

0.8-1.1

79

6 bits Digital

Near infrared1

0.45-0.5230

8 bits Digital

Blue

2

0.52-0.6030

8 bits Digital

Green

3

0.63-0.6930

8 bits DigitalRed

4

0.76-0.9030

8 bits Digital

Near infrared5

1.55-1.75

30

8 bits Digital

Short wave infrared6

10.4-12.5120

8 bits Digital

Thermal infrared7

2.08-2.3530

8 bits Digital

Short wave infrared1

0.45-0.5230

9 bits Digital

Blue

2

0.52-0.6030

9 bits Digital

Green

3

0.63-0.6930

9 bits DigitalRed

4

0.77-0.9030

9 bits Digital

Near infrared5

1.55-1.75

30

9 bits Digital

Short wave infrared

6

10.40-12.50

60

9 bits Digital

Therma infrared7

2.09-2.3530

9 bits Digital

Short wave infrared

8

0.52-0.90

15

9 bits Digital

Panchromatic

Notes

2 gain states 8 bits transmitted

OLI/OLI-2

TIRS/TIRS-2

Landsat 8-9

Landsat 8-9

185 km

185 km10.433-0.453

30

12 bits Digital

Deep blue

20.45-0.515

30

12 bits Digital

Blue

3

0.525-0.60

30

12 bits Digital

Green

4

0.63-0.68

30

12 bits Digital

Red

50.845-0.885

30

12 bits Digital

Near infrared6

1.56-1.66

30

12 bits Digital

Short wave infrared7

2.1-2.3

30

12 bits Digital

Short wave infrared

80.50-0.68

15

12 bits Digital

Panchromatic

9

1.36-1.39

30

12 bits Digital

Short wave infrared1

10.3-11.3

100

12 bits Digital

Thermal infrared2

11.5-12.5

100

12 bits Digital

Thermal infrared

Table 1 - Landsat Imager Characteristics
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19

Figure 1: Landsat 1-9 Digital Imager Band Chart. (Chart courtesy of the U.S. Geological Survey)

Thematic Mapper: Landsat 4-5
Santa Barbara Research Center, the designers of the
MSS, designed the follow-on improved Thematic Mapper(TM) imager used on the Landsat 4 and 5 satellites. The
TM ‘whiskbroom’ imager improved the spatial resolution
from 79 m to 30 m, tightened the spectral resolutions,improved the radiometric resolution from 6 bits to 8 bits,
and added three new bands. Radiometric resolution relates
to the number of gray shades an imager can discern.
Increasing from 6 bits to 8 bits means going from 64
shades of gray to 256. The added bands were blue, shortwave infrared and thermal infrared. The added blue bandallowed red, green and blue images to be combined tomake natural color images.
The short wave infrared image can help in identifying
certain minerals, measure plant health and see throughsmoke or haze. Thermal infrared sensors measure theheat given off by objects unlike the other sensors whichmeasure reflected light. They are suited for measuring
sea surface temperatures, fire detection and otherthermal mapping applications. You may notice different
applications, or themes, were mentioned in describing
the new bands. This is where the thematic mapper
got its name. Scientists were now using existing andadded bands to create application maps for different
Earth science studies. The TM also changed from a
unidirectional scanning sweep to a bi-directional scanning
sweep, and added a sweep corrector to eliminate thesatellite orbital motion component in images. More about
the sweep corrector later.
Enhanced Thematic Mapper
and Enhanced Thematic Mapper Plus: Landsat 6-7
Only Landsat 6 carried the new Enhanced Thematic
Mapper (ETM) but since Landsat 6 failed to reach orbit,
the ETM was never operated.
Raytheon bought Hughes and renamed Santa Barbara
Research Center, Santa Barbara Remote Sensing.
Santa Barbara Remote Sensing designed the Enhanced

Thematic Mapper Plus (ETM+) which was the only imager
aboard Landsat 7. The ETM+ is also a ‘whiskbroom’ typeimager with a sweep corrector. Unfortunately the sweep
corrector failed in May 2003, so there have been image
gaps at the ends of image scenes since. The ETM+
added a 15 m resolution panchromatic band and increased
the radiometric resolution from 8bits to 9 bits. It has a dual
gain selector which determines and then transmits the best
range of 8 bits. The panchromatic band, with its higher
resolution, allows image sharpening when applied to theother bands. Another major ETM+ feature is improved
calibration and radiometric accuracy.
Operational Land Imager
and Operational Land Imager-2: Landsat 8-9
Landsat 8 and 9 carry two new imagers each: theOperational Land Imager (OLI) and the Thermal Infrared
Sensor (TIRS) on Landsat 8, and the OLI-2 and TIRS-2
on Landsat 9. The OLI was built by Ball Aerospace andTechnologies Corporation. Unlike the ‘whiskbroom’ design,both the OLI and TIRS are ‘pushbroom’ designs, meaning
there is a full west-to-east scan line of detectors, withthe satellite’ orbital motion providing the north-to-south
scanning. ‘Pushbroom’ designs have proven themselves
on other types of satellites, with advantages including
instantaneous full image capture, no moving parts, andlighter weight. Disadvantages include the increased
calibration complexity of the 69,160 detectors and far more
detectors than previous designs. The previous designs
would run a simpler calibration routine at the ends of eachscan line.
Other OLI improvements over the ETM+ include two
new channels and a radiometric resolution increase
from 8 bits equal to 256 shades of gray to 12 bits equal
to 4096 shades of gray. The added channels are ‘deep
blue’ for studying aerosols and the coastal zones, and ashort wave-Infrared which is optimized for cirrus clouddetection. The OLI-2 designs are similar to the OLI, witha few improvements such as having 14 bits of radiometricresolution so that darker scenes can be better imaged.

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20

Thermal Infrared Sensor
and Thermal Infrared Sensor-2: Landsat 8-9
Landsat 8 and 9 carry dedicated twin channel ‘pushbroom’
thermal scanners, TIRS and TIRS-2, both built by NASA’s
Goddard Spaceflight Center. Two TIRS-2 improvements
include reducing stray light and added redundancy.
By having a consistent set of base bands, adding
new bands, improving accuracy, increasing spatial
and radiometric resolution, Landsat has been able toallow nearly 50 years of data comparisons while taking
advantage of new technologies.

Landsat Data Applications
With a unique complement of sensor bands, a long
retrospective and global view of Earth, there are awide range of applications that rely on Landsat’s data.
Applications include mapping, agricultural, mineral
exploration, disaster monitoring, and studying land andwater use. People who use the data include government
agencies, educational institutions, private companies
and even farmers. One agency that supports otherswith Landsat education, applied research, workforce
development, technology transfer and community outreachis AmericaView. To learn more go to their website athttps://americaview.org/

Interesting Landsat data applications
Evapotranspiration
Water follows a cycle. A simplistic view of the water cycle
is rain falling to the Earth, being heated by the sun, andevaporating back into the atmosphere to start the cycle
again. But water can also be absorbed by vegetationand the leaves give back the moisture to the atmospherethrough transpiration. When combining evaporation andtranspiration, the term evapotranspiration is formed. Whentranspiration occurs, it cools off the soil and vegetation.
Landsat sensors can measure the temperature using the
TIRS, and when combined with other environmental datasuch as wind, an evapotranspiration (ET) number can becalculated.
Knowing how much moisture is leaving a crop can give
farmers an idea of how much water must be applied tokeep a healthy balance. OpenET.org is one organizationthat makes the ET data available on their website
https://openetdata.org/
where you can display a map, zoom in to individual farm
plots using the 30 meter resolution Landsat data, anddisplay the ET data over time (figure 2).
LANDFIRE
As you probably have seen in the news, California issubject to major wildfires, and the state and federal
government have spent millions on wildfire operations. Partof those operations including planning. LANDFIRE is a
joint program between the U.S. Department of Agriculture
Forest Service and U.S. Department of the Interior.
Its LANDFIRE Data Distribution Site map relies on Landsat
and other data to provide landscape geo-spatial data
(figure 3) to support wildfire planning, management, andoperations. The tool allows you to map data sets ranging
from brush coverage to vegetation types all at the click of
the mouse. To learn more go tohttps://landfire.gov/about.php

Figure 2 - Evapotranspiration
Image courtesy of OpenET.

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21

Figure 3 - Los Angeles California Map
Image courtesy LANDFIRE.

Figure 4 - Landsat and the Calypso Caper YouTube Banner
Image courtesy NASA

Jacques Cousteau
What does one of the world’s most famous
oceanographers, an Apollo 9 astronaut, and Landsat havein common? They all worked together during the summerof 1975 to prove if satellite bathymetry was possible, and itturns out that it is.
Satellite bathymetry is the science of measuring shallow
ocean water depth using satellite data, in this case it used
Landsat 1 and Landsat 2 bands 4 and 5 MSS data. It is
an important measurement, since it is estimated that 80%
of all goods are carried by ships, and shallow waters posea hazard. A team of divers, Jacques Cousteau, Astronaut
Rusty Schwikart, the president’s son Jack Ford and others
gathered on the Calypso and set sail for Montego Bay.
With its clear shallow waters it made for a perfect place topractice.
From there they sailed to the Bahamas, met up with asailboat and started making their measurements. The
Calypso’s radar took depth measurements and, as Landsat
came overhead, divers made temperature, horizontal andvertical visibility measurements, sea floor images andsamples. Every night the boats would sail to a new location

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22

Figure 5 - This false color image of the Anchorage area, Alaska, was observed by the recently
launched Landsat-9 on November 20, 2021. The image was built using infrared, red, and blue
bands of the electromagnetic spectrum and illustrates the satellite’s resolving power.
Image: NASA / USGS

in a grid pattern to make the same measurements. The principal is to measure the sun energy as it passes through theair, water and reflected off the ocean bottom.
A mathematical model was created using the MSS green band 4 and red band 5 high gain data plus the viewing andrefracted sun angle. Analyzing the data showed that satellite bathymetry was possible up to 22 meters depth and helped
revise waterway charts.
I have just touched upon a few applications but there are countless more. One resource that explores 120 applications
can be found athttps://grindgis.com/blog/120-landsat-data-applications
while at NASA’s Goddard Spaceflight Center’s webpage
https://landsat.gsfc.nasa.gov
you can learn more about the satellite and its uses.
Learn more about the ‘Landsat and the Calypso Caper’ on YouTube athttps://www.youtube.com/watch?v=3pSctnQy3B4
Conclusion
In Part 3 you will learn where to download the images, and how to use free tools to manipulate the images.
You will be able to apply what you have just learned about the imagers and data applications to explore the Earth on
your own.

Russia’s Crater of Diamonds
Continued from page 10

thick and about 12 to 13 km away from the impact site. Scientists estimate that diamonds did not form at the impact site
because the collision’s heat and pressure were likely too great to survive there.
Popigai crater is the site of one of the largest diamond fields in the world today, estimated to contain ‘trillions of carats.’
Because they were formed instantly, the ‘impact diamonds’ did not have time to develop as large, single gemstones.
Most are polycrystalline stones smaller than two millimeters and with low purity, making them better for industrial uses
than for jewellery.

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23

A new eruption started at the Anak Krakatoa, or Krakatau, volcano on Rakata Island in Indonesia on February 3 2022, as shown inthis image captured by the Copernicus Sentinel-2 mission. The eruption started at around 16:15 local time, with a thick column of gas,with possible volcanic ash content, rising to around 200 metres above the crater.
Image contains modified Copernicus Sentinel data (2022), processed by ESA, CC BY-SA 3.0 IGO

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24

Tidal Vortices in the Sea of Okhotsk
NASA Earth Observatory
Story by Sara E. Pratt

NASA image by Norman Kuring/NASA’s Ocean Color Web,
using Landsat data from the U.S. Geological Survey.

Some of the highest diurnal tides in the world—nearly 14
metres—have been recorded in the Sea of Okhotsk. In
the Russian Far East, narrow bays funnel and amplify the
incoming tides, making it a prime location for tidal power
generation.
The transition from smooth, laminar flow to mixed,
turbulent flow is visible in this natural-colour image oftidal currents in the western Sea of Okhotsk. The imageof the Shantar Islands and Uda Bay was acquired on
September 24, 2021, by the Operational Land Imager(OLI) on Landsat 8.
The currents around the Shantar Islands are heavily
influenced by the strong tides and by freshwater discharge
from rivers draining into Uda Bay. The waters here arefrozen for much of the year. When the sea ice melts andfreshwater snowmelt swells the Uda River, plumes of lowsalinity water can reach far offshore.
As the strong tides and currents flow through straits in
the Shantar Islands, they encounter rocky outcrops,
headlands, capes, and small islands that disrupt thelaminar flow. This can create chains of spiral eddies thatrotate in alternate directions as they form. These chains
are known as vortex streets or von Kármán vortices. The
physical processes that create the vortices were firstdescribed in 1912 by Theodore von Kármán, a HungarianAmerican physicist and a co-founder of NASA’s Jet
Propulsion Laboratory. In the Shantar Islands, vortices in
the chain propagate mainly to the east at low tide and to
the west at high tide.

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25

After abundant snowfall on 8 December 2021, here’s a rare cloud-free Copernicus
Sentinel-2 mission mosaic image of Liguria, Valle D’Aosta, Piedmont, Lombardy and a little
portion of Tuscany in Italy. Monte Rosa can be seen at the top left corner of the image.
Image contains modified Copernicus Sentinel data (2021), processed by ESA, CC BY-SA 3.0 IGO

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26
26

Lake Manicouagan
MODIS Web Image of the Day

Lake Manicouagan

Once nominated as one of the ‘Seven Wonders of
Canada’, the curiously circular Lake Manicouagan
draws attention both from land-bound tourists
and from space. Tourists and fishermen adore thelake for spectacular scenery and excellent salmon
fishing. And the striking appearance of the ‘eyeof Quebec’ allows rapid orientation to astronauts
and satellites, confirming that there is no otherplace on Earth quite like this striking structure.
In fact, it was an astronaut, Marc Garneau, whonominated this reservoir for the Seven Wonders of
Canada competition.

The lake’s peculiar appearance comes from its
creation. Lake Manicouagan sits in an ancient andheavily eroded impact crater (astrobleme) from anasteroid which struck the Earth about 214 million
years ago. The original diameter of the impact has
been estimated to have been about 100 kilometres,
and the size of the asteroid at about 5 kilometresin diameter. Glaciation and other erosional
processes have reduced the extent of the crater,
leaving its visible diameter at only 72 kilometres,
still the sixth-largest confirmed impact crater on
Earth.

Lake Manicouagan spans an area of 1,942 sqare
kilometres in central Quebec, Canada and has
a volume of 139.8 cubic kilometres, making thereservoir the fifth largest in the world by volume.
The large island in the center of the lake is called
René‑Levasseur Island and helps give the lake it’seye-like appearance.

The Moderate Resolution Imaging
Spectroradiometer (MODIS) on board NASA’s Aqua
satellite acquired this stunning true-colour imageof frozen Lake Manicouagan on January 11, 2022.
Frigid weather has frozen Lake Manicouagan aswell as other lakes and rivers in the region, whilelight snowfall sits on the surrounding landscape.

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27

Ukraine Under Attack

Thanks to Ed Murashie for forwarding this revealing image acquired by the
USGS Landsat-8 satellite.
Captured by the satellite’s Night Acquisition Band, the image details the streetsof the city of Kryvii Rih (located about 300 kilometres southeast of the capital city
Kyiv) and shows hotspots of enemy activity as bright highlights in its southeast
quarter. Kryvii Rih is the largest city in central Ukraine and the seventh mostpopulous in the country with around three-quarters of a million inhabitants.
Image: USGS

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28
28

Seeing Suomi
NASA Earth Observatory
Story by Michael Carlowicz

It is the land of reindeer husbandry—one of the
few places on Earth where these deer have been
domesticated. It is the home of Europe’s only
recognised indigenous people. It is also the ancestral
homeland of ‘The Father of Satellite Meteorology.’
Welcome to Scandinavia.
The image above is part of a global composite
assembled from data acquired in 2016 by the NOAANASA Suomi National Polar-orbiting Partnership(Suomi NPP) satellite. This night time view of
Scandinavia was made possible by the ‘day-night
band’ of the satellite’s Visible Infrared Imaging
Radiometer Suite. VIIRS was built to be sensitive
enough to measure night time light emissions andreflections, to distinguish the intensity of lights andto observe how they change.
The satellite was named after Verner Suomi, ameteorology researcher and revered longtime
professor at the University of Wisconsin–Madison.
https://earthobservatory.nasa.gov/features/Suomi
Suomi built a flat-plate radiometer that was
launched on the Explorer 7 satellite in October 1959.

It was the first of several Earth-observing
instruments that Suomi conceived or built overa five-decade career, and he was instrumental inadvancing the study of clouds, weather and theplanet’s radiation budget.
“When I first began my work with meteorologicalsatellites, no one in the Department ofMeteorology seemed particularly interested,” hewas once quoted as saying. “But they didn’t try
to impede progress in the field, for which I’mforever thankful.”Though he grew up in Minnesota, Suomi was the sonof Finnish immigrants from the Aland Islands. In the
Finnish language, Suomi is the name for Finland.
The winter scene on the following page comesfrom the Sápmi region of Finland (formerly known
as Lapland), not far from Oulanka National
Park. The natural-colour image was acquired on
January 30, 2014, by the Operational Land Imager(OLI) on Landsat 8. At the time, the Sun was just a
few degrees above the southeastern horizon, leading
to long shadows in the valleys and golden rayswww.geo-web.org.uk
https://earthobservatory.nasa.gov/images/149235/seeing-suomi

29touching the peaks of mountains. Some of thelandscape was probably illuminated by alpenglow,
a phenomenon where airborne snow, water, andice reflect sunlight down toward Earth—even if the
Sun is below the local horizon.
The Sápmi region stretches across parts ofFinland, Sweden, Norway, and Russia, and itis the ancient home of the indigenous Sami
people. About 80,000 to 100,000 Sami are spread
across the four nations and they have long lived
a nomadic life of hunting and gathering, andreindeer herding. An estimated 500,000 reindeer

live in Scandinavia, with most of them tended andherded by the Sami.
By some historical accounts, the Sami may havebeen herding reindeer as far back as the ninth
century. Though electronic tools and motorised
vehicles have become part of the now seminomadic herding life, the ancient Sami languages
are still key to animal husbandry in the rugged
and cold region. Reindeer and the herding
units that tend them are central to the culture,providing meals, tools, clothing and a structure tolife amid changing times in northern Europe.

NASA Earth Observatory images by Joshua Stevens, using Black Marble data from NASA/GSFC,
Blue Marble imagery by Reto Stöckli, and Landsat data from the U.S. Geological Survey.

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30

Colorado Faces Winter Urban Firestorm
NASA Earth Observatory
Text by Sara E. Pratt

The Marshall fire, imaged on December 30, 2021 by NASA’s Aqua satellite.

On December 30, 2021, high winds roared out of
the west and down the front slope of the Rocky
Mountains in Colorado. Northwest of Denver,peak gusts reached 185 kilometres per hour—theequivalent of a category 3 hurricane. Those winds
whipped up intense grass and brush fires in south
Boulder and blew them east toward the towns ofSuperior and Louisville, igniting a firestorm. By
the time it was over, nearly 1,100 houses had been
destroyed or damaged, two people were reported
missing, and thousands were displaced.
The Marshall fire is now the most destructive in thestate’s history. Four of the top five largest wildfires
on record in Colorado occurred between 2018 and2021. Unlike many of the megafires in the American
West in recent years—which typically occur inforests and wildlands—the Marshall fire quickly
travelled into densely populated neighborhoods
and transitioned from a wildfire to an urban
conflagration.
Tens of thousands of residents were evacuatedas flames were blown down streets and throughcul‑de‑sacs. The fire was carried by what climate
scientist and Boulder resident Daniel Swain called‘an ember storm.’ Blown by hurricane-force winds,
the embers leapt from house to house, burning manyfrom the inside out, while torching trees, igniting
commercial buildings, and jumping a highway.
The natural-coloir image above was acquired just a
few hours after the fire started on December 30 by
the Moderate Resolution Imaging Spectroradiometer(MODIS) on NASA’s Aqua satellite. At the time, thesmoke plume—which was also visible on radar—stretched about 100 kilometres over Colorado’s
eastern plains. The fire also generated its own
weather: the rising heat created a low-pressure areathat drew surface winds toward the fire from all
directions.
The next day brought much-needed moisture, asa cold front moved in and dropped more than 25
centimetres of snow—dampening the fire but also
complicating the response. As of January 3, 2022,
the perimeter of the 6,200-acre fire was fully
contained.

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31

This map shows the Standardized Precipitation-Evapotranspiration Index (SPEI) for Colorado for the month of December 2021.

High winds and wildfires are not uncommon on
the Front Range, but a December wildfire is, as thenormal fire season lasts from May to September.
One recent study found that increases in extreme
fire weather are being driven by decreases inatmospheric humidity and increasing temperatures.

precipitation and temperature (it does not include
the New Year’s snowfall that helped extinguish thefire). According to the Colorado Climate Center, SPEI
values exceeding minus two are very rare and are
indicative of the extreme warm and dry conditions
across eastern Colorado.

In 2021, Colorado saw an unseasonably warm
summer and fall, coupled with record dryness. The
warm, dry spell followed an unusually wet spring,which reduced wildfires through the summer andfueled the growth of vegetation—which then driedout and provided ample tinder for the December fire.

The map also shows the contrast between theextreme drought in the eastern part of the state,
where the fire occurred, and the snowpack in thewestern part of the state, where significant December
snowfalls brought the snowpack near or above
average. Denver, which normally has 50 centimetresof snow by late December, did not record its firstwinter snowfall until December 10, the latest on
record.

At the time of the fire, the eastern part of Boulder
County was classified with extreme drought,
according to the U.S. Drought Monitor. The map
above shows the Standardized PrecipitationEvapotranspiration Index (SPEI) for Colorado forthe month of December 2021. It accounts for bothNASA Earth Observatory images by Joshua Stevens, using
MODIS data from NASA EOSDIS LANCE and GIBS/Worldview,
and PRISM data courtesy of the West Wide Drought Tracker.

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32

This splendid RGB123 AHRPT image from Meteor M2 was acquired by Enrico Gobbetti on February 8, 2022, showing
clearly his native Italy basking in sunshine. The alps to the north render as cyan, confirming their blanket of winter snow.

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33

A View of Vesuvius
NASA Earth Observatory
Story by Sara E. Pratt

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

Mount Vesuvius, located 12 kilometers (7.5 miles)
southeast of Naples, Italy, is the only active
volcano on Europe’s mainland. It is a composite
stratovolcano, made up of pyroclastic flows, lava
flows, and debris from lahars that accumulated toform the volcanic cone.
In this natural-color image, acquired on January
2, 2022, by the Operational Land Imager (OLI)
on Landsat 8, the cone of Mount Vesuvius
appears through a break in the clouds. The ridge
surrounding the cone is a remnant of the collapsed
caldera of an older volcano, Mount Somma, fromwhich the cone of Vesuvius emerged.
Naples has a population of 3 million people,
800,000 of whom live on the volcano’s slopes.
This makes Vesuvius one of the most dangerous
volcanoes on the planet. Its most famous eruption,
in A.D. 79, destroyed the cities of Pompeiiand Herculaneum. The cities were engulfed inpyroclastic flows—superheated, high-density cloudsof volcanic gas, ash, and rock that flow downslope
at hundreds of kilometers per hour. Pliny theYounger’s eyewitness account of that eruption,
including its towering ash cloud, led volcanologists
to term these types of eruptions “Vesuvian” or“Plinian.”
Such catastrophes are why the area became hometo the world’s first volcanological observatory, built
in the 19th century. Today, Vesuvius remains
one of the most heavily monitored and studied
volcanoes in the world. By dating lavas, scientists
know that the mountain has had eight major
eruptions in the past 17,000 years. The mostrecent, on March 17, 1944, destroyed the village of
San Sebastiano, Italy. Since then, the volcano has
experienced occasional earthquake activity, grounddeformation, and gas venting from the crater.

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34

Visualising EUMETCast SAF products: part 2
Richard Osborne

Ozone Total Column on Mollweide Projection showing high levels over Eastern China.

Introduction
In the December 2021 edition of the GEO Newsletter,
I presented an article about visualising EUMETCast
Satellite Applications Facilities (SAF) products. At thetime of publication, I declared that my work on the
Atmospheric Composition (AC) products was very mucha work in progress as I had only just started to look at
the implementation in detail. I am now able to provide an
update on my efforts so far.
Atmospheric Composition (AC)Over EUMETCast, the AC SAF disseminates data for
Aerosol Absorbing Index (AAI), Absorbing Aerosol Height(AAH) and trace atmospheric gases; namely ozone,
nitrogen dioxide (two products), sulphur dioxide andformaldehyde. The primary distribution format is HDF5
files with BUFR files in a secondary role. I concentrated on
the former as BUFRDisplay takes care of the latter. Twosatellites currently provide the data from their GOME-2
instrument: MetOp-B and MetOp-C.
Looking in detail at the format of the HDF5 files, the AAI
and AAH products have a two dimensional data structurewith full geo-referencing, albeit in a complex format. In
addition, these products are delivered in chunks as asequence of files, each containing three minutes worth ofdata.
The trace atmospheric gas data is also delivered inchunks as a sequence of files, each containing up to threeminutes worth of data (but it could be less). Each chunkcontains the data for all the represented gases and thisis represented in the file name. In contrast to the AAI andAAH products however, the trace gas files have a one
dimensional data structure, possibly because of theirvariable length. They also include full geo-referencing in acomplex format.
As stated in the original article, the format of the HDF5
files, coupled with the need to combine data from multiple
files to produce a global image, means that only general
purpose or bespoke software can provide a satisfactory
method of visualising the data. Following a period of
research, I located some candidate Python scripts on a
EUMETSAT software repository at
https://gitlab.eumetsat.int/
eumetlab/atmosphere/atmosphereand used these as the basis for my experiments.

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Aerosol Index derived from METOP-B on Plate Carree Projection. Positive values are absorbing, negative values are scattering.

Nitrogen Dioxide density over Asia showing hotspots on Plate Carree Projection.
Image quality is denser where MetOp-B and MetOp-C scans overlap.

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AC Scripts
After consulting the AC SAF website for information oneach of the products and the software repository, I electedto ignore AAH and concentrate on the remainder. As theaerosol and each of the trace gases requires a different
treatment to produce the best visual image, I decided to
produce a series of individual Python scripts resulting
in a total of six top level scripts and an additional one
containing common functions. However, the workflow is thesame for all the top level scripts and can be summarised
as follows:• Extract relevant data from all available HDF5 files andcombine into a single data array using Python Xarray
module.
• Filter data array using Xarray to remove or correct
extraneous values.
• Plot data onto a basemap using Python Matplotlib andCartopy modules adding a colourmap legend.
When calling each Python script, I include two argumentsin the command line. The first selects the satellite data forviewing: MetOp-B, MetOp-C or both. The second selects
the map projection such as Plate Carrée, Mollweideor Orthographic. For ease of use, I prepared a simple
Windows batch file to construct the required command
line, based on a series of multiple choice questions whichasks for the desired product, satellite(s) and projection.

The Atmospheric Composition was the most challenging
SAF product for me to visualise as it relies on a purePython solution supported by powerful modules such as
Xarray, MatPlotlib and Cartopy. Unfortunately, as someone
who just dabbles on the edge of programming, I foundthe documentation for these packages to be arcane andalmost impenetrable, making progress very difficult. Even
the act of adding an additional colour map to Matploblib
proved to be difficult.

When I produced my first global plots they didn’t look right,
so I investigated further. I discovered that the observation
data for the aerosols and gases includes the output fromtwo separate scans, each covering the same ground area.
The GOME-2 instrument provides an initial forward scanand then a lower resolution backward scan and I wasplotting one on top of the other. This fact is not mentioned
in the EUMETSAT sample scripts but I did find a way toremove the backward scan contribution from the dataarray to produce a ‘clean’ plot. Examples of the plots areshown above. To define the measurement range for eachproduct and check that the plotted data looked correct, I
referred to two AC SAF related websites which provided
representative images [1,2], and was gratified to observethat they correlated very closely.

Postscript
As started at the beginning of Part 1, my objective wasto provide an overview of my experiments to visualise
EUMETCast SAF products and the article has beenpresented at a ‘high level’ with very little detail. However, if
any reader would like more information, including sample
scripts, I will respond to requests placed on the MSG-1
Groups website athttps://groups.io/g/MSG-1

Commentary
I believe that I have succeeded in my original quest tovisualise as many EUMETCast SAF products as possible
although it took several different methods ranging frominstant ‘point and click’ solutions to bespoke Python
scripts. I’m sure that there are other methods that would
produce equivalent results but I simply used those that I
could find at the time.
On the assumption that I haven’t missed any readily
available ‘off the shelf’ software applications I think that
Python solutions offer the best scope for further selfexperimentation. For example, there is a visualisation
package for derived meteorological products in BUFR,
netCDF and GRIB format called Magics from the European
Centre for Medium-Range Forecasts that looks similar to
Pytroll/Satpy in concept. Maybe I’ll give it a try.

References
1 GOME-2 Vertical Ozone Profiles and Absorbing Aerosol Index
https://www.temis.nl/acsaf/?sat=metopb
2 GOME-2 / MetOp
https://atmos.eoc.dlr.de/app/missions/gome2

Antarctic Eclipse
On December 4, 2021, a handfulof people in Antarctica weretreated to clear views of a total
solar eclipse, the only one tooccur in 2021. This image was
acquired by the Earth Polychromatic
Imaging Camera (EPIC) aboard
the Deep Space Climate
Observatory (DSCVR) from its
position at Lagrange Point 1,
a gravitationally stable point
between the Sun and Earth about
1.5 million kilometres from Earth.
In this view, acquired at 07:58
UTC, the Moon’s shadow can beseen falling on Antarctica.

NASA image courtesy of the DSCOVR EPIC teamwww.geo-web.org.uk
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This striking NOAA 18 APT image, sent in by André T’Kindt from Ronse in Belgium, shows a deep
depression over Iceland driving blustery winds and rain showers across Great Britain on February 27, 2022.

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Bahamas
MODIS Web Image of the Day
https://modis.gsfc.nasa.gov/gallery/showall.php

Image Credit: MODIS Land Rapid Response Team, NASA GSFC

This stunning true-colour image of a portion of the
Bahamas was acquired by the Moderate Resolution
Imaging Spectroradiometer (MODIS) on board NASA’s
Terra satellite on December 16, 2021. The sparkling-clear
sky allows a detailed view of Andros Island in the west,
Eleuthera Island in the east, the bright jewel-tones of
the Great Bahama Bank and the intense blue of a deep
underwater canyon that separates Andros Island from
Eleuthera.
The largest island of the Bahamas, Andros measuresabout 160 kilometres in length by 70 km in width. The
flat, forested island is actually a conglomeration ofmultiple islands which are strung together by a series
of wetlands. To the west, the waters over the limestonerich mound known as the Great Bahama Banks are

extremely shallow—in some areas, under one metre at
most. Limestone is a sedimentary rock formed by theskeletal fragments of sea creatures, including corals andforaminifera, and this particular limestone platform has
been accumulating since at least the Cretaceous Period.
To the east of Andros, the sea floor abruptly plunges
downward, reaching a depth of about 4300 metres. This
deep water appears very dark, in brilliant contrast to thelight colour of the shallowest areas of the Great Bahamas
Bank. The submarine trench appears to take the shapeof a long tongue, giving this unique feature the name of‘Tongue of the Ocean’. Colourful wave-shaped ripples
sit at the southern edge of the Tongue. These are large
underwater dunes that have been shaped by the action of
the waves over time.

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Lake Erie’s February Freeze
MODIS Web Image of the Day
https://modis.gsfc.nasa.gov/gallery/showall.php

Image Credit: MODIS Land Rapid Response Team, NASA GSFC

Each year, frigid winter chill brings a topping of ice
to the Great Lakes while wicked winter winds force
thin ice to shift, breaking it up, and expanding theextent of open water. These wintery dynamics createa sort of dance across the largest lakes in North
America, with ice growing and retreating based
primarily on variations in wind and air temperature.
Since January 2022, the ice cover on Lake Erie has
proven a case in point. In late January, Lake Eriealmost entirely froze over, with ice cover growing
well beyond the seasonal average to reach 94%. By
February 3, the ice cover had dropped to about 62%
before rising again to 90% by February 5. Anothersteep drop in ice occurred after that, with ice coverfalling to about 55% on February 11 only to shootback up to about 72% on February 14.
As the shallowest of the Great Lakes, Erie has
the highest annual maximum ice cover, regularly
reaching more than 80%. Three times in the pasthalf century, Lake Erie reached 100% ice cover:in 1978, 1979, and 1996. Conditions on the lake
are not only highly variable from year to year, butalso from day to day. The first week of February
2022 brought a heavy snowstorm, wildly varying
wind speeds and directions, and days of continuous
cooling. As a result, the ice extent across the Great
Lakes rapidly expanded. On February 1, the average
ice cover across all the lakes was 12%; two days
later it had expanded to 28% and by February 6 it
was 43%. (Between 1973–2021, the Great Lakes’
annual average maximum ice coverage was 53.1
percent.)
The Moderate Resolution Imaging Spectroradiometer(MODIS) on board NASA’s Aqua satellite acquired
this true-colour image of Lake Erie on February
14, 2022. Surrounded by snow and cloud, the lake
was almost completely covered with ice, except forareas near the northern coasts where open water
prevailed. Ice also covered much of the southern tipof Lake Huron while most of the western section of
Lake Ontario remained ice-free.

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Garabogazköl Basin
MODIS Web Image of the Day
https://modis.gsfc.nasa.gov/gallery/showall.php

Pale shades of teal,turquoise, tan, and salty
white filled the watersof the Garabogazköl
Depression in thisstunning true-color
image, which was
acquired by the Moderate
Resolution Imaging
Spectroradiometer(MODIS) on board
NASA’s Terra satellite on
November 19, 2021.
Also known as the
Zaliv Kara-Bogaz-Gol,
Garabogazköl Gulf,
and Garabogazköl Bay,the extremely salty
and shallow basin sits
in an arid location in
Turkmenistan. The
Garabogazköl Basin
was once relatively wellconnected to the darkwaters of the CaspianSea, allowing water fresh
water to flow freely into
the basin. Drought anddiversion of water fromthe major rivers that feed
the Caspian Sea (theVolga and Kur Rivers)
caused the level of the
Sea waters to lower,slowing the freshwater
intrusion into theGarabogazköl. In 1980, a
dam was completed which
completely blocked theconnection between the
Caspian and the basin,creating rapid evaporation
which reduced thatGarabogazköl to about
1/3 of its former size anddropped the average
depth to less than 50 cm(19.5 inches). The dam
was destroyed in 1992
and today the CaspianSea and the Garabogazköl
share a narrow connectionthat allows survival of thewater in the shallow basin.

Image Credit: MODIS Land Rapid Response Team, NASA GSFC

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Water in Uyuni Salt Pan
MODIS Web Image of the Day
https://modis.gsfc.nasa.gov/gallery/showall.php

Image Credit: MODIS Land Rapid Response Team, NASA GSFC

Sitting in the high Altiplano of Bolivia, the Salar de Uyuni
is the largest playa (salt flat) on Earth. Covering an
expanse of 10,582 square kilometres, which is roughly
the size as the ‘Big Island’ island of Hawaii, the salar iscovered with a mineral crust and typically looks brightwhite from space, especially during the dry season(May to November). Even though the Salar de Uyuni
and the smaller Salar de Coipasa—which sits to Uyuni’s
northwest—receive less than 200 millimetres of rain eachyear, the rainy season brings tremendous change. Often,
the mineral crust of the salt flats will become covered
with water, creating a mirror-like effect when viewed from
Earth—a spectacular site adored by tourists.

On February 11, 2022, the Moderate Resolution Imaging
Spectroradiometer (MODIS) on board NASA’s Terrasatellite acquired a beautiful false-colour image of Salarde Uyuni, the Salar de Coipasa, and Lake Poopo. Thisparticular false colour image uses infrared and visible
light (bands 7,2,1), a combination that aids in separatingwater (deep blue) from vegetation (bright green), cloud(white or pale blue) and open land (tan). Lakes covered
with mineral salts appear electric blue. As salt becomeswetter, it takes on a darker tone. This image makes it
clear that all three salt flats contain copious water inearly February, which is approaching the end of the rainyseason.

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Iceberg B-22A
MODIS Web Image of the Day
https://modis.gsfc.nasa.gov/gallery/showall.php

Image Credit: MODIS Land Rapid Response Team, NASA GSFC

Almost twenty years ago, in midMarch 2002, a massive Antarctic
iceberg broke off the ice tongue of
the Thwaites Glacier and slowly
inched its way into Pine Island
Bay, part of the Amundsen Sea.
Shortly after calving, four
fragments broke off the almostDelaware-sized iceberg. Caught
by currents, the smaller fragments

drifted away but the large iceberg,
dubbed B-22A, grounded not far
from the mother tongue.
As of February 18, 2022,
iceberg B-22A has drifted only
53 kilometres—a remarkably slow
crawl of about 2.6 kilometres per
year. The berg initially measured
85 by 65 kilometres. The U.S.
National Ice Center reported

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that, as of February 18, the ‘berg
measured 70.3 by 44.4 kilometres.
That same day, B-22A wasspied sitting in the Amundsen
Sea by the Terra satellite’s
Moderate Resolution Imaging
Spectroradiometer (MODIS), which
captured this true-colour image to
give a beautiful view of the iceberg
at one point in time.

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