Group for Earth Observation

No 76 - December 2022

Hurricane Ian imaged by GOES-E on September 28, 2022
Image: NOAA

Useful User Groups

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

GEO Newsletter Editor

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

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

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

Webmaster and Website Matters

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 tempestuous three months we have experienced since
the September issue. At that time the Northern Hemisphere
was literally on ﬁre, with heatwaves and severe droughts rampant, as
documented in ESA’s article on page 4. But November proved a major
volte-face as a succession of Atlantic depressions brought rain to
Europe by the bucketfull. In Aberdeenshire where I live, one two-day
spell of incessant rain delivered twice the November monthly average
precipitation:: rivers ﬂooded, villages were inundated and yet more
trees were felled.

Across the Atlantic, following a slow start to Hurricane Season,
Hurricane Ian, imaged on the cover of this issue, proved to be themost destructive storm to strike the state of Florida since the 1935
Labor Day hurricane. And excessive rainfall and ﬂooding have not been
conﬁned to the Northern Hemisphere. Southeast Australia has also
had to contend with severe ﬂooding brought on by the prevailing La
Niña effect over the Paciﬁc Ocean.

Let’s hope things calm down for the Festive Season and New Year.
Very best wishes to all readers for health and happiness in 2023,
and just maybe - a new Meteor M satellite to whet our appetites.

Contents
UK Heatwave
Late start to the Atlantic Hurricane Season
A Half Century of Loss in Northwest Greenland
Nicole soake the Eastern United States
Home Reef Erupts
The Caspian Sea’s Shrinking Coastline
Volcanic Plumes in the Kuril Islands
Deadly Flooding in Pakistan
VISAN Gallery
Spain’s Yesa Reservoir Severely Affected by Extreme Drought
Fuel Regulation Reduced Air Pollution from Shipping
Ozone Hole Continues Shrinking in 2022
Svalbard
Rocky Road for Swiss Glaciers
Seasonal changes in Antarctic ice sheet flow Dynamics
Seasonal Greening of th Inner Niger Delta
More Flooding in Australia’s Soggy Southeast
Hudson Bay’s Nastapoka Arc
Italy’s Stromboli Erupts
Satellite Status

www.geo-web.org.uk

European Space Agency
Copernicus Image of the Day
NASA Earth Observatory
MODIS Web Image of the Day
NASA Earth Observatory
NASA Earth Observatory
NASA Earth Observatory
Les Hamilton
Richard Osborne
Copernicus Image of the Day
NASA Earth Observatory
NASA Earth Observatory
European Spage Agency
NASA Earth Observatory
European Space Agency
NASA Earth Observatory
NASA Earth Observatory
NASA Earth Observatory
European Space Aency

4
5
6
7
8
9
10
11
12
14
15
17
18
20
21
23
24
26
27
28

3

UK heatwave
European space Agency

This summer, heatwaves struck
Europe, North Africa, the US andAsia with temperatures reachingover 40°C in places—breaking
many long-standing records.
Images from the Copernicus
Sentinel-3 mission show the scaleof Britain’s heatwave as it baked
in extreme temperatures during
August 2022.
This image, captured on
August 12, shows the United
Kingdom’s previously green land
appear brown (particularly in thesoutheast) amid the scorchingconditions. The heatwave
came after months of extreme
temperatures and low rainfall had
left the landscape parched. The
dry conditions are also visible inparts of France, Belgium and theNetherlands.
The severe heatwaves experienced
across Europe this summer area harsh reminder of what is instore for our future. Extreme
weather events will happen more
frequently and intensely according
to the Intergovernmental Panelon Climate Change (IPCC). This
trend is set to worsen unless therise in atmospheric greenhousegas emissions caused by humanactivities is addressed.
Satellites orbiting our planet play
an important role in delivering
data to understand and monitor
how our world is changing. Theirobservations and data are criticalfor improving model predictionsof our future climate, mitigation
strategies and policy making.
The Copernicus Sentinel-3
mission not only provides twoday global coverage optical data,
but it also carries a Sea and Land
Surface Temperature Radiometer
instrument that measures Earth’s
land surface temperature (how hot
the actual surface would feel tothe touch). During August 2022,
the Sentinel-3 mission recorded
extreme land surface temperatures

Image contains modified Copernicus Sentinel data (2022)
processed by ESA, CC BY-SA 3.0 IGO

of more than 45°C in the United
Kingdom, 50°C in France and
60°C in Spain.
Sentinel-3 data has also been
merged with archived satellite
observations to form a recently
released 25-year record of global
land surface temperatures (from1995 to 2020) developed by ESA’s
Climate Change Initiative alongwith Europe’s leading climate
scientists. This data record showsa stable increase in global land
surface temperature of 0.2°C

www.geo-web.org.uk

per decade, with strong regionalvariability.
Monitoring land-surface
temperatures is useful forscientists because the warmthrising from Earth’s surface
influences weather and climate
patterns. These measurements are
particularly important for farmers
evaluating how much water theircrops need and for urban planners
looking to improve heat-mitigating
strategies.

4

Late start to the Atlantic Hurricane Season
Copernicus Image of the Day

Credit: European Union, Copernicus Sentinel-3 imagery

This image, acquired by one of the Copernicus Sentinel-3 satellites on 4 September at 13:04 UTC, shows
Hurricane Danielle when it was 3,000 km west of the coast of Portugal. It had formed in an anomalous
position, at about 38° latitude North, and was is moving towards Europe where it would arrive as a tropicaldepression. Besides its position, Danielle had another peculiarity, as it was not named by the US National
Hurricane Centre until September 2, 2022.
On average, over the years, the first hurricane of the year in the Atlantic Ocean occurs in early August:this was the first time for quarter of a century that there had not been a single named storm in the Atlantic
Ocean before the start of September.

www.geo-web.org.uk

5

A Half Century of Loss in Northwest GreenlandNASA Earth Observatory
Story by Kathryn Hansen

Figure 1
This Landsat 1 image was acquired on September 3, 1973

Figure 1
This Landsat 8 image was acquired on September 20, 2022

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

A pair of satellite images acquired almost 50 years apartreveals striking changes to the glaciers and ice caps innorthwest Greenland. Few other satellite comparisons span
this much time, especially in such vivid lifelike colour.
Observations of Earth from space are now common. But
prior to the 1970s, no Earth-observing satellites had beenlaunched with the specific intent of monitoring our planet’s
land areas. That changed with the launch of Landsat 1 in
1972. The Landsat mission continues onward through today,with the launch of Landsat 9 in September 2021.
This image pair spans the Landsat era so far, revealingchanges across a peninsula north of Thule Air Base (Pituffik).
The Multispectral Scanner System (MSS) on Landsat 1
acquired the figure on September 3, 1973. Figure 2, acquiredon August 20, 2022, by the Operational Land Imager (OLI) on
Landsat 8, shows the same area 49 years later.
The 1973 image resembles natural colour, but is actuallyfalse color (MSS bands 6-5-4). This becomes apparent alongsome of the ice-free areas where vegetation shows up as
red. But with very little vegetation in northwest Greenland, thefalse-colour Landsat 1 image appears similar in colour to thenatural-colour Landsat 8 image (OLI bands 4-3-2). Bare landis brown, and snow and ice are white.
The similarity in colour makes it easy to see where glacial
ice has retreated, narrowed, and in one case surged. Noticethe clear retreat of the large glaciers flowing into the water ofWolstenholme Fjord. Isolated ice caps and smaller glaciers
throughout the image all generally shrink, and in some places
disconnect from each other. In contrast, the large glacierflowing west from North Ice Cap (Nunatarssuaq Ice Cap)appears to lengthen. Such surging behavior might be causedby ice at higher elevations of the ice cap draining into theglacier.

The images were acquired just two weeks apart in theirrespective years. Notice that in 2022, the edges of theice caps and glaciers generally appear much grayer thanin 1973. A warm summer in 2022 melted away more of
the bright-white snow cover exposing darker, dirtier ice.
Fresh snowfall might also be present in the 1973 image,although September is early in the accumulation season,
which largely runs from September until May.
Inspired by recent research on changes to Greenland’s
peripheral glaciers, Christopher Shuman searched
Landsat data records and identified this image pair.
“Because this is such a cold, northern area, I figuredthat the losses over time would be relatively slow, so
we needed almost 50 years to show the change,”
said Shuman, a glaciologist at University of Maryland,
Baltimore County, based at NASA’s Goddard Space
Flight Center.
The research showed that peripheral glaciers, which
are relatively small and disconnected from the main ice
sheet, account for a small proportion of Greenland’s
ice-covered area (about four percent). But peripheral
glaciers account for eleven percent of the island’s ice
loss, which makes them outsised contributors to current
sea level rise.
Peripheral glaciers in northwest Greenland have been
losing about 3.5 to 7 gigatons of ice per year in recent
decades amid accelerated warming, according to theresearch. That’s more than the peripheral glaciers insoutheast and southwest Greenland are losing, but lessthan in north Greenland, where peripheral glaciers havebeen losing as much as 26 gigatons per year since theearly 2000s.

www.geo-web.org.uk

6

Nicole Soaks the Eastern United States
MODIS Web Image of the Day

Image Credit: MODIS Land Rapid Response Team, NASA GSFC

On November 10, 2022, the Moderate Resolution
Imaging Spectroradiometer (MODIS) on board
NASA’s Aqua satellite acquired a true-colour imageof Tropical Storm Nicole moving northward acrossthe United States. Nicole was a remarkably large
storm, with tropical-storm-force winds extending
outwards up to 555 kilometres from the centre,
especially to the northeast. This image showsconvective bands and clouds stretching fromsouthern Florida to Maryland and West Virginia.
The cloud-filled centre of Nicole sits near Tampa on
Florida’s west coast.
After making landfall near Vero Beach on Florida’s
East Coast as a Category-1 hurricane withmaximum sustained winds of 121 kph, the storm
weakened as it crossed the state. According to the
National Hurricane Center, near the time this image
was acquired, Nicole had become a tropical storm
and was carrying maximum sustained winds of
70 kph. It was located about 70 km north of Tampa,
Florida and about 265 km southeast of Tallahassee,
Florida and was moving northwest. By 10:00 pm
EST on November 10, Nicole had further weakened

to become a tropical depression with maximum
sustained winds of 55 kph. However, it remained asuper-soaking storm as it crossed the US Southeast
and Mid-Atlantic states.
According to meteorologist Jeff Masters, writing
for Yale Climate Connections, ‘Nicole was just the
fourth hurricane on record to hit the contiguous
US after October, and the second-latest
landfalling hurricane on record. Only Hurricane
Kate in 1985, which hit the Florida Panhandle
as a category-2 storm with 160 kph winds on
November 21, made landfall later in the season.’Nicole brought a devastating storm surge whichcaused severe beach erosion to parts of Florida,
especially Volusia County, where beach front
homes were destroyed as the surge undercut thesand beneath the houses and parts of the roadway
crumbled. Coastal flooding occurred as far north asCharleston, South Carolina, including record highwater levels of 1.3 metres above high tide measured
at Jacksonville, Florida. The storm was also
responsible for the deaths of five people in Florida.

www.geo-web.org.uk

7Home Reef Erupts
NASA Earth Observatory
Story by Adam Voiland

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

In the southwest Pacific Ocean, a seafloor ridge thatstretches from New Zealand to Tonga has the highest
density of underwater volcanoes in the world. On
September 10, 2022, one of them awoke. In the days
since, the Home Reef seamount in the Central Tonga
Islands has repeatedly oozed lava, ejected plumes ofsteam and ash, and discolored the surrounding water.
Eleven hours after the eruption began, a new islandrose above the water surface. The Operational Land
Imager-2 (OLI-2) on Landsat 9 captured this naturalcolour view of the young island on September 14 asplumes of discolored water circulated nearby. Previous
research suggests that these plumes of superheated,
acidic seawater contain particulate matter, volcanic rockfragments, and sulfur.
On September 14, researchers with Tonga Geological
Services estimated the area of the island to be
4,000 square metres and the elevation to be 10 meters
above sea level. By September 20, the island had grown
to cover 24,000 square metres. The new island is locatedsouthwest of Late Island, northeast of Hunga TongaHunga Ha‘apai, and northwest of Mo‘unga‘one.
Home Reef sits within the Tonga-Kermadec subduction
zone, an area where three tectonic plates are colliding at

the fastest converging boundary on the planet. The PacificPlate here is sinking beneath two other small plates,
yielding one of Earth’s deepest trenches and most active
volcanic arcs.
Islands created by submarine volcanoes are often shortlived, though they occasionally persist for years. Home
Reef has had four recorded periods of eruptions, including
events in 1852 and 1857. Small islands temporarily
formed after both these events, and eruptions in 1984 and2006 produced ephemeral islands with cliffs that were 50
to 70 meters high. An island created by a 12-day eruption
from nearby Late‘iki Volcano in 2020 washed away after
two months, while an earlier island created in 1995 by thesame volcano remained for 25 years.
“The volcano poses low risks to the aviation community
and the residents of Vava‘u and Ha‘apai,”stated the Tonga Geological Service in an update issued
on September 20.
“All mariners are, however, advised to sail beyond 4
kilometers distance from Home Reef until further notice.”
The service also noted that most ash should fall within a
few kilometers of the vent.

www.geo-web.org.uk

8

The Caspian Sea’s Shrinking Coastline
NASA Earth Observatory
Story by Joanne Howl, adapted for Earth Observatory by Kathryn Hansen

Measured by surface area, the Caspian Sea
is Earth’s largest inland water body, spanningabout 371,000 square kilometres. Measured byeconomic, social, and biodiversity standards, it ispriceless.
The Caspian Sea supports a commercially
important fishery, supplies water for agriculture,and provides recreation and work opportunities
for people living nearby. Its waters are also
home to several threatened species, including
an estimated 90% of the planet’s last-remaining
sturgeon. In the northern Caspian, shallow
waters teem with molluscs, crustaceans, fish, andbirds. Seals raise their pups on winter ice thatusually only forms in this part of the lake. And all
rely on a healthy water level for their existence.
However, the Caspian Sea is rapidly shrinking.
On September 19, 2022, the Moderate
Resolution Imaging Spectroradiometer (MODIS)on NASA’s Terra satellite acquired a naturalcolour image (figure 1) of the northern CaspianSea. Part of the sprawling Volga River Delta(dark green) is visible along the left side of
the image. Sediments, carried into the lake by
the Volga and stirred up from the shallow lake
bed by currents, colour the water with swirls oflight green and tan. Light gray areas along theshoreline and patches of white to the southeast
are probably salt and other minerals left behind
after evaporation.

Figure 1 - Caspian Sea in 2006

For comparison, figure 2 was acquired by Terra
MODIS on September 20, 2006. There is nolight-coloured, salt-laden halo along the northernshore and only a relatively small salt crust in
the east and south. Water filled the serpentine
area that, twelve years later, has become a thickmineral crust.
Radar altimetry data collected by multiple
satellites and compiled by NASA’s Global Water
Monitor indicate that the Caspian’s water levels
have been dropping since the mid-1990s.
Other research suggests that the decline could
continue as climate change brings warmer air
temperatures and increased evaporation.
In one study, scientists ran several models toestimate future water losses due to climatechange. They projected that by 2100, waterlevels in the Caspian Sea could drop by another8 to 30 metres. The use or diversion of water forhuman activity is also an important driver of water
loss in the Caspian. Accounting for this factor
adds up to 7 metres of further loss, they found.

Figure 2 - Caspian Sea in 2022

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

www.geo-web.org.uk

9Volcanic Plumes in the Kuril Islands
NASA Earth Observatory
Story by Kathryn Hansen

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

More than 50 islands comprise the Kuril Islands,
an archipelago that extends from the Kamchatka
Peninsula to Japan. The island chain contains
dozens of active volcanoes capable of unleashing
explosive eruptions. In October 2022, eruptions
at two volcanoes, Chikurachki and Alaid,
simultaneously sent plumes of ash streaming overthe Pacific Ocean.
The two plumes are visible in this natural-colour
image above, acquired on October 16, 2022, with
the Moderate Resolution Imaging Spectroradiometer(MODIS) on NASA’s Aqua satellite. Around the time
this image was acquired, winds had carried the ash
more than 500 kilometers toward the southeast.
The fainter of the two plumes came from Alaid, theisland chain’s tallest and northernmost volcano.
According to the Kamchatkan Volcanic Eruption
Response Team, activity at the volcano had beenongoing since October 7, followed by explosive
activity on October 16. The explosive event lofted ash
almost four kilometres above sea level.
The more prominent plume came from
Chikurachki—one of at least five active volcanoes
on Paramushir Island. Explosive activity from this
volcano also began on October 16, sending ash up to
4.5 kilometers. The aviation colour code was raised
to orange, the second-highest level on the scale,alerting the aviation sector of the actively erupting
volcano and its minor ash emissions. Ash emissions
waned on October 17, and by October 18, thevolcano was emitting only puffs of steam and gas.
Volcanoes in the Kurils and similar island arcs in the
Pacific Ring of Fire are fed by magma generated along
the boundary between two tectonic plates, where one
plate is being driven beneath the other, a process
known as subduction.

www.geo-web.org.uk

10

Deadly Flooding in Pakistan
Les Hamilton
Based on a MODIS Web Image of the Day Report

Image Credit: MODIS Land Rapid Response Team, NASA GSFC

Severe monsoon rains have battered Pakistan since midJune 2022, creating a massive disaster that has affected
about 30 million people. According to the Pakistan National
Disaster Management Authority (NDMA), as of August 29
an estimated 1,136 people had died since June 14 with anadditional 1,634 being injured. Floodwaters damaged morethan 3,400 kilometres of roads—more than the straight-line
north-to-south distance across the United States from its
border with Alberta, Canada and the Mexico border. The
NDMA reported that 162 bridges and 170 shops had beendamaged and 735,375 livestock had died.
Reliefweb, a publication of the UN Office for the
Coordination of Humanitarian Affairs (OCHA) statesthat floods have affected Balochistan, Sindh, GilgitBaltistan, Punjab, Azad Jammu and Kashmir, andKhyber Pakhtunkhwa (KPK) provinces of Pakistan. As of
August 29, they reported that around one million homes
had been totally or partially damaged, leaving behind
millions in need of urgent shelter.

The left-hand image above shows the Indus River andadjacent floodplain in the Sindh province of Pakistan as
acquired by the MODIS instrument on board NASA’s Terrasatellite on August 27, 2022. The right-hand image shows
the identical scene on September 27, 2021.
This type of false-colour image uses infrared and visible
light (MODIS bands 7,2,1) to help distinguish water fromland. Water appears in various shades of blue, depending
on depth and any sediment present in the water, with the
deepest water looking the darkest. Vegetation shows asbright green while open or sparsely vegetated land looks
tan. Cloud ranges from white to electric blue.
These images clearly show the difference between amore normal monsoon season such as in 2021, when
the flood plains near the Indus were green and the river
remained within its banks, and the catastrophic and deadly
inundation of the 2022 monsoon.

www.geo-web.org.uk

11

VISAN Gallery
Richard Osborne

In Issue 74 of the GEO Newsletter [1], I described my early attempts to use the VISAN
tool for visualising Satellite Application Facility (SAF) products. Since that time, I haveproduced a series of Python scripts which allows the use of VISAN across a number of
the SAF areas. Whilst VISAN does not have the analytical features of, say, NASA Panoply
or ESA SNAP, it does have have an interactive 3D globe visualisation capability thatprovides a useful “quick-look” feature. It also allows multiple input files which are notgeographically related to be viewed on a single image.
To demonstrate the capabilities of VISAN, I have prepared a short gallery of globe
images. They are not related in time as they are prepared, at random, from some of myarchived data.
Any reader interested in obtaining further information, including sample scripts, can beobtained from me at the following emil address

info@woodcroft.me.uk
Reference

1 Visualising EUMETCast SAF Products using the VISAN Tool
GEO Quarterly No 74, page 35

Figure 1
Antarctic Sea Ice Concentration from AMSR-2
sensor on GCOM satellite

Figure 2
Arctic Sea Ice Concentration AMSR-2 sensor
on GCOM satellite

Figure 3
Global Snow Cover from METOP observations

Figure 4
Evapotranspiration from MSG observations

www.geo-web.org.uk

12

Figure 5
Land Surface Temperature from MSG
observations

Figure 6
Nitrogen Dioxide (NO2) levels from GOME sensor on
METOP. The “hot-spots” are clearly visible as red areas.

Figure 7
Ozone levels from GOME sensor on METOP. The
depletion over the Antarctic is clearly visible

Figure 8
Soil Moisture levels from METOP observations

Figure 9
Sea Surface Temperature from MSG and GOES
observations. The MSG and GOES data is provided in two
separate files which are combined prior to image generation.

Figure 10
Wind Speed from METOP observations

www.geo-web.org.uk

13Spain’s Yesa Reservoir Severely Affected by Extreme Drought
Copernicus Image of the Day

Credit: European Union, Copernicus Sentinel-2 imagery

The Yesa reservoir, situated in the Pyrenees
mountain range in Spain, is a source of drinking
water for tens of thousands of people living in the
Navarra and Aragón autonomous regions. After avery dry summer, in which several heatwaves withrecord-breaking temperatures hit Western Europe,
Spain remains gripped by an extreme drought. The
Yesa reservoir is currently at 16% of its capacity, thelowest level recorded at this time of the year since
1980.

The striking difference in water levels is visible inthese images, acquired on 2 July 2022 (above) and
20 September 2022 (below) by Copernicus Sentinel-2
satellites.
Open data retrieved by the Copernicus Sentinel
satellites provide key information useful to accurately
map water bodies and extract critical information
during periods of drought.

www.geo-web.org.uk

14

Fuel Regulation Reduced Air Pollution from Shipping
NASA Earth Observatory
Story by Sally Younger/NASA’s Earth Science News Team

Ship tracks, the polluted marine clouds that
trail ocean-crossing vessels, are a signature ofmodern trade. Like ghostly fingerprints, they
trace shipping lanes around the globe, from theNorth Pacific to the Mediterranean Sea. But in
2020, satellite observations showed fewer of thosepollution fingerprints.
Drawing on nearly two decades of satellite imagery,researchers found that the number of ship tracks
fell significantly after a new fuel regulation went into
effect. A global standard implemented in 2020 by theInternational Maritime Organization (IMO)—requiring
an 86% reduction in fuel sulphur content—probably
reduced ship track formation. COVID-19-relatedtrade disruptions also played a small role in the
reduction.
Scientists used advanced computing techniques
to create the first global climatology (a history ofmeasurements) of ship tracks. They used artificial
intelligence to automatically identify ship tracks
across 17 years of daytime images captured between
2003 and 2020 by the Moderate Resolution Imaging
Spectroradiometer (MODIS) on NASA’s Aqua satellite.
The map at the top of this page shows the density ofship tracks identified between those years, calculated
as a percentage of the total low-level marine cloudlayer.

Ship Tracks over the Pacific Ocean imaged by Suomi NPP

on December 7, 2021

“Without this kind of complete and large-scale
sampling of ship tracks, we cannot begin tocompletely understand this problem,” said leadauthor Tianle Yuan, an atmospheric scientist atNASA’s Goddard Space Flight Center.
Ship tracks were first observed as ‘anomalous
cloud lines’ in early weather satellite images

www.geo-web.org.uk

15

acquired in the 1960s. They are formed bywater vapour coalescing around small polluting
aerosol particles in ship exhaust. These highly
concentrated droplets scatter more light—and
therefore appear brighter—than non-polluted
marine clouds, which are seeded by larger
particles such as sea salt. A criss-crossing
pattern of ship tracks off the Pacific coast of
North America is visible in the natural-colour
image above, acquired on December 7, 2021,
with the Visible Infrared Imaging Radiometer
Suite (VIIRS) on the Suomi NPP satellite.
By capping fuel sulphur content at 0.5% (downfrom 3.5%), IMO’s global regulation in 2020changed the chemical and physical compositionof ship exhaust. Less sulphur emissions mean
there are fewer of the aerosol particles released
to form detectable ship tracks.
According to Yuan and colleagues, similar but
regionally defined sulphur regulations—such as
an IMO Emission Control Area in effect since2015 off the west coast of the USA and Canada—
had not had the desired effect because operators
altered their routes and charted longer courses
to avoid the designated zones.
While analysing 2020 data, the researchers
found that ship-track density fell that year in
every major shipping lane. (See the map above.)
Ship-based tracking data indicated that the
COVID-19 pandemic played a role by decreasing

global shipping traffic by 1.4% for a few months.
But this change alone could not explain thelarge decrease in observed ship tracks, which
remained at record-low levels through several
months of 2021 (the most recent data analysed).
The researchers concluded that the new global
fuel regulation played the dominant role in
reducing ship tracks in 2020.
Over the long span of their analysis, Yuan
and colleagues also found that fluctuations ineconomic activity leave distinct traces in thesatellite record. In particular, Trans-Pacific ship
track patterns between Asia and the Americas
reflect dips and spikes in trade. As outlined in
the study, a general upward trend in shipping
activity between 2003 and 2013—reflected in
ship-track clouds—reversed for about a year
in the aftermath of the 2008 global financial
crisis. An even sharper decrease between 2014
and 2016 likely reflected a slowdown in Chinese
imports and exports of raw materials andcommodities.
Beyond their world trade significance, ship
tracks can serve as case studies for anelement of climate change. ‘Ship tracks are
great natural laboratories for studying theinteraction between aerosols and low clouds,
and how that impacts the amount of radiation
Earth receives and reflects back to space,’
Yuan said. ‘That is a key uncertainty we facein terms of what drives climate right now.’

NASA Earth Observatory images by Joshua Stevens, using data courtesy of Yuan, T., et al. (2022) and VIIRS
data from NASA EOSDIS LANCE, GIBS/Worldview, and the Suomi National Polar-orbiting Partnership. .

www.geo-web.org.uk

16

Ozone Hole Continues Shrinking in 2022
NASA Earth Observatory
Story by Kathryn Cawdrey, NASA Earth Science News TeamThe annual Antarctic ozone holereached an average area of
23.2 million square kilometres
between September 7 andOctober 13, 2022. This depleted areaof the ozone layer over the South
Pole was slightly smaller than the
average for the same period last yearand generally continued the overall
shrinking trend of recent years.
‘Over time, steady progress
is being made, and the holeis getting smaller,’ said Paul
Newman, chief scientist for Earthsciences at NASA’s Goddard
Space Flight Center. ‘We seesome wavering as weatherchanges and other factors makethe numbers wiggle slightly fromday to day and week to week.
But overall, we see it decreasing
through the past two decades.
The elimination of ozonedepleting substances through theMontreal Protocol is shrinking thehole.’The ozone layer—the portion of thestratosphere that protects our planet
from the Sun’s ultraviolet rays—
thins to form an ‘ozone hole’ above
the South Pole every September.
Chemically active forms of chlorine
and bromine in the atmosphere,
derived from human-produced
compounds, attach to high-altitudepolar clouds each southern winter.
The reactive chlorine and bromine
then initiate ozone-destroying
reactions as the Sun rises at the endof Antarctica’s winter.
Researchers at NASA and NOAA
detect and measure the growthand breakup of the ozone hole with
instruments aboard the Aura, Suomi
NPP, and NOAA-20 satellites. On
October 5, those satellites observeda single-day maximum ozone hole of
26.4 million square kilometres, slightly
larger than last year. The map at the
top of this page shows the size andshape of the ozone hole over theSouth Pole on that day.

NASA Earth Observatory image by Joshua Stevens, using data
courtesy of NASA Ozone Watch and GEOS-5 data from the Global
Modeling and Assimilation Office at NASA GSFC

When the polar sun rises, NOAA
scientists also make measurementswith a Dobson Spectrophotometer,an optical instrument that records
the total amount of ozone between
the surface and the edge of space—known as the total column ozone
value. Globally, the total column
average is about 300 Dobson Units.
On October. 3, 2022, scientists
recorded a lowest total-column ozone
value of 101 Dobson Units over theSouth Pole. At that time, ozone wasalmost completely absent at altitudes

between 14 and 21 kilometres—apattern very similar to last year.
Some scientists were concerned
about potential stratospheric impacts
from the January 2022 eruption of
the Hunga Tonga-Hunga Ha‘apai
volcano. The 1991 Mount Pinatubo
eruption released substantial amountsof sulfur dioxide that amplified ozone
layer depletion. However, no direct
impacts from Hunga Tonga have been
detected in the Antarctic stratospheric
data.

What is the Ozone Hole?
Learn more about the ozone hole in this YouTube video from NASAhttps://www.youtube.com/watch?v=Q15t5NQ1Aik

NASA Ozone Watch
Follow the status of the oxone hole athttps://ozonewatch.gsfc.nasa.gov/

www.geo-web.org.uk

17

Svalbard
European Space Agency

Svalbard archipelago
Image contains modified Copernicus Sentinel data (2022), processed by ESA, CC BY-SA 3.0 IGO

Extremely high temperatures recorded this summer
caused record melting across Svalbard—one of
the fastest warming places on the planet. The
Copernicus Sentinel-2 mission captured this rare,
cloud-free acquisition of the Norwegian archipelago
during August 2022.

Located north of mainland Europe, Svalbard isapproximately midway between the northern coastof Norway and the North Pole. The archipelago,which spans around 62 700 square kilometres,is composed of nine main islands. The largest is
Spitsbergen, visible above in the far-left, followed bywww.geo-web.org.uk

18

Nordaustlandet in the top-right and
Edgeøya in the bottom-right.
Spitsbergen, which is around the same
size as Switzerland, has a mountainous
terrain with most of the island covered
with glaciers. Its highest point it
Mount Newton, around 1717 metres,in the northeast. The island is deeply
indented by fjords. The longest fjord of
the archipelago is Wijdefjorden, shown
opposite,which is 108 kilometres long.
Opening on Spitsbergen’s north coast,
it runs roughly southwards into theinterior, separating Andrée Land in thewest from Margaretas Land in the east.
Also on Spitsbergen lies the Svalbard
Satellite Station—SvalSat for short—which is operated by Kongsberg
Satellite Services (KSAT), andhas worked with a range of Earthobservation missions including Aeolus,
Swarm, CryoSat and all Copernicus
Sentinel satellites.
The station is also important to the
Galileo satellite navigation system,
Europe’s global navigation satellite
system. Its location makes it one of themost remote Galileo ground stations in
the world.
This summer saw exceptionally warm
air temperatures in Svalbard according
to the Norwegian Meteorological
Institute. An average of 7.4 °C wasrecorded during June, July and August
compared with the 5.5°C average
recorded during the 1991-2020 period.
The heatwave caused exceptional
levels of melting, which ultimately
contributes to sea level rise.
The image on the previous page,
captured on August 21, shows thelarge, colourful sediment discharges
in the Arctic Ocean. This is probably
due to sediments eroded from bedrockby the flow of ice and then carried by
meltwater into the Arctic Ocean. Thereis also some phytoplankton present
in the waters, as seen in the far right,
which colours the water turquoise andgreen.
Data acquired by the Copernicus
Sentinel satellites are used to detectchanges in Earth’s surface in great
detail and monitor the effects of climatechange on remote environments suchas the Arctic region.

A high resolution view of Wijdefjorden
Image contains modified Copernicus Sentinel data (2022),
processed by ESA, CC BY-SA 3.0 IGO

www.geo-web.org.uk

19

Rocky Road for Swiss GlaciersNASA Earth Observatory
Story by Kathryn Hansen

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

In 2022, glaciers in the Swiss Alps melted more than any
other year on record. This was the latest downturn for thecountry’s glaciers, which have lost more than half of theirvolume of ice since the 1930s.

remain snow-covered all year, but in recent decades
winter snow has disappeared in summer, allowing the firn
and ice to melt. The record losses in 2022 finally exposed
the bare ground between the glaciers.

This pair of natural-colour images shows the changes
to a glaciated area in western Switzerland in just overtwo decades. The right image was acquired on August25, 2022, with the Operational Land Imager-2 (OLI-2)
on Landsat 9. For comparison, the left image shows
the same area on August 15, 2021, acquired with the
Enhanced Thematic Mapper Plus (ETM+) on Landsat 7.

The melting season for Switzerland’s snow and ice
typically starts in May and ends in early October. Melting
in 2022 caused the Tsanfleuron and Scex Rouge glaciersto thin by an average of 4 metres—about triple theaverage degree of thinning observed at Swiss glaciers in
the past decade, according to Huss. GLAMOS data showthat across Switzerland in 2022, glaciers lost about 6% of
their remaining volume—exceeding the previous record in2003 when losses were almost 4%.

The images feature the Tsanfleuron and Scex Rouge
glaciers, located in the Diablerets mountain group.
The glaciers rest on different sides of a mountain slope
but have long been connected at Tsanfleuron pass.
According to Matthias Huss, director of the Swiss Glacier
Monitoring Network (GLAMOS), melting during summer
2022 exposed a rocky path between the two glaciers at
Tsanfleuron pass for the first time in several thousand
years.
The pass is located near the highest point of the two
glaciers in an area where snowfall has historicallyaccumulated. The snow eventually turns into acompressed porous layer, known as ‘firn’, which in turn
becomes glacial ice. In a healthy state, the pass should

One reason for the significant amount of melting in 2022
was the small amount of snowfall the previous winter. The
snow melted quickly, speeded up in spring by the warming
effect of dust from the Sahara Desert falling on the snow.
By early summer, the glaciers had lost their protective
blanket of snow, leaving them vulnerable to the summer
heat.
Despite the summer heat, melting stopped relatively early
this year. ‘Already from mid-September onwards there
was a bit of fresh snow every week,’ said Huss. ‘This does
not change anything regarding the incredible losses of2022, but at least they are not going on at the moment.’

www.geo-web.org.uk

20

Seasonal changes in Antarctic ice sheet flow Dynamics
European Space Agency

Certain estimates of Antarctica’s total contribution to
sea-level rise may be over, or even underestimated,
after researchers detected a previously unknown sourceof ice loss variability. In a new paper published in The
Cryosphere, researchers using Copernicus Sentinel-1
data, found that glaciers feeding the George VI Ice Shelf
speed up by approximately 15% during the Antarctic
summer. This is the first time that such seasonal cycles
have been detected on land ice flowing into ice shelves in
Antarctica.
Although it is not unusual for ice flow in the Arctic regions
to speed up during summer, scientists had previously
assumed that ice in Antarctica wasn’t subject to thesame seasonal movements. This was partly becausetemperatures remain below freezing for most of the year,
but also due to the lack of systematic monitoring of ice flow
over the continent’s ice margins.
Prior to the detailed records of ice speed made possible bySentinel-1 satellites, scientists wanting to study short-term

Antarctica

variations in Antarctic-wide ice flow relied on informationcollected by optical satellites such as NASA’s Landsat 8.

Ice flow veloity of the George V Ice Shelf

www.geo-web.org.uk

21

The advantage of radar as a remote sensing tool is thatit can image Earth’s surface through rain and cloud, andregardless of whether it is day or night. This is particularly
useful for monitoring areas prone to long periods ofdarkness.

Ice Sheet, so the questions it raises regarding
the possible presence and causes of seasonality
elsewhere in Antarctica are really interesting. We lookforward to taking a closer look at, and shedding lighton, these important questions.’

Thomas Nagler, co-author of the paper and ENVEO’s
CEO, commented, “Optical measurements can only
observe Earth’s surface on cloud-free days during
summer months, but by using Sentinel-1 radar
imagery, we were able to discover seasonal ice-flowchange thanks to the ability of these satellites tomonitor year-round and in all-weather conditions.”

Radar vision
Sentinel-1A was the first satellite to be launched for
Copernicus—the Earth observation component of theEuropean Union’s space programme. Carrying advanced
radar technology and providing an all-weather, day-andnight supply of imagery of Earth’s surface, the ambitious
Sentinel-1 mission raised the bar for spaceborne radar andset the stage for Europe’s Copernicus programme.

The causes of these seasonal changes are uncertain.
They could be caused by surface meltwater reaching thebase of the ice, acting as a lubricant, or it could also be
due to relatively warm ocean water melting the ice frombelow, thinning the floating ice and allowing upstream
glaciers to move faster.
These results imply that similar seasonal variability may
exist at other, more vulnerable sites in Antarctica, such as
the Pine Island and Thwaites glaciers in West Antarctica.
Co-author Ian Willis stated, ‘It’s the first time thisseasonal signal has been found on the Antarctic

Mark Drinkwater, Head of the ESA’s Earth and Mission
Science Division commented: ‘Systematic, year-roundmonitoring of Antarctica with the Copernicus Sentinels
has revolutionised our insight into the variability in
ice-sheet behaviour on shorter timescales than everbefore.’Over the past few decades, the Antarctic Peninsula ice
has undergone some of the most dramatic changes in
response to climate warming. While we often think thatwhat happens in Antarctica won’t affect us in Europe, thecontinued on page 27

Timing of peak ice flow velocity

www.geo-web.org.uk

22

Seasonal Greening of the Inner Niger Delta
NASA Earth Observatory
Story by Kathryn Hansen

Each year from around August
to December, a burst of green
overtakes the typically brownlandscape of central Mali. The
greening is due to aquatic grasses
and other vegetation taking
advantage of the seasonal inflow
of water that spreads across the
Inner Niger Delta—the largest
inland delta in western Africa. In
October 2022, water reached thehighest levels seen in more than
50 years.
The Moderate Resolution Imaging
Spectroradiometer (MODIS) on
NASA’s Terra satellite acquired
figure 1 on November 3, 2022,
about a week after water levels
peaked in the southern part ofthe inland delta. For comparison,
figure 2 was acquired by MODIS
on NASA’s Aqua satellite shows
the same area in May 2022—atime of year when the delta isrelatively dry.
The Niger River’s headwaters
lie about 900 kilometres tothe southwest in the Guinea
Highlands. Wet season rains
across the Upper Niger Basincause the Niger River to swell,which then flows northeast toward
the inland delta. Joined by theBani River near Mopti, waterfrom the river systems spreads
across the floodplain into a broad
network of channels, wetlands,
and islands.

Figure 1 - The inner Niger Delta on November 3, 2022
NASA Earth Observatory images by Lauren Dauphin, using MODIS data from NASA
EOSDIS LANCE and GIBS/Worldview.

upper basin in July and Augustis usually a good indicationof the amount of flooding thatwill happen across the delta by
October through December. In
July and August 2022, rainfall
was well above the 2001–2021
average. According to a bulletin
from OPIDIN, flooding on the

Inner Niger Delta peaked at the
town of Mopti in late October
2022 at 675 centimetres—thehighest levels seen since 1969.
Water inundated 19,000 square
kilometres of the delta.
As the parched landscape
becomes saturated, the deltacontinued on page 27

The process plays out overmonths, with flooding influenced
by the cumulative amount of
rainfall across the entire wet
season. The timing of the wet
season varies across the Upper
Niger Basin. In the mountainous
upper reaches of the Niger River,
the wet season extends fromMarch to October. Across theentire West Africa region, thewettest month is usually August.
Despite these variations, theamount of rainfall across the

Figure 2 - The inner Niger Delta during May, 2022
NASA Earth Observatory images by Lauren Dauphin, using MODIS data from NASA
EOSDIS LANCE and GIBS/Worldview.

www.geo-web.org.uk

23

More Flooding in Australia’s Soggy Southeast
NASA Earth Observatory
Story by Kathryn Hansen

After an extremely wet October, southeast Australia continued to see heavy rainfall throughout November
2022. With soils already saturated and dams full, the latest storms have added to ongoing flooding across
New South Wales and Victoria.
Widespread flooding
is visible in figure 1,
a false-colour
image acquired on
November 18, 2022
by the Moderate
Resolution Imaging
Spectroradiometer(MODIS) on NASA’s
Terra satellite. Water
appears light to dark
blue.
Vegetation is green andbare land is brown. For
comparison, figure 2(overleaf), a MODIS
image from the Aqua
satellite, shows thesame area on June
28, 2022, prior to theexcessive rainfall.
In the week leading up
to November 14, large
parts of New South
Wales and Victoria
experienced more than
50 millimetres of rain.
The town of Forbes,
New South Wales,
had the highest daily
total for the week, 118
millimetres falling inthe 24-hour period
spanning November
13–14.
The abundant rainacross the region
caused rivers to riseand flood nearby towns.
Forbes saw its third
major flood event in justfour weeks as waters on
the Lachlan River rose
faster than expected.
October 2022 was thewettest October onrecord in the MurrayDarling basin, an

Figure 1
This MODIS image from NASA’s Terra satellie was acquired on November 18, 2022
NASA Earth Observatory image by Lauren Dauphin, using MODIS data from NASA
EOSDIS LANCE and GIBS/Worldview

area that includes
the permanent andimpermanent rivers
and streams pictured
above. With soils alreadysaturated, rainfall in
November quickly led to
flash flooding across New
South Wales and Victoria.
Emergency responders
rescued hundreds ofpeople stranded by flood
waters across the region.

Water that seeps deep
into the soil can influence
groundwater levels
for months. The map(figure 3) depicts shallow
groundwater storage inAustralia from November
11–14, 2022, as
measured by the Gravity
Recovery and Climate
Experiment Follow-On(GRACE-FO) satellites.
The colours depict thewetness percentile: thatis, how the levels ofgroundwater comparewith the long-term record(1948–2012). Blue areas
have more abundant
water than usual, andorange and red areas
have less.
The extent to whichsuch rainfall affects thegroundwater level varies
by location and depends
on a range of factors
continued on page 25

www.geo-web.org.uk

24

Figure 2
This MODIS image from NASA’s Aqua satellie was acquired on June 28, 2022
NASA Earth Observatory image by Lauren Dauphin, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview

continued from page 24

such as soil type, aquifer depth,
and vegetation. Time is also afactor, as rainfall accumulations
from months past can influencecurrent groundwater levels.
One reason for the wetness ismost likely La Niña, which has
returned for three consecutive
years. La Niña events caninfluence weather in different
ways across the planet. In
Australia, they usually bringheavy rainfall and flooding.

Figure 3
NASA Earth Observatory image by Lauren Dauphin, using GRACE datafrom the National Drought Mitigation Center.

www.geo-web.org.uk

25

Hudson Bay’s Nastapoka Arc
NASA Earth Observtory
Story by Sara E. Pratt

NASA Earth Observatory image by Lauren Dauphin, using VIIRS data from NASA EOSDIS LANCE,
GIBS/Worldview, and the Joint Polar Satellite System (JPSS).

In northeastern Canada, just south of the Arctic Circle,
the Hudson Bay spans more than 1.2 million square
kilometres. It is the world’s second-largest bay, after the
Bay of Bengal, and the site of a geologic puzzle.
The southeastern shore of the bay forms a 155-degree
curve, called the Nastapoka Arc, which appears to be partof a nearly perfect circle 450 kilometres in diameter. The
imaginary circle traces the coast of Quebec on one sideand grazes the Ontario shore on the other. At its centre
lie the Belcher Islands. Such a smoothly curved feature is
not often found in nature and has prompted much geologic
debate.
This image, acquired on August 16, 2022, by the Visible
Infrared Imaging Radiometer Suite (VIIRS) on the
NOAA-20 satellite, shows Hudson Bay and its curved
southeastern shore.
This shoreline traces the boundary between two distinctgroups of rocks. Onshore, the Superior Province gneisses
are hard metamorphic rocks that formed 3 billion to 2.7
billion years ago. Offshore lie the Nastapoka Group

supracrustal rocks, which formed during the earlyProterozoic Eon, 2.5 billion to 1.6 billion years ago.
These rock formations are part of the largest single belt ofArchean-aged rocks in the world (the Archean Eon lasted
from 4 billion to 2.5 billion years ago). They form the coreof the Canadian Shield and the North American craton,
the stable central core of the continent on to which othermicrocontinents would later accrete to build the landmass
we know today. This tectonic history is key to the prevailingtheory for the arc’s formation.
Geologists now generally believe the arc resulted from acontinental collision, a 2-billion-year-old mountain-building
episode called the Trans-Hudson orogeny. As ancient
continents collided, the crust buckled and fractured into
slices that could thrust past each other to accommodate
the compression. This formed a fold-and-thrust belt, theremnants of which are exposed today in the folds of theBelcher Islands. Farther to the east, where the Nastapoka
Arc lies today, the collision produced a foreland basin.
Gravity data collected in the early 1990s suggests theload placed on the crust by the fold-and-thrust belt could
continued on page 27

www.geo-web.org.uk

26

Seasonal Greening of the Inner Niger Delta
continued from page 23
greens. Partly floating long-stemmed grasses
dominate the delta, including Echinochloa stagnina.
This species, known locally as bourgou, is often
planted by people and used for animal feed. There isalso plenty of wild rice, or Oryza longistaminata. The
light-brown areas branching across the greenery aresand ridges and drying stream channels.
The flooding progresses from the southwest to thenortheast. After peaking at Mopti, water levels arenext expected to peak in the central part of the deltaduring the last week of November, and then peak in
the north over a week later.

Hudson Bay’s Nastapoka Arc
continued from page 26

have caused the centre of the basin to sink, forcing up theedges, resulting in the curvature.
Other theories have also been put forth. In the late 1960s,
Canadian astrophysicist Carlyle Beals suggested the arc
could be the rim of an ancient impact structure, with theBelcher Islands representing the crater’s uplifted central
peak. However, a field investigation in the 1970s turned
up none of the usual evidence indicative of an impact,
such as shocked quartz, radial fractures, melted rocks, orshatter cones.
Around that time, another researcher suggested theshoreline was a scar marking where a continent had pulled
apart, or rifted. A nearby tectonic plate with a somewhat
curved edge suggests it may have once fit together withthe arc like two puzzle pieces.

The debate continues today. In the mid-2000s, a
researcher suggested that the curving shoreline of Hudson
Bay could be an ancient impact crater that has been soreworked by geologic processes that the evidence of
impact has been obscured.

Seasonal changes in Antarctic ice sheet flow dynamics
detected for the first time
continued from page 22

environmental changes happening in Antarctica will be
felt at a global scale. When the ice sheets melt, sea levelaround the planet will rise—displacing millions of people
and dramatically changing coastlines.
This new evidence of a connection between Antarctic
circumpolar ocean conditions and seasonal ice flow sheds
new light on the regional factors contributing to dynamic
ice loss and sea-level rise.
At the forthcoming ESA Council at Ministerial Level in
November 2022, ESA seeks a second phase of funding for
its Copernicus Space Component Programme, enabling
the first satellites of the Next Generation Sentinel-1 andSentinel-3 Topography series to be developed and further
securing the outlook for long-term persistent monitoring of
Antarctic ice sheet.
With the Next Generation of the Copernicus Sentinels,
together with the ROSE-L, CRISTAL and CIMR Sentinel
Expansion missions already in development, Drinkwater
added that their combined capabilities are going to provide
critical input data for ESA’s pilot Digital Twin Antarctica andthe Destination Earth (DestinE) initiatives. These digital
replicas will in turn will enable us to better predict the
speed and consequences of the ice sheet’s demise.

Italy’s Stromboli Erupts
European Spae Agency
A volcano on the Italian island of Stromboli erupted
early on the morning of October 9, 2022, releasing huge
plumes of smoke and a lava flow pouring into the sea. The
Copernicus Sentinel-2 mission captured this image of theaftermath less than five hours after the eruption.
The eruption caused the partial collapse of the crater
terrace which was followed by major flows of lava
stretching to the sea and enormous plumes of smoke
rising several hundred metres above the volcano.
This Sentinel-2 image has been processed in true colour,
using the shortwave infrared channel to highlight the
new flow of lava. The northernmost island of the Aeolianarchipelago, located just off the northern tip of Sicily,
Stromboli’s volcano has been erupting almost continuously
for the past 90 years.

Image contains modified Copernicus Sentinel data (2022),
processed by ESA, CC BY-SA 3.0 IGO

www.geo-web.org.uk

27

www.geo-web.org.uk

28