Group for Earth Observation

No 66 - June 2020

Mount St Helens eruption anniversary: 40 years since May 18, 1980
Photo © Mike Doukas - USGS Cascades Volcano Observatory
Public Domain, https://commons.wikimedia.org/w/index.php?curid=680506

Useful User Groups

GEO MANAGEMENT TEAM
Director and Public Relations

Weather Satellite Reports

Francis Bell,

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

Coturnix House, Rake Lane,
Milford, Godalming, Surrey GU8 5AB,
England.
Tel:

01483 416 897

email: francis@geo-web.org.uk

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

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

GEO Newsletter Editor

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

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

Technical Consultant (Hardware)David Simmons

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/

email: tech@geo-web.org.uk

Webmaster and Website Matters
Alan Banks,e-mail: webmaster@geo-web.org.uk

Management TeamDavid Anderson
Rob Denton
Nigel Evans
Clive Finnis
Carol FinnisPeter GreenDavid SimmonsDavid Taylor

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Les Hamilton

It will hardly come as a surprise to readers that the planned joint EUMETSAT visit
for Werkgroep Kunstmanen and GEO members in early July has been cancelled.
With much of Europe in lock‑down, airlines inactive and the hospitality industry at
a standstill, EUMETSAT had no option but to cancel the event. Here follows the textof the conﬁrmation email sent to Ben Schellekens by EUMETSAT’s Kim Hui Gaune.
Dear Ben,I hope you are doing well.
I have to inform you, with regret, that considering the current situation, the GEO visit to EUMETSAT
early July has to be cancelled.
We hope to be able to welcome the GEO Group again in the near future.
All the best,
Kim Hui GauneS

ome good has come of the lock-down however, with authors ﬁnding time on
their hands to create articles for the Newsletter. Ed Murashie and David Taylor
have pooled their resources to outline a project to view satellite imagery in Virtual
Reality that may appeal to you, and there are two articles from John Tellick.

There is no leader article this issue as there have been no rally visits or other
GEO activities to report. But Francis Bell remains in good health, and has
provided a rather interesting Quarterly Question. Hopefully, as summer evolves, wewill all be able to enjoy more freedoms, and GEO will be able to show its presence atrallies once more.

Contents
Quarterly Question
Francis Bell
Violent Puffs from Krakatau
NASA Earth Observatory
Sentinel-1 Composite Image of English Channel Shipping Traffic John Tellick
Dutch Tulip Fields come into Bloom
European Space Agency
Viewing Satellite Images using Virtual Reality
Ed Murashie/David Taylor
Launch of Meteor M2-3 delayed till 2021
Les Hamilton
Iceberg Shattered
European Space Agency
Easter Island
European Space Agency
Northwest GreenlandNASA Earth Observatory
Mount St Helens
NASA Earth Observatory
Meteor M2-2 still transmitting AHRPT Imagery
Les Hamilton
Greenland, Antarctica melting six times faster than in the 1990s NASA / JPL
Sun/satellite/dish co-linearity- Solar Outage
John Tellick
What are you doing during Lock-Down?
Les Hamilton
A68-A holding it together
NASA Earth Observatory
Evening Imagery from Meteor M2
Les Hamilton
Satellite Status

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Francis Bell
Quarterly Questions 55
My thanks to those individuals who responded to
the last Quarterly Questions. It’s reassuring to knowthat some people read the questions and take thetrouble to send in their answers.
The previous Quarterly in fact had two questions,
one relating to an image of a group of islands; theother a composite image of Antarctica. The islandgroup shown in the first question was the Faeroe
Islands, which are located in the Atlantic Ocean
about 300 miles north of mainland Scotland. The
pattern of the islands is quite distinct, hence theycaught my eye as a satellite image.
The question relating to Antarctica showed acomposite image of Antarctica but with a hole in the
middle of it. The question asked why was there ahole in the middle of the image. The answer relates
to the fact that it was a composite image which ismade up of a large number of individual images, but
none of the individual images included the South
Pole because the strips of the Earth imaged by eachsatellite pass did not quite include the South Pole.
When the images are put together in an attempt tocover the whole of the continent, the South Pole isjust missing each time.
Many polar orbiting satellites orbit the earth about
16 times a day hence the Antarctic composite
image is probably made up from 16 strips of images
but each one just missing the pole so, when put
together, the polar area is not covered. The resulting
hole will not be a smooth circle but a polygon withperhaps 16 edges. However, the resolution of theimage shown in the question was not fine enough toshow the many straight edges to the hole but rather
it look like smooth circle.
Quarterly Question 66
I notice that the last four Quarterly Questions haverelated to the identification of islands: they were,
Easter Island, Gran Canaria, Bahrain and the Faroe
Islands. This question is almost the opposite, andasks what point on the Earth’s oceanic surface isfarthest from any land?
In your answer give the Latitude and longitude ofthis point to the nearest whole degree or just say
where it is.
To help you identify the location in question it issometimes called Point Nemo (although it does
have other names), and is positioned about 1,670

Point Nemo, the Oceanic Pole of Inaccessibility, lies within theconfines of this 21:00 UT GOES-W image from June 1, 2020.
Image: NOAA

miles from land in any direction. Nearest landfalls
are Ducie Island to its north (part of the Pitcairn
Islands), Motu Nui to its northeast (part of the Easter
Islands group) and Maher Island off the coast ofMarie Byrd Land, Antarctica, to its south.
Here is the real issue in my mind related to thequestion:‘Why is this point so important to
the international space industry?’
And a final part to this Quarterly Question: What is
the English translation/meaning of the Latin word
‘nemo’
Answers to Francis Bell by email tofrancis@francisbell.com

before the copy deadline for our next Quarterly
Newsletter (August 30, 2020).

www.geo-web.org.uk

4Violent Puffs from Krakatau
NASA Earth Observatory
Story by Kathryn Hansen.

Anak Krakatau, imaged on April 13, 2020 by Landsat-8’s OLI instrument.
NASA Earth Observatory image by Lauren Dauphin, using Landsat data from the U.S. Geological Survey.

Anak Krakatau maintains a mighty
and sometimes menacing presencein the Sunda Strait between Java andSumatra, with more than 50 known
periods of eruptions in almost 2,000
years. The Indonesian volcano’s
latest burst of activity has produced
numerous plumes and lava flows,
including some relatively small but
notable events in April.
On April 13, 2020, the Operational
Land Imager on Landsat 8 acquired
this natural-colour image of the volcano(OLI bands 4-3-2) as a plume toweredover the peak. The image is overlain
with the infrared signature detected by
OLI of what is possibly molten rock.
‘The location of the plume suggeststhat it is volcanic in origin,’ said Verity
Flower, a Univrsities Space Research
Association volcanologist based atNASA’s Goddard Space Flight Center.
Flower and colleagues use the Multiangle Imaging Spectroradiometer(MISR) sensor on NASA’s Terrasatellite to measure the height of
volcanic plumes and to observe theshape, size, and light-absorbing
properties of the particles within them.
‘On April 12, I saw a similar feature in
one of the angular MISR images witha plume-like feature above the volcano
summit.’Based on the colour of the plume,
it is probably composed mostly ofwater vapour and gases. These small,reflective particles make a plumeappear white. Conversely, larger anddarker ash particles tend to look grayor brown in natural-colour images.
Note the darker part of the plume
extending toward the north: it appears
lower in altitude than the bright, billowy
part of the plume directly over the
peak. It is possible the heavier ash
particles emitted are staying lower
in the atmosphere and are beingtransported to the north by nearsurface winds. In contrast, any waterand gases within the plume, being lesswww.geo-web.org.uk

dense, would be transported higher
and would condense rapidly in theatmosphere.
Indonesia’s Center of Volcanology andGeological Hazard Mitigation (PVMBG)
reported that incandescent rock had
erupted onto the volcano’s surface with“insignificant intensity” in the days prior
to this image.
Anak Krakatau volcano has displayedthese small eruptive bursts periodicallythrough the last few years. However,it can also display more destructive
activity such as tsunami-triggering
eruptions.
According to the April 11 statementfrom PVMBG, the hazards from thevolcano’s recent activity included
fountains of lava, lava flows, and ash
rain within a radius of two kilometres
around the crater. Thinner ash rain
could extend even farther from thevolcano, depending on the strength ofwinds.

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Sentinel-1 Composite Image of English Channel Shipping Traffic
John Tellick

Figure 1 - English Channel Shipping Lanes as realised by the Copernicus Sentinel-1 Satellites
Copyright contains modified Copernicus Sentinel data (2016-18), processed by ESA, CC BY-SA 3.0 IGO

The two identical Copernicus Sentinel‑1 satellites
carry radar instruments which can see throughclouds and rain and in the dark, to image theEarth’s surface below. In figure 1, hundreds of radar
images spanning 2016 to 2018 over the same area
have been compressed into a single image to outline
the English Channel’s distinct shipping lanes.
.The sea surface reflects the radar signal away fromthe satellite, making water appear dark in the image.
This contrasts metal objects, in this case ships,
which appear as bright dots in the dark water. Boatsthat passed the English Channel in 2016 appear inblue, those from 2017 appear in green, and thosefrom 2018 appear in red.
Owing to its narrowness, as well as its strategic
connection of the Atlantic Ocean and the North Sea,
the Channel is very busy with east-west ship traffic.
Because of the volume of vessels passing throughdaily, a two-lane scheme is used, in order to avoid
collisions. The two lanes can easily be detected in
the image.
Many vessels crossing at the narrowest part of the
English Channel can be seen in the far right of
the image. Connecting Dover in England to Calais
in northern France, the Strait of Dover is anothermajor route, with over 400 vessels crossing everyday. The shortest distance across the Channel is just
33 kilometres, making it possible to see the opposite
coastline on a clear day.
The cities of London and Paris, other towns andbuildings and even wind turbines in the English
Channel are visible in white owing to the strong
reflection of the radar signal.

Figure 2
Detail from the main image showing the Rampion Wind Farm

For me, growing up on the Sussex coast in Lancing
I’m familiar with that part of the UK and also theStrait of Dover looking across to France. A closer
look at the full image of the Channel reveals thatseveral of the offshore wind farms are very noticeable
including the latest offshore wind farm to be built
in the UK between Worthing and Brighton—the
Rampion Wind Farm. Watching its construction
on odd visits to the coast over many months wasinteresting with all the construction and support
vessels just off the coast. Figure 2 shows theRampion Wind Farm off the Sussex coast withconstruction supply vessel routes and cable laying
vessel route.
The electricity cable from this wind farm comesashore to the west of Lancing and then travels

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across the South Downs in a trench for
27 kilometres—avoiding the use of pylons—
to a sub station at Bolney, mid Sussex.
What can clearly been seen in the close-up
image of the Rampion Wind Farm off theSussex coast in figure 2, is the ‘farm’ itself
and the building supply vessel routes fromthe ports of Shoreham (north) and Newhavento the east. The route of the vessels involved
with the laying of the electricity cable toLancing can also be seen.
In the eastern close-up image below, earlier
wind farm installations can be seen off the
Kent and Essex coasts (figure 4).
This image also shows the enormous
amount of shipping that passes throughcongested Strait of Dover, in addition totraffic between Dover and Calais.
CreditIntroductory Text comes from ‘English Channel’
on the European Space Agency website athttps://www.esa.int/ESA_Multimedia/
Images/2019/04/English_Channel

Figure 3 - The offshore and onshore electrical cable routes to
the Rampion Wind Farm.
Image: Rampion Windfarm Tours

Figure 4 - Detail from the main image showing the congested shipping lanes between Dover and Calais
Copyright contains modified Copernicus Sentinel data (2016-18), processed by ESA, CC BY-SA 3.0 IGO

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Dutch Tulip Fields come into Bloom
European Space Agency© Contains modified Copernicus Sentinel data (2020), processed by ESA, Creative Commons CC BY-SA 3.0 IGO

While the COVID-19 virus pandemic is forcing everybody
to stay at home, we bring you these beautiful views fromspace of the Dutch tulip fields coming into bloom. Capturedby the Copernicus Sentinel-2 mission on April 20, 2020,
this image shows the fields resplendent in an array ofvibrant colours. Lasting just a few weeks, the beauty ofthese colours normally attracts millions of visitors from allover the world. Sadly, this is not the case this year, as the
COVID-19 crisis means that people cannot travel and even
locals are actively discouraged from visiting the fields.

The image features the area around the small town ofLisse, home to the world-famous showcase for floriculture,
the Keukenhof flower park. The area, which lies close to
the coast in the Dutch province of South Holland, is famedfor producing bulbs which are exported all over the globe.
The fields are only in bloom for a few short weeks. Whenthe tulips reach full bloom, the farmers quickly remove theircolourful heads to divert the flowers’ energy back to thebulbs to help keep them strong.

www.geo-web.org.uk

8This morning NOAA 15 APT image obtained by Keith Fraser (Buffalo, NY) on March 7, 2020 shows interesting sun glint on Lakes
Ontario and Erie. Also visible, at top right, is the Triassic Manicouagan impact crater, its ice glinting in the sun.

www.geo-web.org.uk

9Viewing Weather Satellite Images Using Virtual Reality
Ed Murashie and David Taylor

Displaying satellite images has come a long way over the years. The first
technique used was photographing the screen of a cathode ray tube (CRT) while
the image was being received using a long exposure (figure 1). Later methods
including using a facsimile machine like the Muirhead (figure 2), or even homebuilt photo-facsimile machines.
Soon after, standalone scan converter designs digitised the signal, stored it inmemory and then read it out on a larger CRT [1] allowing the entire image tobe quickly viewed. The quantum jump came with the invention of the personal
computer and better printers, which allowed zooming, adding latitude andlongitude grids, country outlines, the creation of animations and many otherfeatures.
3D viewing of satellites was bound to happen when technology caught up.
One of the first approaches used two closely spaced polar satellite passes andstereo viewing glasses. The first computer technique used red/blue glasses withcolour anaglyph images. MSA 3-D Anaglyph images are generated using theInfrared image to simulate cloud height and then shift and color the visible image
accordingly. One program that has this capability is WXtoimg [2]. Another computer
based approach is to drape satellite images over digital elevation model data andthen the viewer’s perspective is moved to any height and angle [3,4].

Figure 1 - The man on the left islooking through the camera mounted
to the CRT as it is taking pictures.

NOAA created its unique version of a 3D display, Science on a Sphere [5]. This isa system of computers and projectors that project images and movies on a six footsphere, which has been installed in over 120 locations [6].
The next logical step is displaying satellite images using virtual reality. Using either
HTC VIVE or Oculus VR glasses, the Unity3D software, a remapping program,and either of your received geostationary images or NOAA’s website images [7],you can display the images in VR [8].

Figure 2 - A muirhead
fax machine from the 1960s

From here you have two options, you can either follow along using the step-by-step instructions below or watch a
training video [9] to learn how.
Install the HTC VIVE and then enjoy a game or two.
Minimum PC requirements can be found athttps://www.vive.com/eu/support/vive/category_howto/what-are-the-system-requirements.html

An HP Pavillon gaming desktop model 690-0024 with its AMD Ryzen5-2400G processor and Radeon RX 580 was usedin writing this article and making the tutorial video.
Installing Unity3D• To start, point your web browser to https://unity.com/.
• Click the blue Get started button è Individual tab è Personal è Get Started.
• Click either Start here for new users or Go here for return users.We are going to click on the Go here button.
• Click Accept terms box è Unity Hub è UnityHubSetup.exe.
• If you see a warning screen, click Yes to allow the app to make changes to your device.
• Click I Agree to accept the service terms è accept the default destination folder è Install è Finish.
• You may get a security warning about network access: if so, set the option you feel is safe and then Accept (orCancel to disallow network access).
• Click ADD in the Unity Hub window è NEXT to keep official version default selection (2019.3.9f1 at the time ofwriting.) è NEXT.
• Two boxes should be checked, Microsoft Visual Studio Community 2019 for building scripts, and Documentation,
click NEXT è check box to accept the Visual Studio License Terms è DONE.

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10This is a frame from the sample movie downloadable from reference [8].

• Click YES if warning screen appears about allowing the app to make changes.
• Sit back and wait for the installation to finish.
Start a new project.
• Click on Projects è NEW è Enter project name è CREATE.
• Click on the movie camera icon to left of the sun è Delete Key to delete default camera.
Import Steam VR Plugin• Click the Asset Store tab at the top of the scene window.
• Enter Steam VR in the search box è click on the Steam VR Plugin è Import button.
• Click Import to keep the defaults in the SteamVR Plugin window• Click Accept All in the Steam VR project setting window è OK to close.
You made the right choice window.
Place a Player Steam VR object in the scene, change to a black background and add a 3D sphere• Click the Scene tab at the top of the scene window è enter Player in the Project window search box.
• Drag and drop a grey box with a blue both-direction arrow icon into the scene, anywhere.
• Enter Position x=2, y=0, z=0 and Rotation X=0, Y=270, Z=0 in the inspector window.
• Expand Player menu in the Hierarchy window è expand SteamVRObjects menu è click VRCamera.
• Click Skybox next to Clear Flags è Solid Color è click Background color è move sliders R=0, G=0 and B=0
è close the color selection window.
• In the Unity3D program menu click Edit è Project Settings è verify that the Virtual Reality Supported box ischecked è close the Project Settings window.
• Click the Play button at the top center è Yes at StreamVR actions warning è Yes to open the Input window è
Yes to use example ‘actions.json’ è Save and generate è Save to save work è Close the SteamVR Input
window.
• Click GameObject at the top è 3D Object è Sphere.
• Change the Position to X=0, Y=1, Z=0 è Scale to X=2, Y=2, Z=2 è Rotation is X=0, Y=1, Z=0.
Remap satellite image to equirectangular projection and wrap around the sphere• Download David Taylor’s MapToLinear program [10] and the required runtime library bundle, if not alreadyinstalled [11].
• Unzip both programs èCopy MapToLinear.exe to a folder of your choice, avoiding ‘Program Files’ directories èRun runtimes-setup.exe to install the runtime library.
• Download a geostationary satellite image, for example a GOES GRB image fromhttps://www.star.nesdis.noaa.gov/GOES/index.php

GOES-West or GOES-East è Full Disk è GeoColor 5425 x 5424px.
(And of course, you can make use of images from any other geostationary satellite, to suit your interests).

www.geo-web.org.uk

11• Open the image in an image viewing program like IrFanView and check the image dimensions.
• Rescale to 5424 pixels by 5424 lines if using a larger image è Save the file è Close the program.
• Click on MapToLinear.exe è and drag-and-drop the image on to the program window to process it.
• Click Scenes folder under the Asset folder èdrag and drop the remapped image into the Scenes window.
• Click on the image èchange the Max Size to 8192 and the Compression to High Quality è Apply.
• Click on the sphere in the Scene window è drag and drop the remapped image onto the sphere.
• Click Play, put on your VR googles and enjoy the view—but remember—don’t walk into a wall!
This article and companion video can’t possibly come close to conveying the experience you’ll have viewing satellite
images in virtual reality. You simply must try it!
References
1 A Digital Storage and Scan Converter for Weather Satellite Images, Part 1 pp 194-208, Matjaz Vidmar, YU3UMV		https://www.americanradiohistory.com/Archive-DX/VHF-Communications/VHF-COMM.1982.4.pdf
2		 WXtoImg User Guide
		http://leshamilton.co.uk/wxtoimg.htm
3 David Taylor’s Groundmap program		https://www.satsignal.eu/software/groundmap.htm
4 Creation of 3D images from HRPT Data		http://www.alanbanks.org.uk/3D_HRPT_Images.php
5 Science on a Sphere NOAA)
		https://sos.noaa.gov/What_is_SOS/
6 Science On a SSAphere (Wikipedia)
		https://en.wikipedia.org/wiki/Science_On_a_SSAphere
7 GOES Image View
		https://www.star.nesdis.noaa.gov/GOES/index.php
8 An example 2D view of what the person wearing the VR goggles would see and GRB2.exe, a compiled Unity3D
program ready to be run using VIVE VR goggles.
		https://www.dropbox.com/sh/m7a8pdtzutcb3k0/AADqdjL5nglWyIvXsymGGFqLa?dl=0 contains GRB1.mpg
9 Training Video
https://www.dropbox.com/s/h29lprimpgw7uqr/Earth%20in%203D.mp4?dl=010		 David Taylor’s MapToLinear software		https://www.satsignal.eu/software/MapToLinear.zip
11		 David Taylor’s Runtime Package
https://www.satsignal.eu/software/runtime.html

The launch of Meteor M2-3 is delayed till 2021
Les Hamilton
Enthusiasts lamenting the end of LRPT transmissions from Russian meteorological satellite
Meteor-M2-2 will be disappointed to learn that the anticipated launch of its successor,
Meteor-M2-3 later this year, has now been delayed by twelve months.
On February 21, Russian News Agency TASS reported that Ilya Slobodskoy, a representativeof the VNIIEM corporation—which develops and manufactures the satellite—had stated that
meteorological satellite “Meteor-M” No. 2-3 is now scheduled to be launched from Russia’s
Far Eastern Vostochny spaceport in August 2021.
“The launch of Meteor-M satellite No 2-3 is expected in August 2021,” said Slobodskoy,speaking at the 11th international conference of the Russian Association of Aviation andSpace Insurers.
Earlier, the press service of Roscosmos informed TASS that Meteor-M2-3, which was planned
to be put into orbit in 2020, will be launched in 2021. According to the state corporation, it
was decided to conduct additional testing to ensure the integrity of the spacecraft.

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Iceberg shattered
European Space Agency

This Sentinel-1 image shows the fractured Pine Island Glacier iceberg
Image contains modified Copernicus Sentinel data (2020), processed by ESA, CC BY-SA 3.0 IGO

The Pine Island Glacier recently spawned an iceberg
over 300 square kilometres in area—about the sizeof the island Malta. This huge berg very quickly
broke into many pieces the largest of which has been
named B-49. This almost cloud-free image, captured
on February 11 by the Copernicus Sentinel-2
mission, shows the freshly broken bergs in detail.
Thanks to the combination of both optical andradar images from the Copernicus Sentinel satellite
missions, two large rifts were spotted in Pine Island
Glacier last year and scientists have been keeping aclose eye on how quickly the cracks were growing.
This YouTube animation uses 57 radar images
captured by the Copernicus Sentinel-1 mission
between February 2019 and February 2020 (the last
frame is from 10 February 2020) and shows justhow quickly the emerging cracks grew and led to thiscalving event.

https://youtu.be/dYRcFPI2hhs
Pine Island Glacier, along with its neighbour
Thwaites Glacier, connect the centre of the West
Antarctic Ice Sheet with the ocean—together
discharging significant quantities of ice into theocean. These two glaciers have been losing ice overthe last 25 years.
Owing to their extremely remote location, satellites
play a critical role in measuring and monitoring
Antarctic glaciology – revealing the timing and paceof glacial retreat in Antarctica. Since the early 1990s,
the Pine Island Glacier’s ice velocity has increased
dramatically to values which exceed ten metres perday.

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Easter Island
European Space Agency

The Copernicus Sentinel‑2 mission captured this cloud-free image of Easter Island on April 7, 2019
© Contains modified Copernicus Sentinel data (2020), processed by ESA, Creative Commons CC BY-SA 3.0 IGO

The Copernicus Sentinel-2 mission takes us over
one of the most remote islands in the world: Easter
Island. Located in the Pacific Ocean, over 3500 km
off the west coast of South America, this Chilean
island is also known as Rapa Nui by its original
inhabitants. The island was given its current nameby Dutch navigator Jacob Roggeveen the day
Europeans arrived, on Easter Sunday in 1772.
The island is famous for its monolithic stone
statues, called Moai, said to honour the memoryof the inhabitants’ polynesian ancestors. There arenearly 1000 scattered around the island, usually
positioned near fresh water. Many are located near
the Rano Raraku volcano, on the southeast coast.
The white edges along the southern coast showharsh waves colliding with the shore.
An interesting feature of the image is the ochreorange colour of the Poike—the peninsula on theeastern end of the island. It is said that, in ancient
times, the island was thickly vegetated. However,land clearing for cultivation, and the Polynesianrat, played roles in deforestation, leading to theerosion of the soil, particularly in the east.

Several reforestation projects have been attempted,
including a eucalyptus plantation in the middle ofthe island, visible in dark green. The brown patch
to the right of the plantation is probably a burnscar from a wildfire.
The majority of the island’s inhabitants livein Hanga Roa, the main town and harbour on
the west coast, clearly visible in the image.
Interestingly, the long runway of the island’s only
airport was once designated as an emergency
landing site for the US space shuttle.
At the very edge of the southwest tip of the island
stands Ranu Kao, the island’s largest volcano. Its
shape is distinctive owing to its crater lake, oneof only three natural bodies of water on Easter
Island.
Many tourists are drawn here by Easter Island’s
mysterious history and isolated position. What is
relatively unknown is the existence of two small
beaches on the northeast coast. Anakena beachhas white, coral sand, while the smaller Ovahebeach, surrounded by cliffs, has pink sand.

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This Meteor M2 composite image was created by Joachim Scharrer using the MeteorGIS v 2.24 software system.
The RGB123 image, captured at 9.39 UT on April 12, 2020 is presented in UTM projection

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15

John Cooper provided this splendid Channel-3 LRPT image from Meteor M2, that he received on May 4, 2020.

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Northwest Greenland
European Space Agency

ESA’s Copernicus‑3 satellite acquired this image of northwest Greenland on July 29, 2019.
This Sentinel 3 Image contains modified Copernicus Sentinel data (2019), processed by ESA, CC BY-SA 3.0 IGO

Lying in the North Atlantic Ocean, Greenland is the world’s
largest island and is home to the second largest ice sheet
after Antarctica. Greenland’s ice sheet covers more than
1.7 million square km and covers most of the island.
Ice sheets form in areas where snow that falls in winterdoes not melt entirely over the summer. Over thousandsof years, layers of snow pile up into thick masses of ice,
growing thicker and denser as the new snow and ice
layers compress the older layers. Ice sheets are constantly
in motion. Near the coast, most of the ice moves throughrelatively fast-moving outlets called ice streams, glaciersand ice shelves.
In the top centre of this image, captured on July 29, 2019,
the Petermann glacier is visible. Petermann is one of thelargest glaciers connecting the Greenland ice sheet with
the Arctic Ocean. Upon reaching the sea, a number ofthese large outlet glaciers extend into the water with afloating ‘ice tongue’. Icebergs occasionally break or ‘calve’
off these tongues.
In this image, sea ice and icebergs can be seen in the

Nares Strait—the waterway between Greenland andCanada’s Ellesmere Island, visible top left in the image.
On the tip of Ellesmere Island lies Alert—the northernmost
known settlement in the world. Inhabited mainly by militaryand scientific personnel on rotation, Alert is about 800 km
from the closest community, which is roughly the same
distance between Alert and the North Pole.
Scientists have used data from Earth-observing satellites
to monitor Greenland’s ice sheet. According to a recent
study, both Greenland and Antarctica are losing mass
six times faster than they were in 1990s. Between 1992
and 2017, Greenland lost 3.8 trillion tonnes of ice,
corresponding to around 10 mm contribution to global sealevel rise.
Melting ice sheets caused by rising temperatures andthe subsequent rising of sea levels is a devastatingconsequence of climate change, especially for low-lying
coastal areas. The continued satellite observations of theGreenland ice sheet are critical in understanding whether
ice mass loss will continue to accelerate and the full
implications of this anticipated change.

www.geo-web.org.uk

17

Mount St Helens
NASA Earth Observatory
Story by Kathryn Hansen

In May 1980, a satellite watched the mountain erupt.
Over the next 40 years, satellites have observed it recovering.

Mount St Helens as imaged by Landsat-8 on April 17, 2020
NASA Earth Observatory image by Joshua Stevens, Robert Simmon, and Jesse Allen, using Landsat data from USGS.

Forty years have passed since a tremendous blast at
Mount St Helens—the deadliest eruption in United States
history—transformed the landscape for hundreds of square
miles in the Pacific Northwest. Satellite images acquiredin the days around the eruption on May 18, 1980, helped
scientists to understand the event; images acquired overthe past four decades have given them insights into how alandscape recovers.

The image above, acquired with the Operational Land
Imager (OLI) on Landsat 8, shows the volcano insouthwest Washington on April 17, 2020. Seasonal snow
still blankets its flanks despite the spring sunshine. By
August, most of the snow on the mountain will melt. The
image is the most recent, cloud-free view of the mountainfrom Landsat 8, which acquires images of any given place
on Earth about once every two weeks.

www.geo-web.org.uk

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Comparison: Mount St Helens and its environs immediately after the eruption in 1984, and in 2013.
Earth Observatory images by Joshua Stevens, Robert Simmon, and Jesse Allen, using Landsat data from USGS.

Landsat satellites have been acquiring images of Mount
St Helens for nearly five decades. The image pair above isfrom our World of Change series, which shows the scaleof the eruption and the process of recovery. View the fullseries athttps://earthobservatory.nasa.gov/world-of-change/StHelens

to watch green plants and trees reclaim the land on the far
outskirts of the volcano in the late 1980s and then closer tothe mountain by the late 1990s. Change is still ongoing—
plants are growing on the once sterile Pumice Plain northof the crater—but the changes can be slow and now
appear less dramatic in annual images.
‘I think these long-time series will be useful for
decades to come, possibly out to a century after the
eruption, as change is very slow,’ said Steve Self, aprofessor at the University of California Berkeley.
The Geostationary Operational Environmental Satellite-3(GOES-3) captured black and white images of the eruption
as it happened forty years ago.
https://twitter.com/NWSSeattle/status/865193432771215360

Unlike Landsat satellites, which follow a predeterminedground track to collect imagery from around the entire
planet, GOES satellites provide a constant view of thesame area. This geostationary orbit is most valuable forweather monitoring. In this case, it was useful for watchingan eruption unfold.

This animation, shared by the National Weather Service
in Seattle, shows a series of GOES-3 images acquired
on May 18, 1980. GOES-3 was operated by the National
Oceanic and Atmospheric Administration (NOAA); NASAhelps develop and launch the GOES series of satellites.
The GOES-3 images from that day were also analysed
in research papers published by Self and colleague Rick
Holasek.
‘The Mount St. Helens eruption was possibly the firsttime I saw satellite images from an eruption,’ Self
said. ‘I was very interested in these images because
they gave a huge overview, and Rick and I had NASAsupport to explore this “new” technology.’
Self noted the impressive density of the initial blast cloud,visible in the first three images of the animation, comparedwith those of the later phases, which sent pumice andash flying as far as Idaho. The blast cloud rose quickly,
reaching about 30 kilometres altitude in just four minutes.
Decades later, instruments on weather and researchsatellites are a routine but vital component of observing
eruptions and their plumes. Scientists map the gases andparticles in volcanic emissions to find out how they affectthe air and climate. They also contribute to volcanic ash
advisory centres in their predictions of the movement of
volcanic clouds and, if necessary, the rerouting of aircraft.

www.geo-web.org.uk

19

Meteor M2-2 is still Transmitting AHRP Imagery
Further toour report in
GEOQ 65 that
Russia’s Meteor
M2-2 satellite
had been put
out of action
following acollision with amicrometeorite,
it now transpiresthat a degreeof restoration
has beenaccomplished.
Alas this does
not extend
to the LRPT
capability, but,during periods
when the craft’s
solar panels
are illuminated,
there issufficient power
to operate thehigher resolution
AHRPT stream
on 1700 MHz.
The image
opposite is partof a Meteor M2-2
pass acquired
from the east of
The Netherlands
by Harrie vanDeursen of
Werkgroep
Kunstmanenat 13.50 UT
on March 20
this year, andsubmitted to the
GEO-Subscribers
internet forum
by Rob Alblas.
The image wasreceived using
a home-made‘Werkgroep’receiver anddecoder, and is acolour composite
image fromchannels 1, 2
and 3.

https://groups.io/g/GEO-Subscribers

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20

Greenland, Antarctica Melting Six Times Faster than in the 1990s
NASA / Jet Propulsion Laboratory

Observations from eleven satellite missions
monitoring the Greenland and Antarctic ice sheets
have revealed that they are losing ice six times
faster than they were in the 1990s. If the current
melting trend continues, the regions will be on
track to match the ‘worst-case’ scenario of theIntergovernmental Panel on Climate Change (IPCC) ofan extra 17 centimetres of sea level rise by 2100.

from Greenland’s ice loss and 40% resulted from
Antarctica’s.
‘Satellite observations of polar ice are essential
for monitoring and predicting how climate change
could affect ice losses and sea level rise,’ stated
Ivins. ‘While computer simulations allow us tomake projections from climate change scenarios,
the satellite measurements provide prima facie,
rather irrefutable, evidence.’
The IPCC, in its Fifth Assessment Report issued
in 2014, predicted global sea levels would rise
71 centimetres by 2100. The Ice Sheet Mass Balance
Intercomparison Exercise team’s studies show that
ice loss from Antarctica and Greenland tracks with
the IPCC’s worst-case scenario.

An aerial view of the icebergs near Kulusuk Island, off thesoutheastern coastline of Greenland, a region that is exhibiting an
accelerated rate of ice loss.
Credits: NASA Goddard Space Flight Center

The findings, published online in the journal Naturefrom an international team of 89 polar scientists
from 50 organisations, are the most comprehensive
assessment to date of the changing ice sheets. The
Ice Sheet Mass Balance Intercomparison Exercise
team combined 26 surveys to calculate changes in
the mass of the Greenland and Antarctic ice sheets
between 1992 and 2018.
The assessment was supported by NASA andthe European Space Agency. The surveys usedmeasurements from satellites including NASA’s Ice,
Cloud, and land Elevation Satellite and the joint NASAGerman Aerospace Center Gravity Recovery and Climate
Experiment. Andrew Shepherd at the University ofLeeds in England and Erik Ivins at NASA’s Jet
Propulsion Laboratory in Southern California led thestudy.
The team calculated that the two ice sheets together
lost 81 billion tonnes per year in the 1990s,
compared with 475 billion tons of ice per year in
the 2010s—a sixfold increase. In total, Greenlandand Antarctica have lost 6.4 trillion tons of ice sincethe 1990s, the resulting meltwater rising global sea
levels by 17.8 millimetres. Together, the melting
polar ice sheets are responsible for a third of all sea
level rise. Of this total sea level rise, 60% resulted

Combined losses from both ice sheets peaked at
552 billion tons per year in 2010 and averaged
475 billion tons annually for the remainder of thedecade. The peak loss coincided with several years
of intense surface melting in Greenland, and lastsummer’s Arctic heat wave means that 2019 will
most likely set a new record for polar ice sheet loss.
IPCC projections indicate the resulting sea level
rise could put 400 million people at risk of annual
coastal flooding by the end of the century.
‘Every centimetre of sea level rise leads tocoastal flooding and coastal erosion, disrupting
people’s lives around the planet,’ said Shepherd.
As to what is leading to the ice loss, Antarctica’s
outlet glaciers are being melted by the ocean, whichcauses them to speed up. Whereas this accounts forthe majority of Antarctica’s ice loss, it accounts forhalf of Greenland’s ice loss; the remainder is causedby rising air temperatures melting the surface of its
ice sheet.

Pools of meltwater in southwestern Greenland's ice sheet as
observed by a NASA satellite in 2016.
Credits: NASA Goddard Space Flight Center

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21

André T’Kindt sent in this NOAA 18 image that he captured at 23:19 UT on May 21 2020. It shows a deep,
unseasonal Atlantic depression battering northwest Scotland. This MCIR_with_precipitation with_overlay
composition from WxToImg clearly illustrates the intensity of the associated rainfall.

www.geo-web.org.uk

2222

Sun/satellite/dish co-linearity – Solar Outage
John Tellick
Twice a year, as the Earth ‘moves’ between seasons,the sun will pass behind every geostationary satellite
for a period of several days. This occurs at some timeof day between around February and March as seenfrom a specific location on Earth. This means that,for a few days, receiving stations will experience asituation of sun/satellite/dish co-linearity. The avid
EUMETCast enthusiasts among us are of course wellexperienced with this phenomenon and its effects
through personal experience. But some explanation
may be required for newcomers to the hobby.
During this springs ‘outage period,’ I found a websitethat gave a visual representation of solar outage
which makes it perhaps more understandable thanjust prediction ‘figures and timings.’
Those interested can visit the website athttps://www.satellite-calculations.com/

Many of us get our solar outage prediction timetablefrom David Taylor’s WXtrack satellite prediction
software—mine for this spring was:Satellite solar outage list produced by WXtrack
Location: Surbiton at Lat: 51.38°N Lon: 0.23°W
Satellite: EUTELSAT 10A, separation <= 1.61°

Figure 1 - The blue line in this WXtrack shows Eutelsat’s
theoretical global RF coverage.

Early Period Group
Date
2020 Feb 26
2020 Feb 27
2020 Feb 28
2020 Feb 29
2020 Mar 01
2020 Mar 02
2020 Mar 03
2020 Mar 04
2020 Mar 05

Begin
11:25
11:23
11:21
11:21
11:20
11:20
11:20
11:21
11:23

Peak
11:27:53
11:27:43
11:27:32
11:27:20
11:27:09
11:26:56
11:26:44
11:26:31
11;26:17

End
11:30 UTC
11:32 UTC
11:33 UTC
11:33 UTC
11:33 UTC
11:33 UTC
11:32 UTC
11:31 UTC
11:28 UTC

Closest
1.54°
1.16°
0.79°
0.41°
0.03°
0.36°
0.74°
1.12°
1.51°

The list shows dates and times when the sun is in
the beamwidth of the antenna, and may cause an
outage because of solar noise entering the receiver.
However, the satellite-calculation website map showsthe ‘reduced carrier to noise ratio level cone’ as it passes
your location in realtime giving the expected dropin carrier to noise level as the period of co-linearity
passes. The contours of the cone range from:-6.46 dB at the centre of the cone to -1 dB at its
outer margin, indicating the predicted drop in C/Nratio. Figure 2 illustrates my outage cone at the
point of maximum co-linearity.
The sun is a giant and powerful source of RF
radiation across a wide spectrum. And it is radiating
this ‘noise’ all the time.

Figure 2 - Outage cone at the author’s ‘maximum’ co-linearity

However this is only a problem to us during sun/satellite/dish co-linearity. The sun crosses our ‘dishlongitude’ every day but, outside the co-linearity
period, the sun is either below or above thebeamwidth of our dish at that time, so no solar noise
is focused onto our LNB.
Those of you who use the GEO/MSG-1/SatSignal
internet Groups will often have noticed commentswww.geo-web.org.uk

23

Figure 3 - The theoretical outage cone at the sub satellite point on the day of co-linearity showsdegradation steps from -6 dB at the centre to -1 dB at the outer margin.

Figure 4
The start of Eutelsat 10-A’s outage cone on the day
when the sun was exactly above the Equator.

and recommendations about the importance of
accurate alignment of a satellite dish and LNB.
We need to obtain the maximum level of signal withthe least amount of ‘noise’—Signal to Noise Ratio(SNR) or Carrier to Noise Ratio (C/N) or simply
Es/No. This relationship between signal level andnoise level determines the Link Margin of thereceiving system. And a larger dish will give you
more ‘signal’ level above the noise level leading to ahigher (better) Link Margin.
Link Margin is a measurement that indicates how

Figure 5
The end of Eutelsat 10-A’s outage cone on the day
when the sun was exactly above the Equator.

much MER (Modulation Error Ratio) a digitalchannel can lose before it becomes impossible to‘lock’ on to it. This happens when the Link Margin
measurement is equal, very close to, or below zero.
Then the decoder error corrector is not able torecover data lost at transmission.
MER: The Modulation Error Ratio or MER is ameasure used to quantify the performance ofa digital radio or digital TV transmitter, or thereceiver in a communications system using digitalmodulation.

www.geo-web.org.uk

24

This is all getting a bit technical, but as we see
above, the receiver requires a certain level of link
margin to be able to ‘receive’ the signal.
And for EUMETCast reception, a further
complication arises since EUMETCast’s HVS-1
and HVS-2 data streams use a wider transmission
bandwidth than the Basic Service, meaning that
HVS-1 and HVS-2 require a higher link margin
than that required for the Basic Service.

Eutelsat 10-A’s outages when the sun was at thesame longitude of Eutelsat 10-A.
Figure 7 illustrates the start of my spring 2020
outage period. My location just clearing the-1 dB reduction contour at the end of that day’s
co-linearity.

Now, as we know, the sun appears to pass behind‘our geostationary satellite’—Eutelsat 10‑A in thecase of EUMETCast—twice a year. This is true forevery geostationary satellite, although in actual
fact it is the satellite passing in front of the sun
as seen from Earth as it travels from west to east.
At this particular time our dish will see not
only the wanted satellite but also the noisy sun
behind it. The satellite signal remains at constanttransmitted level, but added to this is thepowerful sun’s broadband ‘radio transmission’—what we term ‘noise’.
The ‘noise signal’ level increases relative to thewanted signal level and our signal to noise level
drops—alarmingly so at maximum co-linearity.
This reduces the link margin towards or below therequired level and we can lose our wanted signal:
it all depends on how much ‘extra’ signal to noiselevel you had in the first place.
Satellite-Calculation Map Representations

Figure 6
The final day of outages when the sun was at thesame longitude of Eutelsat 10-A

I thought it would be interesting to see the outage
cones for a geostationary satellite—in this case
Eutelsat 10-A, not only from my location but fromacross the globe, specifically during the day when
the sun was directly above the equator.
Figure 1 shows the extent of Eutelsat 10-A’s
theoretical global RF coverage as the blue line
in David Taylor’s WXtrack. [Note, Eutelsat 10-A,
being a TV and data broadcast satellite, uses
shaped, wide and spot beams to cover selected
land areas at Ku-Band. It’s not a global beam.]
Figure 2 shows the outage cone at my location atmy ‘maximum’ (closest) co-linearity on March 1.
The red line on the map shows the line of ‘actual’co-linearity on that day.
Figure 3 shows the theoretical outage cone at the
sub satellite point on the Equator at maximum
co-linearity on March 20.
Figures 4 and 5 show the theoretical co-linearity
outage cone at start and end of the day when thesun is above the Equator on March 20th.
Figure 6 shows the outage cone on last day of

Figure 7
The end of the first day of the 2020 outage period
at the author’s location

www.geo-web.org.uk

25

What are you doing during ‘Lock-Down’?
Les Hamilton

Rob Bale’s smart looking QFH
antenna, constructed in an evening
from ‘bits and bobs’

The first NOAA 18 image received on May 22 from the new
QFH. There are over eleven minutes of excellent image
between the facing at each extremity.

With the Covid-19 Lock-Down being only gradually lifted as I write this, and restrictions of some
sort likely to remain in force for the forseeable future, what are you doing to occupy your time?
Have you done anything new or inventive on the weather satellite front?
If so, do feel free to contact the editor and share your experiences with our readers.
I recently received an email from Rob Bale, who was disappointed with his weather satellite
reception and decided to build a new QFH antenna.
Rob stated: “I Made a QFH antenna last night out of some old bits and bobs I had lying around. The four
top horizontal elements need to be a bit longer but I had trouble making the connection inside the 40 mm
tube using choc blocks, and couldn’t pull the wires back out again. I’ll redo it later using solder.
“I was going to make one out of 10 mm copper tubing but thought I’d try this cheap design to see if there
was any improvement in image quality before spending out on more expensive materials. The cost of thisQFH was basically zero as I already had the stuff. Images are a vast improvement on my old antenna.”

www.geo-web.org.uk

26

A-68A Holding it Together
NASA Earth Observatory
Story by Kathryn Hansen

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

Some Antarctic icebergs can persist
for many years. A newborn childcould go off to school, learn to drive,and become an adult all within the
span of time it takes for some of thelargest icebergs to break up and melt
away. Iceberg A-68A—now just a few
months shy of its third birthday—is
a youngster compared to some. But
this mammoth berg has already had
an impressive journey.
On April 9, 2020, theModerate Resolution Imaging
Spectroradiometer (MODIS) on
NASA’s Terra satellite acquired
this image of A-68A floating about
230 kilometres west-southwest of theSouth Orkney Islands. The 150 kmlong iceberg appears to dwarf the
125 km long island chain.
In this image, A-68A is about 800
kilometres from where it broke awayfrom the Larsen C Ice Shelf in July
2017. The journey, however, wasnot exactly direct. In its first year, it
moved just 45 km as tides shuffled
the Delaware-sized block of ice backand forth, occasionally smashingit against a rocky outcrop on the
Antarctic Peninsula. The region’s
powerful currents eventually won,
and the iceberg has since been
winding its way north through theSouthern Ocean.
A-68A seems to have hit the brakes
in recent weeks, rotating without
moving far. NASA/UMBC glaciologist
Christopher Shuman thinks the berg
could be caught up in a circulating
gyre. Christopher Readinger, ascientist at the US National Ice
Center (NIC), agrees that a gyre or
smaller-scale eddy could explain the
berg’s motion. “This is behaviour
we’ve seen many times before withother bergs downstream of thepeninsula”, stated Readinger. “Theyjust start circling for no apparent
reason.”www.geo-web.org.uk

Icebergs passing through this area
are eventually kicked to the east
when they encounter the powerful
Antarctic Circumpolar Current, which
funnels through the Drake Passage.
From that point, the ice can whip
north into the warmer waters of
the South Atlantic—a region where
icebergs melt, break down, andultimately die. That has been thefate of many fragments of anothericeberg, B-15. That Connecticutsized berg was once the largest
ever measured by satellites, but 20
years after breaking from the Ross
Ice Shelf, only one piece is still large
enough to be tracked by the NIC.
A-68A is not quite at that point. “I’msurprised at how well it’s sticking
together,” Readinger said. “It’s been
in warmer water for a few months
now and it’s not exactly a very thickberg, so I expect it will break up
sometime soon, but it’s showing nosigns of that yet.”27

Evening Imagery from Meteor M2
Les Hamilton

Meteor M2’s mid-morning pass over the British
Isles on May 31, 2020

During the winter months Meteor M2 transmitschannel‑5 infrared imagery. But over thesummer, this channel is replaced by thevisible channel‑3, which has in the past mademeaningful colour composite evening images
hard to come by because the satellite was always
flying close to the day/night terminator.
No longer, though! Since Meteor M2’s launch
in 2014 its orbit has been gradually slipping
forward into the daylight side of the terminator

Meteor M2’s mid-evening pass over the British
Isles on May 31, 2020and since mid May this year, much brighter
RGB123 images can be acquired in the evenings.
This situation will continue to improve up to thesummer solstice, and it should be possible tocapture good evening imagery until at least mid
July.
Both image segments shown above wereacquired from Meteor M2 on May 31, 2020, theleft one in the morning and the right-hand one
in the evening.

www.geo-web.org.uk

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