Group for Earth Observation

The Independent Amateur Quarterly Publication for
Earth Observation and Weather Satellite Enthusiasts

52
December 2016
Inside this issue . .
Paul Geissmann, a member
based in Switzerland, hasprovided an interesting essay
relating to the first alpine
weather station in the Swiss
Alps.
The main article this quarter
comes from NASA Earth
Observatory, a detailed
discussion on Sea Ice andhow it is responding to Global
Warming.
For readers just starting out
with NOAA APT reception,
Michael K Butler has compiled
a guide to everything youneed, amply illustrated byimages processed using
WxXtoImg.
Mike Stevens has been
keeping busy downloading
Sentinel and Suomi data via
EUMETCast, and several of
his best images are illustrated
in our pages. Mike has also
trialled yet another DVB S2tuner, the USB TBS 5927.
It’s been a busy year for GEO
Outreach, attending rallies,
and in this issue we carry
Francis Bell’s report andpictures from the recent
London Radio and Computer
Rally at Kempton.
And of course there is theusual eclectic mix of shortfeatures from NASA’s Earth
Observatory.

GEO MANAGEMENT TEAMLes Hamilton

Director and Public Relations
Francis Bell,
Coturnix House, Rake Lane,
Milford, Godalming, Surrey GU8 5AB,
England.
Tel:
01483 416 897
email: francis@geo-web.org.uk
General Information
John Tellick,email: information@geo-web.org.uk
GEO Quarterly Editor
Les Hamilton,
8 Deeside Place,
Aberdeen AB15 7PW, Scotland UK.
email: geoeditor@geo-web.org.uk
GEO Quarterly Despatch
Peter Green
Membership and Subscriptions
David Anderson,
35 Sycamore Road,
East Leake, Loughborough LE12 6PP,
England, UK.
email: members@geo-web.org.uk
Tel:01509 820 067
Technical Consultant (Hardware)David Simmons
email: tech@geo-web.org.uk
Webmaster and Website Matters
Alan Banks,e-mail: webmaster@geo-web.org.uk
GEO Shop Manager
Nigel Evans (Assistant: David Simmons),
email: shop@geo-web.org.uk
International Liaison
Rob Denton,
email: liaison@geo-web.org.uk
Management Committee Members
Clive Finnis
Carol Finnis

Publisher
Published by The Group for Earth
Observation Limited, a company in Englandand Wales, limited by guarantee and nothaving share capital.
The Company Number is 4975597.
The registered office is Coturnix House,
Rake Lane, Milford, Godalming,
Surrey GU8 5AB, England.
Printing (December Issue)
Hedgerow Print,
16 Marsh Lane,
Crediton, Devon EX17 1ES.
Tel: 01363 777 595
Responsibility
Every effort is made to ensure that thetechnical and constructional articles
published in this Quarterly are correct.
However, the ultimate responsibility iswith the reader to ensure the safety of
constructions and for any interfacing withother equipment. GEO cannot accept liability
for shortcomings in any published design or
any constructions carried out by members orother third parties.
Copyright GEO © 2016
The contents of this Quarterly remain theintellectual property of the Group for Earth
Observation Limited and its contributors.
Copying of text or images, either from theprinted Quarterly or from any electronicallystored source, is forbidden without
permission from the Editor.

geoeditor@geo-web.org.uk

As another year comes to a close we have a stellar 56-page issue
to provide you with Festive Season reading. For newcomers tosatellite imaging, Michael K Butler has compiled to everything you needto know about APT reception, still the most popular entry-level route,into an illustrated article on page 19.

T

he topic of Climate Change is headlined to some depth starting withthe article ‘How do we know’ on page 14, followed by a seminal
treatise on Sea Ice from experts at NASA Earth Observatory. The
thread continues by looking at a massive ice avalanche in Tibet and ice
retreat in west Antarctica.

Iwould like to remind you that, as a subscriber to GEO Quarterly, youwill automatically also receive a printed version of this magazine inaddition to this PDF version.

F

inally, a big thank-you to everyone who has contributed to GEO
Quarterly throughout 2016. Material for articles continues to be hard
to come by and the Editor is always pleased to hear from any reader
who feels they have something to contribute.

Everyone on the GEO Management Team wishes every reader thevery best Christmas and New Year wishes as we look forward to
the year ahead.

C

opy deadline for the December issue of GEO
Quarterly is Sunday, February 26, 2017.

Contents
GEO Report
Francis BellEye of the Storm
European Space Agency
Quarterly Question
Francis BellTwo Typhoons strike the Philippines within a Week
John Tellick
Meteor GIS
Les Hamilton
Massive and Mysterious Ice Fall in Tibet
NASA Earth Observatory
The First Weather Station in the Swiss AlpsPaul Geissmann
Climate Change: How do we know?
NASA
Pervasive Ice Retreat in West Antarctica
NASA Earth Observatory
Seeing Equinoxes and Solstices rom SpaceNASA Earth Observatory
Introduction to Receiving APT from the NOAA Satellites Michael K Butler
Sea IceMichon Scott / Kathryn Hansen
Views of ‘Planet Earth’Francis Bell
East Africa’s Virunga Mountains
European Space Agency
Improved GEOSS Web Portal
Francis BellThe TBS 5927 USB DVB S2 Tuner
Mike Stevens
Sentinel 3A Showcase
Mike Stevens
A Curious Ensemble of Wonderful Features
NASA Earth Observatory
Historical Records may Underestimate Sea Level Rise Climate.nasa.gov NewsFirst HVS/Sentinal-3A Data
David Taylor
Swanning Around in SpaceFrancis BellVancouver Island
John Tellick
GEO Outreach - Kempton
Francis Bell
Quarterly Question Extra
Francis Bell
Cover Image Details
Satellite Status
GEO Helplines and Internet Discussion Groups
GEO Membership Application FormGEO Shop Catalogue and Price List

2
3
4
7
8
9
11
14
16
17
19
24
31
32
34
35
37
38
39
40
41
43
46
49
52
53
54
55
56

GEO Quarterly No 52

The Group for Earth Observation

December 2016

Francis Bell

Without reservation, I offer my usual thanks to members
who have contributed to our group over the last quarter,
particularly those who contributed to this Quarterly,
and to our Editor for his work in compiling the materials
into a professional format of which we can all be proud.
At rallies and other meetings where our Quarterly is onshow I continue to be impressed with the compliments
received by the general public.
The above paragraph is followed by the usual request
for members to contribute appropriate, material for the
Quarterly whenever possible. With new satellite data
constantly becoming available it’s a great help if technicalinformation and experiences can be shared within ourgroup. I for one would feel paralysed without this sourceof information even with the Internet in the background.
In addition to the ongoing request for Quarterly copy
there are two other areas to which I would like to draw
your attention.
GEO Symposium 2017
Most years since our formation, GEO has held a oneday annual meeting, usually a busy day with topicaltechnical presentations, followed by our members AGM.
Many of these meetings have been held at the National
Space Centre (NSC) Leicester but also at EUMETSAT’s
HQ in Darmstadt, Germany and once at Surrey Satellite
Technology (SSTL), Guildford. In my last report, in
GEO Quarterly 51, as a measure to help plan for theforthcoming year, I did ask for feedback from memberswith their preferred ideas for a meeting in 2017, plus avenue. Unfortunately I have had little feedback, hence
a decision relating to a 2017 meeting is difficult, but if
such a meeting were to take place, arrangements haveto be made in good time. I do note that, over the years,
the number of members attending these meetings has
declined, but attendance is important and consistently
represents about 10% of our total membership.
Please let me know if you have a preferred option for a
GEO 2017 meeting. Some option are:
• NSC in April/May• EUMETSAT in late June
• SSTL which could include a visit to their satellite
assembly facilities on a date and time table
acceptable to all concerned• Any other suggestion for a location and time which
may be appropriate.
Please email Francis Bell at:
francis@ geo-web.org.uk
with your preferences or ideas.
Widening our Membership
I think we all recognise that our GEO membershipnumbers have declined in recent years. My feeling is2that the increasing access to a wealth of satellite dataand other information via the Internet is so easy andwidespread that it has become an alternative to direct
image reception for some people. Of course I use theInternet myself, and would be sealed in a vacuum
without it but I have never found this an alternative tothe challenge and satisfaction when accessing direct
reception of satellite images from space using my own
equipment.
Currently our membership numbers are:UK
165
Europe78
USA
13
Rest of World20
a grand total of 276.
It would be great if we could increase this membership,
not just for the sake of numbers, but for the potential it
will generate to widen and share our mutual interests inEarth observation. This may be an appropriate time forpromoting GEO membership because of the widespreadinterest in space science that Tim Peake has generated
with his six months aboard the ISS. It would also begreat to have some new people on the GEO Management
Team, who could exploit this interest and use theircontacts with education, science, amateur radio orother technical groups, and I would encourage theirmembership and contributions to our group.
We do earnestly need one or two more people toencourage and promote GEO together with increased
membership so, if you think you can help in any way,please contact Francis Bell by email:francis@geo-web.org.uk
In these days of increasing public interest in spacescience GEO has a great opportunity to respondsupportively by increasing its membership. If you canpossibly respond to the above text in a positive way thenI’m sure there will be many winners.
I envisage a new promotion officer(s) roles as fulfilling one
or more of the following roles:
1 To promote GEO as an organisation using web,social media and other media such as magazines; toensure GEO has at least a weekly presence on the
Amateur Radio/Weather observation scene with aview to increasing membership and participation.
2 To be an active member of GEO-M taking part inmanagement meetings.
3 To assist with events such as rallies and help
contribute to the running of our annual symposium.
4 To be sensitive to the ever broadening access toearth observation data. Support personal andeducational interests beyond live data reception byoffering guidance to the new sources of data which
can now be accessed via the Internet.

www.geo-web.org.uk

December 2016

The Group for Earth Observation

GEO Quarterly – Back Issues
I have recently been in touch with a GEO member
who wishes to complete his collection of printed GEO
Quarterlies. I have been able to supply him with someback issues which were missing from his collection but
I’m unable to find a copies of GEO Quarterlies 24,27 and31. I know these are available as PDF files via our web site
but I’m sympathetic to someone who wants the printed
Quarterly to complete a collection. If any member has one
or more of these Quarterlies, and is willing to part withthem, please email me at francis@geo-web.org.uk or
telephone 01483 416897. By arrangement, postage costs
can be covered and, say, £2.00 for each Quarterly. I hope
you can help.
A Quarterly Challenge
In addition to the Quarterly Question which has been
popular with members ever since our first publication, I
thought it might be interesting on this occasion to issue
an additional challenge to readers. I had the idea whenreading about GEOSS’s new Web Portal—see page 30 ofthis Quarterly. Contained in the introductory text for thePortal it states that the new system permits individuals to

GEO Quarterly No 52

use simple multi criteria searches using only ‘a few clicks’
to find specific data or images.
I haven’t tried this myself yet but the challenge to readers
this quarter is to use this GEOSS web Portal to find yourown specific data or images. It is not satisfactory to roamaround the almost infinite data available and say ‘Oh
that’s interesting’ but rather have a specific target before
beginning a search. So the challenge is to find a visible
spectrum image of one of these:• Sydney Harbour• Singapore• the Panama Canal or• the island of Malta.
Alternatively, you can search for anything in which you areinterested so long as it’s predefined by yourself and you
don’t just come across it by accident.
Please send your images, with appropriate notes relating to
your search, to GEO’s editor ateditor@geo-web.org.uk.

European Space Agency

This image from Copernicus
Sentinel-A shows the temperature
at the top of Hurricane Matthew at
03:13 UT on October 7, 2016 as it
approached Florida in the USA.
The temperature of the clouds at the
top of the storm, about 12 kilometresabove the ocean surface, range fromabout –80°C just outside the eyeof the storm to about 25°C at sea
level in the Gulf of Mexico, where
it is relatively calm. This monster
400 kilometre-wide hurricane wasabout 200 km northwest of Miami
Beach when the image was taken.
Having already caused devastationin the Caribbean, Matthew was themost powerful hurricane to threaten
the US Atlantic coast in more than adecade, and potentially, could havebeen the most catastrophic to hit
Florida in more than 100 years.
Sentinel-3’s sea and land surface
temperature radiometer measuresenergy radiating from Earth’s
surface in nine spectral bands. Thisis a thermal infrared image at aresolution of 1 km.
© contains modified Copernicus Sentinel data
(2016), processed by ESA

www.geo-web.org.uk

3

GEO Quarterly No 52

The Group for Earth Observation

December 2016

Francis Bell
Quarterly Question 51
My thanks to those members who responded to the last Quarterly
Question, which related to the melting of sea ice. The reason for
asking the question was to highlight the mistaken belief, often
promoted by the misguided public media and others, that themelting of sea ice will lead to a rise in sea level.
The point is that if a piece if ice, no matter how large or small, isﬂoating on water it will displace its own mass of water: hence,
when it melts, there will be no change of water volume or level.

In the case of this Question, I did say to ignore temperature andsalinity changes which may be factors but will only contributeminutely to volume changes.
The above comments do not relate to the massive ice caps on
Greenland and Antarctica, which are several kilometres thick,or to the ice on high mountains and their retreating glaciers.
The melting of this ice, which is currently happening, doessignificantly contribute to an overall rise in sea level. But not theﬂoating sea ice.

Figure X - The scale of this image is about 75 x 75 km. An iconic bridge joins its two halves together.
Credit: Sentinel-1A image © ESA 20154www.geo-web.org.uk

December 2016

The Group for Earth Observation

Quarterly Question 52
This question relates to the two images shown in Figures X
and Y. ESA have a short TV programme which they routinely
broadcast on a Friday morning, and often the subject covered
relates to their ‘Image of the Week’, which is available before
their programme. Recently, their images have been fromthe Sentinel satellites which are providing multispectral highresolution images of the earth. On a regular basis I look at theseimages and if I find one particularly interesting I sometimes saveit to a small archive which I am accumulating just for my own
interest.
I was recently browsing through some of these images andtwo came to my attention because they both illustrate major
European cities located on their respective coasts. I guess I’mlike other people: if I see an image showing a coastal outline, I
can often identify the location. But without that reference it canbe difficult for me to immediately identify what I’m looking at. Of
course there is an ESA title to go with each image, but that’s not
the point. The challenge is to identify the image independently.
Although I have visited both countries I have not visited the cities
in this question.

GEO Quarterly No 52

This Quarterly Question is to give the current names of
the two major cities shown in these two satellite images.
Both of the cities are in Europe. One of them is the capital of
its country and the other, which quite recently has had threedifferent names, used to be the capital of its country. The factthat these cities are—or have been—capitals is not surprising,as many countries throughout the world have their capitals on
the coast, or just inland via a major river or estuary, for historicalmaritime communication reasons. Note the difference in scale ofthe two images. In the case of figure Y, several small cities may
be present but the one in question is conspicuous and shown
slightly towards upper right in the image. Another clue is that thiscity’s latitude is exactly 60° north. An additional point of interest
might be to name the other less obvious capital cities which canbe identified in Figure Y.
Answers, just giving the names of the two cities please, should
be sent by email to Francis Bell at
francis@geo-web.org.uk
before Sunday, February 19, 2017.

Figure Y -The scale of this image is about 600 x 600 km and the city in question lies slightly upper right of the centre.
Credit: Envisat MERIS image © ESA 2003

www.geo-web.org.uk

5This beautiful Meteor M2 RGB123 image of India was received from Pune on November 11, 2016 by Devendra Kulkarni.
On rare occasions, Meteor M2 transmits simultaneously on channels 1, 2 and 3, making colour composite images like this possible.

6

www.geo-web.org.uk

December 2016

The Group for Earth Observation

GEO Quarterly No 52

John Tellick
The Philippines do seem to come in for more than their fairshare of typhoons, with the NW Pacific region seemingly quitea breeding ground for these tropical storms. Typhoon Sarika hit
the Philippines on Sunday October 16, leaving at least two dead,houses destroyed, trees uprooted, roads blocked and electric
supply cables brought down.

The centre of Sarika making landfall on October 16 with Haima justa few days away heading towards the same area of the Philippines
Image © EUMETSAT 2016

The track of Typhoon Sarika

Credit: www.tropicalstormrisk.com

Typhoon Haima arrived on October 19, the centre of the storm
tracking somewhat further to the north of Sarika’s path, again
destroying houses, uprooting trees and power cable posts andcausing ﬂooding and the loss of at least four lives. Both were
Category-4 typhoons when they made landfall.

The centre of Haima making landfall on October 19
Image © EUMETAT 2016

The track of Typhoon Haima

Credit: www.tropicalstormrisk.com

Haima had earlier reached Category-5 ‘Super Typhoon’ status
whilst approaching the Philippines, prior to making landfall.
The Philippines experience between 15 and 20 typhoons
during the monsoon season, which begins in June and ends inNovember. In November 2013, Typhoon Haiyan, one of the mostdestructive storms to have touched land in the Philippines, left
6,300 dead, more than 1,000 missing and 14 million affected in
the central part of the country.
The IR images from the Japanese Himawai 8 satellite using
the LUTLandSea-red processing tool in David Taylor’s
MSG Data Manager software, show the structure of thesetyphoons well.

This false-colour Metop-B image of Typhoon Haima was acquired
just a few hours before the storm achieved landfall

www.geo-web.org.uk

Image © EUMETSAT 20167

GEO Quarterly No 52

The Group for Earth Observation

December 2016

Les Hamilton

This image was created by combining images from the 03:36 UT and 05:16 UT passes of Meteor M2

Recently, I was impressed by a Meteor M2 image posted on the
GEO-Subscribers YAHOO group by Mahesh Vhatkar [1] fromMumbai. Not only was it a composite of two successive passesof the satellite, but the ‘reset’ bands had been cleverly disguised
and the whole image provided with an overlay of country
outlines and major cities. I found the concept intriguing, and feltthat other GEO readers might like to follow his example: so I
asked Mahesh how it was accomplished.

Finally, Mahesh carried out a little image enhancement inPhotoshop.

I was informed that both the composite M2 image and the map
overlay were created by a free program called MeteorGIS which
creates projected images from LRPTDecoder. This software
was created by Christophe Marchand, and does everything
once configured correctly. MeteorGIS also fills the reset and anyother interference black lines on the Meteor images.

I don’t plan to investigate MeteorGIS myself, but very muchhope that some of our members will take up the challenge. It
would be highly appreciated if articles for future issues of GEO
Quarterly were forthcoming, hopefully highlighting imagery fromall parts of the globe and explaining how members set up their
reception systems and dealt with any problems encountered.

Norberto Felipe has a website, where you can download theMeteorGIS software and all the necessary information about
how to configure it. Please visit his website at

References

Norberto provides comprehensive instructions for setting up andrunning Meteor GIS. For readers who have already set up a
Meteor reception system, only one additional item is required, acopy of the SGP4.dll file, essential for georeferencing [2].
A Challenge

1 Meteor Images from India, GEOQ 44 (2015), p 14.
2 http://www.satsignal.eu/software/wxtrack.htm#SGP4

http://h347.8k.com/meteor.htm

8

www.geo-web.org.uk

December 2016

The Group for Earth Observation

GEO Quarterly No 52

NASA Earth Observatory
On July 17, 2016, a huge stream of ice androck tumbled down a narrow valley in the Aru
Range of Tibet. When the ice stopped moving,it had spread a 30-metre-thick pile of debris
across 10 square kilometres. Nine people, 350
sheep, and 110 yaks in the remote village ofDungru were killed during the avalanche.
The massive debris field makes this one of
the largest ice avalanches ever recorded. The
only event of a comparable size was a 2002
avalanche from Kolka Glacier in the Caucasus,
explained Andreas Kääb, a glaciologist at the
University of Oslo.
A multispectral imager on the European Space
Agency’s Sentinel-2 satellite captured an imageof the debris field on July 21. The Operational
Land Imager, a similar instrument on Landsat 8,
acquired an image on June 24 that shows thesame area prior to the avalanche.
The cause of the avalanche is unclear. ‘This
is new territory scientifically,’ said Kääb. ‘It is
unknown why an entire glacier tongue would
shear off like this. We would not have thought
this was even possible before Kolka happened.’
Kääb’s preliminary analysis of satellite imagery
indicates that the glacier showed signs ofchange weeks before the avalanche happened.
Normally, such signs would be clues theglacier might be in the process of surging, but
surging glaciers typically flow at a fairly slow
rate rather than collapsing violently in anavalanche.

Landsat 8 image acquired on June 24, 2016, prior to the avalanche.

After inspecting the satellite imagery,
University of Arizona glaciologist Jeffrey Kargel
agreed that a surging glacier could not be thecause. ‘The form is completely wrong,’ he said.
‘It must be a high-energy mass flow. Maybe
liquid water lubrication at the base playedsome role.’
Tian Lide, a glaciologist at the Chinese
Academy of Sciences, visited the site in Augustand described the avalanche as ‘baffling’
because the area where the ice collapse began
is rather flat. ‘We failed to reach the upper partof the glacier for safety reasons,’ he stated inan email, ‘but we do plan to go the upper partto see if we can find some more hints about
what caused the disaster.’NASA Earth Observatory images by Joshua
Stevens, using Landsat data from the US
Geological Survey and Sentinel data from theEuropean Space Agency.
Special thanks to Simon Gascoin for locating the images. Image
interpretation assistance was by Andreas Kääb (University ofOslo), Tian Lide ( Chinese Academy of Sciences), and Jeffrey
Kargel (University of Arizona). Caption by Adam Voiland.

Sentinel 2 image acquired on July 21, 2016, showing the avalanche.

www.geo-web.org.uk

9This was the scene captured from Meteor M2’s 09:59 UT pass on September 11, 2016, as a spell of unseasonably warm
weather swept up from southern Europe to provide an ‘Indian Summer’ to countries bordering the North Sea.

10

www.geo-web.org.uk

December 2016

The Group for Earth Observation

GEO Quarterly No 52

Paul Geissmann HB3YGP
http://satellitenpaul.ch/
My receiving station lies just 15 kilometres from Säntis, at
2504 metres above sea level, the highest mountain in the
Alpstein massif of northeastern Switzerland.
The 1879, the second International Meteorological
Congress in Rome declared it necessary to build weather
stations on suitable, and preferably freely accessible,
mountain peaks. This request was acknowledged by
Switzerland through the establishment of the Säntis
station, whose upstream position north of the Alps proved
to be particularly favourable. A special challenge was thecreation of the necessary telegraph line.
It was in autumn 1882 that the Swiss Society for Natural
Sciences established the first alpine weather stationin Europe in a room in the Säntis Inn, a mountainguesthouse. Säntis, the northernmost peak of the Swiss
Alps (figure 1), is ideal for forecasting approaching
weather. Here weather coming from the west beats down,
usually fiercely, because of the exposed position. The
station was operated by John Beyer and Konrad Saxer,
who initially stayed in the Säntis Inn, meeting up for theirwork only from spring till autumn.

Figure 1 - Säntis, photographed in April, 2015

But in 1887, following a huge construction effort, an
underground passageway blasted through the rocks to thesummit was completed, enabling year-round monitoring
activities. Figure 1 shows photographs of the weather
station as it was over 100 years ago.
The exposed location of Säntis ensures extreme weather
conditions: the average temperature is -1.9°C andprecipitation is 2487 mm per year. The lowest everrecorded temperature was -32°C in January 1905 andthe highest 20.8°C in July 1983. The highest daily total
rainfall was 180 mm in June 1910. The highest rainfall
in one hour was the 81.9 mm measured in July 1991.
Indeed, Säntis is the wettest place in Switzerland.

Figure 2 - Säntis weather station, pictured in 1915 (left) and 1920.

Between April 21-23, 1999, a blizzard deposited 816 cm ofsnow on the mountain’s northern snowfield, the greatest
depth ever measured in Switzerland. And on December 26
the same year, during cyclonic storm Lothar, a record windspeed of 230 km/h was measured on the summit. Snow
can be expected in all months of the year on Säntis, evenduring the summer: fully a metre fell during August 1995.
Säntis is extremely prone to lightning strikes and canexperience as many as 400 annually.
In the beautiful Appenzell region, just nine kilometresfrom Säntis, stands MeteoGroup Switzerland’s ‘Weather
Factory’ (figure 4). This, a branch of Jörg Kachelmann’s
Meteomedia AG Weather Service, currently employsaround 20 people and is a branch of the largest private
European weather information provider.
Weather forecasts for media (German broadcasting service,
ARD, newspapers and radio) are created here (figure 5, 6),
but particularly special forecasts for the transport sector in

Figure 3 - The original meteorological station stands
beside the present-day transmitting tower

www.geo-web.org.uk

11

GEO Quarterly No 52

The Group for Earth Observation

Figure 4 - Dish antennas at the Weather Factory

December 2016

Figure 5 - The Entrance Foyer at Appenzell

Figure 6 - The workplace at Meteo Group in Appenzell

the Alpine region: about the railways, winter maintenanceforecasts for highways, cantons, cities and municipalities
as well as for the airports of Zurich, Milan and Bergamo.
For 10 years, the focus has also been on producing
accurate weather warnings from their website atwww.meteocentrale.ch

Figure 7 - The London office of MeteoGroup, who will replace the
Met Office as the BBC’s official weather provider in 2017.

Soviet Meteor 1‑30 satellite, launched early that year, andshows the Alps and Italy with, at far right, the numericaltelemetry data typical of that satellite. Over the years I
obtained images from a variety of satellites, including theMeteor‑2 and Meteor‑3 series, Okean and SICH. In thosedays the PC was still in its infancy, so these images could
only be recorded on paper.

MeteoGroup Switzerland also operates a private automaticweather monitoring network that, within Switzerland,
currently comprises about 380 stations. This bypasses
the professional meteorologists in the ‘weather-room’ toprovide highly accurate local forecasts.
In the UK, MeteoGroup has been chosen as the company
to replace the Met Office as the BBC’s weather forecasterfrom spring 2017 (figure 7).
My Own Satellite Activities
I first started receiving NOAA images from space with thesimple receivers that were available 40 years ago, but
was later lucky to obtain some discarded equipment from
Kloten Airport. This included a Muirhead ‘Mufax’ chart
recorder and expensive shortwave and longwave receivers.
Finally, I received a satellite receiver for the reception of
the Meteor and NOAA series.
With the Mufax chart recorder I could then display Meteor
and NOAA images on paper, just like the German Weather
Service. Figure 8, acquired in 1980, is most likely from the12

www.geo-web.org.uk

Figure 8 - A 1980 ‘Mufax’ image, probably fromthe Russian satellite Meteor 1-30.

December 2016

The Group for Earth Observation

GEO Quarterly No 52

Figure 9 - The August 26, 2016 noon image from Meteosat

Figure 10
The Author’s first homebrew
Dish Antenna

I also wished to receive
Meteosat’s geostationary
images on the 1691 MHz
frequency, but in thosedays, you could noteasily buy a parabolic
dish antenna; as I could
not afford one, I built adish myself—difficult,and not beautiful—but
it worked. For my firstattempt I started with afibreglass skylight dome
and glued aluminium
foil inside it. This dishactually worked but thesignal was rather weak.
For my second attempt,
I constructed a parabolic
template out of wood andFigure 11 - The author, pictured cooling off outside his homestation during a heatwave on July 5, 2015.

triangular, perforated aluminium plates, the latter being
riveted together and placed inside it. This dish worked
really well but storm Lothar tore the dish from its mount.
Fortunately, an insurance payment for the storm damage
to my property allowed me at last to purchase a proper
1.7 m dish.
At that time it was almost a sensation that amateurs
could receive such images. But thanks to today’s softwareand hardware, amateurs are able to compete with theprofessionals by receiving super, high quality images fromspace.
Nowadays, in addition to the NOAA satellites (figure 12), I
run a EUMETCast system which brings me regular imagesof our entire hemisphere (figure 9).

Figure 12 - Detail from the 12:25 UT NOAA‑19 pass on August 26, 2016.

www.geo-web.org.uk

13

GEO Quarterly No 52

The Group for Earth Observation

December 2016

NASA

Atmospheric carbon dioxide levels during the past 400 000 years.
Credit: Vostok ice core data / J.R. Petit et al.; NOAA Mauna Loa CO2 record.

This graph, based on the comparison of atmosphericsamples contained in ice cores and more recent direct
measurements, provides evidence that atmospheric CO2
has increased since the Industrial Revolution.

The evidence for rapid climate change is compelling.
Indeed, the Intergovernmental Panel on Climate Change [1]has stated that: ‘Scientific evidence for warming of theclimate system is unequivocal.’

The Earth’s climate has changed throughout history.
There have been seven cycles of glacial advance andretreat during the past 650,000 years alone. The abrupt
end of the last ice age—about 7,000 years ago—marked
the beginning of the modern climate era and of humancivilisation. Most of these climate changes can be
attributed to very small variations in Earth’s orbit thatchange the quantity of solar energy our planet receives.

Sea Level Rise

The current warming trend is of particular significancebecause most of it has very likely been humaninduced and it is currently proceeding at a rate that isunprecedented in the past 1,300 years.
Earth-orbiting satellites and other technological advances
have enabled scientists to see the big picture, collecting
many different types of information about our planet andits climate on a global scale. This body of data, collected
over many years, reveals the signals of a changing climate.
The heat-trapping nature of carbon dioxide and othergases was demonstrated in the mid 19th century [2]. Theirability to affect the transfer of infrared energy through theatmosphere is the scientific basis of many instruments
flown by NASA satellites. There is no question that
increased levels of greenhouse gases must cause the Earth
to warm in response.
Ice cores drawn from Greenland, Antarctica and tropicalmountain glaciers show that the Earth’s climate does
respond to changes in greenhouse gas levels. They also
show that, in the past, large changes in climate have
happened very quickly, geologically-speaking: in tens ofyears, rather than millions or even thousands.

14

Global sea level rose about 17 centimetres during the20th century. The rate in the past decade, however, is nearly
double that of the last century
Global Temperature Rise
All three major global surface temperature reconstructions
show that Earth has warmed since 1880. Most of this warming
has occurred since the 1970s, with the twenty warmest years
having occurred since 1981 and the ten warmest of theseoccurring during the past twelve years. Even though the 2000s
witnessed a solar output decline resulting in an unusually deep
solar minimum in 2007-2009, surface temperatures continued toincrease.
Warming Oceans
The oceans have absorbed much of this increased heat, withthe top 700 metres of oceanic water showing warming of 0.168
degrees Celsius since 1969.
Shrinking Ice Sheets
The Greenland and Antarctic ice sheets have decreased in mass.
Data from NASA’s Gravity Recovery and Climate Experiment [3]show that Greenland lost between 150 and 250 cubic kilometresof ice per year between 2002 and 2006, while Antarctica lost
about 152 cubic kilometres of ice between 2002 and 2005.
Declining Arctic Sea Ice
Both the extent and thickness of Arctic sea ice have declined
rapidly over the past several decades.
Glacial Retreat
Glaciers are retreating almost everywhere around the world: in
the Alps, Himalayas, Andes, Rockies, Alaska and Africa.

www.geo-web.org.uk

continued on page 52

The MODIS instrument aboard NASA’s Terra satellite images this scene showing a large iceberg north east of South Georgia on September 26, 2016.
Image: LANCE Rapid Response/NASA/GSFC

www.geo-web.org.uk

15

GEO Quarterly No 52

The Group for Earth Observation

December 2016

NASA Earth Observatory
Along the Bellingshausen Sea coast ofWest Antarctica, ice has been retreating
inland being lost to the sea. Scientists
knew this, but they lacked a full picture of
the scale. Now a team of researchers hascompiled a Landsat-based data-set andfound that such losses have been goingon for at least the past four decades—andalong the vast majority of this coast.
“We knew that ice had been retreatingfrom this region recently,” claimed Frazer
Christie, a doctoral candidate at the
University of Edinburgh and a co-authorof the study. “Now, thanks to a wealth offreely available satellite data, we know thishas been occurring pervasively along thecoastline for almost half a century.”
The Bellingshausen Sea—named for theRussian Admiral who found the continent
in 1820—lies to the west of the Antarctic
Peninsula. Examining Landsat datacollected between 1975 and 2015, theresearchers mapped the approximate
locations of ‘grounding lines’ in theice along the Bellingshausen coast.
These lines mark the intersection where
glacial ice ﬂowing from the continent isconnected, or grounded, to the sea ﬂoor.
Any ice past the grounding line usually
ﬂoats on the sea as an ice shelf. Whenice is lost to the sea, the grounding
line retreats. Meanwhile, the ice loss
contributes to global sea level rise.
Christie and colleagues used Landsat data
to locate ‘inﬂection points’ on the surfaceof the ice that indicate the approximate
location of grounding lines below. An
inﬂection point—which can be tricky todetect by an untrained eye—is defined as
the final location where the slope of the ice
dramatically changes before ﬂattening out
into an ice shelf on meeting the sea. The
team combined its Landsat projections ofinﬂection points with radar data from theEuropean Space Agency’s ERS-1, ERS-2
and CryoSat-2 satellites. They found thatthe majority of the coastline along theBellinghausen Sea had experienced somegrounding line retreat over the past four
decades. The findings were published inGeophysical Research Letters.
The widespread retreat has most likely
been caused by warmer ocean water
licking at the undersides of the ﬂoating ice
near the grounding line—or as the authors
write: ‘an ingress of relatively warm
circumpolar deep water.’
The images above show an area near

16

Eltanin Bay, where the majority of thegrounding line is found at the seaward
front of the ice. The top image was
acquired by Landsat-2’s Multispectral
Scanner on February 18, 1975;
the second image was acquired byLandsat-8’s Operational Land Imager
on March 2, 2015. The ice loss is mostpronounced along the Ferrigno Ice
Stream, which was named for Jane
Ferrigno, a US Geological Survey scientist
who used satellite data to map Antarctica.
www.geo-web.org.uk

This study provides important context forunderstanding the causes of ice retreat
throughout Antarctica as a whole, and
it is now known that West Antarctica
has been changing for many decades.
The next challenge is to ascertain the
key ice, ocean, and atmospheric factors
responsible for such ice losses.
NASA Earth Observatory images by Jesse Allen,
using Landsat data from the US Geological Survey.
Caption by Laura Rocchio, Landsat Communication
and Public Engagement Team.

December 2016

The Group for Earth Observation

GEO Quarterly No 52

NASA Earth Observatory
One of the most frequently misunderstood concepts in science is the reason for Earth’s seasons, so here’s a space-based view ofwhat’s going on.
Around 6 am local time each day, the Sun, Earth, and any geosynchronous satellite lie at the corners of a right angled triangle,
affording a nadir (straight down) view of the terminator—the edge between the shadows of nightfall and the sunlight of dusk anddawn. The position of this line between night and day varies with the seasons, which means different lengths of days and differing
amounts of warming sunshine. (The line is actually a curve, but satellite images only show it in two-dimensions.)
The Spinning Enhanced Visible and Infrared Imager (SEVIRI) on EUMETSAT’s Meteosat-9 captured these four views of Earth fromgeosynchronous orbit. The images show how sunlight fell on the Earth on December 21, 2010 (upper left), and March 20 (upper
right), June 21 (lower left), and September 20, 2011 (lower right). Each image was taken at 6:12 am local time.
continued on page 52

December 21, 2010

March 20, 2011

June 21, 2011

September 20, 2011
Credit: NASA images and animation by Robert Simmon,
www.geo-web.org.uk
usingdata ©2010 EUMETSAT.
Caption by Mike Carlowic

17

This is a section from a Meteor M2 LRPT image acquired from the 07:46 UT pass on September 23, 2016 by Enrico Gobbetti.

18

www.geo-web.org.uk

December 2016

The Group for Earth Observation

GEO Quarterly No 52

Dr Michael K Butler, G4OCR
e-mail: m.k.butler@bolton.ac.uk
Earth imaging satellites have played a key role inmeteorology for over half a century. The very first imagesof Earth from a satellite were obtained on August 14, 1959
by the U.S. satellite Explorer 6. These images were very
crude by today’s standards. The first weather satelliteconsidered to be a success was TIROS‑1 (Television
Infrared Observation Satellite). This was launched on
April 1, 1960, and was operational for 78 days. In total,ten TIROS satellites were launched between 1960 and
1965. These were succeeded by the ESSA (Environmental
Science Services Administration) series of satellites, nineof which were launched between 1966 and 1969, andfinally by the NOAA (National Oceanic and Atmospheric
Administration) satellites, nineteen of which were launchedbetween 1970 and 2009. Of these nineteen, three are stillin operation, and these are the main focus of this article.
An earlier draft of this article was published by the Radio
Society of Great Britain in RadCom volume 92, number 11(November 2016). The copyright of this article belongs to
the RSGB, and it appears here with their kind permission.
Types of Satellite Orbit
There are four different basic types of satellite orbit aroundthe Earth classified according to altitude. Satellites in low
Earth orbit (LEO) typically have an altitude of between
one hundred miles and one thousand miles. Their orbital
periods range between roughly 90 and 120 minutes, andincrease with increasing altitude. The TIROS satellites andtheir successors have all been LEO satellites. Satellites
in medium Earth orbit (MEO) typically have an altitude
of between one thousand miles and twenty-two thousand
miles. Their orbital periods range between roughly twohours and twenty-four hours. Satellites in high Earthorbit (HEO) have an altitude greater than twenty-two
thousand miles, and orbital periods greater than one day.
At the boundary between MEO and HEO, at an altitude of
22,236 miles, the orbital period is precisely one day. Since
the orbit of the satellite synchronises precisely with therotation of the Earth there is no apparent movement of thesatellite. Such an orbit is called a geostationary orbit.
Each of these types or orbit has advantages anddisadvantages. Geostationary orbits are useful because
once the antenna, typically a dish, has been accurately
aimed at the satellite, no further adjustment is required.
Satellites carrying domestic television services are ingeostationary orbits. Signals from geostationary orbit
and HEO are relatively weak, and a high-gain antenna
is required in order to achieve reliable reception. The
images from a given geostationary satellite only coverroughly one third of the Earth’s surface, and the signals
from such a satellite may only be received from a similarly
limited proportion of the Earth’s surface. Low Earthorbits are useful because the signals from these satellites
are relatively strong. Even if the output power of thetransmitter is only a few watts, reception is possible witha quite modest antenna and receiver. As the position of
the satellite is always changing relative to the ground, it

Figure 1 - typical HVCT enhancement of an APT signal

may serve most of the Earth’s surface. From the point ofview of Earth imaging, images from LEO satellites have amuch greater resolution than those from higher altitudesatellites. For this reason, many weather satellites are in
low Earth orbits.
Weather Satellites
In Europe, EUMETSAT (European Organisation for the
Exploitation of Meteorological Satellites) operate theMeteosat series of satellites in geostationary orbit, andthe LEO satellites Metop‑A and Metop‑B. It was originallyintended that the Metop satellites would transmit LRPT
(low rate picture transmission) on 137 MHz, but this wasabandoned due to interference with other instrumentation.
Meteosat‑9 and -10 are located over Africa at longitude
9.5 degrees east and 0 degrees respectively, and provide
imaging of Africa and Europe. At the time of writing,
Meteosat‑8 is in the process of being relocated from overwww.geo-web.org.uk

19

GEO Quarterly No 52

The Group for Earth Observation

December 2016

Africa to over the Indian Ocean, where it will take overfrom the decommissioned Meteosat‑7. Near real-time
reduced resolution imagery from the Meteosat and Metopsatellites is available via the EUMETSAT website. Images
from the Meteosat and Metop satellites are relayed at full
resolution via a system called EUMETCast. The origin of
this system was the failure of the 1.7 GHz power amplifier
on Meteosat‑8. This failure made direct reception fromthe satellite unfeasible without a very large dish antenna.
Instead, images were relayed via a geostationary domestic
television satellite.
Today EUMETCast is relayed via Eutelsat‑10A on afrequency of 11263 MHz in the Ku-band, with a footprint
covering the UK and continental Europe. EUMETCast
uses a format called DVB-S2 (Digital Video Broadcasting– Satellite, second generation). Reception requires only
an 85 cm dish, and a DVB-S2 receiver, both of which arewidely available at affordable prices. The data is encrypted,
and to obtain the decryption key one needs a licenceissued by EUMETSAT to receive EUMETCast products.
Happily, these are available at no charge to amateur
weather satellite enthusiasts.
Coverage of North and South America is provided by the
GOES (Geostationary Operational Environmental Satellites)
operated by the National Environmental Satellite, Data,and Information Service (NESDIS). GOES‑13 (also known
as GOES-East) is positioned at longitude 75°W, whilst
GOES-15 (also known as GOES‑West) is positioned atlongitude 135°W. GOES imagery may be received directfrom the satellite on 1.7 GHz but, following the example
set by EUMETCast, is also relayed via GEONETCast
using the television satellite New Skies NSS‑806 in the
C-band. On November 19, 2016, GOES-R was successfullylaunched. This new geostationary satellite has capabilities
significantly beyond the previous satellites in the GOES
series, including three times more spectral information,
four times greater spatial resolution, and real-time
mapping of lightning activity. The satellite will be renamed
as GOES-16 once it has reached its final designated orbit
in December 2016.
NOAA Polar Orbiting Environmental Satellites
In this article, we are concerned with the NOAA Polar
Orbiting Environmental Satellites (POES), which are
in a very specific type of LEO. These orbit at a mean
altitude of around 525 miles and have an orbital period of
104 minutes. The orbits are sun synchronous, meaningthat the plane in which each satellite orbits remains fixed
relative to the position of the sun. The result of this is thateach pass of the satellite takes place at roughly the same
local time relative to the longitude of the pass. There are
currently three Polar Orbiting Environmental Satellites
in operation, which were launched from Vandenberg Air
Force Base in California on the following dates:
NOAA-15 - Launched May 13, 1998
NOAA-18 - Launched May 20, 2005
NOAA-19 - Launched February 6, 2009
Each POES satellite carries an Advanced Very High
Resolution Radiometer (AVHRR), which is in effect thesatellite’s camera. The AVHRR has sensors that measureelectromagnetic radiation reflected from the Earth in six
spectral bands, or ‘channels’, as described in Table 1.
Data from two channels of the AVHRR is transmittedusing an analogue system known as automatic picturetransmission (APT). The two channels that are used varies.
Whilst the satellite is in sunlight, NOAA‑15 and NOAA‑19

20

Figure 2 - HVC Enhancement of an APT Signal
Wavelength(µm)

Description

Typical Use

10.58 - 0.68

VisibleDaytime cloud and surface mapping2

0.725 - 1.00

VisibleLand-water boundaries

Channel

3A

1.58 - 1.64

3B

3.55 - 3.93

Snow and ice detection

4

10.30 - 11.30

InfraredNight cloud mapping5

11.50 - 12.50

Infrared

Sea surface temperatureNight cloud mapping

Table 1 - NOAA AVHRR Sensors

usually carry channels 2 and 4, and NOAA-18 usually
carries channels 1 and 4. Whilst in darkness all threesatellites carry channels 3 and 4. The data is transmitted
as a horizontal line‑scan at a rate of two lines per second.
Each line is 2080 pixels long, and hence the data rate is4160 baud. The raw data received may be decoded using
suitable software, and appears as monochrome images
from the two channels side by side. The satellites also
provide high-resolution picture transmission (HRPT) in the
1.7 GHz band. The HRPT service carries all of the channels
from the AVHRR. Reception of HRPT requires a steerable
antenna and is beyond the scope of this article. The
frequencies currently in use (as of November 2016) for APT
and HRPT from NOAA-15, 18 and 19 are shown in Table 2.
Of these three, NOAA-19 consistently gives the best
images. From any given location, the APT transmission

www.geo-web.org.uk

December 2016

The Group for Earth Observation

Satellite

APT

HRPT

NOAA 15

137.6200 MHz

1702.5 MHz

NOAA 18

137.9125 MHz

1707.0 MHz

NOAA 19137.1000 MHz

1698.0 MHz

GEO Quarterly No 52

Table 2 - The NOAA AVHRR Frequencies

from each satellite may be received for three passes eachday during the daytime and a further three passes during
the night.
Hardware
Reception of APT from the NOAA satellites requires asuitable receiver and antenna. A general coverage receiveror scanner covering the 137 MHz band will give fair
results but a purpose-built receiver will perform muchbetter. Ideally, the receiver should feature automatic
frequency control, enabling it to compensate for theshift in frequency during the satellite pass that arises
from the Doppler effect. Also, the bandwidth of APT
is around 30 kHz, which is a little too wide for mostscanners, resulting in clipping of the signal. The author
uses the R2ZX receiver (figures 3,4) which was thestandard receiver recommended and sold by GEO for
several years. Unfortunately, this receiver is no longer
being manufactured, but the APT-06 receiver of similar
specification is available from WRAASE Electronic in
Germany.

Figure 3 - The R2ZX receiver for APT on 137 MHz

Running software to process data from the satellites
requires only a PC or laptop of modest specification witha sound card. The audio signal from the receiver is fed
into the microphone input socket on the laptop. The audio
volume of the receiver and the gain of the microphonepreamp need to be carefully set to maximise signal whilst
avoiding distortion. The author uses a ten year old laptop
running Windows XP as a machine dedicated to runningweather satellite software and weather station software. Asan alternative to the receivers mentioned above, receptionof APT may be achieved using a software defined radio
dongle, such as the Newsky RTL2832U/R820T2, withsuitable software.
The APT signals are transmitted with right-hand circularpolarisation. Whilst fair reception can be obtained froma VHF antenna such as a discone intended for use withscanners, the results are much improved if an antenna
designed for circular polarisation at 137 MHz is used. The
author uses a crossed dipole (turnstile) antenna mounted
on a short mast on the chimney stack, and this gives
excellent results. An alternative to the crossed dipole is thequadrifilar helix (QFH) antenna, but these are considerably
more expensive. As with any antenna, good quality
coaxial cable such as RG58 should be used to connect theantenna to the receiver.

Figure 4 - FT-2000, Pakratt PK-232 tnc, R2ZX receiver andDavis Vantage VUE weather console

artificially coloured image. The basic freeware version of
WXtoImg features five different enhancement options for
producing an image. HVC is the most basic, and gives acoloured tint to clouds which varies according to theirtemperature. HVCT and MSA (multi spectral analysis) bothmake use of a map overlay to distinguish land from sea,
allowing a more naturally coloured image to be produced,
with blue for sea and green/brown for land. MCIR (mapcoloured infrared) is used to produce colour images
whilst the satellite is in darkness. The ‘thermal’ option
gives an image which is artificially coloured according totemperature. Figures 1,2,6,7 and 8 show examples of eachof these processing options.
The Standard and Professional editions of WXtoImg
provide several further enhancement options, including
enhancements which show precipitation. There are manyother additional features, including the facility to produce
composite images from two or more consecutive passesof a satellite. Upgrade to the Standard or Professional
editions requires an upgrade key, which used to beavailable for a one-off fee. However, in February 2016 theupgrade keys became available free of charge.
Satellite software uses a set of parameters known as
Keplers (or, more formally, ‘Keplerian elements’) toaccurately predict the times and durations of satellite
passes. These also enable accurate positioning of map
overlays on the received images. The Keplers must be
updated from time to time from the Internet, typically

Software
There are several programs available for decoding APT dataand processing this to give informative and aestheticallypleasing images. One of the most popular is WXtoImg(‘Weather to Image’), and this is the program used by theauthor. Figure 5 is a screen capture of WXtoImg in theprocess of recording a pass of NOAA-19. The software
combines the two AVHRR images to give a single,

Figure 5 - Screen capture of WXtoImg recording NOAA 19 APT

www.geo-web.org.uk

21

GEO Quarterly No 52

The Group for Earth Observation

December 2016

Figure 6 - HVCT enhancement of an APT signal

Figure 7: An MCIR enhancement of an APT Signal.

every two days or so. Updating the Keplers is does not
require any understanding of the numerical parameterson the part of the user and is achieved by a single clickin the file menu of WXtoImg. The software may be set
to automatically record and process data from satellite
passes, and so may be left unattended. The software
will also drive a USB or serial interface to set a suitably
equipped receiver to the correct frequency for eachsatellite during its pass. The R2ZX receiver used by theauthor has a serial interface. Its successor, the R2FU,
and the WRAASE electronic APT-06 have USB interfaces.
The software may be set to record only when a specified
minimum elevation above the horizon is reached, andto ignore satellite passes which fail to reach a specified
threshold at maximum elevation. Careful adjustmentof these parameter avoids recording and attempting toprocess noisy signals that will produce only grainy images.

which left its sensors pointing towards the sun. However,
Meteor M N2 remains operational transmitting LRPT on
a frequency of 137.9 MHz. The bandwidth used by LRPT
is 150 kHz, much wider than that used for APT. Becauseof this, reception of LRPT requires new hardware (forexample, the Newsky SDR dongle mentioned above) andsoftware. Details appear in the web links section.

Further Information
The analogue APT format discussed in this article isbeing phased out, and if future polar orbiting satellites
provide any transmission suitable for reception by theamateur enthusiast on 137 MHz it will probably be in
the low rate picture transmission (LRPT) digital format.
There are already two Russian LEO satellites in operationthat provide LRPT, Meteor M N1 and Meteor M N2.
Unfortunately, Meteor M N1 is now incapable of imaging
the Earth due to an attitude loss on March 20, 201622

There are many useful web resources for the NOAA POES
satellites, and some of these are given in the web links
section below. GEO continue to provide support andup-to-date information for weather satellite enthusiasts,
and the GEO Shop stocks specialised items of hardware
for APT, LRPT and EUMETCast reception, with discounts
for members. Finally, the Radio Society of Great Britain(RSGB) is the UK’s internationally recognised nationalsociety for all radio amateurs, and provides informationand guidance on all aspects of radiocommunication.
Individual membership of the RSGB currently costs £51
per year, and includes twelve issues of the members’magazine RadCom.
Despite there being a wealth of near real-time satellite
images available on the web, there is still excitement anda sense of achievement in receiving images direct from thesatellites. It is hoped that this article will inspire readers
who have not already done so to try experimentation withreception of APT for themselves.

www.geo-web.org.uk

December 2016

The Group for Earth Observation

GEO Quarterly No 52

Web links:• WXtoImg (“Weather to Image”) software
http://www.wxtoimg.com/• National Oceanic and Atmospheric Administration (NOAA)
http://www.noaa.gov/• NOAA POES Operational Status
http://www.ospo.noaa.gov/Operations/POES/status.html• Polar orbiting satellite and geostationary satellite weekly
statushttp://phqfh.co.uk/status.htm• EUMETSAT near real-time images
http://www.eumetsat.int/website/home/Images/
RealTimeImages/index.html• WRAASE electronic (hardware)
http://www.wraase.de/shop.html• LRPT Tutorial
http://www.rtl-sdr.com/rtl-sdr-tutorial-receiving-meteor-m-n2lrpt-weather-satellite-images-rtl-sdr/• Radio Society of Great Britain
http://rsgb.org
The author is a Senior Lecturer in Mathematics in the
School of Engineering, University of Bolton.

Figure 8: Thermal enhancement of APT signal.

This is a Metop‑B image of New Zealand acquired on
October 31, 2016 by Mike Stevens.
Image © EUMETSAT 2016www.geo-web.org.uk

23

GEO Quarterly No 52

The Group for Earth Observation

December 2016

Michon Scott and Kathryn Hansen
A special feature from the NASA Earth Observatory Newsroom
Sea ice is frozen seawater that floats on the ocean surface.
It forms in both the Arctic and the Antarctic in eachhemisphere’s winter; it retreats in the summer, but does
not completely disappear. This floating ice has a profoundinfluence on the polar environment, influencing ocean
circulation, weather, and regional climate.

Figure 2 - Nilas Ice

Photo: Don Perovich, Cold Regions Research and Engineering Laboratory

Figure 1 - Sea ice plays an important role in the climate
and ecosystems of the Arctic and Antarctic.
Photograph ©2008 fruchtzwerg’s world

As ice crystals form at the ocean surface they expel salt,
which increases the salinity of the underlying waters.
This cold, salty water is denser, and can sink to the ocean
floor, where it flows back toward the equator. The sea ice
layer also restricts wind and wave action near coastlines,
lessening coastal erosion and protecting ice shelves.
Sea ice also creates an insulating cap across the ocean
surface, which reduces evaporation and heat loss to theatmosphere. As a result, the weather over ice-covered
areas tends to be colder and drier than it would be without
ice.
Sea ice also plays a fundamental role in polar ecosystems.
When the ice melts in the summer it releases nutrients
into the water, stimulating the growth of phytoplankton,
the centre of the marine food web. As the ice melts, it
exposes ocean water to sunlight, spurring photosynthesisin phytoplankton. When ice freezes, the underlying water
becomes saltier, and sinks, mixing the water column
and bringing nutrients to the surface. The ice itself ishabitat for animals such as seals, Arctic foxes, polar
bears, and penguins. Life thrives along the margins of
sea ice, as melting and freezing enhance circulation andbring nutrients to the surface. Those nutrients nourish
phytoplankton and ultimately animals like killer whales
that are farther up the food chain.

Figure 3 - Pancake ice

Photo: Don Perovich, Cold Regions Research and Engineering Laboratory

The influence of sea ice on the Earth is not just regional:
it’s global. The white surface reflects far more sunlightback to space than ocean water does: in scientific terms,
ice has a high albedo. Once sea ice begins to melt, a
self-reinforcing cycle often begins: as more ice melts andexposes more dark water, ever more sunlight is absorbed.
The sun-warmed water then melts more ice. Over several
years, this positive feedback cycle (the ice-albedo feedback)can influence global climate.

24

Figure 4 - Ice Rafts

Photo: Don Perovich, Cold Regions Research and Engineering Laboratory

www.geo-web.org.uk

Figure 5 - Ice Pressure Ridges
Photo: Ted Scambos, National Snow and Ice Data Center

December 2016

The Group for Earth Observation

GEO Quarterly No 52

Contrary to some public misconceptions, sea ice does
not influence sea level. Because it is already floating in
the ocean, sea ice is already displacing its own weight ofwater. Melting sea ice won’t raise ocean levels any morethan melting ice cubes will cause a glass of ice water tooverflow.

Multiyear ice increasingly loses salt and hardens each yearthat it survives the summer melt. In contrast to multiyear
ice, first-year ice is thinner, saltier, and more prone to meltin the subsequent summer. As of March 2015, multiyear
ice accounted for just 3% of the ice cover. The rest was all
first-year ice.

The Sea Ice Life Cycle

Monitoring Sea Ice

When seawater begins to freeze, it forms tiny crystals justmillimetres wide called frazil. How the crystals coalesce
into larger masses of ice depends on whether the seas arecalm or rough. In calm seas, the crystals form thin sheetsof ice, nilas, so smooth that they have an oily or greasy
appearance. These wafer-thin sheets of ice slide over eachother and form rafts of thicker ice. In rough seas, ice
crystals converge into slushy pancakes. These pancakes
slide over each other to form smooth rafts, or they collide
into each other, creating ridges on the surface and keels
on the bottom.

Dating back to 870 CE, intermittent records assembled by
the Vikings record the number of weeks per year that ice
occurred along the north coast of Iceland. Other scattered
records of Arctic sea ice date back to the mid 1700s, when
sailors kept notes on Northern Hemisphere shipping lanes.
Global air temperature records date back to the 1880s andcan offer a stand-in for Arctic sea ice conditions; but suchtemperature records were initially collected at just elevenlocations. Russia’s Arctic and Antarctic Research Institutehas compiled ice charts since 1933.

Sea ice begins as thin sheets of smooth nilas in calm water(figure 2) or disks of pancake ice in choppy water (figure 3).
Individual pieces pile up to form rafts and eventuallysolidify (figure 4). Over time, large sheets of ice collide,forming thick pressure ridges along the margins (figure 5).
Some sea ice holds fast to a coastline or the sea floor—’fast ice’—while pack ice drifts with winds and currents.
Because pack ice is dynamic, pieces can collide and form
much thicker ice. Leads—narrow, linear openings ranging
in width from metres to kilometres—continually form anddisappear.
Larger and more persistent openings, polynyas, aresustained by upwelling currents of warm water or steadywinds that blow the ice away from a spot as quickly as it
forms. Polynyas often occur along coastlines when winds
blow persistently offshore. As water and air temperaturesrise each summer near the Poles, some sea ice melts.
Differences in geography and climate cause Antarctic sea
ice to melt more completely in the summer than Arctic sea
ice.

Early records of sea ice cover come from explorers like
Robert Peary, who attempted to reach the North Pole in1909. But expeditions were sporadic and only surveyed
their immediate environment, so their records are far fromcomprehensive. Today, scientists studying Arctic sea ice
trends can rely on a fairly comprehensive record datingback to 1953. They use a combination of satellite records,
shipping records, and ice charts from several countries.

Figure 7 - A coloured photograph of members of Peary’s 1909
expedition crossing an open lead on Arctic sea ice.
Credit: Library of Congress Prints and Photographs Division

In the Antarctic, data prior to the satellite era are evenmore sparse. To extend the historical record of Southern
Hemisphere sea ice back in time, scientists have been
investigating two types of proxies. One reference is therecords kept by Antarctic whalers since the 1930s, whichdocument the location of all whales caught. Because
whales tend to congregate and feed near the sea ice edge,
their locations could be a proxy for ice extent.

NASA satellite image courtesy Jacques Descloitres,
MODIS Rapid Response Team.

A second proxy is the detection of phytoplanktonderived organic compounds in Antarctic ice cores. Since
phytoplankton grow most abundantly along the edgesof the ice, the concentration of sulphur-containing
compounds has been proposed as an indicator of how far
the ice edge extended from the continent. Currently, only
the satellite record is considered sufficiently reliable forstudying Antarctic sea ice trends.

Ice that survives the summer melt season may last for
years. For ice to thicken, the ocean must lose heat tothe atmosphere. But the ice also insulates the ocean
like a blanket. Eventually, the ice becomes so thick thatno more heat can escape. Once the ice reaches thisthickness—3 to 4 metres—further thickening isn’t possible
except through collisions and ridge-building.

Since 1979, a collection of satellites has provided acontinuous, nearly complete record of Earth’s sea ice
cover. Valuable data are collected by satellite sensors thatobserve the microwaves emitted by the ice surface. Unlike
visible light, the microwave energy radiated by ice passes
through clouds. This means it can be measured yearround, even through the long polar night.

Figure 6 - This satellite image shows sea ice
features: fast ice, pack ice, a polynya, and leads.

www.geo-web.org.uk

25

GEO Quarterly No 52

The Group for Earth Observation

The continuous sea ice record began with the Scanning
Multichannel Microwave Radiometer (SMMR) on the
Nimbus-7 satellite (1978-1987) and continued with theSpecial Sensor Microwave/Imager (SSM/I) and the Special
Sensor Microwave Imager Sounder (SSMIS) on Defense
Meteorological Satellite Program (DMSP) satellites (1987 topresent). The Advanced Microwave Scanning Radiometer–
for EOS (AMSR-E) on NASA’s Aqua satellite also
contributed data (2002-2011), a record that was extended
with the 2012 launch of the Advanced Microwave ScanningRadiometer 2 (AMSR2) on JAXA’s GCOM-W1 satellite.

Figure 8 - This plot above shows sea ice anomalies—by how
much Arctic sea ice cover was above or below the norm.

NASA Earth Observatory graph by Joshua Stevens, using NSIDC data
provided by Walt Meier/NASA Goddard.

Reliable records of Arctic sea ice began in 1953, andsatellites have offered a near-continuous record since1979. The plot above shows sea ice anomalies—how much
Arctic sea ice cover was above or below the norm.
Because ocean water emits microwaves differently fromsea ice, such ice ‘looks’ different to a satellite sensor. Theseobservations are processed into digital picture elements,
or pixels, each representing a 25 × 25 kilometre square.
Scientists estimate the amount of sea ice in each pixel.
There are two ways to express Earth’s total polar ice
cover: ice area and ice extent. To estimate area, scientists
calculate the percentage of sea ice in each pixel, multiply
by the pixel area, and add up the amounts. To estimate
ice extent, scientists set a threshold percentage, and countevery pixel that meets or exceeds that threshold as ‘icecovered.’ The National Snow and Ice Data Center, one ofNASA’s Distributed Active Archive Centers, monitors sea
ice extent using a threshold of 15%.

December 2016

The threshold–based approach may seem less accurate,
but it has the advantage of being more consistent. Whenscientists are analysing satellite data, it is easier to say
whether there is or isn’t at least 15% ice cover in a pixel,
than it is to say, for example, whether the ice cover is 70%
or 75%. By reducing the uncertainty in the amount of ice,scientists can be more certain that changes over time arereal.
Beyond measuring ice coverage, satellites can also help
scientists get a better handle on ice thickness. In 2010, theEuropean Space Agency launched the CryoSat-2 satellite,
which carries the Synthetic Aperture Interferometric Radar
Altimeter (SIRAL). Data from this instrument are converted
into maps of sea ice thickness—a useful tool for tracking
change over time and for monitoring winter season ice
growth.
Researchers also monitor sea ice using aircraft. In thesummer of 2016, for example, NASA’s Operation IceBridge
mapped the extent, frequency, and depth of melt pondsthat form on top of the sea ice during the melt season.
The number of melt ponds that form early in the season
can affect the minimum extent reached by sea ice in
September. Operation IceBridge has monitored sea ice
during late winter since 2009.
Arctic Sea Ice
Arctic sea ice occupies an ocean basin largely enclosed byland. Because there is no landmass at the North Pole, sea
ice extends all the way to the pole, making the ice subject
to the most extreme oscillations between wintertime
darkness and summertime sunlight. Likewise, because theocean basin is surrounded by land, ice has less freedomof movement to drift into lower latitudes and melt. Sea ice
also forms in areas south of the Arctic Ocean in winter,
including the Sea of Okhotsk, the Bering Sea, Baffin Bay,
Hudson Bay, the Greenland Sea, and the Labrador Sea.

Figure 10 - The Bering Strait is one of the few outlets
through which sea ice exits the Arctic Ocean.
NASA Earth Observatory image by Joshua Stevens andGeorge Riggs using data from Terra MODIS.

Figure 9 - Satellites measure sea ice concentration on a
25 kilometre by 25 kilometre grid. This image illustrates thearea covered by each pixel of the low-resolution microwave
instruments superimposed on a higher-resolution, colour
satellite image. Sea ice concentration is the percentage of eachpixel that is covered by ice. Sea ice extent is calculated byadding up the pixels with an ice concentration of at least 15%.

NASA Earth Observatory image by Joshua Stevens and Robert Simmon,
based on MODIS data.

26

Arctic sea ice generally reaches its maximum extent each
March and its minimum extent each September. This ice
has historically ranged from roughly 14-16 million square
kilometres (Mkm2) in late winter to roughly 7 Mkm2 each
September. In recent years, however, those numbers havebeen much lower.
On time scales of years to decades, the dominant causeof atmospheric variability around the North Pole is the
Arctic Oscillation (AO), an atmospheric seesaw, in which air
masses shift between the polar regions and mid-latitudes.

www.geo-web.org.uk

December 2016

The Group for Earth Observation

The shifting can intensify, weaken, or move the locationof semi-permanent low and high-pressure systems. Thesechanges influence the strength of the prevailing westerly
winds and the track that storms tend to follow.
During the ‘positive’ phase of the AO, winds intensify,
which increases the size of leads in the ice pack. The thin,
young ice that forms in these leads is more likely to meltin the summer. The strong winds also tend to flush ice outof the Arctic through the Fram Strait. During ‘negative’
phases of the oscillation, winds are weaker. Multiyear ice
is then less likely to be swept out of the Arctic basin into
the warmer waters of the Atlantic.
However, in recent years, the relationship between
the Arctic Oscillation and summer sea ice extents has
weakened. For example, a strong negative phase in thewinters of 2009 and 2010 was not enough to maintainhigh levels of ice cover. Clearly some other factors canoverride the relationship.

GEO Quarterly No 52

Between 1979 and 2015, the average monthly extent
for September declined by 13.4% per decade. In every
geographic area, in every month, and every season, Arctic
sea ice extent is lower today than it was during the 1980s
and 1990s.
Natural variability and Global Warming both appear
to have played a role in this decline. The AO’s strongly
positive mode through the mid 1990s flushed thicker,
older ice out of the Arctic, replacing multiyear ice with
first-year ice that is more prone to melting. After themid 1990s, the AO was often neutral or negative, but
sea ice failed to recover. Instead, a pattern of steep
Arctic sea ice decline began in 2002. The AO probably
triggered a phase of accelerated melt that continued into
the next decade because of unusually warm Arctic air
temperatures.
Year

Average
Minimum(Mkm2)

ExtentRelative to
1981-2010
Average(Mkm2)

Differencefrom1981-2010
Average (%)

2002

5.95

-0.55

-8.53

2003

6.13

-0.37

-5.76

2004

6.04

-0.46

-7.15

2005

5.56

-0.94

-14.53

2006

5.91

-0.59

-9.15

2007

4.29

-2.22

-34.05

2008

4.72

-1.79

-27.44

2009

5.38

-1.13

-17.29

2010

4.92

-1.59

-24.37

2011

4.61

-1.90

-29.13

2012

3.62

-2.89

-44.35

2013

5.35

-1.16

-17.76

2014

5.28

-1.23

-18.83

2015

4.63

-1.88

-28.82

Status and Trends
In September 2015, Arctic sea ice reached a minimum
extent of 4.41 Mkm2—the fourth lowest in the satellite
record. The ice then grew during the winter months andreached its annual maximum extent in March 2016,
measuring 14.52 Mkm2. By September 2016, sea ice
dropped to 4.14 Mkm2, the second lowest extent of thesatellite era (figure 11).

Arctic ice extent has dropped steeply since 2002.

Table based on data from the National Snow and Ice Data Center.

Figure 11 - The minimum Arctic sea ice extent occurs in
September. The maximum is in February or March. Arctic sea
ice maxima and minima have been shrinking for three decades.
NASA Earth Observatory maps by Joshua Stevens, based on AMSR2-E
data from NSIDC.

Many global climate models predict that the Arctic will
be ice-free for at least part of the year before the end of
the 21st century. Some models predict an ice-free Arctic
by mid-century. Depending on how much Arctic sea
ice continues to melt, the ice could become extremely
vulnerable to natural variability in cycles such as the
Arctic Oscillation.

The record lowest minimum occurred in September 2012
when sea ice plummeted to 3.41 Mkm2. That was well
below the previous record of 4.17 Mkm2 set in 2007, when
Arctic sea ice extent broke all prior records by mid-August,more than a month before the end of melt season. Since
the mid 2000s, low minimum extents in the Arctic havebecome the ‘new normal.’Figure 13 - Arctic sea ice cover peaks each year in March, and reaches
its minimum in September. In 2012, Arctic ice reached the lowest extent
ever recorded, well below the historical average (blue dashed line).
Earth Observatory graph by Joshua Stevens, based on data from the National
Snow and Ice Data Center.

Figure 12 - Since 1979, the monthly September ice extent has
declined 13.4% per decade relative to the average from 1981 to 2010.
NASA Earth Observatory graph by Joshua Stevens, based on data from the
National Snow and Ice Data Center.

Declining sea ice will lead to a loss of habitat for seals andpolar bears; it also should increase encounters between
polar bears and humans. Indigenous peoples in the Arctic
have already described changes in the health and numbersof polar bears.

www.geo-web.org.uk

27

GEO Quarterly No 52

The Group for Earth Observation

As sea ice retreats from coastlines, wind-driven waves—combined with thawing permafrost—will very likely leadto more rapid coastal erosion. Other potential impacts
include changed weather patterns. This is an area of active
research, as scientists try to tease out the possible links
between sea ice loss and mid-latitude weather patterns.

December 2016

To study patterns and trends in Antarctic sea ice,scientists commonly divide the ice pack into five sectors:
the Weddell Sea, the Indian Ocean, the western Pacific
Ocean, the Ross Sea, and the Bellingshausen andAmundsen seas (figure 16). In some sectors, it is common
for nearly all the sea ice to melt in the summer.
Antarctic sea ice is distributed around the entire fringeof the continent—a much broader area than the Arctic—
and it is exposed to a broader range of land, ocean, andatmospheric influences. Because of the geographic andclimatic diversity, Antarctic sea ice is more variable fromyear to year and climate oscillations don’t affect ice inall sectors the same way. For these reasons, it is moredifficult to generalise the influence of climate patterns to
the entire Southern Hemisphere ice pack.

Figure 14 - The loss of sea ice exposes shorelines to thefull force of wind and waves, resulting in rapid erosion.
This cabin fell into the Beaufort Sea, a region where somecoastlines retreated more than 24 metres in 2007.
Photograph courtesy Benjamin Jones, USGS.

Some researchers have hypothesised that melting sea ice
could interfere with ocean circulation. In the Arctic, ocean
circulation is driven by the sinking of dense, salty water.
Fresh meltwater, coming primarily from the Greenland
Ice Sheet, could interfere with ocean circulation at highlatitudes, slowing it down. Changes in the location andtiming of sea ice growth—where the dense salty waters
are formed and then sink to the bottom—may also be an
important factor.
Antarctic Sea Ice
The Antarctic is in some ways the opposite of the Arctic.
The Arctic is an ocean basin surrounded by land, withthe sea ice corralled in the coldest, darkest part of theNorthern Hemisphere. The Antarctic is a continent
surrounded by ocean. Whereas Northern Hemisphere sea
ice can extend from the North Pole to a latitude of 45°N
(along the northeast coasts of Asia and North America),
most of the ice is found above 70°N. Southern Hemispheresea ice does not get that close to the South Pole; it fringes
the continent and reaches to 55°S latitude at its greatest
extent.

Figure 15 - Sea ice around Antarctica peaks in September andreaches a minimum in February. Roughly 15 million square
kilometres of ice melt and freeze during the annual cycle.

NASA Earth Observatory graph by Joshua Stevens, based on data fromthe National Snow and Ice Data Center.

Because of this geography, Antarctic sea ice coverageis larger than the Arctic’s in winter, but smaller in thesummer. Total Antarctic sea ice peaks in September—theend of Southern Hemisphere winter—historically rising to
an extent of roughly 17-20 Mkm2 . Ice extent reaches its
minimum in February, when it dips to roughly 3-4 Mkm2.

28

Figure 16 - In the Southern Ocean, sea ice fringes the entire Antarctic
continent. Researchers typically subdivide Antarctic sea ice into fivesectors, each influenced by different geography and weather conditions.
NASA Earth Observatory map by Joshua Stevens, based on data from theNorwegian Polar Institute and Natural Earth.

Antarctica experiences atmospheric oscillations andrecurring weather patterns that influence sea ice extent.
The primary variation is the Antarctic Oscillation,
also called the Southern Annular Mode. Like the Arctic
Oscillation, the Antarctic Oscillation involves a largescale see-sawing of atmospheric mass between the poleand the mid-latitudes. This oscillation can intensify,
weaken, or shift the location of low- and high-pressure
weather systems. These changes influence wind speeds,
temperature, and the track that storms follow, any ofwhich may influence sea ice extent.
During positive phases of the Antarctic Oscillation, theprevailing westerly winds that circle Antarctica strengthen
and move southward. This can change the way ice isdistributed among the various sectors. The strengtheningof the westerlies also isolates much of the continent andtends to have an overall cooling effect. However, it does
cause dramatic warming on the Antarctic Peninsula,
as warmer air above the oceans to the north is drawn
southward. Winds may drive the ice away from the coastin some areas and toward the coast in others. Thus, thesame climate influence may lessen sea ice in some sectors
and increase it in others.

www.geo-web.org.uk

December 2016

The Group for Earth Observation

Changes in the El Niño-Southern Oscillation Index(ENSO), an oscillation of ocean temperatures and surface
air pressure in the tropical Pacific, can lead to a delayed
response (three to four seasons later) in Antarctic sea
ice extent. In general, El Niño leads to more ice in the
Weddell Sea and less ice on the other side of the Antarctic
Peninsula, while La Niña causes the opposite conditions.

GEO Quarterly No 52

The variability in Antarctic sea ice patterns in different
sectors and from year to year makes it difficult to predict
how Antarctic ice could change as greenhouse gases
continue to warm the Earth. Climate models predict that
Antarctic sea ice will respond more slowly than Arctic sea
ice, but as temperatures continue to rise, a long-term
decline is expected.

Another bit of atmospheric variability is the periodic
strengthening and weakening of something meteorologists
call ‘zonal wave three’, or ZW3. This pattern alternately
strengthens winds that blow cold air away from Antarctica(toward the equator) and winds that bring warmer air frommiddle latitudes toward Antarctica. When southerly winds
intensify, more cold air is pushed to lower latitudes, andsea ice tends to increase. The effect is most apparent in
the Ross and Weddell Seas and near the Amery Ice Shelf.
As in the Arctic, the interaction of natural cycles iscomplex, and researchers continue to study how theseforces interact and control the Antarctic sea ice extent.
Status and Trends
In October 2015, Antarctic sea ice peaked for the yearat 18.8 Mkm2. That’s smaller than the previous three
years, but falls just about in the middle of maximum
extents measured since 1979. By February 2016, just asmall fraction of that ice remained, reaching an annual
minimum extent of 2.6 Mkm2—the ninth lowest in thesatellite record (figure 17).

Figure 18 - Antarctic sea ice does not plainly show the effects ofglobal warming. There is little evidence of long-term change ineither the maximum (September) or minimum (February) ice extent.
NASA Earth Observatory graph by Joshua Stevens, based on data from the
National Snow and Ice Data Center.

Why do the negative trends in Arctic sea ice seem to be
more important to climate scientists than the increasein Antarctic ice? Part of the reason is that the size of theincrease is much smaller and slightly less certain than the
Arctic trend.

Figure 17 - Antarctic sea ice peaks in September or
October, and reaches a minimum in February. In someplaces, sea ice melts completely in the summer.
NASA Earth Observatory maps by Joshua Stevens, using
AMSR2 data supplied by GCOM-W1/JAXA.

Since 1979, the total annual Antarctic sea ice extent has
increased about 1% per decade. Compared with the Arctic,
the signal has been a ‘noisy’ one, with wide year–to-year
fluctuations. For three consecutive Septembers (2012 to2014), satellites observed new record highs for winter sea
ice extent around Antarctica. The largest of those occurredin September 2014, when the ice reached 20.14 Mkm2.
Still, increases in Antarctic sea ice are exceeded bydecreases in the Arctic; that is to say, global sea ice isdecreasing even as Antarctic sea ice is increasing slightly.
Unlike the Arctic, where the downward trend is consistentin all sectors, in all months, and in all seasons, theAntarctic picture is more complex. Although sea ice
cover expanded in most of the Southern Ocean between
1979 and 2013, it decreased substantially in the
Bellingshausen and Amundsen seas. These two seas areclose to the Antarctic Peninsula, a region that has warmed
significantly in recent decades.

Another reason is that the complete summertime
disappearance of Northern Hemisphere ice would be a
dramatic departure from what has occurred throughout
the satellite record and likely throughout recorded history.
In the Antarctic, however, sea ice already melts almost
completely each summer. Even if it completely disappearedin the summer, the impact on the Earth’s climate
system would probably be much smaller than a similardisappearance of Arctic ice.
You might wonder how Antarctic sea ice could be
increasing while global warming is raising the planet’s
average surface temperature. It’s a question scientists areasking, too. One reason may be that other atmosphericchanges are softening the influence of global warmingon Antarctica. For example, the ozone hole that develops
over Antarctica each spring actually intensifies a vortex ofwinds that circles the South Pole. The stronger this vortex
becomes, the more isolated the Antarctic atmospherebecomes from the rest of the planet. In addition, ocean
circulation around Antarctica behaves differently than it
does in the Arctic. In the Southern Ocean, warm water
tends to sink downward in the ocean’s water column,
making sea ice melt from warm water less likely.
One concern related to Antarctic sea ice loss is how the
relationship between land and sea ice will change. Ice
shelves partly rest on land and partly float, and sea ice
is thought to stabilise the edges of these shelves. Ice
shelves frequently calve icebergs—a natural process thatwww.geo-web.org.uk

29

GEO Quarterly No 52

The Group for Earth Observation

December 2016

Comparing conditions at only two points in time or
examining trends over a short period is not sufficient tounderstand the impact of long-term climate change on
sea ice. Scientists can only understand how sea ice ischanging by comparing current conditions to long-term
averages.

Figure 19 - Icebergs are not sea ice: they’re floating
fragments of glaciers or ice shelves. Iceberg formation (andice shelf retreat) may increase in regions of Antarctica wheresea ice is declining because sea ice protects ice shelves bycooling air temperatures and dampening waves.
Photograph courtesy Patrick Rowe, NSF Antarctic Photo Library.

is not necessarily a sign of climate change. But the rapid
disintegration and retreat of an ice shelf (such as thecollapse of Larsen B in 2002) is a warming signal.
Although sea ice is too thin to physically buttress an ice
shelf, intact sea ice may preserve the cool conditions thatstabilise a shelf. Air masses passing over sea ice are cooler
than air masses passing over open ocean. Sea ice may also
suppress ocean waves that would otherwise flex the shelfand speed ice shelf breakup.
The interaction between sea ice loss and ice shelf retreat
merits careful study because many ice shelves are fed
by glaciers. When an ice shelf disintegrates, the glacierfeeding it often accelerates. Because glacier acceleration
introduces a new ice mass into the ocean, it can raise
global sea levels. So while sea ice melt does not directly
lead to sea level rise, it could contribute to other processes
that do. Glacier acceleration has already been observed on
the Antarctic Peninsula.
Conclusion
Because of differences in geography and climate, theamount, location, and natural variability of sea ice in the
Arctic and the Antarctic are different. Global warming andnatural climate patterns may affect each hemisphere’s
sea ice in different ways or at different rates. Within eachhemisphere, sea ice can change substantially from day today, month to month, and even over the course of a few
years.

Figure 20 - The Sun hangs low on the horizon
above solidified pancake ice in the Arctic Ocean.
Photograph courtesy Andy Mahoney, NSIDC.

30

Since 1979, satellites have provided a consistentcontinuous record of sea ice. Through 2015, the averagemonthly September extent of Arctic sea ice has declinedby 13.4% per decade relative to the average from 1981 to2010. Declines are occurring in every geographic area, inevery month, and every season. Natural variability andrising temperatures linked to global warming appear tohave played a role in this decline. The Arctic may be icefree in summer before the end of this century.
Antarctic sea ice trends are smaller and more complex.
Relative to the average from 1981 to 2010, the Antarctic
sea ice extent increased about 1% per decade, but thetrends were not consistent for all areas or all seasons. The
variability in Antarctic sea ice patterns makes it harderfor scientists to explain Antarctic sea ice trends and to
predict how Southern Hemisphere sea ice may change as
greenhouse gases continue to warm the Earth. Climate
models do predict that Antarctic sea ice will respond more
slowly than Arctic sea ice to warming, but as temperaturescontinue to rise, a long-term decline is expected.
References• Cavalieri, D. J., and C. L. Parkinson (2008) Antarctic
sea ice variability and trends, 1979–2006, Journal ofGeophysical Research Oceans. 113, C07004.
• Comiso, J.C., Parkinson, C.L., Gersten, R., Stock, L. (2008)
Accelerated decline in the Arctic sea ice cover. GeophysicalResearch Letters. 35, L01703.
• de la Mare, W.K. (1997) Abrupt mid-twentieth-century
decline in Antarctic sea-ice extent from whaling records.
Nature. 389, 57-60.
• Goosse, H., Lefebvre, W., de Montety, A., Crespin, E., andOrsi, A.H. (2008) Consistent past half-century trends in theatmosphere, the sea ice and the ocean at high southernlatitudes. Climate Dynamics.
• Intergovernmental Panel on Climate Change. (2007)
Summary for Policymakers. In: Climate Change 2007:
Impacts, Adaptation and Vulnerability. Contribution ofWorking Group II to the Fourth Assessment Report of theIntergovernmental Panel on Climate Change, M.L. Parry,
O.F. Canziani, J.P. Palutikof, P.J. van der Linden, andC.E. Hanson, Eds., Cambridge, UK: Cambridge University
Press, pp. 7-22.
• Mahoney, A.R., Barry, R.G., Smolyanitsky, V., Fetterer,
F. (2008) Observed sea ice extent in the Russian Arctic,
1933–2006 Journal of Geophysical Research. 113, C11005.
• Meier, W.N., Stroeve, J., Fetterer, F. (2007) Whither Arctic
sea ice? A clear signal of decline regionally, seasonally, andextending beyond the satellite record. Annals of Glaciology.
46(1), 428-434.
• National Snow and Ice Data Center:• All About Sea Ice. Accessed March 6, 2009.
• Arctic Sea Ice Down to Second-Lowest Extent; Likely
Record-Low Volume. Accessed March 6, 2009.
• Arctic Sea Ice News and Analysis. Accessed March 6,
2009.
• Frequently Asked Questions about Sea Ice. Accessed
February 4, 2009.
• State of the Cryosphere. Accessed February 4, 2009.
• Overland, J.E., Spillane, M.C., Percival, D.B., Wang, M.,
Mofjeld, H.O. (2004) Seasonal and regional variation of
Pan-Arctic surface air temperature over the instrumental
record. American Meteorological Society. 17(17), 32633282.

Sea Ice design by Joshua Stevens
and Robert Simmon, September 16, 2016www.geo-web.org.uk

December 2016

The Group for Earth Observation

GEO Quarterly No 52

Francis Bell
While brieﬂy sorting through some back issues of my ‘Planet
Earth’ magazines the cover of the Summer 2015 edition caught
my eye. Previously, I had assumed that the cover showed animage taken by Meteosat 7, stationed over the Indian Ocean.
Regular images from this satellite can be received to registeredusers via the EUMETCast service. I receive this service, so I am
familiar with the visible spectrum images displayed using a colour
palette in David Taylor’s software.
However, I have now noticed differences between the images inquestion. The ‘Planet Earth’ image clearly shows Antarctica andmost of the west coast of Africa but not India; Meteosat 7 images
show, in addition to Africa, all of India and much of Asia.
A little research has given me the answer. The ‘Planet Earth’image is a famous photograph taken on December 7, 1972 fromthe Apollo 17 command module when about 29,000 km from
Earth on its journey to the moon. This image has been given thetitle ‘The Blue Marble’. Interestingly, the photograph was taken
at about the same distance from the Earth as geostationary
satellites, so perhaps this is some excuse for my slight confusion
over the origin of the photograph. Use your own judgement bycomparing the ‘Planet Earth’ image with a recent Meteosat 7
image.

The Blue Marble image on the Magazine CoverIn either case, please include a full postal address and reason
for you interest in their publication: e.g. personal interest,
educational, scientific or other.
The 24-page autumn 2016 copy of ‘Planet Earth’ which I recently
received is mainly devoted to atmospheric pollution with London
as a case study. I was interested to read about airborne chemical
pollutants and their toxic effects, but couldn’t help feeling slightly
lucky living in SW Surrey where I judge air pollution from abiological perspective.

A typical Meteosat 7 image‘Planet Earth’ Autumn Edition
This is a reminder to readers who do not regularly receive ‘Planet
Earth’, which is available free of charge. To add your name to the
publisher’s mailing list, write a letter with a request to regularly
receive ‘Planet Earth’ to:Planet Earth Editors,
Natural Environment Research Council (NERC),
Polaris House, North Star Avenue,
Swindon, SN2 1EUor send an email torequests@nerc.ac.uk

Lichens are very sensitive to air pollution so, if you look at yourlocal tree trunks and find them well coated with lichens, then it’s
likely your air quality
is quite good. If you
don’t find that cover,the chances are thatyou are sufferingsome air pollution.
This photographbelow, recently taken
in my garden, shows
substantial lichen
cover on one of mygarden seats which
has not been cleaned
for about six years (IThick lichen encrusting a garden
will clean it next spring).
seat suggests good air quality

www.geo-web.org.uk

31

GEO Quarterly No 52

The Group for Earth Observation

December 2016

European Space Agency

This Sentinel-1 radar composite image features the Virunga Mountains in East Africa: a chain of volcanoes stretchingacross Rwanda’s northern border with Uganda and east into the Democratic Republic of the Congo. While most are
dormant, two of the eight volcanoes are active, with the most recent eruptions in 2006 and 2010.
The mountains lie on the Albertine Rift, where the Somali Plate is splitting away from the rest of the African continent.
The area is one of Africa’s most biologically diverse regions, but high human population density, poverty and conflictpose a challenge to conservation. Across the mountain range, however, a series of national parks has been established toprotect the fauna and flora.
In this image, we can easily identify the delineation between the protected and non-protected lands—the green, orange
and yellow dots indicate changes in the surface of non-protected lands between the radar scans that make up thiscomposite image. These changes are primarily in vegetation as the land surrounding the mountains is blanketed with
agricultural plots. In particular, we can see the grid-like pattern of agriculture, visible in the green and yellow square at
the centre of the image.
Image copyright: contains modified Copernicus Sentinel data (2016), processed by ESA

32
32

www.geo-web.org.uk

This Meteor M2 channel‑2 image showing Hurricane Matthew poised over Florida on October 7,
2016, was posted on the GEO-Subscribers YAHOO Group by Jeff Kelly.

www.geo-web.org.uk

33

GEO Quarterly No 52

The Group for Earth Observation

December 2016

European Space Agency

Introduction by Francis BellGEOSS have just opened a new portal for public use,which could be of interest to our members. Below is some
text I extracted from their promotional page on the Internet
athttp://www.esa.int/Our_Activities/Observing_the_Earth/Refurbished_GEOSS_portal_now_online
I view this development as a challenge to GEO Members
to search the new system for a specific target, subject orimage. I am a beginner in this field but I hope that others
who become more experienced will feel able to offer advice
on how to research this portal, and perhaps contributearticles for the benefit of readers.
Refurbished GOESS Portal now Online
A new and improved version of the Global Earth Observation System
of Systems (GEOSS) web portal is ready to provide users withfaster, more intuitive access to the ever-growing wealth of diverse
Earth observation resources worldwide. The portal is the primary
access point to GEOSS, connecting Earth observation data users
to over 200 million resources such as satellite-based data, aerial
and in-situ data, models, algorithms and web-pages.
The enhanced GEOSS portal was unveiled during the13th annual Group on Earth Observations (GEO) plenary meeting
held in Saint Petersburg, Russia between November 7-10, 2016.
One of the main challenges of GEOSS is that it must connect
a vast amount of data amongst a large variety of users that
includes decision and policy-makers, scientists and data
analysts, as well as value-adders and citizens.
The new portal permits users to use simple and multicriteria
searches to refine results according to their needs, as well as
filter results for the type of data they want to consult: such as
from a particular satellite mission. For example, users searching34

for cloud-free Sentinel-2 imagery over a particular area can findwhat they need within a few clicks.
‘It’s never been easier to access the satellite and in situ dataand information in GEOSS,’ said Barbara Ryan, the Directorof the GEO Secretariat. ‘As we work with existing and newproviders, we can be proud to direct them to the new look andfeel of the GEOSS portal, where an intuitive interface meansthat their data can be discovered and accessed with ease.’
Improving the portal was made possible by portal public–private
partnerships with geolocation software developers Google Maps,
what3words and ESRI.
ESA has been the official GEOSS portal provider since 2012, incooperation with the Italian National Research Council’s Institutefor Atmospheric Pollution Research (CNR-IIA) and the GEO
Discovery and Access Broker. In response to user needs, work to
improve the portal began in 2016.
‘The fruitful cooperation with ESA is important and benefits
the whole GEOSS community, in particular for better informed
decision-making, said Nicola Pirrone, director of CNR-IIA.
ESA plans to continue developing the portal with CNR-IIA andthe GEO Secretariat to render it more user-friendly. Activities will
also be coordinated with other ESA initiatives like the Thematic
Exploitation Platforms and the latest European Earth observation
ground segment evolution strategy.
‘This cooperation between ESA and the EC in GEO is ofstrategic importance, and I expect that such a key European
contribution to GEO will maximise the benefits of Earthobservations to society through effective partnerships within
GEO,’ said Robert-Jan Smits, GEO co-chair and Director
General of the European Commission General Directorate for
Research and Innovation.

www.geo-web.org.uk

December 2016

The Group for Earth Observation

GEO Quarterly No 52

Mike Stevens
I have recently been testing a new tuner from our friends inthe Far East, the TBS-5927. This is, a more advanced versionof the TBS-5925—the original USB unit—now upgraded withthe same successful CY-68013 chip-demodulator as is fitted tothe excellent TBS-6903 PCIe card tuner. This chip has alreadyproved to be an excellent, stable, demodulator when installed
within the TBS-6903, itself is a very reliable tuner for EUMETCast
reception.
The TBS-5927 interfaces with the PC via a USB connection,
power is supplied by 12-volt adaptor, and the tuner supports only
one LNB connection. An early problem relating to the stability ofthe tuner has now been overcome by the inclusion of an internalcooling fan, which prevents it overheating. The TBS-5927 has
proved to have excellent front-end gain, is very selective withextreme sensitivity and is very stable. I started testing this tuner
in July 2016 and have it running 24/7 without any problems. It
has completely new driver software and also new TBS-IP Data
software (version 3.0.5.0), which I also have been using very
successfully on both Windows 8.1 and Windows 10, the latter still
performing extremely well even following Microsoft’s Anniversary
Upgrade.

The TBS-5927 USB DVB-S2 Tuner

This Metop-B image featuring Hurricane Matthew east of Cuba was received with the TBS-5927 on October 4, 2016.
Image © EUMETSAT 2016www.geo-web.org.uk

35

GEO Quarterly No 52

The Group for Earth Observation

December 2016

This Metop‑B image was received with the TBS-5927 on October 2, 2016.
Image © EUMETSAT 2016

As this is a USB tuner, I am sure it will appeal to members
who do not like tampering with the internal workings of their
computers. You just have to plug it into a USB 2.0 socket: it’sthat simple! The Tuner measured 100 × 85 × 20 mm: so small
and neat. The TBS‑5927, which is a DVB-S2 Single Tuner, has
EUMETCast compatibility, and is able to receive ACM/VCM,
supports Multi-Input Stream and is able to handle the HighSpeed Data satellite stream. I can confirm that its EUMETCast
capabilities are very good and, during the test period, when
I experienced some rather inclement weather with strong
winds and some heavy rain with thunderstorms, the tuner still
performed immaculately. During heavy rain SNR was 9.8, missed
packets before FEC was 9 and with FEC Recovered at 9. Under
those conditions this was not at all disappointing, but undernormal conditions it’s zero all-round with no segment loss.
Software Installation is the same as for all TBS tuners. Install
the correct driver and the dpinst x86/64 file (depending onwhether your operating system is 32/64 bit). Those of you whoare already using TBS tuners will be familiar with the installation
procedure: new users who are not should not find it difficult. As
always, the first step is to create a separate ‘Tools’ folder directlyon the ‘C:\’ drive (and not in the Program Files(x86) folder) then,36
36

within the Tools folder, a folder called ‘TBS Software’: install all
TBS software in this folder, following all on-screen prompts.
There are many members willing to help, myself included. Also,
if you have back copies of GEO Quarterly, you can refer tonumerous articles I have written about TBS software installation,
which are listed below.
So there we have it, another DVB-S2 TBS USB Tuner for
EUMETCast reception of weather related data. It’s an amazing
bit of kit that will work well as a main tuner or as a spare for backup. Happy weather watch from Portland.
References
•
•
•
•
•

Testing the TBS 6925 Tuner Card for EUMETCast
GEO Quarterly 42, page 16
Setting up the TBS-6925 Tuner Card for EUMETCast
GEO Quarterly 43, page 13
Testing the TBS 6983 and HD DVB S2 Tuner Cards
GEO Quarterly 46, page 34
The TBS 6908 DVB S2 TunerGEO Quarterly 48, page 6
EUMETCast Reception with the TBS-6903 TunerGEO Quarterly 49, page 34

www.geo-web.org.uk

December 2016

The Group for Earth Observation

GEO Quarterly No 52

Mike Stevens
At the moment I am receiving image segments fromcomplete north to south passes of Sentinal-3A using my
TBS-6903 Tuner, but have no way to join them together.
David Taylor is working on joining software to combine
these segments, along the general style of his Metop

Manager. I’m also hoping that Hugo Van Ruyskensvelde willsoon add this capability to his EUMETCastView software.
Although individual segments measure just 917 × 640
pixels, they nevertheless demonstrate the 300 metres/pixel
resolution of this satellite to perfection.

Northeast Brazil - October 27

Red Sea and River Nile - October 29

The Canary Islands and Morocco - November 2

Detail from the Sahara Desert - October 27

The Persian Gulf and Gulf of Oman - November 5Turkey, Cyprus and eastern Mediterranean - November 5

Image © EUMETSAT 2016

Image © EUMETSAT 2016

Image © EUMETSAT 2016

Image © EUMETSAT 2016

Image © EUMETSAT 2016

Image © EUMETSAT 2016www.geo-web.org.uk

37

GEO Quarterly No 52

The Group for Earth Observation

NASA Earth Observatory
When John Wesley Powell explored the Colorado River in
1869, he made the first thorough survey of one of the lastblank spots on the map. The expedition began in May atGreen River, Wyoming and ended three months later at theconfluence of the Colorado and Virgin Rivers in present-day
Nevada.
About two months into their journey, the nine men of the
expedition found themselves in Glen Canyon. As the men
travelled along the serpentine river channel, they encounteredwhat Powell later described in Canyons of Colorado as“a curious ensemble of wonderful features.”
While the walls were not nearly as high in Glen Canyon as
they were downstream in Marble Canyon or Grand Canyon,
the explorers encountered a labyrinth of overhanging cliffs,
hanging gardens, sweeping river bends, and natural arches
set amidst a backdrop of colourful buttes and mesas.
‘Past these towering monuments, past these mounded billows
of orange sandstone, past these oak-set glens, past these ferndecked alcoves, past these mural curves, we glide hour after
hour, stopping now and then, as our attention is arrested bysome new wonder,’ wrote Powell.
From above, the view of Glen Canyon is equally arresting. In
2016, an astronaut aboard the International Space Station
took several photographs that were combined to make thislong mosaic. The water has an unnatural shade of blue
because of sunglint, an optical phenomenon that occurs whensunlight reflects off the surface of water at the same angle asa camera views it.
One of the most prominent features in this stretch of theColorado is the Rincon, an entrenched and abandoned
meander—or loop—in the river. Geologists believe it formed
several thousand years ago when the river cut straightacross the ends of the loop and shortened its course by
10 kilometres.
The modern view is rather different to what members ofPowell’s expedition would probably have seen. When the Glen
Canyon Dam was finished in 1963, water levels began a slow
rise, submerging many of the geological features—including
an acoustically remarkable side canyon called Music Temple—
that Powell found so compelling. Due to drought and thepresence of porous rock in this area, it a took a full 17 years
for the reservoir (Lake Powell) to reach its maximum capacity.
Wikipedia - Music Temple
Music Temple was a geological feature near the Colorado River inGlen Canyon, southern Utah, which consisted of a grotto with high,vaulting walls and a deep central pool of water. John Wesley Powellnamed it “Music Temple” because of its unusual acoustic properties:
reportedly, a one-second note would reverberate for eleven seconds.
It was considered one of the more beautiful natural formations of
the area in the late 19th century and into the mid-20th century but
following construction of Glen Canyon Dam in the early 1960s, Music
Temple was became submerged by Lake Powell and disappeared as
the lake filled.
This mosaic was assembled from photographs taken from the International Space
Station. A version of it was posted here. Caption by Adam Voiland.

38

www.geo-web.org.uk

December 2016

December 2016

The Group for Earth Observation

GEO Quarterly No 52

Climate.nasa.gov News

Fingerprint of Greenland Ice Melt
Sea level change resulting from Greenland ice melt, derived from NASA GRACE measurements. Black circles show locations of the best
historical water level records, which underestimate global average sea level rise due to Greenland melt by about 25 percent.
Credit: University of Hawaii/NASA-JPL/Caltech.

A new NASA and university study using NASA satellite datafinds that tide gauges—the longest and highest-quality recordsof historical ocean water levels—may have underestimated theamount of global average sea level rise that occurred during the20th century.
A research team led by Philip Thompson, associate directorof the University of Hawaii Sea Level Center in the School of
Ocean and Earth Science and Technology, Manoa, evaluated
how various processes that cause sea level to change differently
in different places may have affected past measurements.
The team also included scientists from NASA’s Jet Propulsion
Laboratory, Pasadena, California, and Old Dominion University,
Norfolk, Virginia.
‘It’s not that there’s something wrong with the instruments or
the data,’ stated Thompson, ‘but for a variety of reasons, sealevel does not change at the same pace everywhere at thesame time. As it turns out, our best historical sea level records
tend to be located where 20th century sea level rise was most
likely less than the true global average.’
One of the key processes the researchers looked at is theeffect of ‘ice melt fingerprints’, which are global patterns of sea
level change caused by deviations in Earth’s rotation and local
gravity that occur when a large ice mass melts. To determine
the unique melt fingerprint for glaciers, ice caps and ice
sheets, the team used data from NASA’s Gravity Recovery andClimate Experiment (GRACE [1]) satellites on Earth’s changing
gravitational field, and a novel modelling tool (developed by study
co-author Surendra Adhikari and the JPL team) that simulates
how ocean mass is redistributed due to ice melting.
One of the most fascinating and counter-intuitive features ofthese fingerprints is that sea level drops in the vicinity of amelting glacier, instead of rising as might be expected. The lossof ice mass reduces the glacier’s gravitational inﬂuence, causing
nearby ocean water to migrate away. But far from the glacier,the water it has added to the ocean causes sea level to rise at amuch greater rate.
During the 20th century, the dominant locations of global ice
melt were in the Northern Hemisphere. The results of this study
showed that many of the highest-quality historical water level
records are taken from places where the melt fingerprints ofNorthern Hemisphere sources result in reduced local sea levelchange compared to the global average. Furthermore, thescientists found that factors capable of enhancing sea level riseat these locations, such as wind or Southern Hemisphere melt,
were not likely to have counteracted the impact of fingerprints
from Northern Hemisphere ice melt.
The study concludes it is highly unlikely that global average sea
level rose less than 14 centimetres during the 20th century. The
most likely amount was closer 17 centimetres.
‘This is really important, because it provides answers to thequestion about how melt ﬁngerprints and the inﬂuence of windon ocean circulation affect our ability to estimate past sea
level rise,’ said Thompson. ‘These results suggest that ourlongest records are most likely to underestimate past global
mean change and allow us to establish the minimum amountof global sea level rise that could have occurred during the lastcentury.’
Results are published in Geophysical Research Letters. To readthe full paper, visit:
http://onlinelibrary.wiley.com/
doi/10.1002/2016GL070552/abstract
Reference
1 GRACE is a joint NASA mission with the German Aerospace Center(DLR) and the German Research Center for Geosciences (GFZ),
in partnership with the University of Texas at Austin. For more
information on the mission, visit:www.geo-web.org.uk

39

GEO Quarterly No 52

The Group for Earth Observation

December 2016

David Taylor

On October 25, 2016, I received my first Sentinel 3A data,
resulting in the stunning image of Scotland reproduced
above, on which you can clearly see the Forth Road Bridge,
a feature indistinguishable in NOAA/Metop HRPT data.
The data is part of the EUMETCast High Volume Service(HVS) which started this year. Anyone with a EUMETCast
system can get access to the HVS which carries Sentinel3A data at a resolution of 300 metres/pixel, but you doneed a good signal which may mean an 85 cm dish in40

southern England or a 1 metre dish in Scotland. Onceyou have acquired the files—roughly 600 Mb for 3-minutesegment—you will require ESA’s Sentinel Application
Platform (SNAP) software for processing. It can be
downloaded fromhttp://step.esa.int/main/download/
I post-processed this image from SNAP in Paintshop Pro to
tweak the levels and sharpen it a little. 300 metres/pixel.

www.geo-web.org.uk

Sentinel Data © EUMETSAT 2016

December 2016

The Group for Earth Observation

GEO Quarterly No 52

Francis BellFor about two years the International Space Station (ISS)
has been carrying out the High Deﬁnition Earth Viewing(HDEV) experiment using HD Colour TV cameras, and myinterest in this relates to the Earth images which are beingtransmitted live from the ISS. There are four cameras inthis experiment, one giving a forward view of the ISS’s
flight path, two providing rear views, and the fourth, whichis my favourite, giving a vertical view towards Earth.
The transmissions from the ISS alternate between thesecameras and it can be difficult to predict which camera
may be in use at any one time. There is regular switching
between cameras, plus intervals when there are no
images—perhaps for communication reasons. Also, ofcourse, for half of every orbit, the ISS will be in darkness:so no worthwhile images are available.
Notwithstanding the above limitation about available
images, I have been intermittently viewing thesetransmissions since the early days of the experiment andoccasionally record an image which I find particularly
attractive. Very often I am attracted to images which show
easily recognisable geographical or meteorological features.
Images from these cameras are constantly available fromthe following website
http://www.ustream.tv/channel/iss-hdev-payload
With a little experience of using this site you can display
live full screen images from the HD TV cameras—
but remember that orbital position, sunlight andcommunication links vary, so eye-catching images are not

Figure 3 - This is a near vertical image showing an almost cloudlessview of the Straight of Gibraltar, with part of mainland Spain to the lower
right and some of Morocco shown at upper left.

available all the time. Figures 1,2 and 3 show examplesof views from the forward looking camera, the rear view
camera and the vertical camera.
The Cygnus Automatic Cargo SpacecraftIn addition to the website listed above, there is anotherwebsite used by NASA for transmitting HD TV. The
attraction for me of this additional channel is that it often
shows views inside the ISS and also carries sound. I havelistened and watched this channel before and sometimes
heard radio exchanges during space walks and otherevents inside the ISS. To receive this channel go to thiswebsitehttp://www.nasa.gov/multimedia/nasatv/iss_ustream.html
Quite by chance, at about 09.30 UT on October 25, 2016,
I logged into this channel to view the ISS transmissions
and was astonished with the first images I saw. Insteadof the unobstructed view of Earth’s surface which I was
expecting, the foreground showed a space vehicle close to
the ISS. Not quite understanding what was happening,
I started to save some of these surprising views comingfrom the ISS. However, it was the voice comments in the
background which revealed to me what was happening.

Figure 1 - This is a screen-shot recorded in mid 2016 showing aforward, slightly to the right, southern view of South Africa. The Capeof Good Hope is towards the centre right of the image with much of theland mass of South Africa appearing cloudless.

Figure 2 - This is a view to the rear looking south and slightly to thewest. The peninsula of Baja California can be seen on the right together
with the Gulf of California, with the right hand side showing part ofmainland Mexico and part of southern USA.

Apparently, a few days previously, a cargo module

Figure 4 - The Cygnus module, caught by the HD TV Earthviewing camera. Comments from NASA ground control indicatedthe module to be about 100 m from the ISS. Rather surprisingly,
the module’s docking port seems to be located at the complex
end of the module as seen on the left of the image.

www.geo-web.org.uk

41

GEO Quarterly No 52

The Group for Earth Observation

December 2016

called Cygnus (as is swan) had been launched froma Russian site to ferry two and a half tonnes of foodand equipment to the ISS. It so happened that I waswatching and listening to the final few minutes of the
manoeuvring and final docking of this cargo vehicle tothe ISS.

Figure 5 - This shot shows the Cygnus module within a very
few metres of the ISS, where it remained for some minutes
while the docking arms on the ISS were activated.

Listening to the ground control comments, I hadn’t
realised just how precise the docking and timings
had to be. When I first saw Cygnus it was reported
to be about 80 metres from the ISS, but it was thenmanoeuvred into a precise holding position 30 m
away for about 20 minutes while docking protocols
were confirmed. From the voice commentary I was
surprised to learn that the final docking only had
a window of opportunity of about 20 minutes. The
docking was achieved while the ISS was flying above
Kurdistan, which I guess was because direct radio
communication was then possible between the ISS
and Russian ground stations, thus making directcommands possible without the need to relay throughother systems.
Docking was achieved at 10.25 UT or, interestingly
quoted by the voice link I was listening to, 6.25 USA
Central Time.
Conclusion
The point of this article is to encourage thoseinterested to access the websites quoted above andfollow the activities on the ISS. Any individual, schoolor other group with access to a computer and an
Internet link can follow the many interesting live
transmission from the ISS. For my part I will be more
attentive to times when there are space walks andother dockings to the ISS.

Figure 6 - This is a close-up of the Cygnus cargo module
after docking with the ISS.

Figure 7 - This image includes part of the ISS’s main structure, and it’s believed that it shows the docking area for
the Cygnus automatic cargo spacecraft. The background shows a substantial coastal boundary on Earth’s surface
Image: NASA.

42

www.geo-web.org.uk

December 2016

The Group for Earth Observation

GEO Quarterly No 52

John Tellick
Vancouver Island is located in
the northeastern Pacific Ocean,just off the coast of Canada,
and is part of the Canadianprovince of British Columbia.
The island is 460 kilometres
long, 100 kilometres at its
widest point, and has an areaof 32,134 km2. It is the largest
island on the West Coast of
North America.
The southern part of Vancouver
Island is the only part of British
Columbia or Western Canada
to lie south of the 49th Parallel,
along with most of the southern
Gulf Islands and minor offshoreislands. This area has one of
the warmest climates in Canada,and since the mid-1990s has been
mild enough in a few areas to growsubtropical Mediterranean crops suchas olives and lemons.
Victoria, the capital city of British
Columbia, is located on the island,

but the larger city of Vancouver is
not—it stands on the North American
mainland, across the Strait of Georgia
from Nanaimo.
Vancouver Island has been thehomeland to many indigenous
peoples for thousands of years. The

island was explored by British
and Spanish expeditions in
the late 18th century, and was
originally named Quadra’s
and Vancouver’s Island incommemoration of the friendly
negotiations held during the
Nootka Crisis in 1792 by
Spanish commander of the
Nootka Sound settlement,
Juan Francisco de la Bodega yQuadra, and by British naval
captain George Vancouver.
Quadra’s name was eventually
dropped from this appellation.
The island is one of several
North American locations named
after George Vancouver, who
explored the Pacific Northwest
coast between 1791 and 1794.
Vancouver Island is the world’s
43rd largest island, Canada’s 11thlargest island, and Canada’s second
most populous one after the Islandof Montreal. It is the largest Pacificisland anywhere east of New Zealand.

This image of the northwest coast of Canada was taken by Metop-B on September 14, 2016, and includes a detailed view of Vancouver Island.
Image © EUMETSAT 2016 - Processed in vegetation mode with David Taylor’s HRPT Reader

www.geo-web.org.uk

43

44

Winter hit Scotland hard starting on November 18, 2016 when polar air streamed south over the country producing contrasting effects. In thewest, a sequence of snow showers blanketed the highlands of the west and northwest, but in the northeast it heralded a spell of clear skies withtemperatures dropping as low as minus 10°C overnight and remaining close to zero during the days.
Image © EUMETSAT 2016www.geo-web.org.uk

This amazing image detailing the Alps and the Mediterranean islands of Corsica and Sardinia is a short segment taken from a hugepole-to-pole image from an NPP-Suomi pass downloaded via EUMETCast by Mike Stevens on November 6, 2016.
Image © EUMETSAT 2016www.geo-web.org.uk

45

GEO Quarterly No 52

The Group for Earth Observation

December 2016

Francis BellI think it’s important to promote GEO at educational and otherevents such as amateur radio rallies and other events with atechnical interest: otherwise these groups may be unawareof GEO and the ability to receive satellite signals directlyfrom space. With this perspective in mind I try to attend
appropriate events, sometimes demonstrating live satellites
reception but always with a display of recorded images andappropriate literature. I’m always pleased with the responseof visitors to our GEO stands. Even after brief conversations
they get useful information and it raises the profile of GEO.
I note that this may be an appropriate time to attend as manyof these events as we can because of the interest in spacescience created by Tim Peake’s recent six months on theISS. Certainly, schools and amateur radio groups have beenstimulated, perhaps to the point where they would like totry satellite reception for themselves. This is an opportunity
for any GEO member to support their local community
by promoting talks, demonstrations and exhibitions
demonstrating satellite reception. GEO will support any suchopportunity, so please respond to this idea and promote GEO
within your own local groups. Contact the GEO management
team if you need help.
Recently GEO has attended the AMSAT-UK three day
colloquium, The ‘Space Link’ educational one day event forschools, the Alton Scouts ‘Thinking day on the Air’ plus the‘South London Radio and Computer Rally’ at Kempton.
Kempton
It was a pleasure to run our GEO stand again this autumn
at the South London Radio and Computer Rally held at
Kempton, SW London. We have regularly attended thesetwice-yearly rallies almost since the formation of GEO overten years ago. It has always been a rewarding experience
because of the positive feedback we receive from thosevisiting our stand. During the weekend, we met a delightfulnine year old girl who had recently become a licensed
radio amateur, and who has used her communication
skills regularly on the mountains of the Lake District. Witha substantial age difference, another notable visitor was agentleman whose job it was to design commercial satellite
ground stations.

The amateur radio station and GEO’s stand at the Alton Scouts Thinking
Day on the Air. We are pictured here while live on air, waiting for the arrivalof the scouts, some together with their families, in October 2016.

On this occasion we ran demonstrations of recordedpolar orbiting satellite images together with the latest
EUMETCast images and their animated sequences. We
also demonstrated the ability of the SDR dongle (which we
had for sale on the stand) to receive a wide range of radio
signals, including tracking the local aircraft as well as polar
orbiting satellites.
New memberships were recorded together with renewals andthe literature we had available on the stand was gratefully
acknowledged by the visitors. My thanks to David Simmons
for attending the rally with me.
If you have an event in your area, then please consider
offering the organisers some contribution from GEO. It would
be great if you could report to the Editor any contributions
you may have which promotes GEO.

46

Delegates and families visiting the exhibition room close to GEO’s exhibition
stand during The AMSAT-UK colloquium in July 2016.

www.geo-web.org.uk

December 2016

The Group for Earth Observation

GEO Quarterly No 52

Fifteen year old Jessica Leigh (far right, seated) and her friend Polly Gupta, both from Sandringham School, are pictured visiting
the amateur radio station at the AMSAT-UK colloquium 2016. Jessica spoke to Tim Peake on the ISS via a scheduled radio link.

A knowledgeable visitor talking to David Simmons at the GEO stand at
the Kempton Rally. Visitors in the background indicate how busy andworthwhile the day was for GEO.

Visitors of all ages examining the NOAA APT slide show running on oneof the three demonstration computers we had available on the GEO
stand at the busy Kempton Rally, November 2016

Examining GEO Quarterly magazines during the AMSAT‑UK Colloquium:
could this youngster be a potential GEO Member for the future?

www.geo-web.org.uk

47

This is a section from a Meteor M2 LRPT image acquired from the 09:26 UT pass on September 23, 2016 by Enrico Gobbetti.

48

www.geo-web.org.uk

December 2016

The Group for Earth Observation

GEO Quarterly No 52

When drafting Quarterly Questions I often pick a subject
which for whatever reason has recently caught my attention.
Sometimes this can be a technical issue but often relates to aneye-catching satellite image of the Earth.
Now here comes a major coincidence - or are there others in
the world just like me? Tim Peake while on the ISS for six months
took many photograph with his own camera and some of thesephotographs have been released to the public. There is a special
collection of Tim’s ten favourite photographs which attracted
my attention and I have archived some of these for my own
collection.

Francis BellI was recently browsing through these photographs when I
noticed an overlap with GEO Quarterly Question images andtwo of Tim Peake’s photographs which exactly matched ourQuarterly Questions 50 and 52. These photographs are shownin Figures 1 and 2. Recognising the coincidence with GEO
Quarterly Questions it’s up to the reader to identify the areasof the Earth which Tim photographed. Just as a guide note that
Figure 1 photograph shows an image about 30 km wide while in
Figure 2 the width is about 200 km.
Other photographs in Tim Peake’s top ten photographs include
Istanbul, the UK, Italy at night, the Sinai Peninsula with the Dead
Sea, Grand Canyon USA, Scotland by day and a detailed view of
New York. There is a huge selection of photographs of Earth on
Tim Peake’s Flickr site at
Figure 1 - This photograph was taken by Tim Peake during his stayaboard the International Space Station.

https://www.ﬂickr.com/photos/timpeake/albums/72157660209464584

Figure 2 - This photograph was taken by Tim Peake during his stay aboard the International Space Station.

www.geo-web.org.uk

49

The MODIS instrument aboard NASA’s Aqua satellite captured this scene detailing a fine set of Von Karman
vortices shedding from Jan Mayen Island, in the North Atlantic.on September 30, 2016.

50

Image: LANCE Rapid Response/NASA/GSFC

www.geo-web.org.uk

Enrico Gobbetti sent in this unusual image from Meteor M2, acquired on October 24, 2016, which shows adust storm from the Algerian Sahara blowing across the Mediterranean Sea towards Sardinia.

www.geo-web.org.uk

51

GEO Quarterly No 52

The Group for Earth Observation

December 2016

continued from page 17

continued from page 14

On March 20 and September 20, the terminator is a vertical
north-south line, and the Sun is sits directly above the equator.
On December 21, the Sun resides directly over the Tropic of
Capricorn when viewed from the ground, and sunlight spreads
over more of the Southern Hemisphere. On June 21, the Sun sits
above the Tropic of Cancer, spreading more sunlight in the northand turning the tables on the south. The bulge of our spherical
Earth blocks sunlight from the far hemisphere at the solstices;that same curvature allows the Sun’s rays to spread over agreater area near the top and bottom of the globe.
Of course, it is not the Sun that is moving north or south throughthe seasons, but a change in the orientation and angles between
the Earth and its nearest star. The axis of the Earth is tilted
23.5° relative to the Sun and the ecliptic plane. The axis is tilted
away from the Sun at the December solstice and toward the
Sun at the June solstice, spreading more and less light on eachhemisphere. At the equinoxes, the tilt is at a right angle to the
Sun and the light is spread evenly.

Extreme Events
The number of record high temperature events in the UnitedStates has been increasing, while the number of record low
temperature events has been decreasing, since 1950. The US
has also witnessed increasing numbers of intense rainfall events.
Ocean Acidiﬁcation
Since the beginning of the Industrial Revolution, the acidity ofsurface ocean waters has increased by about 30%. This increaseis the result of humans emitting more carbon dioxide into theatmosphere and hence more of this gas being absorbed into theoceans. The quantity of carbon dioxide absorbed by the upper
layer of the oceans is increasing by about 2 billion tons per year.
Decreased Snow CoverSatellite observations reveal that the amount of spring snow
cover in the Northern Hemisphere has decreased over the past
five decades and that the snow is melting earlier.

Equinox means ‘equal night’ in Latin, capturing the idea thatdaytime and nighttime are equal lengths everywhere on theplanet. That is true of the Sun’s presence above the horizon,
though it does not account for twilight, when the Sun’s rays
extend from beyond the horizon to illuminate our gas-filledatmosphere.

Acknowledgement and Further Reading

You can view a day-by-day Meteosat animation of the processdescribed above on NASA’s website at

The web article concluded with a comprehensive listof sixteen references to original sources of information
presented, and these are well worth exploring by anyone
interested in Climate Change.

http://earthobservatory.nasa.gov/IOTD/view.php?id=52248

The text of this article has been reproduced from thewebsite of the Earth Science Communications Team atNASA’s Jet Propulsion Laboratory/California Institute ofTechnology. The original content can be found at
http://climate.nasa.gov/evidence/

References

Front CoverThis detailed image segment depicting part of the Red Sea,
with the River Nile to its west, comes from a Sentinel-3A frame
downloaded via EUMETCast by Mike Stevens. You can view afull version of this image, and several more of Mike’s Sentinel-3A
imagesa on page 33.

1 Intergovernmental Panel on Climate Change
https://www.ipcc.ch/
2 In the 1860s, physicist John Tyndall recognised the Earth’s
natural greenhouse effect and suggested that slight changes in
the atmospheric composition could bring about climatic variations.
In 1896, a seminal paper by Swedish scientist Svante Arrhenius
first speculated that changes in the levels of carbon dioxide in theatmosphere could substantially alter the surface temperature throughthe greenhouse effect.
3 Gravity Recovery and Climate Experiment
http://www.nasa.gov/mission_pages/Grace/

Image © EUMETSAT 2016

Inside Front CoverDavid Taylor provided this HRPT image of a splendid sunny
day in the British Isles on September 22, 2016, the result of aridge of high pressure between depressions, as captured by
NOAA 19’s 14:06 UT pass, via EUMETCast.
Image © EUMETSAT 2016

Inside Back Cover
Hurricane Matthew, at one point a Category-5 storm, imaged by
NASA’s Terra satellite on October 2, 2016, as it headed towards
Haiti and Cuba.
Image: LANCE Rapid Response/NASA/GSFC

Back Cover (upper)
Enrico Gobbetti submitted this Meteor-M2 image stretching fromthe eastern Mediterranean Sea to the Caspian and Aral Seas,acquired from the 06:50 UT pass on October 6, 2016.
Back Cover (lower)
Peter Kooistra sent in this Meteor-M2 image showing aplume of sand being blown towards Crete from Libya on
November 5, 2016.

52www.geo-web.org.uk

December 2016

The Group for Earth Observation

www.geo-web.org.uk

GEO Quarterly No 52

53

GEO Quarterly No 52

EUMETCast On-Line
Registration Guide
If you require to register as a first-timeuser for any of the free EUMETCast
data streams such as MSG, NOAAAVHRR, Metop etc., or need to renew
an existing subscription, this must be
done on-line.
GEO has produced a step-by-stepguide to the entire process at
http://www.geo-web.org.uk/eumreg.
phpThis guide also contains a direct linkto the official EUMETCast on-line
registration form, which can otherwise
prove somewhat tricky to locate.

Weather Satellite Reports
If there is a single Internet Forumthat is relevant to all weather satellite
enthusiasts, it must surely be Douglas
Deans’ Weather Satellite reports.
Here you will find every conceivabletype of information about weather
satellites, whether polar or
geostationary, APT, HRPT, LRIT,
EUMETCast or whatever.
Absolutely everything is covered, andthe information is updated every week.
Special additional bulletins may be
issued if an important change takes
place mid week.
You can read the bulletins from thisURL
https://groups.yahoo.com/neo/groups/weather-satellite-reports/info
or, even better, elect to have thereports sent to you by email every
Monday.

Internet Discussion Groups
There are a numerous Internet-based
discussion groups of interest to weather
satellite enthusiasts. The home pagefor each group provides an email
address through which you can request
membership. Even a blank email
containing the word ‘subscribe’ in its
Subject line is all that is required.
APT Decoder
This is a group where users ofPatrik Tast’s APTDecoder can share
information and problems.
https://groups.yahoo.com/neo/groups/APTDecoder/info
GEO-Subscribers
This is GEO’s own group, where
members can exchange information

54

The Group for Earth Observationand post queries relating to any
aspect related to weather satellite
reception (hardware, software,antennas etc), Earth observation
satellites and any GEO-related matter.
https://groups.yahoo.com/neo/groups/GEO-Subscribers/info
Satsignal
An end-user self‑help group for users ofDavid Taylor’s Satellite Software Tools(SatSignal, WXtrack, GeoSatSignal,
HRPT Reader, GroundMap, MSG DataManager, AVHRR Manager and the
ATOVS Reader).
https://groups.yahoo.com/neo/groups/SatSignal/info
MSG-1
A forum dedicated to Meteosat
Second Generation (MSG), where
members share information about the
EUMETCast reception hardware andsoftware.
https://groups.yahoo.com/neo/groups/MSG-1/info

GEO Helplines
Douglas Deans, Dunblane, Scotland.
All aspects of weather satellites from
APT, HRPT to Meteosat-9 DVB/EUMETCast systems.
• telephone:(01786) 82 28 28• e-mail: dsdeans@btinternet.com
John Tellick, Surrey, England.
Meteosat advice: registering for thevarious MSG services, hardware
and software installation andtroubleshooting. John will also
field general queries about any
aspect of receiving weather satellite
transmissions.
• telephone: (0208) 390 3315
• e-mail: info@geo-web.org.uk
Geoff Morris, Flintshire, NE Wales.
Geoff has lots of experience with aerial,
coax connectors, mounting hardware
etc. and has also done a lot of work withthe orbiting satellites. Geoff has beena EUMETCast Meteosat user for sometime and is familiar with David Taylor’s
MSG software. He should be able toshare his experiences with newcomers
to this branch of the hobby.
• Tel: (01244) 818252• e-mail: gw3atz@btopenworld.com
www.geo-web.org.uk

December 2016
Mike Stevens, Dorset, England.
Assistance with reception of
EUMETCast to include Metop-A andMetop-B; also MSG Data reception
and set-up within the PC, assistancewith dish alignment and set-up, andinstallation and set-up of TBS DVB-S2
units.
• email: mikeg4cfz@gmail.com
Guy Martin, Kent, England.
Guy is prepared to advise anyone who
wishing to receive MSG/Metop using
Windows 2000 or XP. Can also help with
networking and ADSL router setup.
•

gmartin@electroweb.co.uk

Hector Cintron, Puerto Rico, USA.
Hector is prepared to field enquiries on
HRPT, APT, EMWIN and NOAAPORT••

Phone: 787-774-8657
e-mail: n1tkk@hwic.net

Email contact can of course be madeat any time, but we would ask you torespect privacy by restricting telephone
contact to the period 7.00 - 9.00 pm in
the evenings.

Copy for GEO Quarterly
Original contributions relating to
any aspect of Earth Imaging should
be submitted in electronic format(although handwritten and typed copy
will be accepted).
Please note that major articles whichcontain a large number of illustrations
should be submitted as early as
possible before copy deadline,
to give time for preparation prior to
publication.
Please note that it is preferred thatsatellite images are provided without
added grid lines, country outlines or
captions unless these are consideredessential for illustrative purposes in an
accompanying article.
Submission of Copy
Materials for publication should be sent
to the editor,
Les Hamilton
8 Deeside Place
Aberdeen AB15 7PW
ScotlandThe most efficient way to do this is byemail attachments to the following
address
geoeditor@geo-web.org.uk
Particularly large attachments (8 MB
and above) can be transmitted via
Hightail
https://wwwhightail.com/

December 2016

The Group for Earth Observation

www.geo-web.org.uk

GEO Quarterly No 52

55

GEO Quarterly No 52

56

The Group for Earth Observation

www.geo-web.org.uk

December 2016