Group for Earth Observation

The Independent Amateur Quarterly Publication for

Number 16

Earth Observation and Weather Satellite Enthusiasts

December 2007

Inside this issue . . .
The image opposite depicts
how desertification has
befallen the Aral Sea basinin recent years. Les
Hamilton investigates theorigins of this problem andexplains how, at last,measures are being taken toreverse its decline
Ed Murashie examines thehistory of low-resolution
weather satellite imaging
and explains how LRIT has
developed into the presentday standard
With more and more users
involving themselves with
automatic download ofimagery to their websites,
Giuseppe Cico unlocks thesecrets of using command
files for automatic-FTP
Rob Hollander details arecent experimental project
conducted in the
Netherlands to compare
different types of APTantennas
Arne van Belle looks back tolast summer’s fires in
Greece through a variety offalse-colour Meteosat
imagesPlus many more features ...

Keep up with the latest
WXsat News every Month
Radio and Communications Monitoring Monthly (ISSN
1749-7809) aims to be the magazine of choice for all
serious radio enthusiasts and to serve all the specialist
areas of the hobby. ‘I am pleased to say that all our regularcolumns provide more information than any current orformer alternative’, commented Editor Kevin Nice.
The magazine provides a regular 4-page Weather Satellite
column, Satellites' View, by Lawrence Harris. In addition,
the May issue is normally a ‘wxsat special’ which includes
additional features concentrating on specific aspects ofweather satellite imaging and monitoring.
Radio and Communications Monitoring Monthly is available
from most good newsagents as well as direct from its
publishers.
Subscriptions are available world-wide. For more
information contact Nice One Publishing Ltd, Tel: +44(0)1202 862690 or visit the website.

www.monitoringmonthly.co.uk

MANAGEMENT TEAMO

ur cover image should certainly have caught your eye as soon as you
picked up this issue of GEO Quarterly. It provides a highly graphic
illustration of how the hand of Man has, during the past half-century, slowly
but surely turned the Aral Sea basin into a dustbowl of sand, salt and toxic
chemicals. The last few years have seen developments which may be thebeginnings of a recovery. You can read the story of the Aral Sea in our flagshiparticle, starting on page 25.
EO Readers will be interested to learn that, over in the States,
Ed Murashie has put together a home-built, fully functional prototype
LRIT Ground Station which has been fully operational since August. GOESWEFAX transmissions came to an end a couple of years ago, depriving many
enthusiasts in the States of easy access to geostationary weather imagery.
Inside this issue, in the first of a series of articles, Ed details the history of
weather satellite imagery and outlines the path whereby LRIT has become
today’s standard low-resolution access mode to geostationary imaging. Futureissues of the Quarterly will describe the hardware requirements to receive
LRIT transmissions from the GOES satellites, followed by an exposé of LRIT
structure and processing. Ed is also currently developing software that willallow the same hardware to process the high resolution GVAR signals. For
those of you who can’t wait to learn more, have a peek at Ed’s webpages atG

http://home.att.net/~emurashie/ED

d’s first article begins on page 15 and includes some superb LRIT GOES
images to whet your appetite. As a taster, a colour composite LRIT image
from GOES-11 is reproduced inside the back cover.
ynamically maintaining a website is becoming ever more popular thesedays as enthusiasts strive to present the most up-to-date images on-line as
rapidly as possible. Giuseppe Cico explains how the use of command files canbe a boon in achieving this aim.
inally, as a pictorial treat, we present a spectacular image from theEuropean Space Agency’s Mars Express orbiter (page 20). This colour imageof the shallow 90 kilometre wide Maunder crater, just 900 metres in depth, wastaken at an amazing resolution of 15 metres per pixel and shows staggering
detail of irregular hummocky hills and valleys, the legacy of a landslide longaeons ago.

F

Contents

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: info@geo-web.org.uk

GEO Quarterly Editor
Les Hamilton,
8 Deeside Place
Aberdeen AB15 7PW
Scotland, UK.
email: geoeditor@geo-web.org.uk

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
Fax:
01509 559 015

Meteorological Consultant
Peter Wakelin
email: meteo@geo-web.org.uk

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

Webmaster and Website Matters
Ray Godden
e-mail: ray-geo@lescharriols.eu

Education Coordinator
David Painteremail: education@geo-web.org.uk

GEO Shop Manager
Clive Finnis
email: shop@geo-web.org.uk

International LiaisonPeter Green‘Hollowtree’
Eggesford
Devon EX18 7QX
Tel:
01769 580 700
email: international@geo-web.org.uk

2
3
4
4
5
6
10
11
15
21

Nigel Evansemail: nigel@geo-web.org.uk

GEO Shop
NOAA Satellite Predictions for the UK and Western Europe
Helplines and Internet Discussion Groups
Copy Deadline for January issue
GEO Membership Renewal Form

i
ii
iii
iii
iv

Printing

Auto-FTP: Upload images to your website in real-time
Aral Sea
EUMETCast without RAM Disk - Update
SeaWiFS
Imaging the Greek Fires
New Software - ‘DownloadPrograms’
Customised Icons for your Desktop
Tips on installing RAMDisk for EUMETCast
Weather Days
Software Showcase
EUMETSAT adds NOAA-18 Data to its Polar System
Hurricane? . . . What Hurricane?
Script Snippets

23
25
30
32
36
38
39
40
40
41
42
43
44

GEO Report
GEO Symposium - 2008
Cover and Full Page Images
Beware Wildlife!
News in Brief
It’s a CLASS Act - Metop imagery from NOAA
Kamchatka
Comparison of Antennas for 137 MHz
LRIT - Part1: History
Earth Imaging News

Francis Bell

Alan Banks
Les Hamilton
Robert Moore
Rob Hollander
Ed MurashiePeter Wakelin

Giuseppe Cico
Les Hamilton
Mike Stevens
Peter Wakelin
Arne van Belle
Fred van den Bosch
Robert Moore
Rob DentonPeter Green
Douglas DeansDavid Taylor
John Tellick
David Taylor

PublisherGroup for Earth Observation Ltd.
The Group for Earth Observation Limited is acompany in England and Wales limited byguarantee and not having share capital. Company
number 4975597.
The registered office is Coturnix House, Rake
Lane, Milford, Godalming, Surrey GU8 5AB
Advent Print Group,
19 East Portway Industrial Estate,
Andover,
Hampshire SP10 3LU.

Responsibility for Constructional
Projects and Software
Every effort is made to ensure that the technicaland constructional articles published in thisQuarterly are correct. However, the ultimate
responsibility is with the reader to ensure thesafety of constructions and for any interfacingwith other equipment. GEO cannot accept liability
for shortcomings in any published design or any
constructions carried out by members or otherthird parties.

Copyright GEO © 2007
The contents of this Quarterly remain theintellectual property of the Group for Earth
Observation Ltd. and its contributors. Copying oftext or images, either from the printed Quarterly
or from any electronically stored source, isforbidden without permission from the editor.

GEO Quarterly No 16

Group for Earth Observation

December 2007

Francis BellAt the time of writing I notice that GEO iswithin a few days of its fourth birthday. Ourcertificate of incorporation is dated
November 25, 2003. Established members
will know that we have a company structure
which provides some formalities but, by
guarantee, limits individual liabilities should
there be unforeseen problems.
I know that for some of our membership
this will be the first Quarterly to be received
through the post. A sincere welcome to newmembers. Please let GEO’s management
team have any feedback relating to yourideas for the future. This invitation is also
directed towards the existing membership.
A note here must be a request for themembership to contribute to the Group’s
activities. Articles for publication in the
Quarterly, ideas for the website anddiscussions on our Internet forum all needmembership participation and ideas. It
places an extra burden on GEO’s
management unless the membership help
with their own contributions and ideas.
As usual, a plea not to forget to renew yourmembership when it becomes due. I’m
always happy to process renewals at rallies
and exhibitions but if I do it generallymeans that the member in question has not
responded to the renewal reminder
enclosed with their last Quarterly. It justmakes work and incurs expense whenmembers fail to renew on time. Of course
interests change, and individuals may
actively decide not to renew theirmembership, and I understand this: butotherwise please renew on time.
Spreading the Word about GEO
I was sensitive to a comment made by
Dr Lars Prahm, Director General of
EUMETSAT, during a conversation I had
with him during GEO’s visit to Damstadt
last summer. When I showed him a list of
GEO’s membership by country, he
expressed mild surprise the we did nothave more European members. I agreed,
stating that this was an area we should
research for new membership.
I note the figure of about 1500 users whoare privately registered to receive
EUMETCast and my feeling is that many ofthese would benefit by being members of
GEO. I feel the same is true for North
America, where there are potential
members who do not know about GEO,
and could also benefit by joining us..

2

GEO requires more members, particularly
in continental Europe and the UnitedStates. If you are acquainted withindividuals or organisations in the UK,
Europe or North America who share ourinterests, then do please invite them to join
GEO. An increase in our membershipnumbers would secure more financial
security for GEO.
My thanks to GEO’s management team
who have promoted our group for four
years with distinction, and thanks to themembership who are the contributors to
our Quarterly publication which I believe,
along with other facets, plays a vital role in
our activities.
LARS
This year GEO attended the two-day
Leicester Amateur Radio Rally (LARS) for
the first time. The location was Donington
in Leicestershire, adjacent to the popular
motor racing circuit.

GEO’s EUMETCast Display at the
AMSAT-UK Colloquium last July

It's difficult to judge numbers but perhaps
1000 visitors stopped to look at thedisplays on our stand. I have never seen
so much literature disappear so quickly. I
just hope everyone appreciated what they
had taken away.
The second day was less busy following
major traffic congestion due to the crowds
attending the motor racing event and theorganisers say they will avoid such a clashof events next year.
I can’t conclude without a formal thanks toDavid Anderson, John Tellick, Peter Green,David Taylor and Cecilia Taylor—none ofwhom received expenses for their time,
travel, or hotels—for their time establishingand running our stand over the two days.

GEO’s Stand at LARS last September

The rally was based in an exhibition arearather like an aircraft hanger, and withsimilar acoustics. The GEO team arrived a
day early to establish our stand as we
wished to run live satellite signals to it on
both days. We requisitioned extra display
tables and turned what was pre-booked asa modest stand into something more
worthy of our efforts. With the aid ofextending ladders, helpful electricians
provided us with electricity from a pillar
adjacent to our stand and fed co-ax fromour satellite dish in the nearby car-park,through the rafters to the stand.
We had our new banner advertising GEO,
and which contains two images received byour own members, on display along withthree computers; lots of literature provided
by EUMETSAT and BNSC; and some backissues of GEO Quarterly.
On the first day we were rewardingly busy.

www.geo-web.org.uk

UK Periodicals
Visiting a UK High Street newsagent
recently, I found myself with a few minutes
to spare. Out of curiosity, I looked at theradio related magazines which were on
sale. There were five titles, one of which
was Monitoring Monthly. I subscribe to thispublication, so do not have to go into theshop each month. Monitoring Monthly is aninteresting publication and each month
devotes a few pages to weather satellites,
plus other regular features about satellite
reception. I would certainly recommend
buying a copy so that you can judge
whether or not you would like to subscribe
on a regular basis. There is anadvertisement for Monitoring Monthly inside
the front cover of this Quarterly.
ESA Bulletin
I recently received my copy of ESA Bulletin
No 131, a quarterly publication which
covers all aspects of ESA's space
programmes. The feature content varies ineach issue but sometimes concentrates on

December 2007

one aspect of their space programme.
Bulletin 131 features the ‘Sentinel’
programme and Earth observation, which I
found particularly interesting. The Sentinels
will be the first in a series of operational
satellites to meet the Earth observationneeds of the 'European Union ESA Global
Monitoring for Environment and Security'(GMES) programme. The Sentinel-1
satellite will image with synthetic apertureradar (launch date 2011), Sentinel-2 will befor high resolution optical imaging (launchdate 2012) while Sentinel-3 will provide
ocean ice and land observations (launchdate 2011/2012).
Bulletin 131 also has a beautiful image of
the Caspian Sea, which was the subject of
a GEO quarterly question in one of lastyear’s issues. It is tempting to think that thelevels of all large inland water masses arein equilibrium. However, this is far fromtrue: Lake Chad in Africa, Lake Eyre inAustralia and, I have just discovered, Lake
Titicaca in South America are all dynamic
with respect to level and area.
The Dead Sea is an interesting case. I
have recently read about a plan to fill it up
with water from the Red Sea. The special
case the Aral Sea is the subject of afeature in this issue of GEO Quarterly.
The ESA Bulletin is an interesting
publication and it is most worthwhile having
your name on their mailing list. The
publication is free of charge. If you areinterested, I suggest you write to
ESA Communication Publication Office
PO Box 299
2200 AG
Noordwijk
The Netherlands

Give your full postal address, ask for a
copy of Bulletin 131, and request yourname to go on their mailing list.
Image
EUMETSAT's regular in-house publication
is Image and this is available on their website. As usual I like a printed copy so I amon their mailing list. Interestingly the current
issue of Image briefly reports GEO's visit totheir Darmstadt and Usingen facilities.
The get on the mailing list write to
EUMETSAT User services
Am Kavallerisand 31
64295 Damstadt
Germany

Group for Earth Observation

GEO Quarterly No 16

The Quarterly Question I set last issue
was certainly more of a challenge thanusual, and did not elicit many correct
answers. I am indebted to Peter Wakelin
for the following in-depth answer andexplanation.
“The point on Earth which comes closest
to the sun in its annual cycle must be
the place where the sun is overhead at
the time of Earth’s closest approach tothe sun. As this occurs on January 3, 4
or 5 (this depends on the phase of themoon) it must lie near latitude 22.7°S.
“The longitude will vary from year toyear but, as no specific year is mentioned
in the question, the answer is the highest
point at latitude 22.7°S. This is thevolcano Licancabur in the Andes whichreaches an altitude of 5,921metres.
“There’s another peak 129 m higher
some 50 km to the south but it would
need to be about 80 m higher still tocome closer to the sun.”This Quarter’s Question
The Quarterly Question this time should
prove a little more straightforward. It
was prompted by reading ESA
Bulletin 131.
The Sentinel-1 satellite will carry
Synthetic Aperture Radar (SAR), hence
the satellite has to illuminate the Earth's
surface with C-band radar and detect thereflected signal. This requiresconsiderable electrical power.
The question is: ‘how much power, on
average, will be generated by Sentinel-1's
solar array.’
The answer is contained within thearticle in Bulletin 131. A clue might bethat I could run my home indefinitely,summer or winter, on this level of power
availability, even with all my homeelectrical equipment.
Answers to Francis Bell at
francis@geo-web.org.uk

or by mail to the address on page 1.
A winning entry will be chosen on
December 25, 2007, and the winner willwith receive an illustrated space calendar.

GEO’s annual Symposium is a long way
ahead yet, but preparations are alreadyin motion. The NSC Leicester has been
booked for Symposium 2008 on Saturday,
May 10. This date has been chosen in
anticipation of avoiding the Bank
Holiday weekend and other events suchas major sporting fixtures.
Invitations have been issued to speakers
but the day's programme is not yet fixed.
It is hoped to have representatives fromour own British National Space Centre
and EUMETSAT in attendance.
Members who attended last time verymuch appreciated the more informal
approach which offered more time fordiscussions and workshops.
We would like our members to have a say
in developing the programme for
Symposium 2008. If there are any
specific topics or workshops you would
like to see placed on the agenda, or if you
would like to make a presentation ordemonstration yourself, please get intouch with Francis Bell at
francis@geo-web.org.uk

or by mail or telephone (details on
page 1).
A more detailed programme will be
published in our March 2008 Quarterly.
In the meantime, please put the date inyour 2008 diary.
Other Dates for 2008
GEO will be represented in some form at
the Radio-Active Rally in Nantwich on
Sunday, February 3, 2008.
GEO are planning to attend the West
London Radio & Electronics Show at
Kempton. The date is usually mid-March.
This is a busy, well attended show.

or email ops@eumetsat.int

I hope GEO will be invited to AMSAT-UK'sannual colloquium in Guildford. The dates
should be July 25-27, 2008; however theinvitation and dates need to be confirmed.

Alternatively, you can download the 8-pagepublication in PDF format from their website at www.eumetsat.int.

GEO will also be at the LARS rally at
Donington in September. This is a wellattended two day show.

GEO has published these contact details
before but for new members it should be
new worthwhile information.

GEO may, additionally, be present at otherevents. Check the March issue of GEO
Quarterly for the latest news.

www.geo-web.org.uk

3

GEO Quarterly No 16

Group for Earth Observation

December 2007

Cover and Full-Page Images
Front CoverThis striking MODIS image of the Aral
Sea was acquired by NASA’s Terrasatellite on April 8, 2007. You can read ourmajor feature on the Aral Sea on page 25.
Image: MODIS Rapid Response Team at
NASA/GSFC
Inside Front CoverGraham Whitehead sent in this evocative
Metop-A image of Hurricane Felix as it
cartwheeled towards Yucatan on
September 3.
Image © EUMETCAST 2007

Inside Back CoverThe upper image is a colour composite
produced from the visible and infrared fulldisc images transmitted from GOES-11 at
21:00 UT on September 2 this year. The
LRIT images were acquired by Ed Murashi
on his recently completed homebrew
hardware.
Image processing: David Taylor

At lower left is a section from a MODIS
image showing the Kamchatka peninsula
and its volcanoes.
Image: MODIS Rapid Response Team at NASA/GSFC

At lower right is a MODIS image from
Terra which shows the course of the River
Volga as it enters the Caspian Sea
particularly well.
Image: MODIS Rapid Response Team at NASA/GSFC

Anders Hook from Vallentuna in Sweden sent us this attractive image acquired from NOAA-17
on April 5, 2007. Cloud streets are conspicuous flowing off northeast Greenland and a prominentrope cloud can be seen stretching from Denmark and arcing north of the British Isles

Beware Wildlife!
Alan Banks
One morning recently, at 8.00 am, I
noticed that my EUMETCast signal
quality had suddenly fallen.My wife hadseen a couple of squirrels collecting
berries and nuts in the front garden andat about 9.30 am, as I went out to do a
bit of shopping, I noted that there weremuddy pawprints on the dish, which isonly a couple of feet from the ground.
Closer inspection showed mud on the
LNB and support arm. The cable seemed
intact and I wiped everything down andwent on my way. On returning home I
found the signal was even worse!
Further inspection showed that the cable
had been partly pulled out of the LNB.

4

The squirrels must be suspects but I had
probably made it worse when giving thedish its quick wipe down. Remaking theconnection improved matters.
Wildlife can impact on our hobby! It
reminded me of when I had a garden
railway—hedgehogs and cats in thetunnels, ants along the rails, wasp nests
under the track, frogs and toads in theretaining walls. Once, I even found a
newt and worst of all were the thrushes
which used the rail-head to smash theirsnails, leaving a neat pile for my smallscale locos to trip over.
Moral: beware squirrels collecting nuts inautumn (or any wildlife for that matter).
I’m glad I have nothing bigger thansquirrels to contend with.

www.geo-web.org.uk

Back CoverThis August 26, 2007 Envisat image
highlights Japan, an archipelago of over3000 islands stretching some 2400 km
across the western Pacific Ocean. The four
principal islands are, from north to south,
Hokkaido (top right corner), Honshu (thelong island stretching in a northeastsouthwest arc), Shikoku (visible justbeneath the lower part of Honshu) andKyushu (hidden by clouds).
This image was acquired by Envisat’s
Medium Resolution Imaging Spectrometer(MERIS) instrument, working in Full
Resolution mode to provide a spatial
resolution of 300 metres.
© European Space Agency. All rights reserved

Page 35
This October 2, channel-4 Metop-A image
from Mike Stevens shows a predominantly
cloud-free view of Sakhalin Island, Japanand part of the Russian region of
Khabarovsk Krai. Note in particular thecourse of the Amur river (the world’s ninth
longest 4444 km in length) which defines
the border between China and Russia’s
Far East.
Image © EUMETSAT 2007

Page 37
Mike Stevens sent in this striking
channel-3 mid-IR AVHRR image of theUK, France and Spain as seen from
Metop-A on October 20 this year.
Image © EUMETSAT 2007

December 2007

Group for Earth Observation

NOAA-18 Frequency Change
Readers in pager-prone parts of the UK will be delighted to learn
that, following EUMETSAT’s decision to abandon the disseminationof Metop-A LRIT in the 137.1 MHz band, NOAA-18 switched its
frequency from 137.91 MHz to 137.1 MHz on August 18, 2007, achange that will continue for the foreseeable future (until it isrequired for Metop-B).
NOAA-12 Decommissioned
Following increasing problems with power regulation aboard
NOAA-12, this weather satellite was decommissioned on August 10
this year following more than 16 years of service.

GEO Quarterly No 16

meeting was a great chance for GEO members to make newfriends, and Roger tells us that Carsten Arnheiter is planning tovisit him for a few days before the end of the year.
California Forest Fires
This MODIS image from NASA’s Terra satellite shows the massive
plume of smoke spilling over the Pacific Ocean in the wake of severe
wildfires which ravaged some 2000 square kilometres of southern
California stretching from from Santa Barbara down to the Mexican
border. At the height of the conflagration, than a million people were
evacuated from their homes. In all, at least 1,600 properties were totally
destroyed, almost a hundred people were injured and there were
fourteen fatalities..

ReunionCementing a friendship made during the GEO visit to EUMETSAT’s
Headquarters in Darmstadt earlier this year, Giuseppe Cico tooktime out from his visit to Bath and Stonehenge to spend the AugustBank Holiday Monday in Exeter, to meet up with Peter Bradley andPete Green.
Giuseppe was met at St David’s station and shown around thehistoric Exeter Cathedral, the Quay where the Onedin Line wasfilmed, the ‘House that moved’ and the very historic, original Exe
Bridges, as well as other interesting historic sites that the city has
to offer. Giuseppe is a very keen photographer and took many
pictures during his visit to the West Country. The day was drawn toa close with a visit to Peter Bradley’s house following a pub lunchin the Devon countryside.
If you are planning a day trip in the future I would suggest you
consult Giuseppe! When his trip was originally confirmed England
was having the worst summer weather for years. Devon always
seems to have bad weather on Bank Holidays but Giuseppe wasable to forecast some six weeks in advance that we would have abeautiful day—and we did. In fact he had a beautiful week!
Obscured
Our apologies to Roger Jones from Bishop Auckland for failing to
identify him in the GEO photograph taken at Darmstadt. The

Fires in Southern Calfornia spws smoke over the Pacific Ocean
Image: MODIS Rapid Response Team at NASA/GSFC

Storm Dunlop’s Dictionary of Weather
Following Storm Dunlop's talk at the
May 2008 GEO Symposium inLeicester, Oxford University Press areoffering GEO members copies of
Storm's Dictionary of Weather, with aprice of £8.75 (including P&P). The
Dictionary has been described as'the definitive reference for all things
mteorological' and 'a welcome andimportant contribution'

Pete Smith, Giuseppe Cico and Peter Bradley pictured in
front one of Peter’s reception dishes

Copies may be obtained directly from
Storm (140 Stocks Lane, East
Wittering, Chichester, West Sussex
PO20 8NT), to whom cheques should
be made payable. Storm will be happy
to sign copies for you if you wish, butplease indicate clearly if you require a
copy to be dedicated to a specificperson as a gift.
www.geo-web.org.uk

5

GEO Quarterly No 16

Group for Earth Observation

December 2007

Les Hamilton
It’s now over two years since we first
explained how you can obtain raw HRPT
data files from the NOAA archives andprocess them yourself using David
Taylor’s HRPT Reader and GroundMap
software [1]. The Satellite Active Archive(SAA) as it was then known has
continued to develop and now provides
high-resolution data from Europe’s Metopsatellite in addition to the American
NOAA orbiters. The upgraded Internet
site, now termed the Comprehensive
Large Array-data Stewardship System(CLASS), is a valuable resource, speciallyfor readers who would wish to enjoy thedelights of HRPT imaging but for whom a
dedicated EUMETCast system is not an
option.
Uniquely, Metop provides full world
coverage, 24 hours a day, unlike therestricted regions of ‘HRP’ or ‘LAC’ data
provided from the NOAA satellites. Dueto this enhanced recording capability,
data from each full pass is dumped every
orbit over Svalbard. This means that you
are no longer restricted to data fromfixed receiving stations (HRP) or recorded
from predefined regions (LAC) as you arewith the NOAA satellites. This newformat is denoted ‘FRAC’ data.
Additionally, while the NOAA HRPT
data is provided already segmented into
chunks of varying duration (generally
between 8 and 15 minutes), Metop Full
Resolution Area Coverage (FRAC) data
can be ordered to cover the maximum
permitted 80° latitude span (about 23
minutes duration). Additionally, provided
you do not select a specific region fromthe map (figure 4), you can download acomplete orbit dump (around 560 MB).
Registration with CLASS
Although anyone can browse freely
through the CLASS website by directing
an Internet browser tohttp:www.class.noaa.gov/

it is not possible to actually download
any data until you have registered a few
basic details with them. Registration isfree and immediate, and is required
principally to allow NOAA to email you
links from which your requested data
may be downloaded.
Click ‘Register’ on the black menu-bar at
the top of the page and add yoursurname, forename and email address in6

the appropriate fields. Finally, provide a
password (of your own choosing) andclick the ‘Register’ button at the foot of
the page. You may now click the ‘login’
link then enter your User name(forename) and Password to gain fullaccess to the site (figure 1).

like the one shown in figure 5 will appear
showing each pass, accompanied by its
start and end times, and filename. To
visualise your preferred image, tick it in
the Shopping Cart column then click thenumbered button in the View Details
column. The following screen displays theprecise area of the pass on a map of theworld (figure 2) as well as providing
thumbnail views of the channel-2(visible) and channel-4 (infrared) images
available from the dataset (figure 3).

Figure 1 - Entering Username and Password

Finding Metop HRPT Data
Once safely into the CLASS website,
open the drop-down menu at the top of
the page and select the second item inthe list, Advanced Very High Resolution
Radiometer (AVHRR), then click the ‘Go’
icon beside the menu. This brings up the
Search-AVHRR options displayed infigure 4, opposite.
It is here that you define your search,
your first task normally being to outline
the region of the world map for which
you require a Metop image. There are
restrictions—80° longitude and latitude
ranges—and you will be warned if you
overstep these. Select your area by
dragging a rectangle across the map withthe mouse. If need be you can define thearea precisely by adjusting the input
fields to the right of the map.

Figure 2 - Graphic showing the area selected

Select a time interval for your searchusing the Start Date and End Datecalendars. The maximum interval
allowed is 160 days. More usually you
will search just a single day, in whichcase choose the same date for both. The
search can be fine-tuned by amending theStart Time and End Time fields.
Metop raw data is provided in the ‘FRAC’
datatype so only this item should bechecked from the Datatype list. Finally, if
you wish to restrict your search tomorning (daylight) Metop passes, checkthe Descending radio button then selectMetop from the Satellite drop-down list.
It is as well to leave all the Receiving
Station options ticked. These are needed
for the NOAA HRPT data that is alsoavailable from CLASS and which you willprobably wish to investigate too. Now
start your search by clicking the Searchbutton at the foot of the page. A listingwww.geo-web.org.uk

Figure 3 - Image thumbnails

December 2007

Group for Earth Observation

GEO Quarterly No 16

Figure 4(above)Figure 5(left)

www.geo-web.org.uk

7

GEO Quarterly No 16

Group for Earth Observation

December 2007

If you are happy with this selection,
rewind your browser to the previous pageand click the Go to Cart button.
In this screen (figure 6), which confirms
your selection, make sure that the Include
Archive Header box beside your selection
is ticked then click the Place Orderbutton. A final screen will appear showing
your order confirmation number. Press
Confirm and the deed is done.
After a short interval, often just a coupleof minutes, you will receive an email
confirming your order. Shortly thereafter,a second email provides you with links todownload the file either by FTP or using
your Web browser.
I have discovered that a degree of
patience is sometimes required whenordering Metop data. Whereas the NOAA
satellite HRPT files become available
within a few hours of a satellite pass, Metop HRPT data can on
occasions take several days to appear. If you cannot find thepass/region you require, try again later.

Figure 6 - The Shopping Cart

Full Metop Orbit Dumps
If you are interested in examining several regions from thesame Metop pass, it is often more convenient to download the
FRAC file for the complete orbit. These files weigh in at 560 MB
but, with modern broadband connections, can be downloaded in
the background, while another task is being undertaken, in just
15 minutes or so.
To download such a file, follow the procedures described above
but do not draw a rectangle on the map (don’t even click on themap). When the list of passes appears, check the file you requireand order it as described.
Splitting Orbit Dumps into Sections
Once you have your full orbit of Metop data available, one
hurdle remains. Even with a high specification PC that can load
the full file into HRPT Reader [2] you may be disappointed to
discover that processing is slow and scrolling through thedisplayed image is like watching paint dry!
The answer is simple in concept—just split the file into moremanageable segments. The question is: ‘how?’ I have written asmall utility program that does this task for you: Metop File
Splitter [3]. The program can be downloaded from my website asa self-installing archive. After selecting a Metop FRAC filename(figure 7), use the sliders to select the section you require, either
by image lines of by duration (in minutes). On clicking ‘OK’, thesplitting takes place and a new file, which includes the selection
limits in its filename for reference, is automatically saved in thesame folder as the original file.
Tests have proved successful when loading up to 40 minutes
worth of Metop data into HRPT Reader. Though slower thannormal, images process and display in a reasonable time
(though this may depend on the specification of the PC used).
Country outlines, if required, will plot correctly on these images.
The first problem that emerges when excessively large segments
are processed is that the country outline feature ceases working
correctly, followed by a rapid slowing of all processing features.
In reality, there should rarely be a need to use sections longer
than 15 minutes duration.
HRPT Console
The final stage of processing images produced from Metop
FRAC files generally involves selecting a map projection(Mercator, orthographic etc.) and correcting an image for theeffects of the Earth’s curvature using David Taylor’s

8

Figure 7 - Metop Splitter

GroundMap software [2]. With numerous sections from a fullorbit of Metop data this means continually selecting a new
region of the globe. There is also the question of which of themany output types from HRPT Reader you require. I havewritten HRPT Console as an interface program which allows theuser to select command-line parameters for both HRPT Reader
and GroundMap, and select a relevant area of the Earth’s
surface. Once these have been established on the program’s
configuration screen, a selected image output by HRPT Reader
can be fed into GroundMap and rectified on the click of abutton. The program comes with an extensive help file andshould be intuitive in use. Note, however, that it only operates
with registered versions of HRPT Reader and GroundMap (asthe free versions are not responsive to command line
parameters).
References
1 HRPT Images from the NOAA Archive, GEOQ 5, page 18, 2005
2 HRPT Reader and GroundMap can be downloaded from the link at
http://www.satsignal.eu
3 Metop File Splitter may be downloaded fromhttp://myweb.tiscali.co.uk/software.htm
4 HRPT Console may be downloaded fromhttp://myweb.tiscali.co.uk/software.htm

www.geo-web.org.uk

December 2007

Group for Earth Observation

GEO Quarterly No 16

The NOAA-17 image above, dating from April 27, 2007, shows high pressure over the UK during a spell of warm early summer weather—before the torrential
rains of May, June and July descended, robbing the British Isles of its traditional summer.
Image: NOAA CLASS Archive (http://www.class.noaa.gov/)

Metop-A captured this cyclone over southeast Spain on October 12, 2007
Image: NOAA CLASS Archive (http://www.class.noaa.gov/)

www.geo-web.org.uk

9

GEO Quarterly No 16

Group for Earth Observation

December 2007

Robert Moore
My two professional careers have taken
me right across the northern hemisphereand just into the southern one but one
place I know I will never visit is the
Kamchatka Peninsula, a wild andinaccessible part of the world on the far
eastern edge of Russia. Yet this is thefirst part of the world we see every
morning on the descending path ofMetop-A. More often than not the region
is covered in cloud. But sometimes thecloud structures themselves are worthy ofcloser examination, as in figure 1, a quite
stupendous display of wave cloud in the
Zaliv Selichova—the area of sea enclosedby the neck of the peninsula. The scene
measures some 750 km from top tobottom. The peninsula itself is under the
cloud to the right (east) of the image.
The Kamchatka Peninsula is part of the‘ring of fire’ and a UNESCO World
Heritage Site because of its volcanoes,
renowned both for the great beauty of
their almost perfect cones and for theirdeadly danger to climbers. When theclouds clear, some of the volcanoes may
be seen in a line in Metop-A images (seecolour image on the inside back cover).
Recently there was an eruption of
Kliuchevskoi volcano which was clearlyvisible in the ch4-ch5 imagery over
several days (figure 2).
Events such as this may set us off onother observational paths; for example
there were press reports of mudslides
destroying parts of the geyser valley, oneof the most spectacular features of the
UNESCO site. There is also a webcam
watching the volcano, which usuallyconfirms it to be cloud-covered. But
Kliuchevskoi sometimes clears, and its
plume may then be seen rising into a
blue sky. Some of the webcam images arespectacularly beautiful and a selection
appeara overleaf.

The Internet encyclopaedia Wikipedia
will tell you more about the geology ofthe peninsula but you may find it hard toresist reading on about the history,
language and folklore of the area as well.
Then, as in most parts of the world, there
are links to follow to meteorologicalstations, geological surveys or university
departments, to help you to gain evenmore information about observations
taken, records kept and research
conducted in the region.
Once you start exploring Kamchatka you
might well find the Institute of Volcanic
Geology and Geochemistry, Far East
Division, Russian Academy of Sciencesat:
http://www.wovo.org/0900_1000_IVGG.htm

and then the World Organization ofVolcano Observatories at:
http://www.wovo.org/index.htm

and so on.
How the time slips by! But it is never awaste of time—learning something new
every day is not only enjoyable andstimulating but very good for you. Also I
can’t see much point in a hobby where
you spend time and effort in getting good
images and then you don’t actually lookat the pictures!

Figure 1 - Wave cloud in the Zaliv Selichova
Metop-A image © EUMETSAT 2007

You can view these and real-time imagesof the volcano at:
http://data.emsd.iks.ru/video/video.htm

Once your interest has been stimulated
by pictures from space and ground level
you may be drawn to other sources of
information—the World Wide Web, forexample, will give you more images at:
http://volcano.und.edu/vwdocs/
current_volcs/kliuchevskoi/
kliuchevskoi.html

10

Figure 2 - Kliuchevskoi erupts
Metop-A image © EUMETSAT 2007www.geo-web.org.uk

December 2007

Group for Earth Observation

GEO Quarterly No 16

R W Hollander
A team from the Dutch Werkgroep Kunstmanen, consisting ofArne van Belle, Harrie van Deursen, Ruud Jansen, Ben
Schellekens and Rob Hollander decided in April 2006 tocompare the performance of several types of 137 MHz antennas.
After a series of test measurements, a setup was finallyapproved in October 2006 which allowed the performance of up
to six antennas to be compared using the signal transmitted bya polar satellite. Satellite passes with different maximal
elevation were used, to the west as well as to the east, to gain
an overall impression of the performance of the antennas under
test. This method was adopted because of the problems we had
met with reflections in our previous measurements of radiation
patterns of antennas [1].
Measurement Setup
One of the antennas was connected to a HRX-137 satellite
receiver, designed by Harrie van Deursen. This particular
receiver has a calibrated signal-strength output connected to a
Conrad 12 bit ADC, controlled and read from via the serial portof a laptop. A coaxial relay, controlled via the parallel port ofthe laptop, was used to connect up to six antennas to the
HRX-137 in a cyclical way. Finally a Dartcom-137 antenna
amplifier with a gain of 11 dB was placed between the co-ax
relays and the HRX-137 to boost the signal in order to achieve a
better linear relationship between the signal strength output
and the log of the input signal. The RF part of the measurement
setup had an impedance of 50 ohm, including the input andoutput impedances of the HRX-137 and the Dartcom-137. Our
measurements were controlled by software running on thelaptop but before starting, the PC-clock was precisely set to
DCF-77 time.
The time was recorded (PC-clock) and the first antennaconnected then, after a 1 second interval to allow the receiver tosettle, the signal strength of the first antenna was sampled 10
times and the mean value calculated and recorded. The otherantennas were connected and measured in turn. Once the signal
strength of all the antennas had been recorded, we constructeda single measurement record containing the start time for eachseries of measurements and the signal strength of eachantenna. The result was shown on the screen of the laptop, bothgraphically and numerically.
This cycle was repeated, starting some minutes before thesatellite was due to rise above the horizon until some minutes
after the satellite had disappeared. This was done to allow us todetermine the noise level of the setup for each different
antenna. Once the measurements had been completed, therecorded time was used to calculate the azimuth (AZ) andelevation (EL) of the satellite using a satellite tracking program.
Strictly speaking, we should have calculated AZ and EL
individually for each antenna; however, the error that we madewas negligible for the purpose of our measurements since anentire record only took 7.6 seconds!
It was important to calibrate the signal strength output of the
HRX-137, in dB relative to an RF-input level of the HRX-137.

We used -50 dB at an input of 0.707 microvolt in 50 ohm. The
relation between the signal strength output voltage and thelogarithm of the RF-input voltage is almost linear in the range
of input signals that were used. Only a small sinusoidal
correction term was needed (due to the three log-converter
stages in the NE604) to obtain a good fit between thecalibration curve and the data. The deviation over the whole
range was less than 0.2 dB.
Measurement Conditions
Harrie van Deursen decided that October 14, 2006 should be theday of the real comparison. On that day there were to be four
useful satellite passes (table 1).
A.O.S.

Satellite

Direction Maximum Frequency
Elevation
(MHz)

12:42

NOAA-17

N —> S

82° W

13:41

NOAA-18

S —> N

42° E

137.91

14:21

NOAA-17

N —> S

18° W

137.62

15:22

NOAA-18

S —> N

39° W

137.91137.62

Table 1 - The satellite passes used in the tests

The measurement location was a flat grassy field next to asmall lake called the Noord Aa in Zoetermeer, which was withineasy reach of Harrie’s house by car. There is a free line of sightfrom horizon to horizon and the nearby lake allows acomparison of passes over land and over water. The location isshown by the red circle in figure 1. We set out to compare fourtypes of 137 MHz antenna, using the horizontal open dipole
antenna as a reference (table 2).
entre
Type of Antenna Owner Height Impedance FrC
equency
RQHA
RQHA
RQHA
Turnstile
Folded X-dipole
Hor. open dipole

Rob
Ruud
B en
Rob
Arne
Rob

3.0 m
3.5 m
2.3 m
2.0 m
2.3 m
4.0 m

Cable Attenuation
Run

51.3 - 53.5 138.5 MHz 8.9 m
43.9 - 43.9 138.0 MHz 9.0 m
65.5 - 56.7 139.3 MHz 11.5 m
43.1 - 45.2 137.0 MHz 8.2 m
45.2 - 47.4 not clear
9.0 m
56.1 - 55.5 137.5 MHz 14.2 m

2.5 dB
2.5 dB
3.0 dB
2.8 dB *2.6 dB
3.8 dB* The attenuation is too high, probably due to abad contact in one of the BNC-connectors.

Table 2 - Antenna details

The heights listed in the table are those of the bottom of each
mounted antenna. This means that it is the height of thereflector in the case of the turnstile and the folded cross dipole.
The impedances in the table are the absolute values of Z (at137.48 MHz and 137.9 MHz respectively) for each antenna. The
phase of Z was not measured. The centre frequency value isthat for which the impedance of the antenna showed a kind ofsymmetry. Ideally, this value should be 137.5 MHz while theimpedance (which should be real) should be 50 ohm. The
attenuation caused by the connecting cables was measured toallow for a precise comparison of the antennas. The differences,
however, were small, and were not included in our analyses.

www.geo-web.org.uk

11

GEO Quarterly No 16

Group for Earth Observation

Figure 1 - Noord Aa (red circle), the measurement location near Zoetermeer in the Netherlands.

Figures 2-5
In each measurement series, the signal strength is read from the scale on the left-hand axis and the elevation of thesatellite is read from the scale on the right-hand axis, using the red curve. The azimuth information is not used inthese comparisons.

12

www.geo-web.org.uk

December 2007

December 2007

Group for Earth Observation

The Dartcom-137 antenna amplifier was used in allmeasurements in this series. Input and output impedance wereprecisely adjusted to 50 ohm.
Measurement Series 1• In the first measurement series, NOAA-17 rose over landand set over water.
• Ruud’s RQHA performed extremely poorly in this series.
Following this result Ruud checked the mounting of his
antenna, discovered an error, and corrected it.
• The turnstile was connected by means of a cable with afaulty BNC-connector, as we found out later. So theturnstile antenna was omitted from this series.
• Arne’s folded dipole antenna (the only ‘professional’
antenna in this comparison) produced such weak signals
that, probably, something was wrong with the connections;
we could not find what this was, however. This type ofantenna can be connected with the wrong phase between
both dipoles too. So the folded dipole antenna was notincluded in figure 2.
From the variations in signal strength of Rob’s horizontal
open dipole (reference), it was clear that this type of dipole
suffered from destructive interference due to reflections. At theelevation angles where this dipole showed dips in the signal
strength, the other antennas also had problems withinterference, though less severely. A closer look at the curves
reveals that the dips do not occur at exactly the same ELangles! This is due to the difference in height of the different
antennas.
The dips for the open dipole were at 15°, 32° and 55° elevation,
angles which corresponded with exactly 1, 2 and 3 wavelengths(218 cm) of path length between the direct and the reflectedwave.
The height was exactly 4.0 m. The phase shift on reflection ofhorizontally polarised waves is 180° [1]. Since this phase shift
was also 180° at the 15° point, it meant that the Brewster angle
was smaller than 15 degrees—and therefore that the ground at
the measurement location was behaving better than a ‘mean’
ground (showing higher conductivity). The ground near the lake
was rather wet!
Rob and Ben’s RQHAs look the same, both in theirconstruction and their performance.
Reconstructing Radiation Patterns
It is possible to reconstruct the radiation pattern of an antenna
by measuring many passes of the same satellite at different
maximal elevation angles. When we restrict ourselves to theelevation, it is clear that the sensitivity of an RQHA is goodenough to receive the signal above noise level immediately thesatellite reaches the horizon.
The sensitivity at angles greater than 30° may be designed to besmaller. This can be accomplished by designing the RQHA
slimmer and taller. This is the case with Ruud’s design, whichuses a quarter-turn rather than half-turn design. In the nextseries it will become clear that the sensitivity of Ruud’s RQHA
at the horizon is indeed higher than Rob’s RQHA but lesssensitive at high elevation angles.
These measurements demonstrate that interference cannot be
avoided nor can it be neglected. Some days after this series ofmeasurements, Harrie wanted to be sure that we saw
reflections and not something else. At the same location, hemeasured the signal strength of an open horizontal dipole about
one metre above the wet ground and indeed the dips were notpresent. Moreover, he found that an RQHA 64 cm above theground produced an almost ideal sensitivity curve as a functionof its elevation. The message is that it is possible to exploit thereflections to enhance the radiation pattern, by making a proper

GEO Quarterly No 16

choice of the antenna height. To be fair; this only works when
the reflecting plane is large and flat and rather conductive.
Measurement series 2 (figure 3)• In the second measurement series, NOAA-18 both rose andset over land.
• Ruud’s RQHA seemed healthy again and was included in
the comparison.
• Rob’s turnstile still seems to suffer from the bad cableconnector.
• Arne’s folded dipole was withdrawn from the contest.
The horizontal dipole again shows dips in signal strength at 15°
and 32°. The dip at 55° is absent because the maximal elevationin this series was only 42°.
All three RQHAs performed more or less equally. The higher
sensitivity of Ruud’s design at low elevations was clearly
demonstrated. The sensitivity at maximal elevation of Rob andBen’s RQHAs was slightly higher than Ruud’s RQHA but thedifference was marginal.
Signal strength dropped sharply for all antennas when thesatellite sets to the north. The drop was 10 dB over only 4°
difference in elevation! The increase in signal strength when thesatellite rose above the horizon to the south was also rather
sharp, but the dipole showed a dip while the other antennas
showed irregularity (maybe because of a reflection from that
direction that we had overlooked?).
Measurement series 3 (figure 4)• In the third measurement series NOAA-17 rose over landand set over the boundary between water and land.
• At the end of this series it was clear that the turnstile had
recovered from the bad BNC connector problem but wehave not included it in this measurement series.
The maximum elevation for this satellite pass was very low to
the west. The open dipole antenna, directed E-W for maximal
sensitivity in the N-S direction, was unable to receive signals
during the whole pass. All three RQHAs, however, showed
excellent reception during the entire period that the satellite
was more than 3° above the horizon. Ruud’s RQHA performed alittle better near the horizon. Above 17° elevation, all three
RQHAs performed equally well.
Measurement series 4 (figure 5)• In this measurement series NOAA-18 rose over water andset over the boundary between water and land.
In figure 5, all antennas are included, except for Arne’s folded
dipole, which again showed deep dips due to destructive
interference at the well known elevation angles.
The turnstile antenna performed remarkably well, itssensitivity pattern showing the same reduced sensitivity forhigh elevation angles as Ruud’s RQHA but shows an evenhigher sensitivity between 30° and 35°! The relatively deep dip
in the turnstile’s pattern at 19°s corresponds with that for the
open dipole at 15°, due to the much lower height that was used
for the turnstile.
The turnstile suffers more from interference at low elevation
angles than the RQHAs. Its polarisation is perfectly circular at
the zenith but becomes linear (horizontal) at the horizon. The
polarisation of an RQHA at the horizon is still quite close tocircular! The sense of circular polarisation is reversed when
EM-waves are reflected at angles larger than the Brewster
angle. The RHCP (right handed circular polarised) RQHAs arealmost blind to reflected LHCP-waves. The remaining
destructive interference (the RHCP of an RQHA at the horizon
is not 100%), however, is small and the signal strength remains
well above noise level.

www.geo-web.org.uk

13

GEO Quarterly No 16

Group for Earth Observation

Conclusions• The first lesson is to invest in good cables and connectors.
• Secondly, it is clear that a good antenna design (withcircular polarisation and radiation pattern) is important;but a good antenna location (to minimise reflections) iseven more so.
• Connecting an antenna is not simple! Arne’s folded dipole
was apparently not connected properly and even Ruud’s
RQHA had problems in the first measurement series (anerror in connecting the loops, creating a phase mismatch).
• The open dipole antenna was included as a reference
antenna but, as we already knew, was clearly not a good
choice for satellite reception. However, an E-W oriented
dipole positioned about one metre above a good conducting
ground does perform very well for high elevation passes
and might be a good choice for the reception of polarsatellites during holidays.
• The differences in performance of the other antennas isimportant only at low elevation angles. At high elevation
angles all the antennas performed more than satisfactorily.
• RQHAs perform better at low elevation angles thanturnstiles, but not dramatically so.
• Ruud’s slim, tall RQHA design, with more sensitivity at thehorizon, is a good choice. However, this design also has ahigher sensitivity below the horizon, which makes ittheoretically more sensitive for destructive interference at
low elevation angles. Moreover, the RHCP of Ruud's
quarter-turn RQHA design at the horizon is 69% while

December 2007

Rob's half-turn RQHA shows 82% RHCP at the horizon.
The radiation patterns of RQHA antennas have also been
described elsewhere {2,3].
The reflection problem varies with the antenna location. An
antenna on a roof in a city 'sees' a totally different reflecting
environment than an antenna in an open field. In an open field
it is advisable to position the antenna 60-100 cm above thereflecting ground to avoid signal dips due to destructive
interference. The area around the antenna location that is
important in this regard is relatively small; even for an antenna
on a 4-metre pole, the radius of that area is only 16 metres.
In a city there are many reflecting objects and there, it is notpossible to give general rules to avoid reflections. In a city it ismore important to avoid the effect of multiple reflections. An
antenna that is ‘blind’ for the reflected LHCP waves that arrive
from all directions, like an RQHA, is a good choice. Moreover, an
RQHA that is only sensitive in the upper hemisphere will havelittle problems with interference sources like computers etc.,from which the radiation will reach the antenna from below its
own 'horizon'.
References
1 Reflections of EM Waves, R W Hollander, GEO Q15, 2007
2 Antenna Theory and Measurement, R W Hollander, GEO Q3, 2004
3 Tech Note 2004-1
www.kunstmanen.nl

Striking details of meanders in the lower course of the Mississippi river are captured in this September 20 Metop-A image sent in by Alan Banks.
Image © EUMETSAT 200714www.geo-web.org.uk

December 2007

Group for Earth Observation

GEO Quarterly No 16

Ed Murashie
When you say LRIT, some people will cringe and then give you anearfull; others will smile and talk about the wonderful improved
images; yet more will look puzzled and ask what you’re talking
about. I have the first one down well and sometimes have beenfound doing the second one. As for the third, that’s why I am
writing this article. Let’s see your reaction after you have read it..
Before I get started describing the LRIT format, I want todescribe the evolution of the weather satellite image formats thatlead to LRIT. This includes the Weather Facsimile (WEFAX)
format, the immediate predecessor of LRIT.
The first weather satellite to image the Earth was TIROS 1, on
the day of its launch, April 1, 1960. TIROS 1 had two vidicon
cameras mounted on the base of the satellite, one with a wide
angle lens and the other a narrow angle lens. The vidicon tube
would be charged, a shutter would expose it to the Earth viewfor 0.0015 seconds and then an electron beam would scan thestored image for 2 seconds creating a 500 line image. The slow
scan rate meant a narrow transmission bandwidth. The highest
ground resolution was between 2 and 3 miles. The video signal
would frequency modulate (FM) an 85 kHz sub carrier whichthen FM modulated a 2 watt 235 MHz carrier. The pictures
were sent to either Command and Data Acquisition (CDA)
stations within range or recorded on tape for later transmission.

quickly to the end user without having to wait for the satellite
to pass over a CDA station be processed was critical. The APT
system used a new type of vidicon tube which contained asecondary surface where the image would last longer before
fading and thus could be scanned more slowly. This slower
scanning meant an even lower transmission bandwidth, that
could be received on relatively inexpensive equipment (around$30,000 US in those days), therefore enabling more receiving
stations to be built. The vidicon tube was charged, exposed to
the Earth view, and the image transferred to the storage layer,
taking about 8 seconds. During the next 200 seconds, the image
was scanned at 4 lines per second and the video signal
amplitude modulated (AM) on to a 2400 Hz sub carrier. The
brighter the scene, the stronger the sub-carrier signal. Finally,
this sub-carrier signal was FM modulated on to a 136.234 MHz
carrier wave. Each image covered 1000 miles on a side and had
a resolution of about 1 mile. Thus APT’s roots derived from FAX
technology that had been around for years.
The First GeoStationary Satellite
The first geostationary satellite with cameras to orbit the Earthwas Application Technology Satellites’ ATS-1 on December 6,
1966. Interestingly, the primary mission of the ATS satellites
involved experimental communication technologies, one ofwhich was WEFAX. The National Environmental Satellite
Center transmitted weather satellite pictures from Nimbus and
ESSA satellites to the ATS Mojave California station whichthen sent them up to ATS-1 on 149.22 MHz. ATS-1 would thenretransmit these down to APT receiving stations on
135.60 MHz. ATS-1 was a transponder in space, with APT
characteristics similar to those for TIROS—so the sameequipment could be used for reception. Later, ATS satellites
were even larger and transmitted at higher power levels,
allowing inexpensive ground stations to receive their images.

The first ever TIROS-1 image, of New England and the Gulf of St Lawrence
Image: NOAA

CDA stations recorded the pictures onto 35 mm film, whichwere processed into photographs then combined into a single
map, annotated and gridded. These nephanalyses were thenfacsimiled (faxed) to the National Weather Satellite Center
where more information was added and rechecked before being
faxed to local and foreign weather services and the military.
Different camera positions, camera lens and transmission
methods were tested during the TIROS program. One of themost significant advances was Automatic Pictures Transmission(APT). The weather service realised that large atmospheric
events like hurricanes lasted for days but thunderstorms only
lasted for hours. The need to deliver the satellite pictures

www.geo-web.org.uk

An ATS-1 Image
Image: NOAA

15

GEO Quarterly No 16

Group for Earth Observation

December 2007

Indeed, ATS-6 was powerful enough to be able to transmit
educational programs to remote areas of India and the UnitedStates using these same inexpensive ground stations.
One of the secondary missions of the ATS satellites was toimage the Earth from a geostationary orbit. The advantage of ageostationary satellite is that it remains over a fixed point on
the Earth since its orbit matches the Earth’s rotation. Anotheris that this orbit, some 22,000 miles above the Earth, is highenough that the camera sees the entire planet in a single frame.
Combining these two advantages allowed a series of images tobe animated, showing the flow of cloud patterns over time.
ATS-1 used a spin-scan cloud camera (SSCC) that utilised thesatellite’s 100 rpm spin rate, with a scanning mirror, to produce
a 2000 line image in 20 minutes. ATS-3 contained a colour
version of the SSCC which took the first colour pictures of thefull Earth (page 17).
The first satellites having a primary mission of weather
observation were the Geostationary Operational Environmental
Satellite (GOES) series. The prototype for the GOES satellite
was the Synchronous Meteorological Satellite (SMS), and SMS-1
was launched on May 17, 1974. The SMS 1, 2 and GOES 1-3
satellites were almost identical and contained and improved
SSCC called the Visible and Infrared Spin Scan Radiometer(VISSR) that could scan grayscale images at visible andinfrared frequencies. These satellites carried eight visible
sensors and one infrared sensor and a full Earth picture wascompleted in 1821 rotations, taking about 18 minutes. This
provided a 14,568 line visible image with half mile resolution
and an 1821 line infrared image with 5 mile resolution.

GOES-9 NE IR image from January 1996
Image: NOAA

Satellite Services (NESS). NESS reformatted the data bysectoring it and adding header information. The data was
finally returned to the CDA who transmitted it to the satellite
as an analog WEFAX signal on 2033 MHz. The satellite thenshifted the signal frequency, amplified it and sent it back down
to WEFAX ground stations on 1691 MHz .
SMS and GOES also maintained the ATS WEFAX capability sothat current facsimile equipment could be used, but changed theradio frequency from the VHF
band (137 MHz) to S-band(1691 MHz). NASA and NOAA
helped in the WEFAX transition
by publishing papers like the‘SMS GOES WEFAX Users
Guide’ and promoted the use of
S-band to VHF frequency
downconverters. The European
Meteosat-1 satellite was basedon the SMS/GOES satellite
The author’s home-built photo fax
series and also carried theWEFAX service.

This GOES-1 visible image dates from October 1975
Image: NOAAThe Raw VISSR data (digital 14 megabit per second - Mbps)
was sent down to the CDA station, reformed and gridded
forming the lower data rate signal Stretched VISSR (digital
1.75 Mbps). The CDA station then sent this signal back to thesatellite where it was retransmitted on a different frequency toreceiving stations including the National Environmental

16

www.geo-web.org.uk

A GOES-E VS image produced on the author’s photo fax

December 2007

Group for Earth Observation

GEO Quarterly No 16

The first ever colour weather satellite image, from ATS-3, received at 18:00 UT on January 21, 1968
Image: NOAA

GOES 8 was the first 3-axis stabilised satellite, unlike theprevious spin-stabilised ones. Being 3-axis stabilised, theimager is always facing the Earth, allowing for more imaging
time and greater flexibility. It could, for instance, image
thunderstorms in the southwest United States every
15 minutes. The higher resolution Stretched VISSR data format
was replaced by GOES Variable (GVAR) format to accommodate
the imaging flexibility. The same kind of flexibility is used in
the LRIT transmissions. The WEFAX capability remained thesame as in the previous series of satellites.
The GOES satellites, being transponders in space, would relay
images from other satellites, as well as charts and schedules. A
typical GOES West schedule included full disk and sectorised
images from the Japanese GMS satellite, the GOES Westsatellite, the GOES East satellite, Meteosat and the polar
orbiting NOAA satellites. There were also aviation charts,
significant weather charts, TBUS satellite status reports andtransmission schedules.

GOES-12 and GOES-10 WEFAX transmissions werediscontinued and replaced by LRIT on March 1, 2005 andOctober 3, 2005 respectively, ending the long legacy of GOESWEFAX. On June 14, 2006, Meteosat-7 direct broadcasts were
terminated ending WEFAX service for the European
community. The only satellite still broadcasting WEFAX service
is MTSAT-IR covering the Japanese region and this service isdue to be discontinued on March 12, 2008.
A typical GOES WEFAX amateur station, as described in
Dr Ralph Taggart’s New Weather Satellite Handbook (1981),
consisted of a 4-foot surplus parabolic dish with a 2-lb coffee canfeedhorn connected to either a commercial S-band
downconverter like Microcomm’s or a homebrew one as
described by Emilani and Rhighini’s QST (November 1980). The
output from the downconverter was connected to either acommercial VHF receiver like the Vanguard, a scanner such as
the Radio Shack PRO-2008 or a kit built unit like theHamtronic R75A. The output of the VHF receiver was the

www.geo-web.org.uk

17

GEO Quarterly No 16

Group for Earth Observation

December 2007

speaker and was a 2.4 kHz signal that varied in
loudness as the signal was received. This output
signal was tape-recorded for storage, fed to amodified fax machine like the Western Union
Telefax Transceiver or displayed on an
oscilloscope and the screen photographed. Somepeople, including myself, built their own photo
fax machine. If you wanted to receive the polar
orbiting weather satellite signal, you attached
an antenna to the VHF receiver and you wereready to go.
An Earfull
For myself and others who are hardware
oriented, those were the good old days! You
could get up and running on APT for as little asa few hundred dollars using surplus equipment.
You could hear the signal and see it on an
oscilloscope. How many of you still enjoy hearingthat static as a NOAA satellite comes up overthe horizon, the signal building to a strong ticktock sound and then disappearing back into
static as it slips over the opposite horizon? You
could add the WEFAX capability later as yourallowance would permit (about $500) and could
experiment with just wires, transistors (or tubes
for those as old as myself) and a soldering iron.
As the digital age dawned, everyone wanted tobuild that YU3UMV digital frame store forgreater convenience and improved picture
quality. With the appearance of computers you
could build that CoCo (Tandy colour computer)or Amiga interface so that pictures could beelectronically saved and shared. The point wasthat you could do as little or as much as you
wanted and were capable of, and had more
options and areas to experiment in.

Following the failure of GOES -6 in 1989, EUMETSAT loaned their redundant Meteosat-3 to
NOAA. Meteosat-3 was drifted from 0°W to a new station at 75°W over the Atlantic Ocean.
This WEFAX image from Meteosat 3 was obtained during March 1993.

By the mid 80’s, schools were installing weather
satellite equipment so that students could learn
about electronics, satellite technology, tracking
satellites, image processing and weather. Thiswas promoted by NASA issuing educator’s
guides and inviting them to satellite launches.
By the end of the 90s the size of the WEFAX
antenna and electronics had shrunk enough to
fit in a suitcase! Many times I took myequipment to share with teachers at the NOAA
satellite launches and to Ham Radio clubmeetings. I even sneaked the equipment up on
the roof of where I worked so I could capture
images.
Now that LRIT has replaced WEFAX, all thathas disappeared and you have to be a computer
programmer to experiment with the limited
hardware. Unfortunately, we don’t have the funof pointing the small dish or loop Yagi at a
GOES satellite and switching on the receiver tohear the buzzing of the header followed by thestrange sounds of the image and the zipping
sound of the grids. We can no longer view anotebook PC displaying the steady advancementof images across its display and see newcomers
amazed at how we are picking up a satellite
image with such simple equipment. Luckily westill have NOAA APT transmissions for a few
more years before they are also replaced bydigital counterparts.
References
William K Widger, Jr., 1966: “Meteorological Satellites”
John Jakes, 1966: “TIROS Weather Eye in Space”
Janice Hill, 1991: “Weather from Above”

18

Judge the resolution and quality of LRIT from this visible image clip from GOES 11. Hurricane
Henrietta shows south of Baja, yet the image above is shown at only 31% of its full resolution.

www.geo-web.org.uk

December 2007

Group for Earth Observation

GEO Quarterly No 16

Above, a GOES 11 channel-1 LRIT visible image acquired at 20:46 UT on September 2, 2007 showing Hurricane Henrietta south of the Baja peninsulaThis GOES 11
channel-4 LRIT infrared
image image acquired
at 20:45 UT on
September 2, 2007shows Hurricane Dean
over the Caribbean

www.geo-web.org.uk

19

GEO Quarterly No 16

Group for Earth Observation

Kaguya images the crescent Earthfrom a distance of 110 000 km

December 2007

A high-resolution CCD image taken over Brazil’s Matto Grosso by the CBERS-2B satellite
Image: INPE

Image: JAXA/NHK

This image shows the striking Maunder crater
located in the region of Noachis Terra on Mars.
The High Resolution Stereo Camera (HRSC) on
ESA’s Mars Express orbiter imaged the Noachis

Terra region during December 2005, with a ground
resolution of approximately 15 metres per pixel.
Named after the British astronomer Edward W
Maunder, the crater is located mid way between

Argyre Planitia and Hellas Planitia on the southernHighlands of Mars. This perspective view has been
calculated from the digital terrain model derived
from the HRSC stereo channels.

Credits: ESA/DLR/FU Berlin (G. Neukum) - Copyright 2000 - 2007 © European Space Agency. All rights reserved.

20

www.geo-web.org.uk

December 2007

Group for Earth Observation

GEO Quarterly No 16

Peter Wakelin
Japanese Spacecraft Heading for Moon Images Earth
The Japan Aerospace Exploration Agency (JAXA) and theJapan Broadcasting Corporation (NHK) have successfully taken
moving images from the Kaguya (also known as Selene)
spacecraft which was launched towards the moon from theTanegashima Space Center on September 14.

At the time of writing, in late October, Landsat-5 is not imaging
but the FOT have a better understanding of the problem andare confident that imaging can resume even if No. 2 battery
cannot be brought back on-line. This is quite an achievement for
an imager that has already made well over 100,000 daytime
passes across the world.

The High Definition Televison (HDTV) camera used wasdeveloped especially for space use by NHK and operates at eighttimes the normal frame rate. The image at far left wasprocessed by NHK from data obtained when Kaguya wasapproximately 110,000 km from Earth, which is nearly threetimes the distance of geostationary satellites, on September 29.

China Launches Another Brazilian Satellite

Kaguya has successfully entered orbit around the moon from
where radio amateurs report a surprisingly strong S-band signal
which can be detected using just a 3.5 turn helical antenna andno dish.
WorldView-1 Successfully Launched
DigitalGlobe's WorldView-1 spacecraft was successfullylaunched by a Boeing Delta-2 vehicle to a 494 km sunsynchronous orbit from Vandenberg Air Force Base, California,
on September 18. This was the 75th consecutive successful
launch of the Delta-2 rocket since May 1997 and 25 remain to
be flown. Built by Ball Aerospace and Technologies Corporation,with the imaging sensor provided by ITT Corporation,
WorldView-1's 60 cm aperture telescope/camera systemproduces 50 cm-resolution panchromatic images. The advanced,
high-capacity system is capable of imaging up to 750,000 square
kilometres of half-metre imagery every day.
The anticipated quality has the US government signed up as acustomer to receive WorldView's images of specific global
hotspots and areas for intelligence-gathering. Although the US
National Geospatial-Intelligence Agency contributed $500
million towards the project, most of the imagery will go to therelatively young commercial Earth-imaging industry where
demand for high-resolution imagery is soaring.
DigitalGlobe's other operating satellite, QuickBird, is expected
to operate for another two years by which time WorldView-2,
now under construction, should be in orbit.

CBERS-2B, the third China-Brazil Environmental ResearchSatellite, was launched from China's Taiyuan space centre on
September 19 into a 736 x 741 km sun-synchronous orbit. It has
since manoeuvred to the usual 778 km circular orbit for CBERS
spacecraft, which enables complete global coverage every 26
days for the narrow field-of-view sensor and every five days forthe wider field-of-view sensor.
CBERS-1 was launched in 1999 andoperated for almost 4 years. CBERS2 was launched in October, 2003 andis still operational but is notexpected to survive until the moreadvanced CBERS-3 is available forlaunch in 2009, so CBERS-2B was
built as an interim measure. It isvery similar to CBERS-2 but has
some enhanced instrumentation andis expected to operate for at least two
years. The Infrared Multispectral
Scanner (IRMS) on the earlier craft
CBERS-1
has been replaced by a panchromatic
Image:INPE
CCD camera with a resolution of just
2.7 metre/pixel. The spacecraft also has a new GPS (Global
Positioning System) and a star tracker in its attitude and orbit
control system. CBERS-2B has a total mass of 1,450 kg and isof cubic shape with dimensions of 1.8 x 2.0 x 2.2 metres and asolar panel 6.3 x 2.6 metres continuously oriented towards the
sun using an automatic control system.
CBERS-2B was built by Brazil's National Institute of Space
Research (INPE) and shipped to the Chinese Academy of SpaceTechnology where twelve Brazilian technicians prepared it forlaunch. Integration with the CZ-4B launch vehicle took place on
September 14 and without any further problems the successful
launch occured five days later.

DigitalGlobe have already released high-resolution images of
Yokohama, Japan, Addis Ababa, Ethiopia and Houston, Texas,
and a part of the latter is reproduced on page 23. The images canbe found at
Launch of CBERS-2

http://www.digitalglobe.com/worldview-1_images.html

Landsat-5 Develops Battery Problems
Although Landsat-5 has now lost redundancy in some onboard
systems, it has continued to return high-quality global data
since its launch more than 22 years ago. On October 6, theLandsat Flight Operations Team (FOT) noticed that battery
No. 2 had been automatically taken off-line and imaging was
stopped to conserve power. Battery power is needed to supply
the satellite's power needs whilst in the non-sunlit part of eachorbit, and one of the three 22-cell nickel-cadmium batteries has
already failed. With the loss of another battery, the remaining
battery may have sufficient capacity to maintain a healthy
spacecraft and continue with some daytime imaging operations.

Image:Chinese Academyof Space technology

INPE have already made available some early images from the
new spacecraft and the one at top right on page 20 shows anarea in the Aripuanã region of Mato Grosso, Brazil. In this highresolution CCD image, rivers are shown as deep red whilst bareearth (tracks and deforested areas) are shown as a lighter red.
One of the uses of this new satellite will be to monitor
deforestation in the Amazon region.

www.geo-web.org.uk

21

GEO Quarterly No 16

Group for Earth Observation

Part of a WorldView-1 image of Houston, Texas, at just 40% of its full resolution!
Image DigitalGlobe

22

www.geo-web.org.uk

December 2007

December 2007

Group for Earth Observation

GEO Quarterly No 16

www.geo-web.org.uk

iGEO Quarterly No 16

ii

Group for Earth Observation

December 2007

December 2007

Group for Earth Observation

GEO Quarterly No 16

www.geo-web.org.uk

iii

GEO Quarterly No 16

iv

Group for Earth Observation

www.geo-web.org.uk

December 2007

December 2007

Group for Earth Observation

GEO Quarterly No 16

Giuseppe Cico
When I started receiving EUMETCast digital services I found theimages produced by David Taylor’s software quite stunning. So
much so that I was eager to find a way to look at them whileworking at my office. The problem was how to make regular
automatic updates to my website, something I solved byscheduling GeoSatSignal sessions using batch files—like the one
listed in figure 4. Note that text has been modified for the purposesof this article, removing customised paths and personal information
to make the lines shorter.

Figure 1 - Meteosat full disc image
Image © EUMETSAT 2007

At the very beginning, in line 2 of the script, there is a strange
command, realdate. Realdate.com is a useful DOS executable
which allows the creation of dynamic time-related commands. It
can be downloaded fromhttp://www.huweb.hu/maques/realdate.htm

and should be placed in the C:\WINDOWS\system32 folder so thatyou have this new command available.
Data collected from EUMETCast are organised in folders withnames related to date. In my script, CCYY means ‘century andyear’, MM ‘month’ and DD ‘day’, in accordance with the commandline syntax explained on the web page. In the example shown,
realdate creates, runs and then deletes a temporary batch filewhich sets the variable today to ‘2007\09\24\20070924’. I use thisto solve the problem ‘how do I get today’s latest free 6-hour
image?’

Figure 2 - Meteosat: Europe zoom
Image © EUMETSAT 2007

In line-6, realdate is used again, to extract the current hour in thevariable timeHH and the loop from lines 7 to 10 obtains the free
image at 6 am. It is important to use the today variable here,
otherwise, using the conventional ‘…*0600-msg…’ time format getsdata from the previous day. When the script uses timeHH ittranslates into“<GSS path>\GeoSatSignal.exe” <MSG data
path>\HRIT\2007\09\24\200709240600-msg-ch01.jpg -j37 colour:<public path>\MSG_VISIBLE.jpg –min ( wrapped line )If the image 200709240600-msg-ch01.jpg doesn’t exist, nothing isdone and the destination file MSG_VISIBLE.jpg is not modified.
This way, an MSG_VISIBLE.jpg file is generated at 06:00, 12:00
and 18:00 using only the current day’s data, provided that valid
data has been received. In my setup, the file MSG_VISIBLE.jpg is
generated with job37 from GSS (‘-j37’ in line 8), and is aquarter-sized full disk image (figure 1). MSG_REMAP.jpg, aremapping of Europe (figure 2) is created with job5 (‘-j5’ in line 9).
The batch file continues, creating hourly IR images but limiting
visible ones to between 6-17 hours (lines 28,29 - 33).

www.geo-web.org.uk

Figure 3 - FTP Voyager

23

GEO Quarterly No 16

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36

Group for Earth Observation

December 2007

title “MSG JPEG ( @ hh.15 )”realdate /f=”set today=\CCYY\MM\DD\CCYYMMDD” >set_today.bat
call set_today.bat
del set_today.bat
rem *** 6-hourly public at 6
for /f %%i in (‘realdate.com /f=”hh”’) do (set timeHH=%%i)if %timeHH% EQU 06 (“<GSS path>\GeoSatSignal.exe” <MSG data path>\HRIT\%today%0600-msg-ch01.jpg -j37 -colour:<public path>\MSG_VISIBLE.jpg -min“<GSS path>\GeoSatSignal.exe” <MSG data path>\HRIT\%today%0600-msg-ch01.jpg -j5 -remap:< public path>\MSG_REMAP.jpg -min)rem *** 6-hourly public at 12
for /f %%i in (‘realdate.com /f=”hh”’) do (set timeHH=%%i)if %timeHH% EQU 12 (“<GSS path>\GeoSatSignal.exe” <MSG data path>\HRIT\%today%1200-msg-ch01.jpg -j37 -colour:<public path>\MSG_VISIBLE.jpg -min“<GSS path>\GeoSatSignal.exe” <MSG data path>\HRIT\%today%1200-msg-ch01.jpg -j5 -remap:<public path>\MSG_REMAP.jpg -min)rem *** 6-hourly public at 18
for /f %%i in (‘realdate.com /f=”hh”’) do (set timeHH=%%i)if %timeHH% EQU 18 (“<GSS path>\GeoSatSignal.exe” <MSG data path>\HRIT\%today%1800-msg-ch01.jpg -j37 -colour:<public path>\MSG_VISIBLE.jpg -min“<GSS path>\GeoSatSignal.exe” <MSG data path>\HRIT\%today%1800-msg-ch01.jpg -j5 -remap:<public path>\MSG_REMAP.jpg -min)rem *** create hourly IR MSG“<GSS path>\GeoSatSignal.exe” <MSG data path>\HRIT\*-msg-ch07.jpg -j39 -remap:<private path>\\MSG_THERMAL_1H.jpg -min“<GSS path>\GeoSatSignal.exe” <MSG data path>\HRIT\*-msg-ch07.jpg -j47 -remap:<private path>\MSG_NW_CH7_1H.jpg -minrem *** create Vis MSG between 6-17 GMT hours
for /f %%i in (‘realdate.com /f=”hh”’) do (set timeHH=%%i)if %timeHH% GEQ 06 (if %timeHH% LEQ 17 (“<GSS path>\GeoSatSignal.exe” <MSG data path>\HRIT\*-msg-ch01.jpg -j40 -remap:<private path>\MSG_REMAP_1H.jpg -min“<GSS path>\GeoSatSignal.exe” <MSG data path>\HRIT\*-msg-ch01.jpg -j35 -colour:<private path>\MSG_VISIBLE_1H.jpg -min))rem *** files upload“<ftp path>\FTP Voyager\FTPVoyager.exe” host=<ftp host> user=<user> pass=<password> remote=<remote folder> local=<local folder>
autoquit=1 autosync=1 syncoptions=2334 maxthreads=2 –nosplash
exit
Figure 4 - The complete batch file (the line numbers are not part of the file and are provided only for reference from the text)

The batch procedure ends with files uploading (line 35). Obviously, in respect of
my EUMETSAT licensed data policy, licensed images are not available for public
viewing.
FtpVoyager is a licensed ftp client which you can download fromwww.ftpvoyager.com

I prefer using this client instead of native ftp because of certain features. You cansynchronise folders (allowing you to mirror files and folders between a local PC
and a remote server) and limit bandwidth. For example, I have a 256 kb/s upload
ADSL, so use two sessions with approximately 100 kb/s (13 kByte/s) each to leaveme around 50 kb/s available for email etc.
The syntax I use in line 35 of my batch file means ‘upload modified files, two at thesame time, to the remote folder from my local folder’, and is controlled by the
options ‘syncoptions=2334’ and ‘maxthreads=2’. Note that this is a long line which
wraps around over two text lines.
Option ‘syncoptions=<value>’ states which synchronisation has to be made and<value> is the sum (0+2+4+8+16+256+2048 = 2334 ) of selected parameters froma table listed in the program’s on-line help. The option ‘maxthreads=2’ means ‘send
two files at same time’. The bandwith for each upload is set in the generalconfiguration screen of the client (figure 3).
I have similar batch files which create FSD and other files which you can view inthe public area of my web site
http://www.giuseppecico.eu

by selecting ‘viewing Earth from space’.

24

www.geo-web.org.uk

December 2007

Group for Earth Observation

GEO Quarterly No 16

Les Hamilton
Pick up any atlas more than 10 years old,
flip to the page showing central Asia andhome in on the border between Kazakhstan
and Uzbekistan; straddling it is thecharacteristic ‘inkblot’ outline of the Aral
Sea. But a glance at any recent weather
satellite image shows a very different
scene. As recently as 1960 the Aral was theworld’s fourth largest lake boasting asurface area of 60 000 km2. But in what is
now widely considered to be the greatest
ecological disaster of modern times, theAral had, by 2004, shrunk by anastonishing 70% to under 18 000 km2 andits surface fallen from 53 metres above sea
level to just 36 m a.s.l. Placed inperspective, this is equivalent to completely
draining the Great Lakes Erie and Ontario
in North America.
The two satellite views reproduced heregraphically illustrate the magnitude of thechanges that have taken place as recently
as the past decade alone. Figure 1 is a 1996
NOAA-14 image showing that the Aral had
already divided into two separate bodies ofwater, the Small Aral Sea and the Large
Aral Sea. In figure 2, a Metop-A image
acquired in August 2007, the recession of
the Aral shoreline, particularly in its larger
southern basin, is starkly revealed.

Figure 1 - NOAA 14 at 09:32 UT on June 3, 1996
Image: NOAA CLASS Archive (http://www.class.noaa.gov)

By way of illustration, the city of Aralsk
stood on the northern shore of the Aral Sea
as recently as 1970 (figure 4). Three
decades later, the water level had fallen byover 16 metres and the sea had recededalmost 100 kilometres from the former
fishing port. Today, numerous fishing boats
lie rusting on the exposed bed of the formersea (figure 5), shipyards where thesevessels used to be built stand empty andthe town's fish processing plant, once thelargest in the former Soviet Union, hasbeen abandoned.
Geographical Context
Millions of years ago, the region thatnowadays comprises northwestern
Uzbekistan and southern Kazakhstan wasa large inland sea. Over the millennia thisdried out, leaving behind broad plains ofhighly saline soil and the body of waterthat we now call the Aral Sea. Located in a
low-lying near-desert region in the centreof the world's largest landmass, the Aralbasin experiences a continental climate
where summer temperatures can exceed

Figure 2 - Metop-A at 13:07 UT on August 23, 2007
Image: NOAA CLASS Archive (http://www.class.noaa.gov)

www.geo-web.org.uk

25

GEO Quarterly No 16

Group for Earth Observation

December 2007

Figure 3 - The Caspian Sea and Aral Sea basin - Metop-A image from Eric Dean (© EUMETSAT 2007)

40°C while those in winter frequently
plummet to -20°C and below. Since
evaporation rates are high, the Aral’swater balance depends almost entirely on
the inflow from central Asia’s two majorrivers, the 2,580 km long Amu Darya
which originates in the snow-capped
Pamir Mountains and the 2,220 km Syr
Darya which develops from tributaries
rising in the snowy Tien Shan ranges ofeast Kyrgistan. Eric Dean’s splendid
Metop-A image (figure 3) details thecourses of both rivers.

Figure 4 - The Aral sea and its feeder rivers

The Situation 50 Years Ago
The word ‘Aral’ means ‘island’ in the
Kazakh language, a reference to the factthat the sea used to be dotted by morethan a thousand small islands. Half acentury ago the Aral was a brackish lakewith a salinity level of just 10 grams per
litre, less than one third of that typicallypresent in the planet’s oceans. This
supported a thriving fishing industry,
principally of freshwater species. As

26recently as 1960, half the combined
annual discharge from the two rivers,
some 56 cubic kilometres of fresh water,
was reaching the Aral But developments
during the sixties and seventies were to
radically change that.
The Aral Sea Plan
Irrigation of the fertile lands between the
Amu Darya and the Syr Darya had beenpractised for many centuries, yet the Aral
Sea had endured in a delicate balancewith the needs of mankind. During theearly 1960s, the Soviet Union undertooka major irrigation project, the ‘Aral Sea
Plan’ designed to convert thesurrounding plains into the nation’s
major crop producing region, with theemphasis on cereals, rice and inparticular, cotton. But due to the arid
climate of the region, almost 90% of
cultivated land has to be irrigated.
A series of dams was constructed along
the lengths of both rivers, creating
94 reservoirs from which a 40 000 km
network of canals could distribute water
to the surrounding lowlands. By 1990 thearea of cultivated land had more thandoubled in area to 7.5 million hectares.
Cotton production in particular soaredand Uzbekistan became one of theworld’s major cotton producers.
But this agricultural success came at aheavy cost to the Aral Sea itself. As
abstraction continued to escalate theannual inflow of fresh water into the Aral
dropped below one tenth of its former
value. Indeed, during some summers,
inflow would dry up altogether as theriver’s final trickles evaporated before
even reaching the sea's shoreline.

www.geo-web.org.uk

Finally, the Amu Darya ceased supplying
the Aral altogether, leaving thediminished Syr Darya with theimpossible task of supplying the entire
Aral basin with water. Figure 4 shows
the Aral Sea coastline as it was pre-1960
with the remnant 2004 sea shaded. The
Aral Sea had by now lost 80% of its
volume in 30 years and salinity had
increased fourfold.
Disaster Escalates
Although the reduced volume of riverwater debouching into the Aral wascertainly a major player in the disasterthat had befallen it, it was by no means
the sole culprit. What water did succeed
in reaching the Aral was becoming
increasingly polluted by the chemicalfertilisers and pesticides needed tosustain the crops, not to mention theinevitable industrial waste from theregion. As the sea continued to shrink
these pollutants became ever moreconcentrated, rendering the environment
hostile to all its freshwater life. Many ofthe endemic plant and animal species
died out and the local fishing industry
collapsed completely. Commercial fishing

Figure 5a - Derelict Ships in the Aral Sea
Photo: David Swanson (IRIN)

December 2007

came to an end in 1982 and entire fishingcommunities lost their livelihood.
In 1960, when the Aral Sea had been arich source of fish, Muynak, located on its
southern shore, had been a thriving
fishing town where over 3000 fishermen
plied their trade. In 1957, Muyank
fishermen harvested 26,000 tonnes offish, about half of the total year’s catchfrom the entire Aral Sea. Today, Muynak
finds itself in the middle of a desert andover 200 km from the nearest sea-shore.
Only rusting fishing boats sitting on aparched desert of salt scrub, sand andbroken sea shell now hint at its past
prosperity. All twenty species offreshwater fish that used to inhabit theLarge Aral Sea have become extinct,
unable to survive in the toxic, saline soupthat remains.

Figure 5b - A Derelict Ship on the Aral Sea Bed
Photo: © 2007 Buzznet Inc

As the Aral has continued to recede it
deposited thousands of tonnes of salt
laced with toxic chemicals over morethan 36,000 km2 of exposed sea bed.
When the winds blow, these materials
are whipped from the arid surface,carried off as dust clouds, and depositedover thousands of square kilometers ofarable land.
Major dust storms rage on more than 90days annually, redepositing most of thesematerials within a 300 km radius; but
some travels thousands of kilometres anddust from the Aral basin has been
detected as far away as Belarus, over
1,000 kilometres to the northwest.
Currently, winds carry an
incredible 200,000 tonnes ofsalt and sand away from theAral Sea region every day.
It has been estimated that every square
kilometre of land receives over 40 tonnesof this dust annually, poisoning the soil,
reducing the area available for
agriculture, destroying pastures, andcreating a shortage of forage forlivestock. The dust has also seriously
compromised the health of the local
population amongst whom anaemia,
allergies and cancer have all become
more prevalent while tuberculosis hasreached epidemic proportions. The city ofAralsk suffers one of the highest infantmortality rates in the world.

Group for Earth Observation

Pesticides and fertilisers have also foundtheir way into water and irrigation
channels, poisoning the food and drinking
water of some five million people. In
some localities the water is socontaminated with fertilisers andchemicals that it is no longer suitable for
either human consumption or
agriculture. In general, drinking water
throughout the region now contains fourtimes more salt than the recommended
WHO maximum, leading to increases inkidney disease, diarrhoea and otherserious ailments. It is scarcely surprisingthat, over the past three decades, mean
life expectancy has fallen from 64 years
to just 51 years.
In former times the waters of the Aral
Sea had provided a moderating influenceon the climate of its hinterland,
mitigating the effect of cold Siberian
winters, providing a degree of coolingagainst the summer heat andhumidifying the atmosphere. But withdecreased surface area the climate of its
surrounding region has become more
continental: summers are shorter, hotter
and almost rainless; winters are longer
and relatively free from snow. Together,
these effects have shortened the growing
season to an average of just 170 days ayear, leading to an inevitable reduction
in crop yields.
Thus far the ecological disaster in theAral basin has displaced more than
100,000 people and affected the health of
more than five million throughout theregion.
Recovery
It seems improbable that the Aral Sea
will ever fully recover, not least because
Russia and Uzbekistan are moreinterested in exploiting the southern
Large Aral Sea for deposits of gas and oil
rather than trying to reverse theenvironmental damage. Recent estimatessuggest that over two billion tons ofcrude oil and two trillion cubic meters ofnatural gas lie below the sea bed, nearly
double the reserves estimated for the
Caspian Sea's Russian continental
shelf [2].
But it is a different matter for the Small
Aral Sea to the north where, following
the collapse of the Soviet Union, local
initiatives raised money to build a dam toprevent its waters draining into thesouthern basin. The first dam, little morethan a barrier of sand, was built 1992
and lasted 9 months until rising sea
levels washed it away. A replacementdyke 14 km long by 30 metres wide was
erected in 1996 but was badly breachedduring a storm in 1999 when a 3-km
section was washed away.
Nevertheless, the dam had alreadyproved its worth by stabilising the levelof the Small Aral and reducing its
salinity by half (during which time thewww.geo-web.org.uk

GEO Quarterly No 16

Large Aral fell a further 20 metres), andin 2001 a US$85 million initiative jointly
financed between the Kazakh
government and the World Bank
embarked on the ‘Syr Darya Control andNorthern Aral Sea’ project. This beganwith the reconstruction of nearly 100 kmof canals, sluices, and waterworks on the
Syr Darya river. The old Soviet sluicegates had become badly rusted and were
full of holes while most of the original
canals, which had been poorly
constructed, lacked a waterproof concrete
lining. At least 40% of the waters
extracted from the Syr Darya were
simply being lost through leakage—if not
more!. The remediation effort brought
about a rapid improvement—doubling
the flow in the river. Not only were thewaters of the Syr Darya now irrigating
the fields along its banks much more
efficiently: it was at last providing an
increased inflow of fresh water to the
Small Aral Sea.
The next stage of the effort, completed inAugust 2005, was the construction of the
Kokaral dam [3], physically separating
the two parts of the Aral Sea. Althoughseparation of the Aral had occurred
naturally in 1989, water had continued tospill into the Large Aral via the narrow
Berg Strait that linked the two regions of
the sea. The new dam, this time
constructed from a sand and limestone
fill topped by a layer of concrete,effectively sealed this channel, trapping
all the increased flow from the Syr Darya
within the Small Aral Sea. The dam,more than 13 kilometers long with afoundation 300 metres wide, averages
four metres in height (10 metres above
the former channel) and is eight metreswide at its top.

Figure 6 - The Kokaral Dam
Photo:Brigitte Brefort / World Bank

It had been anticipated that it would be
at least five years before the dam made asignificant impact on the level of the
Small Aral Sea but, as early as mid 2006,
its effect had hugely exceeded
expectations. The sea surface had risen
four metres and increased in area by athird while salinity had dropped by morethan 50%. Already, freshwater fish havestarted to return from the rivers andfishermen are working the waters again
for the first time in a generation. It isplanned to reintroduce sturgeon to thesea during late 2007 while some 30 000
fish native to the Aral are currently

27

GEO Quarterly No 16

Group for Earth Observation

Figure 7: MODIS Images from the NASA Terra satellite showing the Small Aral Sea on June 14, 2001
Images: MODIS Rapid response Team at NASA/GSFC

Figure 8: MODIS Images from the NASA Terra satellite showing the Small Aral Sea on May 9, 2007
Images: MODIS Rapid response Team at NASA/GSFC

28

www.geo-web.org.uk

December 2007

December 2007

Group for Earth Observation

GEO Quarterly No 16

being reared in hatcheries for a planned release into the sea
during 2009. Additional remedial work on the Syr Darya delta
is aimed at restoring fishing lakes which will be used as anadditional resource for rearing fish for restocking the Aral.
The coastline is already beginning to return to some of thestranded fishing villages while Aralsk, once almost 100 km fromthe sea, now stands just 12 km from the current shoreline.
Though the port still stands some distance from the sea it isalready showing signs of revival and a new fish-processing plant
handled 2000 tons of fish during 2006.
As of February 2007 [5], the northern sea’s area has expanded
by a third and water levels had risen over ten metres. Should
this progress be maintained then prospects for rehabilitatingfishing communities and restoring sustainability are highly
promising.
Figures 7 and 8, MODIS images from NASA’s Terra satellite,
provide dramatic evidence of this progress, particularly in thenorth-eastern bay south of Aralsk. The lower image shows theline of the Kokaral Dam is an unmistakable sharp, angled line
crossing the Berg Strait while the lower left-hand portion of theimage is partly obscured by one of the frequent dust storms.
The next phase of the project, which may involve increasing theheight of the dam itself, could bring water all the way back to
Aralsk. Work could begin in 2009, but the design of the project
and availability of all-important finance will be key indetermining whether the Small Aral Sea can indeed become
fully restored to its former depth and area.
A Possible Plan for Complete Recovery
When plans for the original canal system for the Syr Darya andAmu Darya rivers was drawn up it was already foreseen that
the Aral Sea would be starved of water. It was originallyintended that further canals could be built specifically toaddress this problem by diverting some of the flow from two
major rivers outwith the Aral basin, the Volga and Ob, into theAral Sea. Sadly, the cost proved prohibitive at the time and theplan was shelved. But as the Aral Sea disaster continues toescalate, particularly in the south of the basin, many prominent
Russian political leaders and scientists are once more discussing
this option to restore the Aral.
The river Volga flows into the Caspian Sea and has a flow rate
three times that of the Syr Darya. Moreover, the Caspian Sea
has risen 2.5 metres during the past three decades and coastal
cities are at risk of flooding. Diverting perhaps 10% of theVolga’s flow into the Aral basin would therefore be doubly
advantageous. The plan would require the construction of acanal 800 km in length, 200 metres wide and five metres deep
at a projected cost of US$8Bn. This would drain in asouthwesterly direction towards the Aral basin and require very
little in the way of assisted pumping because much of theintervening terrain is relatively low-lying. There are no major
physical barriers to be overcome and the the flow of water could
largely be maintained under the influence of gravity alone. The
MODIS image on the inside back cover clearly shows the Volga
entering the Caspian Sea.
The Ob is an even larger river, which flows north throughalready saturated terrain towards the Arctic Ocean. To carry its
waters towards the Aral would require a canal of similar crosssection but three times the length, running from the confluenceof the Ob with the Irtysh river. This canal would have tonegotiate the Turgay Plateau in northwest Kazakhstan, an
upland region with an average elevation of about 300 metres.
This plateau is bisected north-to-south by the 600 km long
Turgay Depression, a former glacial meltwater channel
containing a chain of lakes. This channel rises to a maximum
elevation of 126 metres and would provide the line of least
resistance. Nevertheless, large pumping stations requiring
2.5 GW of power would be needed to maintain the flow of water.
Although the cost is estimated at US$22Bn, this would almost

Figure 9
Possible courses for the projected canals linking
the Volga and Ob rivers with the Aral Sea

certainly be recouped several times over by the region’s
eventual prosperity.
Such projects are eminently feasible and these canals would be
similar in scale to existing modern systems already in existencein the syr Darya/Amu Darya catchment area and elsewhere.
Once these projected canals were operational, the Aral Sea
could be completely refilled in around 20 years, major fisheries
could be resurrected and there would be sufficient irrigationwater to turn the surrounding region into one of thebreadbaskets of the planet. The relief map shown in figure 9
has been mapped from the NOAA/NGDC one kilometre GLOBE
dataset using proprietary software. The possible routes of thesetwo canals are superimposed on it.
Acknowledgement
Thanks to Eric Dean for useful discussions during the
preparation of this article.
Further Reading
The information contained in this article has been gleaned fromdozens of sources on the Internet. Readers can learn more about
the Aral Sea in the following references.
References
1 Aral Sea History
http://www.orexca.com/aral_sea.shtml
2 The Aral Sea’s Buried Treasure
http://www.mnweekly.ru/business/20070614/55257968.html
3 Kazakhstan News Bulletin
http://www.kazakhembus.com/030306.html
4 Release the Rivers
http://www.ecoworld.com/home/articles2.cfm?tid=354
5 UNESCO Water Portal Weekly Update No.175: The Aral Sea
http://www.unesco.org/water/news/newsletter/175.shtml

www.geo-web.org.uk

29

GEO Quarterly No 16

Group for Earth Observation

December 2007

Mike Stevens (G4CFZ)
My previous article certainly seems to have produced a lot ofinterest, especially amongst our leading exponents. I will admit thatthey do have points of interest but they must appreciate that there
are times when we—as amateurs—will experiment with different
methods to solve a problem. They must respect the fact that insome cases alternative solutions may work perfectly well.
My system has now been running since early February this year
without as much as a hiccup. It is normally active for approximately
8 to 10 hours per day, every day, except when there are storms
around when I will run it for longer. I do not run the system 24/7,
mainly because I am trying to reduce my carbon footprint at thislocation.
Memory Upgrade
Since the last article [1] I have upgraded the memory in the desktop
PC to 1.5 GB of RAM which has made a considerable difference toits operation. Everything is much smarter and quicker; in fact
EUMETCast is running in the back ground as I write this article.
The external Hard-drive is a Lacie 250GB/HDD USB 2.0, Porsche
running at 7200 rpm with an NTFS file system. It was
manufactured in the USA and has now been operating on mysystem for just over two and a half years with no problems at all.

expect we shall find the same with the new Vista systems. I for one
will wait until the dust settles before going down that road.
Reliability
So, in conclusion, is my system reliable? Yes it is! Nothing has
happened to make me say otherwise—there are no hard-drive orfile issues, nor do I have problems with files filling up or having toreboot during operation as some people report. Sorting out the‘recv-channels.ini’ file should put that right. Also, there is no severe
overheating of the USB hard drive at all. It runs at a reasonabletemperature for an 8 to 10 hour session. It has been suggested
that the external hard drive could possibly fail; well so could theinternal one. And as for being a poorer solution, I can only say thattime will tell. If a failure does occur, surely it will be easier toreplace an external drive. As long as you keep all the files backed
up this would not be a complete disaster.
Final Thoughts
Is a USB hard drive a viable alternative to RAMdisk? That is the
big question. I believe it is but others must decide for themselves.
If you are unable to use RAMdisk you could purchase one of thecommercially available RAM Drives: this would of course besupported but cost might prove prohibitive.
You can use the excellent TQChanSel software from Rob Alblas [2],which enables you to decide which transmissions you wish toreceive, to avoid filling up your hard drive with unnecessary files.
Nice one Rob!
So the final word is that it works for me and as long as it does so I
shall continue to receive the excellent pictures being transmitted by
EUMETCast.

Hurricane Dean, captured by the author’s EUMETCast system
Image © EUMETSAT 2007

The system is still as laid out as in the previous article and is
producing excellent pictures to this day. I occasionally have acouple of chunks missing but nothing too serious. The messages inMetop Manager show that some orbits do have missing chunks,
most of which seem to appear over the sea or on the dark side of
the planet; but the main areas of vision over mainland Europe, theMiddle East and the Americas are mostly intact with full runs ofdata chunks.
Software
The other item I have changed is the Tellicast software, revertingback to version 4.0 as version 5.0 gave me a few problems though,given time, I am sure it can be sorted out. I have come to theconclusion that, on certain PCs, Windows XP works fine while onothers it can be a bit problematic, depending on what othersoftware you are trying to use: ARSoft RAMdisk seems to be oneof these, working better on some PCs than others, especially underWindows 2000. I have been informed that ARSoft RAM Disk was
not designed for Windows XP, so therein lies a problem.
I had a similar problem when trying to load some Amateur Radio
software on my Laptop: it just would not settle in with XP and I

30

This hobby of ours is a very exciting one. We just do not knowwhat we are going to see next. With global warming now firmly
fixed in our minds and the extreme weather we have experienced
in the U.K this summer, we are all looking for the unexpected on
our screens, plus experimenting with different procedures andsoftware to see if we can get the very best from our systems. Its
something I did for most of my career in the civil service: trial anderror, the mother of invention.
One other item I should mention is that having the satellite meter incircuit with the dish could be handy should you require to
disconnect your system from the antenna due to severe electricalstorms. I do this every time a storm is in the area for safety
reasons. A friend of mine lost his satellite system due to a nearby
lightning strike.
I hope that those of you who have RAMdisk are finding everything
OK and I wish you well with it. For those of you who cannot get it
to work there are alternatives; it’s just a case of finding the one thatworks for you, so keep on trying and experimenting. If all else fails
there is plenty of help available within GEO. After all, we all had tostart some where at sometime.
I would like to thank those of you who contacted me regarding theprevious article. Your comments were appreciated.
References
1 Receive EUMETCast without a RAMDisk
Mike Stevens, GEO Q14, page 11.
2. TQChanSel - Control EUMETCast Channels
Rob Alblas, GEO Q14, page 34

www.geo-web.org.uk

December 2007

Group for Earth Observation

GEO Quarterly No 16

Metop-A imaged this Atlantic storm south of Greenland on August 3, 2007
Image processed by Mike Stevens, © EUMETSAT 2007www.geo-web.org.uk

31

GEO Quarterly No 16

Group for Earth Observation

December 2007

Peter Wakelin

In late 1997, many hobbyists were busy modifying their HRPT
equipment to receive the multi-spectral imagery from SeaWiFS
following the announcement that during the testing and checkout phase, which was expected to last for 90 days, the data would
be unencrypted. Despite the approaching winter and falling lightlevels, many amateurs in temperate northern latitudes, andelsewhere, did receive excellent imagery for several weeks before
encryption began. I suspect the amateur community largely
forgot about SeaWiFS following encryption but it continues inreasonably good health and has amassed a huge amount ofvaluable data as it begins its second decade of service.
Background
SeaWiFS (Sea-viewing Wide Field-of-view Sensor) was designed
to significantly improve on the historical proof-of-concept
successes of its predecessor, the Coastal Zone Color Scanner(CZCS) which was launched on the Nimbus-7 weather researchsatellite in 1978 and operated for eight years.
SeaWiFS is a part of NASA’s Mission to Planet Earth and was
one of NASA’s early attempts at a commercial partnership.
Orbital Sciences Corporation (now called GeoEye) won the fixedprice contract. SeaWiFS is the only instrument on the SeaStar
satellite (later renamed OrbView-2) and was launched into a
low orbit by a Pegasus XL vehicle dropped from an aircraft off
the coast of California on August 1, 1997. The spacecraft’s
thrusters later raised it to the operational 705 km near-noonsun- synchronous orbit.
The Instrument
There are four sensors for each of the eight spectral bands
whose centre wavelengths range between 412 and 865
nanometres in the visible and near-infrared parts of thespectrum. Band 1, at the violet end of the spectrum, is best
suited to detect dissolved organic matter whereas bands 2, 3
and 4 in the blue and blue-green zone are used for chlorophyll
and pigment absorption. Band 5 is primarily for pigments,
optical properties and sediments. The longer red and infrared
bands are used mainly to determine atmospheric corrections but
the infrared, in particular, is ideal for detecting aerosols. The
sensors are mounted on a tilt mechanism permitting a ±20°
offset to avoid sunglint from water surfaces. On May 31, 1998,
an image was captured at Dundee University in Scotland, whichshowed a discontinuity caused by activation of this tilt
mechanism. As the instrument operates largely in the visible
part of the spectrum, it is switched off when the solar zenith
angle is greater than 73° to conserve power.
Examples of applications include:• providing information on the global cycles of carbon,
oxygen and nitrogen into and out of the oceans• helping scientists determine the contributions ofphytoplankton in reducing global carbon dioxide• showing the location of pollutants• providing information on harmful organisms (e.g. the ‘redtides’ of the Karenia brevis species of phytoplankton)• showing scientists where ocean currents provide plant
nutrients• providing information on the location of fish populations
for the commercial fishing industry

32

Figure 1 - The sensor tilt mechanism was activated during this passCredit: Dundee University• knowledge of ocean currents for the shipping industry• knowledge of ocean eddies and jets for oil drilling
Local area coverage data are transmitted in real time in the
HRPT format on 1702.56 MHz whilst global data are stored on
board and dumped to the Wallops Flight Facility on 2272.5 MHz
as the spacecraft passes overhead.
More technical data on the SeaWiFS instrument and its uses
can be found on the Internet; typing the keyword ‘SeaWiFS’ into
any search engine will reveal many sources of information andshow how widely the data have been used in research projects
throughout the world.
The Future
The successor to SeaWiFS is the MODIS (Moderate resolution
Imaging Spectroradiometer) which incorporates many more
spectral bands but the wavelengths used in SeaWiFS are also

www.geo-web.org.uk

December 2007

Group for Earth Observation

Figure 2 - Currents converge off Southern Africa

GEO Quarterly No 16

Figure 3 - Chlorophyll in the Gulf of California

Figure 4 - A nutrient-rich upwelling off the coast of California

www.geo-web.org.uk

33

GEO Quarterly No 16

Group for Earth Observation

December 2007

utilised in MODIS so that direct comparisons can be made.
Although MODIS is now flying aboard several satellites, NASAare continuing to operate SeaWiFS nearly six years beyond its
designed lifetime as the returned data are valuable and theoperating costs are minimal. Deteriorating batteries willprobably end the mission soon but for a low-cost, small satellite,
the SeaWiFS mission has been a resounding success.

Figure 6 -High turbidity is evident in the Sea of Azov
compared with the Black Sea

run-off can lead to the harmful blooms knows as ‘red tides’
which release toxins into the water that can poison molluscs
and fish.

Figure 5 -The red and infrared bands on SeaWiFS readily
detect these Namibian dust plumes but do strange
things to the clouds in the lower leftSome SeaWiFS False-Colour Images
Figure 2 shows interesting features off the coast of South Africa
on March 28, 1999. Here the warm Agulhas current of thewestern Indian Ocean converges with the cold Benguela current
that originates off Antarctica and moves up the west coast ofSouth Africa. The large, straight convergence zone is marked byhigh-productivity waters (the higher chlorophyll concentrations
appear as red, orange and yellow in this false-colour image)where the Agulhas current is forced to make a sharp turn to thesouth. The strong dynamics of the area can be seen in thepatterns of eddies near the convergence zone. Strong upwellingin the Benguela current brings nutrient-rich water to thesurface where phytoplankton multiply rapidly leading to highchlorophyll levels. Marine life is rich and varied in this area.
Figure 3 shows a chlorophyll-rich area off the Mexican coast in
the Sea of Cortez (also known as the Gulf of California) whichscientists from Stanford University have shown to be caused byfertiliser run-off from the intensively farmed Yaqui Valley. Twocrops of irrigated wheat are grown in an area in excess of 2,000
square kilometres each year requiring large quantities ofartificial fertilisers. Excess water from irrigation carries
nitrogen and other nutrients into the river and eventually to thesea resulting in greatly increased algal (phytoplankton) growth.
Researchers at Stanford University, led by Pamela Matson,
examined SeaWiFS images over a 5-year period and were able
to show that these algal blooms consistently appeared withindays of irrigation events. Although such blooms occur naturally,
scientists have long suspected that blooms fuelled by fertiliser

34

Figure 4 is part of a SeaWiFS image taken on 6 October, 2002
as the spacecraft was southbound off the coast of California.
The southward moving shallow current off the Californian coast
tends to move away from the coast in response to the Coriolis
force resulting from the Earth’s rotation. In so doing, cold,
nutrient-rich water wells up from below to replace it. This
upwelling fuels the growth of phytoplankton which, along withlarger seaweeds, in turn nourish the incredible diversity ofcreatures found along the Californian coast. SeaWiFS can easily‘see’ this upwelling and associated ocean turbulence by locating
the chlorophyll-bearing phytoplankton. High chlorophyll levels
are shown as red and orange in this false-colour image whereas
land and clouds are depicted close to their natural colours.
Acknowledgement
Images are courtesy the NASA SeaWiFS team unless stated otherwise.

Figure 7 -www.geo-web.org.uk

This SeaWiFS view of the northeastern U.S. shows
several eddies along the north edge of the Gulf Stream

35

GEO Quarterly No 16

Group for Earth Observation

December 2007

Arne van Belle
Like many GEO Quarterly readers, I followed the forest fires in
Greece and elsewhere with interest on my EUMETCast images. It
is often possible to highlight specific features by carefulmanipulation of the colour channels in David Taylor’s HRPT Reader
program. I hope readers will find the selection of images presented
below of interest.

Metop-A image from August 25, 2007, processed in R3G2B1 mode, showing
huge smoke trails from the wildfires in Greece.

This NOAA18 image from August 25, 2007shows the Greek fires at their peak
and was processed using HRPT Reader / FalseColour-FireDetection mode

Image: via EPS-Global on EUMETCast, © EUMETSAT 2007

Image received over EARS-AVHRR, © Eumetcast 2007

The two images above come from the same NOAA-18 image dating from
August 29, 2007. The clip on the left, processed using HRPT Reader’s falsecolour/fire-detection mode, shows up the many small fires raging in Algeria.
The right-hand clip shows that most of the Greek fires have at last beensuccessfully extinguished. Processing in HRPT Reader used R3iG2B1 mode
(where Red = channel-3 inverse, Green = channel-2 and Blue = channel-1).

NOAA18 images using channel 3B during daylight passes are particularly well
suited for fire detection. Clearly visible are the huge scorched areas (darkred), while the still active fires colour a fierce orange/red. As you can see,other countries like Bosnia and Bulgaria were also hit by large fires.

36

www.geo-web.org.uk

Image received over EARS-AVHRR, © Eumetcast 2007

GEO Quarterly No 16

Group for Earth Observation

This article describes new software called DownloadPrograms thatchecks various Internet sites for new versions of weather satellite
related software and, if there is a newer version than the one
installed on your own computer, automatically downloads it.
Motive and designDavid Taylor [1] regularly brings out new versions of his programs.
If there are new developments, or there is a beta version, several
new updates of a program can appear during a single same day. If
you have a large number of programs running on your system it
can be difficult to remember which versions are installed and which
ones you still have to download. If you are lazy as me that’s a
problem! So I grabbed my keyboard and keyed in this program.
The design is as follows.

David’s website contains a version file containing all the program
names with associated version numbers. These are read in andstored by DownloadPrograms, then compared with a similar local
file (on your own PC) containing the names of all the programs you
have downloaded from his site, with their version number.
If a newer version is available on David’s website, it isautomatically downloaded and the version number in your local fileis updated.
Once the program was working, I realised that there are several
other websites with programs for satellites; so I added additional38

December 2007

websites for Rob Alblas [2], myself [3] and Les Hamilton [4] to it.
There is not a great selection of sites (unfortunately!).
Nevertheless, anyone who has written software that they would like
added, or who has other suggestions, can email me at:
fred@vandenbosch.speedlinq.nl

How the Program Works
Download a copy of DownloadPrograms fromhttp://www.fredvandenbosch.nl/downloads.html

and unzip it into an appropriate folder.
Run DownloadPrograms.exe to display the screen shown below.
The contents of this screen are built up from the data on your PC(from the previous time DownloadPrograms was run) plus any newprograms on the various Internet sites. The latter can berecognised by the empty field in the column headed ‘Old’. The firsttime the program is started up, the ‘Old’ column is empty.
Programs that are selected, and for which new version exists, areshown in bold, so that they can be easily recognised.
The Download Folder
Here you must enter the folder where files are to be stored after
downloading. The name can be keyed in directly or you canbrowse for a suitable folder, which must already exist, using the<Find> button. Confirm the folder by means of the <Select> button.

www.geo-web.org.uk

December 2007

Group for Earth Observation

Checking Programs
For each program to be checked you must tick the box beside its
name. All ticked programs are checked, and if necessary
downloaded. Select therefore only those programs that you actuallyuse! If a new program appears, it is automatically incorporated into
the list. A new program can be recognised by the lack of a version
number in the ‘Old’ column. These must therefore, if required for
downloading, be provided with a tick.
Download Selected Programs
Check first if there are new programs and tick these if necessary. If
needed, the tick can be removed from emboldened lines if, for any
reason, you do not require that program to be downloaded. Clickon <Download selected programs> and all items where the ‘new’version number is greater than the ‘old’ one will be downloaded.
Because the ‘Old’ column is empty the first time the program is run,all ticked programs will be downloaded. If all programs arechecked, a report is given if there are updates. If this is the case, a‘Y’ in the ‘Install’ column indicates that the program concerned canbe installed. The <Close> button quits the program.
The <Version> button displays a separate screen showing version
details for DownloadPrograms as well as the date of the version
files on the various websites. The <Go to site> buttons take you
directly to the appropriate software website (this page isdetermined by the site owner). If you let the mouse hover over the
buttons the date on which the site details were last updated isshown.
Batch Operation
What I’ve described so far is the interactive use of the
DownloadPrograms. It is also possible to run this software in batch
mode, executing the program during a Windows start-up or at a
specific time via a task manager. To do so, the following steps mustbe followed:• Create a shortcut by right-clicking the mouse on
DownloadPrograms.exe and selecting ‘Make Shortcut’.
• Right-click on this new shortcut and select ‘Properties’.

GEO Quarterly No 16• In the ‘Target’ field you will see the pathname to
DownloadPrograms• Here you must add ‘-Batch’ to this path. In my case the line
under ‘Target’ becomes
C:\Program Files\POVIM\DownloadPrograms\
DownloadPrograms.exe –Batch

Now, when you click the shortcut, the program will open in batchmode with the following consequences. If there are new versions
available, the execution is the same as above: you see the screen
illustrated and the new versions can be downloaded. When there
are no new versions, the program immediately closes and thescreen is not shown.
If you wish DownloadPrograms to run automatically when you
switch on your PC, make a copy of the shortcut and place it in thestartup folder e.g. ‘C:\Document and Settings\All users\...’
If you wish to run DownloadPrograms at a specific time, place theaddress of the shortcut in a Task Manager.
Future Developments
I will be interested to receive observations and wishes for thisprogram. As a new development I am thinking of a program which
can automatically install downloaded files on one or more PC’s.
This will, hopefully, follow in the future.
Forum
There is an Internet forum where you can ask questions about myprograms
http://tech.groups.yahoo.com/group/POVIM-Software/

References
1 David Taylor, http://www.satsignal.net/
2 Rob Alblas, http://www.alblas.demon.nl/wsat/
3 Fred van den Bosch, http://www.fredvandenbosch.nl
4 Les Hamilton, http://myweb.tiscali.co.uk/wxsatellite/

Robert Moore
The default icons which reside asshortcuts on your PC’s desktop are
perfectly serviceable. However, you may
tire of the icons which the programsupplies by default, or you may prefer todistinguish between various programswith similar icons.
For my processing programs such as
ATOVSReader, GRIBViewer and
GroundMap I have always used icons
based on typical, colourful, output images
from the programs themselves. For MSG
Data Manager I used an image ofMeteosat-8 borrowed from a
EUMETSAT website. You can also create
icons from your own digital photographs.
Those of us who took photographs atUsingen now have images that can beconverted to icons using any of the many
icon-maker programs downloadable fromthe Internet. It only takes a minute toproduce an icon from an image, althoughperhaps a little longer if you need toheighten the image contrast in a graphics

MSG Receiving Antenna and Microwave Tower

The Hot Bird Uplink Antenna

package in order to make the small icon
image bolder.

Desktop and selecting ‘Properties’, you
can access the ‘Change Icon’ button andselect a new icon (don’t forget to hit‘Apply’ before leaving ‘Properties’)

Here are two as yet unassigned icons I
have created from Usingen photographs,
without any image enhancement. The left
hand icon shows the MSG receiving
antenna and the microwave tower linking
to Darmstadt while the right hand one
shows of the uplink antenna to Hot Bird.
I keep my home-made icons in an Icon
folder in ‘My Pictures’. By simply rightclicking any current shortcut on the

www.geo-web.org.uk

These icons are non-essential andentirely decorative, although I do findthem useful for quickly identifying
programs on my desktop.

The resulting icons

39

GEO Quarterly No 16

Group for Earth Observation

December 2007

Tips on Installing‘Weather Days’

RAM Disc forPeter GreenDavid made use of a large screen
attached to his laptop, so that everyonein the room had a good view of his
presentation before we finally broke forlunch.

EUMETCastRob Denton
On a recent overcast day I decided totake my first step towards
streamlining my EUMETCast station,
installing a RAM Disc and networking
with a second PC.
Following the guidelines in GEO
Quarterly and on the web, I decided totry RAM Disk for the first time. The
fact that I had put it off till now gives
some indication of how worried I wasthat this might upset my system. In
truth, I hadn’t even wanted to try it
before. Following Instructions wereobeyed to the letter, and though it was
not as difficult as I had feared, deep
down I was still thinking: ‘is thismachine going to run again?’
I waited ... and waited. Nothing! I
was tempted to simply give up and reinstall the back-up file I had made.
But I wasn’t going to let it beat methat easily. Just where had I gonewrong?
I carefully went through everything
again and checked all the possibilities.
For a start, there was no ‘.fsy’ file in
RAMDisk! I checked all the folders in‘T-Sytems’, and it was there that I
finally spotted the error.
For some reason, in the recv.ini file,
there was a hash (#) at the start of theline
linefile_database_directory=Z:\receiving

I promptly deleted the ‘#’ and, sureenough, after restarting T-systems,
the ‘.fsy’ file appeared in the
RAMDisk! Data started to flow again.
Phew!
I thought I would share this withreaders in case anyone else had thesame problem on setting up.
I can’t believe how quiet the PC isnow, and the hard disk light hardly
ever comes on. I have to keep checking
that the software is still working—but
it surely is.
Following this success, I just had tosee if I could network the 2 PCs.
Following Mark Edward’s advice in
GEO Q15, I took the plunge andeverything went perfectly, without aglitch. I'm so delighted.
Thanks to all you GEO readers forsharing advice. I have now joined the2-PC brigade and it wasn't nearly as
difficult as I originally thought itwould be.

40

Recently, I came across the UK Weather
Shop, who run courses under the banner
Weather Days; these offer participants anunderstanding and interpretation of
weather charts and the implications ofclimate change, as well as instruction insetting up a weather station.
We see images of the weather daily fromthe systems available to us, but I havealways wanted to learn more about theweather and forecasting. For £20 and atrip to Eastbourne I thought, why not?
Booking on-line by credit card was easy
was confirmed by email. A couple of days
prior to the event, Liz Bishop from theWeather Shop sent an email reminder
giving directions etc—a nice touch I
thought.
Very early on a Saturday morning I madethe trip to Eastbourne, a bit of a hike forme at some four and a half hours. I
arrived early at the marina where an
arcade of shops is situated within themarina complex. The Weather Shop does
not open until 10 am, however, so there
was no chance to look around it before
the course.
The course was held in Chart Room of
the new yacht club, very nicely appointed
and of course with great sea views.
We started with tea and coffee as thedelegates getting to know each otherinformally. Fourteen of us were there forthe day and what surprised me was themale/female mix, seven of each; normallywith the GEO Symposium it is very much
male dominated.
Following a short welcome from Weather
Shop director Alistair Barron, it was
down to business. The course waspresented by Dave Wiseman, proprietor
of Wiseweather. Dave has been involved
with just about every aspect of theweather since he joined the Met Officealmost thirty years ago. He outlined the
day for us and presented everyone withthe course schedule, notes and charts.
We started with a basic climate primer:
discussing climate types and patterns
before moving on to mapping our weather
and learning how to interpret and use
weather maps. The morning session
concluded with an introduction to thedevelopment and process of weather
systems, including the main modes ofatmospheric circulation, case studies ofdepression types and air masses and a
discussion of some ‘extreme’ weather
events and why they occurred. All thetime we had to use our notes and wereencouraged to plot our own synoptic
chart.

www.geo-web.org.uk

There are many places to eat atSovereign Harbour, from the yacht club
restaurant itself to the many cafes, pubs
and restaurants surrounding the marina.
If you were quick, there was even time
for a look around the Weather Shop.
The afternoon session covered setting up
a weather station. Dave passed aroundbasic thermometers and progressed on
the more elaborate electronic
instruments with explanations on theuses and usefulness for each.
We then covered the symbols used forplotting weather data, combining thiswith observations of cloud, temperature
and wind made from the balcony of theyacht club. The course concluded with ashort presentation on Climate Change
and forecasting for the future.
There was time throughout for questions
and discussion and I am sure we all cameaway with a better understanding of thebasics of weather and what to look for in
the sky on a daily basis.
I thought the course was good value formoney although this is a huge subject tocover. Each of the areas that we exploredwould benefit from much more detail andyou could spend a day at least on each ofthem. If anything, they tried to pack too
much into the day. This is definitely acase of less is more.
Next year, the Weather Shop are hoping
to take their ‘Weather Days’ on the roadand, if there is sufficient interest, makethem more specialised; so if you would
like to have a ‘Weather Day’ close to you,and would like it to cover areas of specificinterest to yourself, then an e-mail would
not go amiss.
At the end of the day there was sufficient
time for a leisurely look around theWeather Shop. This place has the lot!
From a weather wristwatch to the latest
electronic weather station from Davies;
from a hand-held anemometer tobeautiful hand made barometers; even astunning Campbell Stokes Sunshine
Recorder. A large selection of books andcharts are also available.
The staff will even gift wrap these items
for you should you wish to give someonethat special present (or even get someone
to buy you what you really want for
Christmas).
References•

http://www.ukweathershop.co.uk/index.html•

http://www.ukweathershop.co.uk/acatalog/
weather_days.html (weather days)•

http://www.wiseweather.co.uk/

December 2007

Group for Earth Observation

GEO Quarterly No 16

Douglas Deans - dsdeans@tiscali.co.uk

There’s something of an unusual
introduction to my column this quarter, as I
would like to involve the membership in
shaping the future of Software Showcase. I
have been reviewing software andproviding a CD library for GEO now forsome three and half years. In that time,and despite the increasing use of theInternet and in particular the huge rise in
fast broadband take-up, well over 200 CDs
have been dispatched following 15
quarterly publications. Although the CDs
are provided basically at cost and are
inexpensive, this is nevertheless quite asurprising statistic given the immediacy andzero cost of the alternative Internet option.
However, and more importantly, there
has so far this year only been one
request for a CD. Clearly the Internet
is now the favoured and mostefficient route for obtaining software.
I have always dispatched CDs on thesame day as the order was received
but I cannot compete with the few
minutes required to download and its
zero cost.
My own opinion is that it is time to move on
and to seriously consider the need to keepa CD library, the updating of whichconstitutes the majority of my workload. It
also uses valuable copy space which could
perhaps be better used on other topics.
For this publication I will retain the status
quo but I would very much welcome some
input from the membership. Please feel
free to contact me directly at the above
e-mail address, although it might perhaps
be better to use a public forum so thatpeople's views can be seen and debated.
Possible public forums are the GEO group,
http://tech.groups.yahoo.com/
group/GEO-Subscribers

or you might even consider a letter to the
Editor of the Quarterly—I would prefer not
to work on the basis of ‘nothing heardmeans the membership agree’.
So please, set apathy aside and make apositive contribution ….. it is after all yourorganisation and your magazine. I will try
and summarise the members' input in mycolumn for the next issue.
In addition, if the library is to terminate, doreaders feel that the column should
continue highlighting upgrades or new
software when the writer manages to spot
it! There is still shareware about but,increasingly, it is a trial followed by apayment. Of course, if there is no library,then this is not so important, as a futurecolumn need only identify the new or
upgraded software and provide an Internet
source for more information anddownloading. Again your views would bemuch appreciated.
I would also like to advise members that I
have removed the program 'Splitter andMerger v 4.0' from CD2. I have been
unable to trace this since the Internet URL

vanished. There is a myriad of splitter andmerger programs available, many for free,some for a limited trial but most very
inexpensive. Just try putting Splitter andMerger into a search engine. Under thecircumstances there seems little point on
picking one at random for the CD as eventhose still with 56k modem capability will beable to download such programs in little
time.

All D avi d Taylor's weather satelli te programs and li brari es, i ncludi ng the current releases of WXtrack,
GS1 Satsignal, HRPT Reader, GeoSatsignal, GroundMap, RX2 PassControl and many other program extras.
This disc also contains a large quantity of sample files, many of high-resolution data, for use with these
programs.
AVHRR Manager
Processes and manages the files for HRPT via EUMETCastv 1.3.8
GeoSatSignal

Manipulates Geostationary weather satellite images

GRIB Viewer

Viewer for GRIB format files

v 6.1.0
v 2.1.4

GroundMap

Rescales satellite images

v 2.0.6

HRPT Reader

Converts raw HRPT data files into images

v 2.7.0

Kepler Manager

Organises files of 2-line element data

v 1.2.8

Metop Manager

Processes and manages AVHRR files from Metop satellites

v 1.1.4

MSG Animator

Automatic animation of MSG images following reception

v 2.5.8
v 2.5.8

MSG Data Manager

Processes and manages MSG data files

RX2 PassControl

Computer control program for the RX2 receiverv 3.1.0

SatSignal

Creates images from wave files

v 5.0.6

WXtrack

Satellite Tracking Programv 3.6.6

A wi de range of software for all aspects of weather satelli te recepti on, i ncludi ng tracki ng, recei vi ng,
GS2 monitoring and image manipulation. Content is detailed below but many other extras are provided. Titles
correspond with folder names. * implies a DOS program.
Collection D02
Recall (wave file recorder), Palette (modifies Wxsat colour palettes).
Scanner recorder v 1.8 (wave file recorder), *NOAA95/*FENG99 (software
Collection D03
for the NOAA 95 HRPT project)
Wxsat (wave file recorder/decoder), Satmon (wave file
Collection D04
v 2.59recorder).
AGSatTrack
Satellite tracking programv 1.33
APTDecoder

Program for capturing APT audio and processing images

CirkitDocuments for the Cirkit Wxsat receiver and the UOSat receiver (PDF)

v 2.0.4.76

Element Manager

2-line element manager

Footprint

Satellite tracking programv 1.59v 2.24

Irfan View

Image/slideshow viewer

v 3.80v 1.40 pre

JVcomm32

Evaluation version (APT/FAX/SSTV decoder)Macintosh kepler editor

Edits verbose AMSAT format elements. Mac OS X and OS9 only.

NeoPaint

Image processing program (30 day evaluation)

v 4.60

OrbitronSatellite Tracking Programv 3.70

Paintshop Pro

Image processing program (30-day evaluation)

PhotoFiltre

Image retouching program with many extras

v 6.2.7

Satscape

Satellite tracker and wave file recorder

v 2.02

Space-Track TLE Retriever Generates TLE files in 'Celestrak' style from'Space Track' data sets
Xrit2Pic

Processes MSG and Metop data

WXtoImg

WAV file recorder/decoder program with many options.

v 2007.03
v 2.7.3

3DEM Package for 3D Terrain Visualisation
GS3 This CD includes the full set of GLOBE Tiles to allow you to produce excellent images and flybys from
HRPT inages. Also included is a selection of Mars MOLA files, sample images and helpful guides by Ed
Murashie.
Image CD
GS4 A wide selection of high-resolution remote images from a range of satellites, including stunning imagery
from the Space Shuttle missions. A full description and source if provided for each image.
Mars Rover Panoramics
GS5 A chronological account, in panoramic images, of the NASA Mars Rovers' progress across the MartianTerrainwww.geo-web.org.uk

41

GEO Quarterly No 16

PhotoFiltre v 6.2.7
Since last writing about this program
there has been a number of updates.
As a reminder to readers I suggest you
have a look at my brief introduction to
the software in GEO Quarterly 8,
December 2005. One of the appealing
features of the software was its ability tohandle multiple channels/wavelengths.
Perhaps there is less need given thevery extensive facilities that David
Taylor now provides within his own
programs, in particular GeoSatSignal.
There are, of course, some moresophisticated versions of PhotoFiltre
available to purchase but Version 6
remains freeware.
PhotoFiltre v 6.2.7 is available on GEO
software CD, GS2 For further
information or to download the program
go to :-

http://www.photofiltre.com/
How to Purchase CDs
Write to the address below
requesting GS1, GS2, GS3, GS4 or
GS5. Prices are £5 for any single
CD, 2 for £8, 3 for £11, 4 for £14 or
all 5 for £17. Please enclose cash or
cheque (made payable to Douglas
Deans - not GEO please) for theappropriate amount. Nothing else isrequired.

Group for Earth Observation

December 2007

David Taylor
Towards the end of September 2007, amajor new source of data was added to
the EUMETCast data stream. As partof the European Polar System (EPS),
the Metop satellite provides themorning coverage of any particularregion, and a NOAA satellite provides
the afternoon coverage. For about ayear now, EUMETCast users haveenjoyed a continuous stream of highresolution data, 24-hours a day, from allround the world. As Metop-A orbits theplanet, data is dumped at
EUMETSAT’s Svalbard ground stationand then sent out to users over theduration of the next orbit. Actually, thedata is sent slightly more quickly sothat there is a little margin and, when
watching the transmitted 3-minute data
chunks in real-time, it almost looks as if
Metop has halted over the pole!
This coverage has now been extended toinclude afternoon coverage from thecompared with the full 2048 pixels of the
AVHRR. Only every one out of every
three AVHRR lines is used, reducing thealong-track sampling to about 4 km.
As ever, software to decode thesetransmissions has been available fromthe outset [1] as a free update to the
Metop Manager software [2], which not
only processes the GAC data into
attractive images but also creates acomposite world-view of it. This provides
you with a continuously-updated pictorial
view of weather across the whole world.
Even better, the picture moves with thesatellite, giving you the experience oftravelling on the satellite and watching
the Earth pass beneath your feet.
A full-sized, false-colour version of theabove image (2.7 MB) fromhttp://www.satsignal.eu => Metop Manager

The cost includes CDs, packaging,posting and a small donation
towards the cost of overheads. No
fee is asked from overseas
members although an exchange ofsoftware or interesting satellite
images is always welcome.
Orders are normally dispatched on
the day of receipt.
Order your CDs from:
Douglas Deans, 17 Montrose Way,
Dunblane, Perthshire FK15 9JL,
Scotland.

A typical GAC composite World View from the Metop Manager
Image © EUMETSAT 2007

NOAA-18 satellite. Data from NOAA-18
is collected from various locations and,in order to include information from thefull orbit, an on-board device records
the instrument data from the Advanced
Very High Resolution Radiometer(AVHRR). This is later dumped to theground stations as NOAA-18 flies overthem. As the recording capacity on
NOAA-18 is limited compared with themore recent Metop satellite, only
reduced resolution imagery is possible,
comparable with that achieved by the
Automatic Picture Transmission (APT)data from the same satellite. This data
format is known as General Area
Coverage (GAC) and is 409 pixels wide

42

www.geo-web.org.uk

To obtain this data, you need to registerfor the NOAA-AVHRR data on the GEO
Web site at
http://www.geo-web.org.uk/eumreg.html

Look for the section named ‘Polar Data
Services, Global Data Service (Level 1data)’.

References
1 SatSignal Software
http://www.satsignal.eu
2 Metop Manager
http://www.satsignal.eu => Metop Manager

December 2007

Group for Earth Observation

GEO Quarterly No 16

John Tellick“Earlier on today apparently a woman rang the BBC and said she’dheard there was a hurricane on the way. Well, if you’re watching –there isn’t”.
These few words turned out to be the most famous—or should thatbe infamous—words ever spoken by a British TV weather
forecaster. The forecaster in question was Michael Fish, presenting
the early evening forecast on October 15, 1987. What followed thatnight will never be forgotten by those who experienced it—nor byMichael Fish, who has suffered ‘the blame’ ever since.
To be fair to Michael Fish, his ‘hurricane’ remark, taken wholly out of context,
actually referred to the likelihood that Hurricane Floyd (in the Caribbean) would hit
Florida. Forecasters had in fact been predicting strong winds over England forseveral days, but the track of thedepression was predicted to befurther south than it turned out.
Michael Fish added ‘But having
said that, the weather will become
very windy, but most of the strong
winds will be down over Spain andacross into France—but there is avicious-looking area of low
pressure on our doorstep
nevertheless.’ His chart for 13:00
showed a deep depression of 974
mbar over the Bay of Biscay.
Michael Fish, pictured presenting
In the final forecast of the day, Billa typical forecast in 1982
Giles (with the centre of thedepression now off Brittany at 959 mbar) said: ‘It looks like most of the strong winds
will stay away, although it’s still going to be very breezy up through the Channel’.

The aftermath of the ‘Great Storm’, a NOAA-10 channel-4 IR image
acquired at 8.00 am on October 16, 1987.
Image NOAA CLASS Archive (www.class.noaa.gov/)

A classic understatement one can say with hindsight! But it was always
Michael Fish’s comment that was remembered—and is to this day.
The storm over southern England wasn’t a hurricane in meteorological terms; it wasa ‘bomb’ [1], which produced hurricane force winds over land and is now
remembered as The Great Storm . Moreover, born out of warm humid air meetingcold dry polar air, the system intensified rapidly and its centre, originally thought tobe passing over France, instead tracked from the Bristol Channel across central
England with particularly devastating winds on its southern edge.
When most people went to bed that night it was just windy, nothing out of theordinary for southern England; but as the night progressed it became a terrifying
experience of lashing rain and howling, roaring winds till you felt it couldn’t get any
worse. It seemed like the house itself was shaking, and nobody could sleep whilst
trees, chimney pots, slates—indeed whole roofs—crashed to the ground all around.
Daylight revealed a changed landscape with 15 million trees felled and the forestsof Surrey, Sussex and Kent destroyed. Nor did the towns and cities escape, withbuildings, parks and gardens devastated. 18 people in the UK lost their lives andthe toll would have been much worse had the storm occurred during daylight hours.
The Great Storm was the worst event of its kind since 1703 and one could well
imagine being in the tropics during a hurricane: but this was England! Inland,sustained wind speeds of over 80 kph raged for four hours, frequently gusting toover 120 kph and occasionally 140 kph. Gusts along the East Sussex and Kent
coasts reached 160 kph with the highest recorded gust of 195 kph being recorded
at Gorleston in Suffolk. Parts of northern France and Belgium also suffered in thestorm.
Our beloved countryside here in the southeast of England bore the scars foryears—and still does in a few places. Many feared southern England would neverbe the same again. But, driving through these counties 20 years later, it is again agreen and pleasant land: Nature has regenerated its woodlands and the Downs areagain covered in trees. You would hardly know the scale of the devastation wroughtthat night if you had not lived through it.
Nature, it seems, has such a propensity to destroy and regenerate? Well wewouldn’t expect to have another storm like that for 300 years, would we? One might
have thought not but that supposition didn’t last long.
Large areas of Great Britain and northern Europe were again battered anddevastated by storm force winds on January 25, 1990 in what has been called theBurns’ Day Storm.
The meteorologists were much better prepared this time and severe gale warnings
were issued four days in advance—though the eventual track across the UK was
not known that early on. More precise forecasts were issued on January 24 as thestorm intensified, its central pressure falling continuously as it approached Ireland.
The lowest central pressure was estimated as 949 mbar as it passed to the east of
Edinburgh at around 16:00 UT on January 25. Sustained winds reached 120 kph(comparable with a Category-1 hurricane) while gusts of up to 170 kph were
responsible for most of the damage it inflicted.
This storm produced winds of comparable strength to the Great Storm but over amuch wider area of northwestern Europe. At least 97 people lost their lives—half of
those in the UK. The numbers of casualties were significantly higher than in 1987
because this storm struck during daytime; most of the fatalities resulted from falling
masonry and wind-blown debris. Buildings were damaged, travel by road, rail, sea
and air were all severely disrupted and an estimated three million trees werebrought down in the UK alone.
1 Bomb: an extratropical cyclone in which the pressure drops morethan a millibar per hour

www.geo-web.org.uk

43

GEO Quarterly No 16

Group for Earth Observation

December 2007

David Taylor
The Problem
I recently had a request for some Metop AVHRR data, so that areader who did not have access to EUMETCast could test out myMetop Manager program. As you will have read in past issues of
GEO Quarterly, Metop data does occupy rather a lot of disk spaceeven though it is compressed during transmission over the
EUMETCast system.
What I wanted to achieve was to compress a whole set of Metopfiles in order to write them on to a DVD. However, simply placing
all the files into a Zip archive would still have resulted in a file over
4 GB in size. This would need something bigger than a single DVD
to carry it (as I had more than a day's worth of Metop data tocompress). My solution was to compress each individual 3-minute
Metop data chunk automatically, looping through all the files in a
directory. However, I wanted to be able to stop and start theprocess at will (it's quite CPU-intensive), and hence be able todetect if I had already Zipped a file and avoid Zipping it again.
The Solution
I achieved my objective by using the script below—looks quite
simple, doesn't it?
FOR %%F IN (C:\EPS-AVHRR-raw\AVHR*) DO (IF NOT EXIST %%~nF.zip PKZIP25 -add -max %%~nF.zip %%F)

Explanation
Essentially there are two parts to this script, a loop over all the files
and, for each file, testing whether a Zip exists and, if not, creating
it. I use an old version of the PKZIP25 program from PKware(www.pkware.com) for compressing the actual data.
In developing a script like this, I tend to develop the loop first sothat I can see if the files I am picking up are the correct ones.
Although the loop can be written on a single line, splitting the loop
over more than one line may make the operation clearer if you
have a complex set of operations to perform on each file.
Here is how you might loop through all the MS Word documents inthe current directory and do a directory listing of each:
FOR %%F IN (*.doc) DO DIR %%F

At the command prompt, you can type ‘HELP FOR’ to understandthe syntax of the FOR command. in this case, for each file with a‘.doc’ extension in the current directory, the command after the DO
is run, with the %%F being replaced by the file name for each file.
Note that in a script, the %F which the HELP FOR refers to must
be replaced with a double percent mark: %%F.
We can lay out the same FOR command over two lines using
round brackets like this:
FOR %%F IN (*.doc) DO (DIR %%F)

44This has explained the FOR statement in the script—except for thefact that, rather than specifying all the files in the current directory, I
choose in this script to specify a different directory, and to specify itcompletely:
FOR %%F IN (C:\EPS-AVHRR-raw\AVHR*) DO (In this case, as stated earlier, should the Zip file already exists, I
don't wish to create it again. To test for the existence of a file,
scripting offers the IF command:
IF EXIST <filename> <command-to-run>

For my script, I want to create the Zip only if the Zip-file doesn't
already exist:
IF NOT EXIST <filename> <command-to-run>I now want to reply on another innovation of the more recent
versions of Windows scripts, the ability to split a full filename down
into components.
In this case, I want just the filename part, without the directory or
file extension parts, and I can get this by using %%~nF command
instead of %%F.
The basic syntax for the PKZIP25 command is:
PKZIP25 -add <Zip-file-name> <file-to-add>such as:PKZIP25 -add Document.zip my-file.doc
In this case, I wanted to use the maximum compression, even at
the expense of CPU time, so I used another parameter to PKZIP:
PKZIP25 -add -max Document.zip my-file.doc

and of course, I wanted the filename of the Zip file to match thefilename of the Metop AVHRR file, and use the full path to the
Metop AVHRR file as the name of the file to compress. Hence my
Zip command is, using the FOR variables:
PKZIP25 -add -max %%~nF.zip %%F

Of course, I don't want to invoke PKZIP if the Zip file alreadyexists:IF NOT EXIST %%~nF.Zip PKZIP25 -add -max %%~nF.zip %%F

So what looks fairly simple actually turns out to be a little more
involved, but nothing that any reader could not tackle.

www.geo-web.org.uk

This is a colour composite image, created by David Taylor with his GeoSatSignal software, from
GOES-11 LRIT images received by Ed Murashie using his home-built LRIT receiving hardware.

Volcanos in Kamchatka - see article on page 10
image © EUMETSAT 2007

The Caspian and Aral seas imaged by Terra on October 11, 2007
See article on page 25
image: MODIS Rapid Response Team at NASA/GSFC