Group for Earth Observation
The Independent Amateur Quarterly Publication for

Number 6

Earth Observation and Weather Satellite Enthusiasts

June 2005
Inside this issue . . .
‘Ruud Jansen describes his
visit to the Funceme
meteorological station in
BrazilPeter Wakelin continues his
discussion about the
Indian Space Programme
Ship Trails: Les Hamilton
writes about these weird
tracks that can appear on
weather satellite images
Highway in the Sky France’s tallest motorway
bridge viewed from orbit
Arne van Belle explains
how to use a RAMdisc to
optimise EUMETCast
reception
Kimberley and C S Loh
describe how the Boxing
Day Tsunami affected
coastlines around theStrait of Malacca
Beginners’ Guide to
installing and using
Digital AtmosphereWorkstation
Learn to splice together
NOAA HRPT images using
Paintshop Pro
Mike Stevens returns withmore reports on the successof his MSG station
Plus all the regularfeatures ...

The era of Meteosat WEFAX imaging is nearing its end—transmissions are due to be switched off for good sometime during December 2005. The GEO Shop can help you toprepare for the future by migrating to Meteosat-8.
Meteosat-8 data is disseminated via a domestic DVB linkfrom the Hot Bird-6 geostationary satellite. You will find all
the hardware your require on this page.

You have to register with EUMETSAT and obtain an amateur
user licence from the Met Office and, in addition, purchase theTellique software and e-Token key unit. If you are unsure how to
obtain these, please consult ‘Meteosat 8—the Challenge’ by
Mike Stevens in GEO Quarterly No 4. You can find a detailed
guide to completing your EUMETCast Registration Form on the
GEO website at http://www.geo-web.org.uk/eumreg.html

TechniSat SkyStar 2 PCI Card
A 'free to air' DVB satellite TV and data
receiver card as recommended by
EUMETSAT. This card requires
installing inside the computer andcomes with comprehensive installation
instructions and CD-ROM of driver
software (if you do not feel confident
about installing cards inside yourcomputer use the USB version below)
UK£49.50Continental Europe £51.00

Meteosat-8 image - © EUMETSAT 2004

TechniSat SkyStar 2 USB Box
The external version of the above
which plugs into the computer's USB
socket and does not require installing
inside the computer.It comes completewith power supply, USB cable & CDROM of driver software.
UK£109.50
Continental Europe £121.50

TechniSat SatFinder
Alignment Meter
A very useful and sensitive meter
which is a great help in setting up andaligning the dish for maximum signal.
The meter comes with full instructions.
UK£21.50Continental Europe £24.50

GEO PIC 1.0 for the RX2
Programmed with the new channel
frequencies required for NOAA-18.
UK£7.00
Continental Europe £7.40
Rest of World£8.40

Ordering and Shipping

Telestar 80 cm dish (or similar
model) and Universal 0.6 dB
LNB
A quality German made aluminium
dish and LNB with an AZ/EL mount to
fit onto a vertical pole. (Wall or patio
mounts are available from local
satellite TV dealers)UK£49.00Continental Europe enquire

We will ship by post, so please allow a few
days for items to arrive in Europe andperhaps a few weeks for the Rest of theWorld.

Orders should be sent to:Telestar Universal Ku-band 0.6 dB
Universal LNB (or similar model)
Digital satellite TV Universal LNB for
use with the SkyStar receivers above or
any DVB satellite TV receiver.
UK£11.00Continental Europe £12.50

GEO Shop,PO Box 1375,
Christchurch BH23 9AS,
England.

Check the complete GEO Shopcatalogue in our centre pages

CONTACT INFORMATIONs you can scarcely fail to notice from our advertisement on theAopposite page, the GEO Shop is now fully operational, stocking
just about everything you need to set up your own MSG-1 station forreceiving EUMETCast’s Meteosat-8 dissemination service. Readers
still relying on WEFAX and PDUS transmissions from Meteosat-7
have little more than six months to migrate to the new technology
before these services are terminated (some time during December
this year). A full GEO Shop listing can be found in our centre pages,
along with contact information and details of how to place orders.

EO was highly honoured to receive a request from none otherGthan Gordon Bridge, EUMETSAT’s Training Consultant, for
permission to use articles authored by two of our members in theirtraining programme. The articles in question came from GEO Q4:‘Meteosat-8 - the Challenge’ by Mike Stevens and ‘Receiving MSG by
C-Band’ from Kobus Botha. This request reflects highly on thecalibre of these individuals and of course enhances the international
profile of GEO itself.

T

he GEO Symposium at Leicester last April proved even better
than last year and a full report will appear next issue.
Meanwhile, a few photographs sprinkled throughout this issue
provide a taste of the event.

Contents
GEO Report
NOAA-N Launch
Mega Sastrugi in East Antarctica
Snapshots from Sich-1M
Earth Imaging News
News in Brief
Meteorological Charts and Satellite Images
The Indian Space Programme - part 4
B15a Iceberg Latest
Highway in the Sky
Spectacular Cloud Eddies
EUMETCast Reception using a RAMdisc
News from EUMETSATThe Indian Ocean Tsunami
Desert Moons
Unusual Cloud Whorl over France
Brownies
GEO Shop Page
NOAA Satellite Predictions for the UK
Helplines etc
GEO Membership Form
Upside-down Weather Down-under
Severe Interference on NOAA 15 Images
My Trip to Brazil
HRPT for Mac Users
Silting of the Irrawaddy
Understanding Ship Trails
Software Showcase
AMSAT-UK Space Colloquium, 2005
Meteosat 8 - the Results
Introducing Digital Atmosphere Workstation
Spectacular Sunglint from NOAA 15
Unusual Cloud Plume over Scotland
In Tray - Readers’ Letters and Comment
Merge HRPT Images using Paint Shop Pro - 1
News from Down Under

Francis Bell
Douglas Deans
NASA
Peter Wakelin
Robert Moore
Peter Wakelin
John Tellick
Peter Wakelin
Arne van BelleC S Loh, K Loh
Francis Bell
Francis Bell

Lindsay Vincent
Ruud Jansen
C S LohLes Hamilton
Douglas Deans
Mike Stevens
Les HamiltonPeter Wakelin
Les Hamilton
Doug Thwaites

2
3
4
5
6
8
9
10
11
12
13
14
15
16
19
21
21
i
ii
iii
iv
23
23
24
26
27
28
30
31
32
34
37
38
39
40
44

Public Relations
Francis Bell,
Coturnix House,
Rake Lane,
Milford,Godalming,
Surrey GU8 5AB
England.
Tel:(01483) 416 897
e-mail: francis@geo-web.org.uk
General Information
John Tellick
e-mail: info@geo-web.org.uk
Articles and Images for Publication
Les Hamilton,
8 Deeside Place
Aberdeen AB15 7PW
Scotland, UK.
e-mail: editor@geo-web.org.uk
Membership and Subscriptions
Nigel Evans,
L’Eventail, 7 Gloster Ropewalk, Aycliffe,
Dover CT17 9ES
England, UK.
e-mail: members@geo-web.org.uk
Meteorological Consultant
Peter Wakelin
e-mail: meteo@geo-web.org.uk
Webmaster and Website Matters
Ray Godden
e-mail: webmaster@geo-web.org.uk
Education Coordinator
David Paintere-mail: education@geo-web.org.uk
GEO Shop Manager
Clive Finnis
e-mail: shop@geo-web.org.uk
International LiaisonPeter Green‘Hollowtree’
Eggesford
Devon EX18 7QX
Tel:(01769) 580 700
e-mail: international@geo-web.org.uk

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
Printing
Toptown Printers, Vicarage Lawn,
Barnstaple, Devon EX32 7BN.
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 designor any constructions carried out by members orother third parties.
Copyright GEO © 2005
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 6

Group for Earth Observation

June 2005

Francis Bell
Symposium
As I write I have only just come backfrom the recent GEO Symposium inLeicester. I hope a full and illustrated
report of the symposium will be included
in our next Quarterly publication.
However, in anticipation of that, just a
few sentences now seem appropriate.
Judging from the feedback I havereceived, the event was a great success.
The venue was the National Space
Centre in Leicester which is ideal, with
its exhibition area, technical support
and lecture room. The programme weran was as published on our web sitewith the inclusion of one additional
speaker. The speakers were all
outstanding and the lunch-timeworkshops were well attended. The day
concluded with most delegates staying
for GEO’s AGM. Thanks must go to all
involved: GEO management, speakers,
delegates and the NSC for their cooperation and technical support.

our membership renewing for a further
year. I take that as a vote of confidence
in the group as a whole. However, areminder to all is that, with some small
exceptions, it is the membershipsubscriptions which are our main sourceof income. This has to support theprinting and distribution of ourQuarterly publication. Multiply the
number of members by the annual
subscription and we are just short of afinancial break-even point. Pleaseencourage any friends, acquaintances,local radio club members to join GEO.
Currently GEO membership is mainly in
the UK but we also have members in the
Netherlands, the rest of Europe andother parts of the world.
With reference to the Netherlands, theirown Werkgroep Kunstmanen is very
supportive of GEO and six of theirmembers came to Leicester this year. I
went to Utrecht last year for one of their
meetings and will try to do so again thisyear. I know other GEO members havebeen to their meetings. The dates of
their meetings in Utrecht later this year
are September 10 and November 19.

question was to indicate how little
atmosphere we actually have. The figure
surprised me when I worked it out formyself. Our planet only has a thin skinof atmosphere and ocean; they are
equally fragile so we must care for both
environments.
Now I’m in trouble again. Increased
carbon dioxide in the atmosphere as thecause of global warming? I don’t believe
it! Try looking in the sky on a sunny day
to find the cause. There isn’t much
atmosphere to shield us from our local
star.
On a light hearted note, a physicist
commented on the modal answer
provided to the last quarterly question. I
thought the additional comments were
just going off at a tangent.

Guildford

Antenna alignment workshop
at the GEO Symposium
Photo: David Taylor

One point which did arise in Leicester
was the legal and administrative
structure of GEO. The management
team had discussed this and, as a matterof policy, have decided for the time being
not to superimpose any additional rules
or bylaws beyond GEO’s existing legal
structure, which was professionally
written and registered with Companies
House. The membership’s interests arein safe hands within this structure.
Membership
Turning to membership. It has beenencouraging to note the percentage of2

AMSAT-UK hold their annual colloquium
in Guildford again this year, at the
University of Surrey. An announcement
appears on page 31. As I write this, GEO
has just received an invitation toparticipate, and will give a presentation
and run live satellite reception. If you
missed GEO at Leicester this year,
perhaps a day visit to Guildford may be
an alternative for you. A chance to meetsome of GEO’s management team andexperience appropriate demonstrations
and talks. Check our web site for details
which still have to be confirmed but I
expect GEO to be most active this event
on Saturday, July 30.
Quarterly Question
My thanks to John Bunting for being thefirst to provide an answer to the last
Quarterly Question which related to theratio of the Earth’s oceans to theatmosphere if it was all measured at sea
level pressure. His answer was ocean toatmosphere 1 to 0.7. The point of the
www.geo-web.org.uk

The RSGB GB4 FUN vehicle
at the GEO Symposium
Photo: Cecilia Taylor

GEO Shop
The GEO shop is progressing with arange of items for our membership. Thiscan be seen on our website and in our
advertisements inside the front coverand on the centrefold.
The initiative for the ‘shop’ came fromwithin the management team. Thanks to
Clive and John for starting this; theirinitiative adds an extra dimension to thebenefits enjoyed by GEO members. At
Leicester a delegate said to me: ‘Does
GEO make any profit from running the
shop?’ Although I don’t know the finedetail (which is left with Clive andJohn), I do know that time and effort

June 2005

goes into the shop. I replied: ‘Yes wemake a small margin’. Response: ‘I’ll use
the GEO shop then’. I thought that wasvery supportive. I smiled and said:‘Okay! That’ nice.
APT
Another point arising from Leicester is a
new APT receiver. Personally I haveseven APT receivers all of which work
well but each with a different degree ofpager interference resistance. Please be
assured that GEO’s management teamare aware of the issues relating to APT
reception. APT transmissions will lastfor perhaps ten years. A new receiver,pager resistant and a year’s work on
design, all interrogative: but we arelooking at the issues.
In the next few days I am going to visit
my son and his family in Raleigh, North
Carolina USA. Sometimes, in the past, I
have taken my APT receiving station
around the world. With the EUMETcast
relay of GOES E I can follow theweather in NC but I would love to see an
HRPT image of Raleigh. Does GEO havea member in the USA who can send us ahigh resolution satellite image of thisarea? If you have something that fits the
specification please send it to myself or
our editor.

Group for Earth Observation

Decoding and displaying NOAA HRPT
telemetry files has been exclusively thepreserve of the PC user—until now thatis! Sergei Ludanov describes the
MacHRPT software he has written to
decode HRPT files from NOAA’s CLASS(formerly SAA) site on the Apple Mac.
There will be a feature evaluating the
R2FX weather satellite receiver thatcaught so many member’s attention
during GEO’s Leicester Symposium,
more on splicing satellite images using
Paintshop Pro, and an overview of thefirst results from NASA’s Aura satellite.

Our poser this time comes from David
Taylor, who asks: ‘To which satellite
does MSG-1 (i.e. Meteosat-8) causeinterference? This will test whether you
read ESA’s Bulletin, or simply look at
the pictures!’Answers, as usual, to Francis Bell by
post or e-mail (details on page 1)

A respectful note here. A few hours ago I
received news about the death of Ron
Broadbent MBE. Ron was a good friend,an occasional guest at my house and mymentor in my early days of amateur
satellite reception. He was AMSAT-UK’ssecretary for many years. I sent him acopy of GEO Launch edition. He
telephoned me a few days later to say hewould join: and he did.
My final comment as usual is a ‘thankyou’ to our contributors. Please keep
sending your copy, images, comments oranalysis to our editor. We try to cover afull spectrum of interests from theabsolute beginner to the frontiers ofwhat’s possible. Wouldn’t you like tohave something published in a GEO
Quarterly?

Coming in the
September Issue
Our in-depth look at Digital AtmosphereWorkstation continues when Fred van
den Bosch demystifies the program’s
scripting features, and shows how easy
it to overlay all kinds of synoptic dataover your charts and weather satellite
imagesGEO Quarterly No 6

minutes after launch.
• NOAA-N will be launched into an
870 kilometre circular, near polar
orbit with an inclination of 98.73°,
giving an orbital period of
approximately 102.14 minutes.
• The spacecraft will cross the equator
at about 2 pm northbound and 2 am
southbound, local solar time.
• At the time of writing there is stillsome doubt regarding the APT
frequency but it is likely to be
137.9125 MHz. (NB: this is a new
NOAA frequency).
• If this launch follows the course ofprevious ones, we can expect the
HRPT and APT transmitters to be
activated perhaps within hours ofsuccessful injection into orbit (visible
imagers only).
• For several weeks the APT will carry
2 visible images (channels 1 and 2).
The infrared system requires outgassing before being switched on
and is the reason for the delay(usually about 2/3 weeks) in its
operation. My understanding is thatthe out-gassing prevents
precipitation (and contamination)
when the coolers are switched on.
Thereafter the APT format should
follow the norm of Channel 2(visible) and channel 4 (IR) during
daylight passes, switching
automatically to channels 3 (3A) and4 during darkness. All being well, theIR channels should be activated on
28th May 2005.
• Let’s wish NOAA-18 a long andsuccessful life (especially its APT !).
Any updates or changes will be posted to
the Weather-Satellite-Reports group at:
http://groups.yahoo.com/group/
weather-satellite-reports

The NOAA-N Launch
Douglas Deans
By the time you read this, NOAA-N
should have been successfully launched
and renamed NOAA-18. I have prepareda few notes for those not familiar withNOAA launches. Hopefully this willanswer some of your questions andoutline what can be expected for the firsthours, days and indeed weeks following
a successful launch. Information is alittle scarce so some details are best
guess from previous launches.
• The launch was scheduled to takeplace from Vandenberg Air Force
Base between 10.22.01 and10.32.01 UTC on Wednesday 11th
May 2005.
• If all goes to plan, hand over to orbit
mode should happen about 84

www.geo-web.org.uk

Cover Images
Front
This striking NOAA-17 APT image ofAustralia dates from February 4, 2005
and shows what is known locally as a‘southern cyclone’ bringing chaos to theregion around Melbourne.
Image: Lindsay Vincent

Processing: WXtoImg

Back coverThis NOAA-17 HRPT image inazimuthal equidistant projection dates
from 10:25 UT on March 18, 2005 anddepicts a wintry scene over Scandinavia.
Ice is apparent in the Gulf of Bothnia
while streamers of cold air can be seen
picking up moisture as they stream
south past the Gulf of Finland.
Telemetry: NOAA
Processing HRPT Reader and GroundMap

3

GEO Quarterly No 6

Group for Earth Observation

NASA Earth Observatory
At first glance the casual observer
might well mistake the wavy
features in this image as being acloud feature, perhaps akin to a‘herringbone’
sky.
But
the
underlying landmass is East
Antarctica, and imaging throughout
the period 2002-2004 has indicatedthat the feature is stationary.
As it passed over Antarctica on
December 16, 2004, the Multi-angle
Imaging SpectroRadiometer (MISR)
on NASA’s Terra satellite captured
this image showing a wavy pattern
in a field of white. At most otherlatitudes, such wavy patterns would
likely indicate clouds but MISR saw
something different. By using
information from several of its
multiple cameras (each of whichlooks at the Earth’s surface from adifferent angle), MISR was able toshow that the feature was actually awavy pattern on the ice surface.
The view shown here, which camefrom
MISR’smostobliquebackward-viewing camera actuallyshows sastrugi, long, wavelike
ridges of snow formed by the windand found on the polar plains.
Usually sastrugi are only several
centimetres high and several metersapart. However, large portions ofEast Antarctica are covered bymega-sastrugi ice fields, where theripples have assumed dune-like
proportions and can be as high asfour meters, separated by two to fivekilometers. These mega-sastrugi
resultfrom
unusualsnow
accumulation and redistribution
processes that are influenced by theprevailing winds and climate
conditions. The features provide
information that is useful for icecore interpretation.
This image area covers about 277
kilometers by 421 kilometers in theinterior of the East Antarctic ice
sheet.
Acknowledgements
Image courtesy
NASA/GSFC/LaRC/JPL, MISR Team.
Text based on original material posted
on NASA’s ‘Earth Observatory’ website.

4

www.geo-web.org.uk

June 2005

June 2005

Group for Earth Observation

GEO Quarterly No 6

As you will read in Peter Wakelin’s article overleaf, Ukraine’s
Sich-1M satellite has proved a massive disappointment, with very
little imagery being received. Two of the most revealing images

are presented below. They clearly fall far short of the quality wenormally publish in GEO Quarterly, but they are included as ahistorical record of this satellite’s brief active lifetime.

This is the first Sich-1M image detected from the UK and was obtained
from David Taylor in Edinburgh, Scotland at 08:12 UT on January 29,
2005. The only readily recognisable feature is the snow-covered Alps at
lower left. The sharp division between light and dark at the right-hand sideof the image is believed to be the limb of the Earth itself, due to thesatellite’s attitude irregularity. (Paul Hayes QFH antenna, RX2 receiver,WXSAT wave capture software, processing software SatSignal.)

GEO member Nigel Heasman relocated to Cyprus last year, and is better
placed than most to receive Sich-1M transmissions, which only occur wellto the east when the satellite is flying over its command station in Ukraine.
The image above is one of the best he received and was clearly recorded
while Sich-1M flew over Uruguay on March 23. The image was latertransmitted when the satellite was passing over Ukraine. Clearly visible isthe estuary of the River Plate between Uruguay and Argentina. In thecentral radar image the bright smudges are the signatures of the cities
Buenos Aires and its conurbation. Again, there is evidence suggestive ofEarth’s limb on the extreme left of the image.

www.geo-web.org.uk

5

GEO Quarterly No 6

Group for Earth Observation

June 2005

Peter Wakelin
Sich-1M Abandoned
Following a shortfall in velocity of about 100 m/s after thecircularisation burn of the third-stage rocket, Sich-1M wasleft, not in the planned 650 km circular orbit, but in an
eccentric one with apogee about 637 km and perigee of 280 km
where atmospheric drag is significant. The MK-1TS subsatellite, which was attached to Sich, was ejected from it atabout 2100 UTC on December 25, some 34 hours after launch
and is in a similar orbit.
The first known transmissions on 137.40 MHz were picked up
in the UK on January 29 (see David Taylor’s image on page 5)
and they continued sporadically until late March. Imagery
was of a similar format to that of the earlier Sich and Okean
spacecraft but it was obvious from the earliest images that
there was a serious orientation or stability problem.
This type of spacecraft relies, in part, on a gravity gradientstabilisation system to maintain pointing accuracy. In such asystem, the main body of the spacecraft is separated fromanother mass by a long boom and the tiny difference ingravitational acceleration between the two masses ensuresthat the boom remains perpendicular to the Earth’s surface.
At 650 km this stabilisation method would work satisfactorily
as atmospheric drag is extremely low but with a perigee of
only 280 km it seems probable that the increased drag, which
is much greater on the main spacecraft than on the boom’s
end-mass, generated a torque too great for the stabilisation
system to cope with.
On March 18, ITAR-TASS, the Russian news agency, reported
that the Ukrainian National Space Agency’s press service had
said, inter alia, that ‘Sich 1M had taken the first pictures ofdesignated areas of the Earth and beamed them back to themission control centre’. There was no mention in the report ofany problems with the spacecraft. It was another month
before the Ukrainian authorities admitted that there was aninsurmountable stability problem. At the time of writing, inlate April, nothing has been heard on 137.40 MHz for about
five weeks and no further transmissions are expected. The
instruments of the VARIANT international experiment,
which is incorporated in Sich-1M, are less dependent on astable platform and scientists from Ukraine, Russia, France,
the UK and elsewhere are retrieving some useful data.
By late April, the loss of energy at each perigee passage had
caused the apogee to lower from 637 km at launch in
December to 570 km and the perigee to drop 4 km to 276 km(all altitudes relative to a spherical Earth). Most of the orbit
decay occurs when the perigee passes over the Earth’s
equatorial bulge where the satellite passes closer to thesurface and in Sich-1M’s case this happens every 51 days. The
fourth such event occurs around May 31 but the spacecraft
will probably not meet its fiery end until late this year.
MTSAT-1R Successfully Launched
Japan’s H-IIA rocket returned to flight at 0725 UTC on
February 26 and the 7th flight vehicle placed MTSAT-1R in
the planned geostationary transfer orbit from where it was

6

MTSAT-1R schematiclater raised to geostationary altitude. Its final location will be
above 140°E when it becomes operational and it will replace
the aged GMS 5 spacecraft which has been relaying GOES 9
imagery since its own imager developed problems.
The launch restores some confidence in the troubled Japanese
Aerospace Exploration Agency (JAXA). JAXA’s next major
launch is the scientific Astro-E2 satellite on the M-V rocket.
The previous H-IIA launch failed soon after lift-off anddeposited its payload—a pair of Information Gathering
Satellites (IGS 3 and 4)—in the Pacific Ocean. An M-V flightin 2000 carrying Astro-E1 also failed but M-V successfullylaunched the Hayabusa asteroid probe in 2003. H-IIA launch
operations are carried out by Rocket Systems Corporation andthe major components are built by Mitsubishi Heavy
Industries Ltd. MTSAT-1R is an SS/L-1300 satellite built bySpace Systems/Loral in the USA. In addition to providing
weather data to the Japanese Meteorological Agency, MTSAT1R carries air traffic control support equipment for theJapanese Civil Aviation Bureau. The design lifetime for themeteorological payload is 5 years and 10 years for the ATC
equipment.
MTSAT-1R, also known as Himawari-6 (sunflower), is athree-axis stabilised, cubic structure with a single solar arrayconcluded on page 8 ...

First MTSAT-1R Image
The first infrared and visible test images from MTSAT-1R were acquired
on March 24, 2005. The image presented here comes from the visible
channel (0.55-0.90 µm). The original image, which includes the entire
hemisphere, measures 2750 pixels square. Only a section from it isreproduced opposite.

www.geo-web.org.uk

GEO Quarterly No 6

2-Line Element Latest
The United States Strategic Command(USSTRATCOM) has recently takenover responsibility from NASA for
distributing the two-line element setsrequired by satellite tracking programs.
The Space-Track website (www.spacetrack.org) has been set up for thispurpose. Before you can download
element sets from this site you mustfirst register (there is no charge) andapply for a password. However, youmust be aware that use of the element
sets you download is restricted; you can
use them for your own purposes but are
not normally permitted to transfer
them, or products derived from them(e.g. satellite predictions), to any third
party.
There is, however, a process whereby
organisations can apply for permission
to redistribute this information, andboth Celestrak (www.celestrak.com)
and GEO have been successful in thisrespect. This means that GEO cancontinue to publish pass predictions for
the NOAA satellites and that GEO
members can continue to download their
keplerian element sets from Celestrak.

Group for Earth Observationsome of the many satellite images
provided by Envisat as it makes its
journey around the world. There are
options to select a particular country,
follow in the footsteps of Jules Verne ordevise your own route around the world.
In all cases you are zoomed into aninterestingterrestrial
featureaccompanied by a text annotation.
Both the above can be ordered directlyfrom the web page, and provide a useful
overview of Envisat and its applications.

Meteosat Spies Ariane Launch
Nick Hewgill spotted what he believes tobe the launch plume from the firstproving flight of the upgraded Ariane-5
ECA launcher that lifted off from
Kourou in French Guiana at 21:03 UT
on February 12, 2005.

GEO is grateful to the USSTRATCOM
Orbital Data Release Authority forconsidering our application favourably.

Free CD-ROMs from ESA
Did you know that there are someinteresting CD-ROMs available (free)from ESA’s Earth Observation Library?
Visit
http://earth.esa.int/
services/esa_doc/doc_env.html
Among the wealth of brochures andbulletins available are two interesting
CD-ROMs.
Envisat in Action
This CD-Rom presents a first overview
of the Envisat results, in the form of acompilation of images and findings
provided by the Envisat data user
community. The information and images
are categorised under the headings‘Land’, ‘Ocean’, ‘Ice’ and ‘Atmosphere’.
Around the World in 80 Images
This CD aims to present an enjoyable
and informative way of introducing just

8This Meteosat-8 image was obtained
shortly before night fell on the launch
pad at Kourou. The Ariane exhaust
plume is clearly visible at upper centre,
casting a conspicuous shadow to the easton the ground beneath. The Amazon
estuary appears at lower right.

Russian Anglers Drown in
Frozen Lake
A popular winter pastime among
Russian anglers is ice fishing; where
they venture out on to the frozen ice overlakes and rivers to cast their lines
through holes cut in the ice.
A group of anglers who were fishing on
Europe’s largest freshwater lake, Lake
Ladoga, near St Petersburg perishedlast February after the ice gave way
beneath their car.
Although one angler did manage toescape from the car, his three
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June 2005

companions drowned. Ice fishing is also
carried out over the frozen waters of the
Gulf of Finland and dozens of fishermen
have to be rescued every winter after
becoming trapped on ice floes whichhave broken away from the shore.
Look out for NOAA 18
If all goes well, NOAA 18 will have beenlaunched by the time you read this (onMay 11). Visible light images were due
to start transmission immediately, with
the IR channels operating from May 28.
Remember the satellite will transmit on
a new frequency: either 137.10 MHz or
137.9125 MHz.
Earth Imaging News... continued from page 6

mounted on the south facing side. On
the north side is a 15 m boom carrying asolar sail to counteract the torquegenerated by solar radiation pressure on
the 19 square metres of solar panels. 12
small thrusters are available for
attitude control and orbit stationkeeping manoeuvres (see schematic
above).
In the focal plane of the 31 cm diameter
optical system there are sensors
sensitive to five wavelengths: 0.55-0.80
micrometres (visible), 3.5-4.0 (nearinfrared), 6.5-7.0 (water vapour) and thetwo infrared channels centred on 10.8
and 12.0 micrometres. Imager data arereceived at the Command and Data
Acquisition Center and retransmitted tousers in various formats. The WEFAX
and HiRID imagery familiar to GMS 5
users will continue to be broadcast, on atime-shared basis, with the new, digital
LRIT and HRIT formats until the end of
2007. Only LRIT and HRIT will beavailable from 2008.
Acknowledgements
The following websites provided some of
the information in this report:• Dr Kelso’s CelesTrak for Two Line
Elements
http://www.celestrak.com• Bureau of Meteorology, Australia
http://www.bom.gov.au• Japan Meteorological Agency
http://www.jma.go.jp• Jonathan McDowell’s Space
Reports
http://www.planet4589.org/jsr.html

June 2005

Group for Earth Observation

GEO Quarterly No 6

Robert Moore
In GEO Quarterly No 4, Ton
Lindemann explained how to use
Fleetcode data to plot synoptic
charts as overlays on Meteosat-8
images. Thus we now have (atleast) two means of enhancing
our imagery with charts—or perhaps elaborating our charts withsatellite imagery.
In figure 1, David Taylor’s
Geosatsignal has been used tooverlay the Bracknell chart on to
an IR image of the North Atlantic
acquired at 1400 UTC on
January 17, 2005. Figure 2 shows
the same image overlain by
Fleetcode data using Digital
Atmosphere Workstation. Bothfigures show an Atlantic highpressure area and a low between
Greenland and Iceland that was tobring stormy weather to the UK.
The fronts associated with thesesystems are also clearly shown.
The charts are slightly different
interpretations of the meteorological data—meteorologists andtheir computer programs areunlikely always to produce identical analyses of the available data.

Figure 1 - Overlaying a Bracknell chart on to a GeoSatsignal image
Bracknell chart reproduced with permission of the Met Office, Crown Copyright reserved

Is there much to choose
between the two presentations?
Figure 1 covers more of northern
Greenland; the chart is clearlydrawn and uncluttered. Figure 2
is in colour although the lines andlabelling are not so refined. The
Digital Atmosphere Workstation
presentation is potentially a more
dynamic one in that it is possible
to add additional features such asindividual station plots, wind barbs
or streamlines, temperature andhumidity data etc. So whilst
Geosatsignal with the Bracknell
chart overlay gives one a very
pleasing picture, and enhances
the interpretation of the satellite
imagery, GeoSatsignal allied with
Digital Atmosphere enables one toselect and manipulate data.
Figure 2 - Overlaying Fleetcode data on a DA basemap created from a Meteosat-8 image

If we are only interested in plotting
the basic surface features of theNorth Atlantic then there is little tochoose between the twopresentations: aesthetic

judgements may prevail. The non-specialist
will probably not invest in Digital Atmosphere
software anyhow so will continue to enjoy
the output of Geosatsignal alone. Morewww.geo-web.org.uk

specialist users with a particular interest in
weather or climate may prefer the flexibility
and versatility of Digital AtmosphereWorkstation coupled with Geosatsignal.

9

GEO Quarterly No 6

Group for Earth Observation

June 2005

Peter Wakelin
Earlier parts in this series described the developmental SLV-3(Satellite Launch Vehicle), the ASLV (Advanced Satellite
Launch Vehicle) and the PSLV (Polar Satellite Launch
Vehicle)—which was the first to operate on a commercial
basis—together with some of their payloads. The fourthgeneration vehicle was developed to place heavy
communications satellites into highly elliptical geostationarytransfer orbits (GTO) from where the payload’s own
propulsive system would raise the orbit to geostationary
altitude above the equator. Unsurprisingly, it was named
GSLV (Geostationary Satellite Launch Vehicle).
GSLV’s Early Development Plans
Conceptual studies for the GSLV started more than 20 years
ago when development work on the PSLV was still under way,
but by 1989, after studying numerous possible configurations,a design was selected which would utilise modules andinfrastructure already developed for the PSLV wherever
possible. These plans were approved by the Indian
Government in 1990. This design included a cryogenic third
stage utilising liquid hydrogen as fuel and liquid oxygen but,as the Indians knew they could not develop such a stage in areasonable time, it was decided to purchase the third stage
and associated technical services from Glavkosmos in Russia.

GSLV pictured shortly prior to launch

The Russian Connection
The advantage of using hydrogen as a fuel lies in its muchgreater propulsive efficiency than solid fuels or other liquids
such as the commonly used UDMH (unsymmetrical dimethyl
hydrazine) but has the drawback of having to be maintained
at extremely low temperatures to keep it in the liquid state.
The specific impulse of a hydrogen-powered stage is about 200
seconds greater than that of other fuels and, for the GSLV
configuration, each additional second of gain in specificimpulse increases the payload capability by more than 10 kg.
Soon after the agreement with Russia was signed it took asevere setback when the Soviet Union disintegrated andPresident Yeltsin refused to honour it. There were additional
problems in 1993 when Russia joined the Missile Technology
Control Regime and, at this stage, the Indians decided to go
ahead with the development of their own cryogenic stage.
However, it was eventually agreed that up to seven cryogenic
stages could be purchased but with limited technology
transfer, which meant that India would have to develop its
own flight guidance and control systems for the third stage.
First Propulsion Stage

The latest launch of GSLV on September 20, 2004

10

The first stage comprises a solid-fuelled core with four strapon liquid-fuelled motors. The core is 2.8 m in diameter, 20.1 m
in length and contains 138 tonnes of hydroxyl terminatedpolybutadiene (HTPB)-based propellant; it develops a thrustof about 4,700 kilonewtons (kN) and burns for about 107
seconds. The 2.1 m diameter, 19.7 m long strap-on motors
each contain 40 tonnes of the hypergolic propellants UDMH
and nitrogen tetroxide, develop a thrust of 765 kN and burnfor up to 160 s by which time the altitude is about
73 kilometres.
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June 2005

Group for Earth Observation

The Upper Stages
The second stage is 2.8 m in diameter, 11.6 m long and is filledwith up to 40 tonnes of UDMH and nitrogen tetroxide which
generates about 800 kN thrust for up to 140 s, raising thealtitude to about 127 km. Unusually, this stage is ignited 1.6 s
before the first-stage separation charge is detonated, thereby
utilising its exhaust gases to assist in making a clean
separation. During this part of the flight the payload fairing,which protects the payload during ascent through the denser
lower atmosphere, is jettisoned at around 115 km altitude.
The third stage, from Russia, is also 2.8 m in diameter andincorporates two separate aluminium alloy tanks for 12.5
tonnes of fuel and oxidiser in its 8.7 m length. It develops athrust of 73 kN for up to 12 minutes. The pyro-actuatedrelease mechanism and retro thrusters on the second stageensure a clean separation before the third stage is ignited.
When the third stage has completed its job it is at 195 km
altitude and has a speed of 10.2 km/s. A spring mechanism
separates the spacecraft from the third stage which thenperforms a small manoeuvre to eliminate the possibility of acollision with the payload during the coast phase togeostationary altitude. Also, all residual fuel and gases in thethird stage are vented into space to prevent build-up ofpressure which could lead to an explosion and debris
fragments hazardous to other spacecraft.
From GTO to Geostationary Orbit
GSLVs are launched from Sriharikota on the east coast ofIndia about 100 km north of Chennai (Madras) to an azimuthof 104° which results in an inclination of about 19° for thegeostationary transfer orbit. The perigee is typically 180 km
and the apogee close to the geostationary altitude, 36,000 km.
The launch profile is such that apogee occurs close to theequator so that the circularisation burn of the payload’s
apogee motor can also reduce the inclination to zero in themost fuel efficient manner. The apogee motor used on all
GSLV payloads to date is the 440 newton Indian-developed
motor which has been used on INSATs launched on foreign
rockets.

GSAT-2 weighed 1823 kg at launch including 840 kg ofpropellant for the apogee motor and for the 16 small(22 newton) reaction control thrusters used for attitudecontrol. The solar panels span 9.55 metres and generate
1,380 W of power backed up by two 24 Ah Ni-Cd batteries.

The latest launch of GSLV on September 20, 2004,
successfully placed EDUSAT at 74°E longitude (illustration
above). Dedicated exclusively to education, this satellite
provides a C-band beam and a Ku band beam covering thewhole of India and 5 Ku band regional beams. Each beam cansupport up to 5 television channels simultaneously and 72
channels have already been established by schools anduniversities throughout the country.
The final part in this series will detail some of India’s future
space plans.
Acknowledgement
I am grateful to ISRO and the National Remote Sensing
Agency for making so much information available on theirwebsites:
http://www.isro.org
http://www.nrsa.gov.in

Satellites Launched by PSLV
Although the first developmental test flight was intended tovalidate the vehicle design and its performance
characteristics, the opportunity was taken to launch the1540 kg experimental satellite GSAT-1. The launch took place
on April 18, 2001 and was successful in all respects. GSAT-1
also performed well and, in addition to carrying experiments
to prove new spacecraft elements for use in future flights, italso had on board three C-band and two S-band transponders
which were used to demonstrate digital audio broadcasting,Internet services and to carry out digital TV experiments.
Two years later, on May 8, 2003, the second test flight
successfully placed another experimental payload, GSAT-2, in
GTO from where it propulsion system moved it in three stages
to geostationary orbit at longitude 48°E. In addition to six
transponders GSAT-2 carries four scientific payloads:• Total Radiation Dose Monitor to measure radiation doses
within the satellite using a radiation-sensitive field effecttransistor.
• Surface Charge Monitor to indicate the charge state in
the vicinity of the spacecraft.
• Solar X-ray Spectrometer to study solar flares.
• Coherent Radio Beacon Experiment for ionospherestudies and to investigate several aspects of equatorial
electrodynamics.

GEO Quarterly No 6

B15A Iceberg Latest
The B15a iceberg
has finally driftedaway from
McMurdo Sound in
Antarctica since
our last report inQuarterly No 5,
page 27).
On April 18, thegiant ‘berg collided
with the tip of the
Drygalski ice
tongue as shown inthis ENVISATASAR wide-swath
radar image.
Credit: ESA

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11

GEO Quarterly No 6

Group for Earth Observation

June 2005

John Tellick
The new 394 million Millau Viaduct across the Tarn Valley
to the south of France’s Massif Central region opened totraffic on December 17, 2004. The 2460 metre-long bridge,
which reaches a maximum height of 270 metres above thevalley floor, is now the world’s highest road bridge. It is
expected to carry between 10 000 and 25 000 vehicles per day(toll 4.90 for a light car).
The bridge, which was designed by English architect Sir
Norman Foster, is supported by seven concrete pillars, thetallest of which, at 336 metres, is higher than the Eiffel
Tower in Paris (324 m including its flagpole). Each of the six
central spans measure 342 metres. The bridge was actuallyconstructed by Compagnie Eiffage, the same group that built
the Eiffel Tower. There is enough steel in the decking alone—
36 000 tonnes—to build the equivalent of five Eiffel Towers
while 205 000 tonnes of concrete were used for the pillars andsupports.

The Worlds tallest road bridge is seen from space by the European
Space Agency’s PROBA microsatellite on December 11, 2004.
Image: ESA

The Millau bridge, which is part of the A75 motorway, can beseen from space and was photographed by the ESA Proba
satellite’s high resolution camera [HRC] which has a 5-metre
spatial resolution, on December 11, 2004.

Proba
Proba is a microsatellite developed by ESA’s General Support
Technology Programme (GSTP) and built by an industrial
consortium led by the Belgian company Verhaert. Proba waslaunched from India on October 22, 2001 and is operated fromthe ESA Ground Station at Redu in Belgium. Its main Compact
High Resolution Imaging Spectrometer (CHRIS) instrument was
funded by the British National Space Centre (BNSC) and built
by UK company SIRA Space.
Proba was intended as a one-year technology demonstration
mission but has had its lifetime extended to serve as an Earth
Observation mission.
A follow-on technology demonstrator called Proba-2 is due to be
deployed in late 2006 or early 2007 depending on the available
launch opportunities.
Thanks to ESA for the image and information about Proba.

Above: the Millau Viaduct sweeps majestically above the Tarn Valley

Artist’s impression of PROBA in orbit.

Photo: Daniel Lavabre

Image: ESA

12

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June 2005

Group for Earth Observation

GEO Quarterly No 6

Peter Wakelin

The MODIS instrument aboard NASA’s Terra satellite
imaged this spectacular set of vortices stretching across thenorth Atlantic between Iceland and Norway on March 28,
2005.
These vortices were not caused by a physical obstruction as
in the case of von Karman vortices but are almost certainly
caused by pronounced wind shear on the curved trajectoryblowing around an anticyclone to the north. The strong, cold,
dry, northeasterly flow off Norway is cloudless initially but
soon picks up moisture from the relatively warm North Sea
and shallow convective clouds develop which enable theeddies in the turbulent flow to be seen.
This can be likened to the flow in a fast stream; the flow inthe deeper, fast flowing middle is usually laminar andturbulence-free whereas, towards the edges, and especiallyon bends, the flow speed is reduced by friction and eddies or
whirlpools can often be seen.
Quite remarkable cloud patterns associated with wind shear
can frequently be seen at any level in the atmosphere where
there is a significant change in wind speed over a shortdistance either in the horizontal or vertical. One of the bestplaces to look is on the north side of the sub-tropical jet
stream over north Africa which is usually evident as a bandof high-level cirrus cloud on Meteosat images. The cirrus is
usually tenuous and often inconspicuous on the visible
images so the turbulence patterning, often of a 'herring-bone'nature, is best seen in the thermal IR channels. Speeds inexcess of 100m/s (200 knots) are regularly recorded here withmarked wind shear, especially when the airflow is curved.
Although the height of the sub-tropical jet's core is generally
above the flight levels of civilian aircraft, pilots are aware of
the risk of extreme turbulence in this region.

GEO held a highly successful Weather Satellite Symposium
at the end of April and a full report on proceedings will appear
in our September issue. Over 60 delegates and speakers
attended including several from overseas. One of thehighlights of the day was a talk on the US weather satellite
program from Ed Murashi while several members of the
Dutch Werkgroep Kunstmanen held workshops and spoke ona variety of topics.

Pictured above enjoying informal discussions over breakfast prior to the
GEO Symposium in the National Space Centre are (l to r) Ed Murashiewith Rob Alblas, Arne van Belle and Ferdinand Valk from the Netherlands.

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13

GEO Quarterly No 6

Group for Earth Observation

June 2005

Arne van Belle - Co-ordinator, Radio Observers, Werkgroep Kunstmanen
EUMETSAT recommends use of quite a powerful PC for the
reception of EUMETCast, its DVB dissemination route for
Meteosat-8 pictures and the many other data products that aretransmitted using the Hot Bird 6 satellite. This is not without
reason! From experiments it has become clear that a lowspecification PC rapidly becomes overloaded and starts to lose
image segments (horizontal segments of the picture remainblank).
After a thorough study of the complete reception process,experiments and discussions with David Taylor, I concluded
that the hard disk is mainly to blame. By reserving part of the
PC memory as a RAMdisk, andinstructing the reception process to
use this instead of the hard disk,
you can receive EUMETCast using
a much lower specification PC.
A clean installation of Windows2000 (Service Pack 3 or higher)
plus sufficient memory in your PC
is a first requirement. Windows 98
and ME are not suitable. In these
operating systems, the reception
buffer is too small and it is thisproblem that causes many missing
segments.

A Meteosat-8 channel-9 IR
image illustrating a missing
segment© EUMETSAT 2005

The RAMdisc approach does also work with Windows XP, but
tends to load the CPU and memory a bit more compared with
Windows 2000, especially on older PCs where resources may
be scarce.
Why Does a RAMdisk Help?
The Tellique software uses a temporary file (called ‘0.fsy’) tobuffer the received data stream. All received data is ‘dumped’directly into a database to keep up with the continuous stream.
Only later is this database analysed and the data assembled
into complete files. There is a separate file for each segment ofimage data.
From my experiments it has become clear that you can losesegments at times when there is a lot of activity on the harddisk. At these moments, Tellique is not able to access the
database in the 0.fsy file quickly enough and therefore loses
some of the incoming data stream.
As a side-effect you may notice that, during bad reception
conditions or when using a slow PC, the 0.fsy file size increases
rapidly. This is because the database is becoming clogged withincomplete data that could not be converted into files.
By telling Tellique to maintain this database on RAMdisk, you
can drastically improve access times and so prevent data loss.
Tests have shown that disk usage will decrease from 30% to
7% when Tellique is using a RAMdisk instead of the hard disk.

14

Using the method described here I can now receive
EUMETCast using a 400 MHz Pentium II. This PC can receive
all the HRIT + FSD data and decode them using MSG DataManager while at the same time updating and displaying an
HRV animation using MSG Animator.
Before using the RAMdisk I had to be very cautious whenmoving decoded images to my GeoSatSignal processing PC; I
even had to lower my network transfer speed to 10 Mbit/s toprevent segment loss. But now I don’t suffer from lost
segments when moving all one day’s images at 100 Mbit/s.
But you do need sufficient memory in the PC and take care tolimit tasks on it. Using 384 Mb of memory I can receive anddecode all HRIT channels and FSD (GOES 9,10,12 and Met-5)
as well as run MSG Animator (although updating only one
animation). You can run with less memory by decoding only aselect number of HRIT channels and not running MSG
Animator. To prevent heavy paging to hard disk you shouldhave at least 192 Mb RAM.
Also, disable all other tasks like virus scanner, screensaver,automatic updates etc. to free up as much memory as possible.
But never use an unprotected PC to perform any downloads
from the Internet.
Adapting Your EUMETCast PC to run with RAMdisk
I assume that you already have the Skystar2 DVB card,
Tellique software and the EKU installed on this PC. Download
the RAMdisk software (just 93 kb) from:http://www.arsoft-online.de/products/product.php?id=1
It is a free program suitable for Windows NT, Windows 2000
and Windows XP. Install the RAMdisk, by double-clicking on
RAMdisk setup.exe.
• Go to Start, Settings, Control Panel and double-click the‘RAM disk’ icon
• Set the drive letter to ‘Z:’ and click on the ‘Geometry’ tab• Set ‘Disk size’ to 25 Mb (using the slider or arrow keys
left/right)
When running Windows XP, you must also set ‘Emulate a local
hard disk’ under the ‘General’ tab.
Now Reboot the PC
First make a backup of the folder
C:\Program Files\T-Systems\BusinessTV-IP
called
C:\Program Files\T-Systems \BusinessTV-IP-backup
If you use an older setup you will find all the files in folder
C:\Tellique but the changes mentioned below are the same.
Edit the file ‘recv.ini’• Change ‘log_file_number = 30’ to ‘log_file_number = 2’
• Change also ‘log_level = normal’ to ‘log_level = quiet’

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June 2005

Group for Earth Observation

GEO Quarterly No 6

Now edit file ‘recv-channels.ini’Change the line‘#temp_directory = receiving/tmp’
to‘temp_directory = Z:\receiving/tmp’
Pay attention to the use of ‘\’ and ‘/’. They must be enteredexactly as shown (Tellique’s origin is UNIX !).
This change instructs Tellique to buffer received data on
RAMdisk during build-up of a file. Only once a file is completed
is it moved to the target directory on hard disk.
You need to restart Tellique to make these changes effective.
Tellique will create a file called ‘0.fsy’ in ‘Z:\receiving\’.
Within a couple of minutes data should be coming in again.
Points to watch during first week running with
RAMdisk
The free space on Drive Z: should never be less than 1 Mb; ifnecessary increase RAM disk size a bit.
Setting the size of the RAMdisc

These changes ensure that Tellique does less logging andcauses less hard disk access. A side effect is that you will only
see errors in the log, not the normal messages.
Under [locations] add the line below
file_database_directory=Z:\receiving
This entry instructs Tellique to place the 0.fsy file on RAMdisk
in folder ‘receiving’ and not on the hard disk.
Under [parameters] add the line below(If this line already exists, then only change the number)
file_database_size = 24 576 000
This ensures that the 0.fsy file cannot overfill the RAMdisk(24 x 1024 kb).

EUMETSAT’s latest Operations Bulletin, No 11, was issued in
January this year, updating its predecessor, issued in December
2003.
New EUMETSAT Domain Name
As of February 2005, the official EUMETSAT Internet domainchanged from eumetsat.de to eumetsat.int. Users wishing toaccess EUMETSAT Web pages should update their web
browsers with the new address. Likewise, the new Helpdesk
e-mail address is ops@eumetsat.int.
Geostationary Satellites after 2005
As was intimated in GEO Q4, page 26, all direct transmissions
from Meteosat-6 and Meteosat-7 will cease once Meteosat-9(MSG-2) is successfully commissioned. The date for this switchoff is anticipated to be during December 2005 and all Wefax and
PDUS users should have equipped themselves for EUMETCast
reception by that time.

Check Task Manager, Performance and ‘Memory usage’
regularly. The average over a day should be below the total
amount of physical memory. A temporary peak can be handled
by paging to hard disk but excessive paging will lead tosegment loss. If necessary free up memory by de-selecting
channels in MSG Data Manager or installing more RAM.
Normally the hard disk LED will light up regularly in shortbursts. But if the LED lights up almost continuously forseveral minutes the load on the disk might be too high. You
should be aware that older hard disks not only have a smaller
capacity but also have a lower transfer rate. Replacing by adisk with 7200 rpm and an 8 Mb buffer can improve the overall
performance of an older PC considerably. But be careful withlarge hard disks (over 40 Gb). Check in your motherboard
manual about using large hard disks as you may need to
upgrade your BIOS to use them.

The following paragraph is of p[articular interest!
The forthcoming EUMETSAT Polar Services (EPS) will include:
Metop Direct Readout (local reception) – consisting of direct
instrument readout data delivered to the user as the satellite
passes over the field of view of the local reception station.
These data are available in high and low resolution and canbe received by Advanced High Resolution Picture Transfer(AHRPT) and Low Resolution Picture Transfer (LRPT)
reception stations respectively. Under nominal operations,these data will be unencrypted and available to users
without licence and without charge.
Operations Bulletin No 11 may be downloaded from:www.geo-web.org.uk

http://www.eumetsat.int/en/dps/helpdesk/
documentation/pdf/newsbulletin11.pdf

15

GEO Quarterly No 6

Group for Earth Observation

June 2005

C.S. Loh and Kimberley Loh Ying-Ying
Much has been written elsewhere about
the tsunami event that devastated many
countries bordering the Indian Ocean on
December 26 last year. But peninsular
Malaysia, though much closer to theearthquake epicentre than Sri Lanka andabout the same distance away as
Thailand, suffered comparatively fewer
casualties. We believe that this probably
resulted from specific local conditions.

shallow water. This allows the following
waves to pile on top of it, adding to its
overall height. This is illustrated for Khao
Lak on the Thailand coast in the IKONOS
images reproduced on page 17 of GEO
Quarterly No 5. More images and a DEMgenerated flypass by Kwoh Leong Keongcan be viewed at:

The Geophysical Facts

It is also noted that coral reefs, islets andother smaller islands (like Pulau Singa
Besar, Pulau Dayang Bunting and Pulau
Tuba which surround the main Langkawi
island) were able to deflect the impact bydisrupting some of the energetic wave
forms. Chalets in Langkawi, built withincoves and bays, and those facing reef
islets or islands offshore, escaped major
damage.

The earthquake induced thrust-faulting
and slippage along approximately 1200
kilometres of the boundary between theAustralia-India and the Burma-Sundraplates. It was estimated that the average
displacement on the fault plane was about
fifteen meters, uplifting the sea floor anddisplacing the overburden of water. This
caused waves to radiate out from thatlocation, those travelling towards the east
and west carrying much more energy thanthose heading to the north and south.

http://www.crisp.nus.edu.sg/
tsunami/khaolak_fly.wmv

The minimal damage incurred bypeninsular Malaysia compared with theIndian subcontinent and Thailand could
also possibly be attributed to the low tidecondition in the Strait of Malacca at thattime (figure 2). Bagan Datoh, which faces
the Strait at the estuary of Sungai Perak,
had a receding tide at 10:58 am on
December 26, 2004 and was shelteredfrom the monsoon winds by the Central
Highlands. Had the tsunami crashed inwith a monsoon behind it and at high tide,
it could have destroyed a lot more of thecoastal infrastructure along the Strait.
At Galle (Sri Lanka), Mergui (Myanmar)and Port Blair (Andaman Islands), it wasapproaching high tide when the tsunami
waves arrived. It is therefore not surprisingthat the waves were much bigger andstronger at those locations. Examples ofthe damage wreaked on Katchall Island in
the Nicobars is illustrated in figure 3.

Figure 1 - The earthquake epicentre

Location

Topographic Map: USGS

Whereas shallow coastlines such as thatof western Thailand tend to be hit by high,steep and often very destructive waves, alandmass rising abruptly from the ocean
depth, like the chain of Langkawi islands,
absorbs the energy of the waves andsuffers less severe damage.
The explanation is that the tsunami’s
leading wave slows down as it enters

16

Galle
MadrasTrincomalee
Port Blair
Mergui
Belawan
Bagan Datoh
Port Dickson
Malacca
Singapore

Longitude(east)
80°13'
80°18'
81°13'
92°46'
98°36'
98°43'
100°45'101°47'102°15'103°51'

Latitude(north)06°02'
13°06'
08°33'
11°41'
12°26'
03°50'
04°00'
02°31'
02°11'
01°16'

Following the earthquake, it was reported
that the land elevation at Port Blair in the
Andaman Islands had shifted by as muchas 1.2 metres and fishermen were sighted
standing knee-deep on flooded roads tocast their nets: ‘The sea has brought thefish closer to us’, said one resident.
The Geographical Features
Mangrove forests, known locally as bakau,
act as a ‘vegetable belt’ that protects theStrait’s coastal areas from the states ofPerlis in the north to Johore in the south. It
may well be that they helped to soften thetsunami’s impact by absorbing much of theenergy of the waves pounding upon the
shores.
On Penang island, fishermen found that
there was less damage to their houses inareas where the mangrove swamps weremore abundant. The mangrove tree(rhizophora) is an efficient soil binder, witha dense root and branch structure, andthus contributed to a large extent to thecushioning of the impact of the oncoming
waves. At the height of the waves’
insurgence many fishermen clung to themangrove trees and indeed, some evenHigh Tide(metre)
0.57
0.94
0.55
1.64
4.27
1.98
2.34
2.53
2.17
2.84

Local Time
2:23 pm
8:06 am
7:59 am
8:50 am
10:23 am
1:43 pm
4:47 pm
6:40 am
8:09 am
10:42 am

LOW TIDE(metre)
0.21
0.28
0.23
0.49
0.77
0.60
0.48
0.69
0.60
0.30

Figure 2 - Tide Conditions in Selective Locations on December 26, 2004
www.geo-web.org.uk

Local Time
8:34 am
2:05 pm
1:39 pm
2:3 pm
4:27 pm
7:35 am
10:58 am
1:12 pm
3:10 pm
5:37 pm

June 2005

Group for Earth Observation

GEO Quarterly No 6

Figure 3 - SPOT-5 images showing Tsunami damage on Katchall Island - July 10, 2004 (left) and December 28, 2004 (right)
SPOT-5 images © CNES 2004, acquired and processed by CRISP, National University of Singapore

Figure 4 - Mangroves, with aerial roots exposed
Photo: C S Loh

Figure 5 - Beach lookout tower

Figure 6 - Location of Batu Ferringhi on Penang Island

Photo: ‘The Star’ local newspaper

Credit: Tiungsat-1, May 17, 2001 - © Astronautic Technology (M) Sdn Bhd

www.geo-web.org.uk

17

GEO Quarterly No 6

Group for Earth Observation

took refuge within the mangrove swamps
where they were shielded from the fullforce of the tsunami.

Bypassed by the Indian Ocean’s cyclones
and Pacific Ocean’s typhoons, andsituated just outside the volcanic belt ofSoutheast Asia, the perceived security has
been shattered by this seismic movement.

The tiny island of Simeuleu, situated off
the devastated Banda Aceh peninsula innorthern Sumatra, and just 40 kilometresfrom the earthquake epicentre, was saved
by wide belts of mangroves which acted
as natural buffers between the sea and thecoast. These limited the full fury and wrathof the tidal waves and the island suffered
only four fatalities. Eyewitnesses reported
that although the tsunami penetrated themangrove belt, the water rose smoothly,
like a rising tide.
However, mangrove forests in Southeast
Asia (figure 4) are under threat, partly by
man-made pollution (which limits the
propagation of mangrove plants) and as aresult of development. It is no coincidence
that there were higher casualties in the
Kuala Muda estuary of Kedah where morethan 2 500 acres of mangrove forest had
been cleared since the 1990s.
Off the state of Kedah in the north-west of
Malaysia lies a cluster of 104 islands, thePulau Langkawi archipelago, which is aholiday resort not unlike Phuket in
Thailand. Although there were mud anddebris to be cleaned up following thetsunami, the hotels remained intact andthe airport remained operational, as did
the ferry services between the islands andthe mainland. And although Langkawi
emerged from this event relatively
unscathed and without any tourist
casualties, there was physical damage toproperties, especially luxury boats moored
off hotels facing the Indian Ocean.
The extensive coral reefs and scatteredoffshore islets surrounding the main Pulau
Langkawi islands acted as solid barriers
against the sea, limiting the power of thetsunami surge and protecting beach-side
hotels and villas. Also, some beaches
were sheltered within bays protected by aheadland facing the Indian Ocean (e.g.
Penang’s Batu Ferringhi, behind Mukah
Head), which partly reduced the strengthof the onrushing waves. Even so, some of
the waves were as high as palm trees.
Another reason why sunbathing tourists
escaped major casualties may be that
Penang island was partially sheltered fromthe impact of oncoming tsunami waves by
the headland of Sumatra.
The Human Factors
The Ferringhi Baywatch Tower early
warning system on the Penang coast iscredited with saving many lives and there
were no reported casualties along the twokilometre beachfront in Batu Ferringhi.
The location is shown in figure 6, a 72-

18

June 2005

Acknowledgments
The satellite images from IKONOS and SPOT 5
in this article were acquired by the Centre for
Remote Imaging, Sensing and Processing(CRISP) at the National University ofSingapore, with gratitude from the authors.

Figure 7 - An IKONOS image showing the seawall sheltering Pulau Langkawi International
Airport - December 29, 2004.
Image: Spaceimaging

metre false colour image from Malaysia’s
Tiungsat-1 microsatellite.
Around noon on that fateful Saturday,
lifeguards at a beach tower (figure 5)
noticed rough and choppy waters and a
red flag was raised to warn people that thebeach was not safe. All beachfront hotels
then warned their guests to stop all
activities and move away from the beach.
Several minutes later, the first of the large
waves hit the beachfront. Between Kuala
Teriang and the Cehang river, an 8 km
long 3-metre high sea wall softened theimpact of the waves on the coastal
defences sheltering the Pulau LangkawiInternational Airport (figure 7). This
structure prevented the incoming tsunami
from destroying more inland areas.
However, the nearby fishing village of
Kuala Teriang was not sheltered by thisbarrier and the tsunami killed one villager
and damaged or demolished 139 houses.

Figure 8 - C S Loh is a lecturer with Informatics
in Kuala Lumpur. He is pictured above amidst
mangroves, receiving wxsat signals with ahome-made QFH built from SWG21 copper
wire and a 1.8 metre glassfibre fishing rod—the
CAST (Compact Antenna for Satellite Tracking).
The antenna is connected to an RX2 receiver
operated from a 9-volt battery and enclosed
within a video-cassette holder: the CLEAR(Compact Light-mobile Experimental APT
Receiving) system.

The Aftermath
Following the devastation from thetsunami there were numerous amazing
tales of survival: one of the more
miraculous was that of Malawati Daud.
Malawati was washing clothes at herhouse two kilometres from the sea when
the killer waves swept through her home in
the Aceh Jaya district of Sumatra andswept her out to sea.
Malawati was eventually rescued, fivedays later, by the crew of a Penang-based
tuna boat 185 kilometres out in the Indian
Ocean. She was discovered clinging to an
uprooted one-metre length of nipah palmand had survived by eating small clustersof nipah fruit.
The Indian Ocean tsunami experience hada deep impact upon Malaysians.
www.geo-web.org.uk

Kimberley (above) is a Form Four Gamma pupilof Sekolah Menengah Kebangsaan (National
Secondary School) Seri Bintang Utara (BrightNorth Star), Kuala Lumpur where she is aschool prefect and basketball player.
Kimberley has twice attended the Outward
Bound School’s programme in Lumut, Perak. In
November 2004, Kimberley had the fortunate
opportunity to greet Prince Andrew when, as its
Patron, he visited the School. Kimberley enjoys
reading, kayaking and travelling. Kimberleyresearched this article as part of her term
assignment on “Typhoons, Tornados andTsunamis”.
Homepage of C.S. Loh:http://geosat.homestead.com/
homepage.html
Homepage of Kimberley Loh:http://kimberley.homestead.com/
loh.html

June 2005

Group for Earth Observation

GEO Quarterly No 6

Francis BellI would like to report an observation I made recently which I
have never seen before and which I am unable to explain.
Perhaps one of GEO’s readers could offer an explanation.
This observation relates to a double image of the moon as seenfrom the southern tip of the Sinai desert, Egypt at 7.00 pm
local time on March 11, 2005. The location was latitude 28°N,
longitude 34°E; the angle of the moon in the sky was adjudged
to be about 40 degrees (not measured).
There had been some intermittent winds during the day but
the sky was mostly clear with sunshine. The daytime
temperature had been about 32°C, dropping to around 25°C
that evening. The early night sky appeared to be quite clear.
Figure 1 illustrates, as best I can judge, what I saw.
Unfortunately I have no photographs just naked eyeobservations.
This is what happened. At the location described I received atelephone call from a friend who was staying in a building
about 200 m away. He said: ‘I can see two moons’. In mild
disbelief I went outside, looked up at the sky, and indeed there
were two distinct images of the moon. There were two crescentmoons slightly, but distinctly from my perspective, verticallydisplaced. Also, the rest of the moon’s face was faintly
illuminated. In total a very unusual sight.
When the angles are correct I know the moon can beilluminated by reflected light from the Earth as well as direct
sunlight. I have seen this many times before. So had
Shakespeare: ‘The new moon with the old moon in her arms’.
But an explanation for this double image defeated me.
I know that people can sometimes see double. Two eyes with a
confused brain, by accident, indulgence, or other reason may
see double. However, unless you are in a very unusual position
this effect produces a horizontal displacement of an image; butwhat I saw was a vertical displacement. It was not just I who
saw this—four of us agreed on the observation. I rashly
promised one of my friends an explanation within six months.
Keeping my mouth shut I mentally ran through a few possible
explanations. I know the atmosphere is not uniform and light
can be bent by refraction as it passes through the atmosphere.
Unusual effects can be observed. From a low cliff top in
western Wales I have seen the silhouette of the Comeragh
Mountains in County Waterford, Ireland. With light travellingin a straight line this should be impossible. Under somecircumstances, usually at evening time, low angle incident
sunlight is progressively refracted into a curve so that it
becomes possible to see structures below the geographic
horizon.
This type of explanation does not seem viable in this casebecause it would still generate a single image. I am trying to
explain a double image of the moon.

Figure 1 - An artist’s reconstruction of the double moon

I know that the mineral calcite, in its very pure form Iceland
Spar, can refract light in two directions.
with light striking the crystals at a particular angle the light
can be refracted in two directions, that is, Iceland Spa exhibits
two refractive indices. But I was not looking through Iceland
Spar I was looking through the atmosphere. I understanddiffraction but I think that, if this was the explanation, I
might have seen a series of images. I only observed two very
sharp images.
Our atmosphere contains a mixture of gases and is variously
layered, some of the layers being ionised. I also know that it
contains particulate matter; dust and a wide range of
microscopic crystals from sea water. Can this particulatematter under some circumstances, behave like Iceland Sparby generating a double refractive index in the atmosphere?
There are two questions.
• Why did I see two images of the moon on the evening inquestion?
• Are the sensors on weather satellites subject to this effectfor reflected light and other emitted radiation comingback from the Earth to a weather satellite’s sensors? The
radiation must pass through the same effect in theatmosphere if this effect exists.
If anybody can explain my/our observation and its impact on
weather satellite imaging it would be great to know theanswer.

www.geo-web.org.uk

19

GEO Quarterly No 6

Group for Earth Observation

June 2005‘Vegetation’ images showing the unusual whorl of cloud over France on February 5 (l to r: NOAA 17 at 11:05 UT and NOAA 16 at 14:06 UT)Image: NOAA CLASS Library - Processing HRPT Reader

The entire Brownie troup

Brownies Lorraine (left) and Stephanie at the Meteosat-8 station, supervised by Francis Bell20

www.geo-web.org.uk

The Meteosat-8 ground station

June 2005

Group for Earth Observation

In early February this year there
was some discussion on the MSG1 Internet group concerning aninteresting cloud phenomenon
spotted over northern France.
One report likened it to a 'mini
hurricane' and David Taylor
provided a NOAA 16 image forcomment. His image, and asimilar one from NOAA 17 taken
three
hours
earlier,arereproduced here together withpart of a surface pressure chart
for about the same time.

hilly area in the vicinity of l'Aigle
is near the bottom left corner ofthe images with flat, low-lying
ground to the east towards Paris.
Now stable air prefers to goaround hills rather than overthem and the pressure chart
confirms that this is happening
with the tightening of thepressure gradient (closer isobars)
in this region. This results ineddies forming to the lee of thehigh ground which, eventually,
break away and travel downwind.

We asked our meteorologicalexpert, Peter Wakelin, for histhoughts.

I was puzzled by the apparent
continuation of the wave motion
through these eddies; it isdifficult to visualise the physicalprocess which permits rotation
and wave motion in the samecloud so I suspect that the wave
cloud is at a higher level than theeddies.

Peter wrote:
Clearly there is a stable southerly
airflow over the area with amarked wave motion evident in
the shallow stratocumulus cloud
which is nicely enhanced by the
low elevation of the winter sun.
The NOAA 17 image shows asecond vortex near the bottom left
corner and, three hours later in
the NOAA 16 image, there's ahint of a third one developing.
I believe a glance at a
topographical map of the area
reveals what is happening here. A

The fact that the wave motion isevident over a wide area suggests
it originated over hills further
south, possibly in central France,
so it may well be at a higher level.
Temperature data from thethermal infrared channel isinconclusive on this point as thecloud is too thin and fragmented
to derive accurate temperatures.

GEO Quarterly No 6

Synoptic chart (12:00 UT)Francis BellIn February each year there is aninternational event for Brownies. Even
now I’m not quite sure what it is called,
Thinking Day on the Air or somethingsimilar. The idea is that, on a particular
weekend, Brownies from all over theworld contact each other either throughamateur radio or, nowadays, also via theInternet.
My local Three Counties Amateur RadioClub has been supportive of the local
Brownies, Guides and Scouts for many
years but this was only the second time I
had contributed to this event—for a
Brownie group in Hampshire. TCARC
club members, David, Paul, Damian andBob supervised the amateur radio andInternet communications while I took
my Meteosat-8 ground station (plus astandby laptop) along to the weekend
meeting. I set up the station quite
quickly and ran live images andanimations.
I was taken a little by surprise because I
thought I would set up on the Friday
afternoon, run the station all day
Saturday and then go home. But no!
Somebody slipped an extra day into theexperience and it lasted until the
Sunday afternoon. The Brownies hadbrought their own beds and bedding, and‘slept over’ rather than going home. I
must say they were delightful company.
My creature comforts dictated: home tobed—but I returned each morning.
The Brownies did take a fleeting interestin the weather satellite station but the
www.geo-web.org.uk

repeated question I was asked was: ‘Is it
going to snow?’ The UK Met. Office’s
forecast for Hampshire had been
marginal. I looked at the incoming
images and said: ‘Snow: I don’t think so’.
But I was wrong! Two days later we had
about 2 millimetres of snow which
managed to survive for half a day.
My laptop. Well, that was commandeered for Internet use but I was
happy to see it productively used by the
Brownies for Internet messages.
I was very pleased I attended. It’s great
to promote communications by andbetween young people. My thanks to the
Brownies for their company, friendshipand for feeding me at every opportunity.
(See photographs on page 20)

21

GEO Quarterly No 6

Group for Earth Observation

June 2005

This spectacular display of the Aurora Borealis over Europe was obtained by the USAF DMSP-15 satellite at 18:50 UT on January 21, 2005
Image: US Air Force Weather Agency

This NOAA 17 HRPT image from April 7, 2005 illustrates the flow of Arctic air thatbrought snow to much of Great Britain. Where the flow is intercepted by Jan Mayen
island, a clearly defined street of Von Kármán vortices is being generated.

This image of the vortex street was taken on the same date,
at a resolution of 250 metres per pixel, by the MODIS
imager aboard NASA’s Terra satellite.

Image: NOAA CL:ASS Library

Image: MODIS Rapid Response Team22

www.geo-web.org.uk

June 2005

Group for Earth Observation

GEO Quarterly No 6

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I

NOAA 12NOAA 15NOAA 17NOAA 12NOAA 15NOAA 17

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10:48 12:28 20:36 22:15
10:25 12:05 20:13 21:52
10:02 11:42 21:29 23:11
09:40 11:19 21:06 22:47
10:57 12:37 20:44 22:24
10:34 12:14 20:22 22:01

Jul 01 05:41 07:22 15:28 17:08
Jul 02 05:17 06:57 15:04 16:43
Jul 03 04:52 06:32 14:40 16:18
Jul 04 04:27 06:07 15:53 17:35
Jul 05 05:43 07:23 15:29 17:09
Jul 06 05:18 06:58 15:05 16:44
Jul 07 04:53 06:33 14:41 16:19
Jul 08 04:29 06:09 15:55 17:36
Jul 09 05:44 07:24 15:30 17:10
Jul 10 05:19 06:59 15:06 16:45
Jul 11 04:55 06:35 14:42 16:21
Jul 12 04:30 06:10 15:56 17:37
Jul 13 05:45 07:25 15:32 17:12
Jul 14 05:20 07:01 15:07 16:47
Jul 15 04:56 06:36 14:43 16:22
Jul 16 04:31 06:11 15:57 17:38
Jul 17 04:07 05:46 15:33 17:13
Jul 18 05:22 07:02 15:09 16:48
Jul 19 04:57 06:37 14:45 16:23
Jul 20 04:33 06:12 15:59 17:40
Jul 21 04:08 05:48 15:34 17:14
Jul 22 05:23 07:03 15:10 16:49
Jul 23 04:58 06:38 14:46 16:24
Jul 24 04:34 06:14 16:00 17:41
Jul 25 04:09 05:49 15:35 17:16
Jul 26 05:24 07:04 15:11 16:51
Jul 27 05:00 06:40 14:47 16:26
Jul 28 04:35 06:15 16:01 17:42
Jul 29 04:11 05:50 15:37 17:17
Jul 30 05:26 07:06 15:12 16:52
Jul 31 05:01 06:41 14:48 16:27

06:41 08:22 16:28 18:08
06:18 07:58 16:05 17:44
05:54 07:34 15:42 17:20
05:30 07:10 16:57 18:38
06:46 08:27 16:33 18:13
06:23 08:03 16:10 17:49
05:59 07:39 15:47 17:26
05:36 07:15 17:02 18:43
06:52 08:32 16:39 18:19
06:28 08:08 16:15 17:55
06:04 07:44 15:52 17:31
05:41 07:21 17:07 18:48
05:17 06:57 16:44 18:24
06:33 08:13 16:20 18:00
06:10 07:50 15:57 17:36
05:46 07:26 17:12 18:54
05:22 07:02 16:49 18:29
06:38 08:19 16:25 18:05
06:15 07:55 16:02 17:41
05:51 07:31 15:39 17:17
05:28 07:07 16:54 18:35
06:44 08:24 16:31 18:10
06:20 08:00 16:07 17:46
05:56 07:36 15:44 17:23
05:33 07:13 16:59 18:40
06:49 08:29 16:36 18:16
06:25 08:05 16:12 17:52
06:01 07:42 15:49 17:28
05:38 07:18 17:04 18:45
05:14 06:54 16:41 18:21
06:30 08:11 16:18 17:57

10:28 12:08 20:16 21:55
10:05 11:45 21:32 23:13
09:43 11:22 21:09 22:50
10:59 12:40 20:47 22:27
10:36 12:17 20:24 22:03
10:14 11:54 20:02 21:41
09:51 11:31 21:18 22:59
11:08 12:48 20:55 22:35
10:45 12:25 20:33 22:12
10:22 12:02 20:11 21:49
10:00 11:39 21:26 23:08
11:16 12:57 21:04 22:44
10:54 12:34 20:41 22:21
10:31 12:11 20:19 21:58
10:08 11:48 21:35 23:16
09:45 11:25 21:12 22:53
11:02 12:43 20:50 22:29
10:39 12:20 20:27 22:06
10:17 11:57 20:05 21:43
09:54 11:34 21:21 23:02
11:11 12:51 20:58 22:38
10:48 12:28 20:36 22:15
10:25 12:05 20:13 21:52
10:02 11:42 21:29 23:10
09:40 11:19 21:06 22:47
10:56 12:37 20:44 22:24
10:34 12:14 20:22 22:01
10:11 11:51 20:00 21:38
09:48 11:28 21:15 22:56
11:05 12:45 20:52 22:32
10:42 12:22 20:30 22:09

Sep 01 05:11 06:51 14:58 16:37
Sep 02 04:46 06:26 14:34 16:12
Sep 03 04:22 06:02 15:48 17:28
Sep 04 05:37 07:17 15:23 17:03
Sep 05 05:12 06:52 14:59 16:38
Sep 06 04:48 06:27 14:35 16:13
Sep 07 04:23 06:03 15:49 17:30
Sep 08 05:38 07:18 15:25 17:04
Sep 09 05:13 06:53 15:00 16:39
Sep 10 04:49 06:29 14:36 16:15
Sep 11 04:24 06:04 15:50 17:31
Sep 12 05:39 07:20 15:26 17:06
Sep 13 05:15 06:55 15:02 16:41
Sep 14 04:50 06:30 14:38 16:16
Sep 15 04:26 06:05 15:51 17:32
Sep 16 05:40 07:21 15:27 17:07
Sep 17 05:16 06:56 15:03 16:42
Sep 18 04:51 06:31 14:39 16:17
Sep 19 04:27 06:06 15:53 17:33
Sep 20 05:42 07:22 15:28 17:08
Sep 21 05:17 06:57 15:04 16:43
Sep 22 04:52 06:32 14:40 16:18
Sep 23 04:28 06:08 15:54 17:35
Sep 24 05:43 07:23 15:29 17:09
Sep 25 05:18 06:58 15:05 16:44
Sep 26 04:54 06:34 14:41 16:19
Sep 27 04:29 06:09 15:55 17:36
Sep 28 05:44 07:24 15:31 17:11
Sep 29 05:19 07:00 15:06 16:46
Sep 30 04:55 06:35 14:42 16:21

05:32 07:12 16:58 18:39
06:48 08:29 16:35 18:15
06:24 08:05 16:12 17:51
06:01 07:41 15:49 17:27
05:37 07:17 17:04 18:45
05:14 06:53 16:40 18:20
06:30 08:10 16:17 17:56
06:06 07:46 15:54 17:32
05:42 07:22 17:09 18:50
05:19 06:58 16:45 18:26
06:35 08:15 16:22 18:02
06:11 07:51 15:59 17:38
05:47 07:27 15:36 17:14
05:24 07:04 16:50 18:31
06:40 08:20 16:27 18:07
06:16 07:56 16:04 17:43
05:53 07:33 15:41 17:19
05:29 07:09 16:55 18:36
06:45 08:25 16:32 18:12
06:21 08:02 16:09 17:48
05:58 07:38 15:46 17:24
05:34 07:14 17:01 18:42
05:11 06:50 16:37 18:17
06:27 08:07 16:14 17:53
06:03 07:43 15:51 17:29
05:39 07:19 17:06 18:47
05:16 06:55 16:42 18:23
06:32 08:12 16:19 17:59
06:08 07:48 15:56 17:35
05:44 07:24 17:11 18:53

10:11 11:51 20:00 21:38
09:48 11:28 21:15 22:56
11:05 12:46 20:52 22:32
10:42 12:23 20:30 22:09
10:20 12:00 20:08 21:46
09:57 11:37 21:23 23:05
11:14 12:54 21:01 22:41
10:51 12:31 20:38 22:18
10:28 12:08 20:16 21:55
10:05 11:45 21:32 23:13
09:43 11:22 21:09 22:50
10:59 12:40 20:47 22:27
10:37 12:17 20:25 22:03
10:14 11:54 20:02 21:41
09:51 11:31 21:18 22:59
11:08 12:48 20:55 22:35
10:45 12:25 20:33 22:12
10:22 12:02 20:11 21:49
10:00 11:39 21:26 23:08
09:37 11:17 21:04 22:44
10:54 12:34 20:41 22:21
10:31 12:11 20:19 21:58
10:08 11:48 21:35 23:16
09:45 11:25 21:12 22:53
11:02 12:43 20:50 22:29
10:39 12:20 20:27 22:06
10:17 11:57 20:05 21:43
09:54 11:34 21:21 23:02
11:11 12:51 20:58 22:38
10:48 12:28 20:36 22:15

You can download a PDF version of these predictions from: http://www.geo-web.org.uk/predictions.pdf

IIwww.geo-web.org.uk

June 2005

Group for Earth Observation

GEO Quarterly No 6

MSG-1
A forum dedicated to Meteosat-8 (formerly MSG-1), where members
can share information about the reception hardware and software.

GEO Helplines

e-mail: MSG-1-subscribe@yahoogroups.com

Douglas Deans, Dunblane, Perthshire, SCOTLAND
All aspects of weather satellites from APT, HRPT to Meteosat-8
DVB/EUMETCast systems.
• telephone:(01786) 82 28 28• e-mail: douglas@dsdeans.freeserve.co.uk
John Tellick, Surbiton, Surrey, ENGLAND
Information about the hardware required to receive Meteosat-8 andadvice about registering for the various MSG services. John will also‘field’ any queries of a more general nature about any aspect of receiving weather satellite transmissions.
• telephone: (0208) 390 3315
• e-mail: info@geo-web.org.uk

Weather Satellite Reports
A group providing reports, updates and news on operational aspects ofweather satellites.
e-mail: weather-satellite-reports-subscribe@yahoogroups.com

WXtoImg
Users of the WXtoImg software package for capturing and imaging
NOAA APT can air their problems, discuss its features and ask questions about it.
e-mail: wxtoimg-subscribe@yahoogroups.com

Copy Deadline

Keith Holland, London, ENGLAND
Specifically, help for APT users (137 MHz band) and Meteosat-7 wefax.
• e-mail: geo@koholland.plus.com
David Strickland, Truro, Cornwall, ENGLANDDavid has set up his own wireless network system of three computers.
He has interests in electronic design and prototyping, general computing, microchip processors with various facilities and of course MSG
satellite imaging. He will be happy to discuss any of the above topics,
and to help anyone local, including viewing his setup.
• e-mail: David@Strickland.uk.com
Geoff Morris GW3ATZ, Shotton, Flintshire, NE WALES
Geoff has lots of experience aerial, coax,connectors, mounting hardware etc. Also done a lot of work with the orbiting satellites. Geoff isknow his way with most of David Taylor’s software. He has recently
started with MSG, so should be able to share his experiences with othernewcomers to this branch of the hobby.
• Tel: (01244) 818252• e-mail: gw3atz@btopenworld.com
Guy Martin G8NFU, Biggin Hill NW Kent, ENGLAND
Guy is prepared to advise anyone who wishes to receive MSG underWindows 2000. He also runs Meteosat-7 SDUS.
• agm@tonbridge-school.org
Hector Cintron, San Juan, Puerto Rico, USA
Hector is prepared to field enquiries on HRPT, APT, WEFAX, EMWIN
and NOAAPORT• Phone: 787-774-8657• e-mail: n1tkk@hwic.net
E-mail contact can of course be made at any time, but
we would ask you to restrict telephone contact to theperiod 7.00-9.00 pm in the evenings.

for GEO Quarterly No 6

Sunday, July 31, 2005
The Editor is always on the lookout for articles and images for inclusion
in GEO Quarterly. These can relate to all aspects of Earth Imaging,
especially:• Technical articles concerning relevant hardware• Construction projects• Weather satellite images• Reports on weather phenomena• Description of readers’ satellite imaging stations• Activities from overseas• Letters to the Editor• Problems and Queries for our experts to answer
Contributions should of course be original and, where possible, should
be submitted to the editor in electronic format (floppy disc, CD or email attachment). But we will also accept handwritten or typed copy
should the need arise.
Please note, however, that major articles which contain large numbersof satellite images, photographs or other illustrations should be submitted well before this date so that they can be prepared and made up
into pages in time for publication.
Images and Diagrams

Useful Internet
Discussion Groups

Images can be accepted in any of the major bitmap formats, e,g, JPG,
BMP, GIF, TIFF etc. Images in both monochrome and colour are welcomed for inclusion. Line drawings and diagrams are preferred in
Windows metafile and postscript formats.

There are a number of Internet-based discussion groups available toweather satellite enthusiasts. You can join any of these by sending an
e-mail to the appropriate address, with a request to subscribe. Indeed,a blank e-mail containing the word ‘subscribe’ in its Subject line is all thatis required. Some of the more useful groups and their contact addresses are listed below.

We can also scan original photographs, negatives and slides.
If your article submission contains embedded images and diagrams,
please note that we do also require, in addition, individual copies ofeach image or drawing which is not embedded within the article, formake-up purposes.

GEO-Subscribers
This is a group where GEO members can exchange information relating
to either GEO itself or Earth observation satellites and related matters.

Submission of Copy

e-mail:GEO-Subscribers-subscribe@yahoogroups.com

Satsignal
An end-user self help group for users of David Taylor's Satellite
Software Tools including the orbit predictor WXtrack, the file decoders
GeoSatSignal and SatSignal, the ATOVS and HRPT Reader programs,
the remapper GroundMap, and the MSG Data Manager
e-mail: SatSignal-subscribe@yahoogroups.com

All materials for publication should be sent to the Editor, Les Hamilton,
8 Deeside Place, Aberdeen, AB15 7PW, Scotland.
Materials may also be sent as attachments to the following e-mailaddress:
editor@geo-web.org.uk

Large attachments (1 Mb or greater) can be sent to:lesw.hamilton@gmail.com

www.geo-web.org.uk

IIIGEO Quarterly No 6

Group for Earth Observation

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June 2005

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IV

www.geo-web.org.uk

June 2005

Group for Earth Observation

GEO Quarterly No 6

Lindsay Vincent
On the front cover of this Quarterly is a NOAA-17 APT pic I
received on February 4, 2005, showing what was called in someparts of the media (and we all know how exited some parts of themedia can get!) a ‘southern cyclone’. It was reported that
‘Meteorologists described it as a southern Australian cyclone—similar to a tropical cyclone, but in a cold climate’. It did rotate
clockwise for several days.!
Most of Australia has been in drought for the best part of eight
years and here in Melbourne, we’ve had below average rainfall forthe last seven years. Our major dam (the Thomson) has fallen to
below 40% capacity. We’ve had stage 2 water restrictions forsome time, although, as I type this, the restrictions have eased,
as summer is now over.
Anyway, having set the scene….
This low pressure system caused a fair bit of chaos. It sat over
Melbourne for two whole days, dumping record rainfall on a dry
and parched state. Here in southeast Melbourne, I received a
total of 128 mm in 48 hours, with 120 mm of that falling in one
24-hour period. Some places in outer Melbourne experienced asmuch as 168 mm! Our average rainfall for February is only
40 mm, so we tripled that in one day!
The pic shows moist air from the tropical north coming down the
East Coast, and being fed into the low, along with cold and wet air
from the south which was being drawn into it as well.
Some Interesting Facts about this Low• It was the coldest day on record in Melbourne: 36°C on one
day followed by just 11°C the next!

• Wind speeds to 104 km/h, with gusts to 120 km/h in the
Snowy Mountains• 12 cm of snow fell on the Victorian Alps. Snow and sleet
were reported in Canberra, and on the New South WalesSouthern Highlands• Waves of up to 20 meters were reported in Bass Strait(between mainland Australia and Tasmania) causing minor
damage to some cabins of the passenger and car ferry(some portholes blew in!)
Early estimates of damage were put at AU $100 million just for
Melbourne. Trees and power lines were down everywhere, train
tracks blocked, major roads flooded. The wind woke me up at
3 am, so I lay there listening to the roof tiles rattling. The power
went off three times in 20 minutes and a transformer on a power
pole on the other side of the road put on a wonderful display!
Sydney, New South Wales, also took a beating, with severe
thunderstorms and golf ball-sized hailstones.
Down here in southern Australia, our weather patterns always
come from the west and head east. Not this time! The Bureau of
Meteorology issued a severe weather warning which included: ‘Adeep low pressure system, currently east of Melbourne, is
expected to move slowly westwards and will remain near
Melbourne this morning.’ Westwards? What the..?
It was one I wont forget in a hurry!.
I use an RX2 receiver, a 142 MHz pre-amp (mounted at theantenna) tuned down to 137 MHz, a tall narrow QFH (SteveBlackmore’s design) and the WXtoImg imaging software.

During February 15 the Internet newsgroups were abuzz with
reports of a sudden deterioration in the quality of APT signals
from NOAA-15. The signal was experiencing frequent nulls andit was widely speculated that another satellite, transmitting onor around NOAA-15’s frequency of 137.50 MHz, was the culprit.
Two days later, the problem was gone and all seemed well until
the interference returned with a vengeance on March 1.

It was eventually discovered that NOAA-6, a weather satellite
officially deactivated as long ago as 1987 had come back to life
and was emitting a carrier frequency that was interfering withthat of NOAA-15. The map above indicates the degree of overlapof the footprints of the two satellites on March 1.

This NOAA-15 channel-4 APT image acquired at 08:11 UT on March 1
this year is streaked with black lines. The effect, which manifests itself
every 15-days or so, is believed to result from co-channel interference
by a ‘rogue’ carrier frequency from the long-decommissioned NOAA-6

www.geo-web.org.uk

23

GEO Quarterly No 6

Group for Earth Observation

June 2005

Ruud Jansen
Translated by Chris van Lint

Around November last year, my wife
was once again looking for one of the socalled ‘last minute’ travel ‘specials’. Ourpreference has always been to visit theFar East but unfortunately there were
no cheap fares available on the Net atthe time. Next we thought we might
visit Goa (India) again: however the
hotel we wanted to reserve was fully
booked and this left us no alternative
but to look for somewhere else—as longas there was plenty of sunshine and aminimum temperature of around 25°C.
After some searching, my wife located avery appealing and reasonably priced
offer in a rather large country to thesouthwest—Brazil. We made a quick
booking, paid, and only then started tothink about the place we were about tovisit. The location was in the northeastof Brazil (Ceará Province), toward thesouthern border of the city of Fortaleza.
Our next step was to buy a Portuguese
dictionary and of course to surf theInternet for as much information as
possible (such things as whether ourmobile phone would work, availability of
ATM machines, city maps, transportetc.).
Naturally I had to gather my portable
weather satellite receiving equipment,
test it and carefully pack it away fortransport in my backpack as handluggage. I deliberately do not pack thiskit in my suitcase as, following thesecurity scan, the rather strange
collection of electronic items, wires andplastic components sometimes cause theairport security people to open myluggage for a more detailed check. In
any case, I often have to open myscanned backpack as well, following thesecurity scan, but by offering a plausible
explanation with the aid of copies of our
De Kunstmaan magazine and satellite
images I have produced myself, any
misunderstanding is quickly resolved.
While I was packing, I suddenly
remembered that I had read an article
in GEO Quarterly No 3 written by Les
Hamilton and Raul Fritz Teixeira. Rauldoes in fact live and work in the sameprovince where I was to spend myholidays, so I obtained his e-mailaddress from Les and contacted Raul.

24

In his reply Raul and his wife extended
a cordial invitation to us to visit thebuilding where he works as a
meteorologist. Not only that, he and hiswife insisted on showing us around theFortaleza area and introducing us to the
local culinary delights.
Funceme
My first visit was to Raul’s workplace,
the Fundação Cearence de Meteorologia
e Resoursos Hidricos (abbreviated to
Funceme). His department is called
DEMET, and at present they are very
busy predicting climatic developments
for the period of February to May. This
periodencompasses
theseasonthroughout which most of the rain falls.
Climatic prediction is more important
than a weather report since a major
problem in this province is the severe
droughts. Large reservoirs in the hills,
pipelines and artificial water channels
excavated by machines must ensurethat sufficient water is delivered for
agriculture and the population alike.
Many farmers in the hinterland moved
to the big cities after the last severe
drought and are now living in the city’spoor slum quarters. The weather iscritical for agriculture, fishery, road
construction, water processing andwater supply. DEMET also produces
daily 12-hourly weather forecasts(reduced 24-hourly at week-ends).
I was picked up by an official vehicle andtaken to a two-storied white building
which in the past belonged to theadjoining church, and was ushered to
the reception desk, from where I was
taken to Raul’s department (figure 1).
There Raul provided me with detailed
explanations about all the equipment
and software being used and I was able
to experience ‘live’ reception of a
NOAA-17 satellite pass. I was suitably
impressed with this organisation; they
have considerable computer capacity, asizeable number of network servers andlarge plotters. The reception antennas
are located elsewhere and we did nothave time visit them. But there are anumber of photographs showing theantenna arrangement on the Funceme
website where you can also learn more
about Funceme itself as well as viewwww.geo-web.org.uk

some recent weather images
Fortaleza (Ceará province). Visit:of

http://www.funceme.brAt our first meeting I had given Raul a
few copies of ‘De Kunstmaan’ containingsome of the weather images I had
obtained in Thailand using my homemade kit (the Pita 137 aerial, Kecil 137
receiver, minidisk and Sony miniature
notebook). He and his colleagues wereabsolutely amazed at the results. I gave
Raul a short demonstration of the
WXtrack, SatSignal and WXtoImg
software.
The Weather station
A demonstration weather shack has
been constructed in the courtyard of thebuilding, surrounded by a number of
meteorological instruments (figure 2).
The first of these to catch my eye was
the RVS rain gauge which records
precipitation (figure 3). An actinographto measure the intensity of the sun’sradiation (figure 4), a rain intensity
meter (figure 5), a sunshine autographto record the hours of sunshine during
the day (figure 6) and the weather shackitself, complete with wet and dry bulb
thermometers (figure 7), provide thevisitor with a good idea of how weather
conditions can beobserved andrecorded.
My own images
Of course I did not take my gear along
just to show it to others. I wasdetermined to make my own images.
After starting up my notebook and
WXtrack, I determined which satellite
would be most suitable to produce a niceimage from my location. Since Fortaleza
is located on the very northeast coast,
only water would be visible to the northand east. Hence only satellite passes
directly overhead or to the west ofFortaleza could be considered. The lateafternoon passes of NOAA-17 were notreally useable since the sun would beclose to the westerly horizon and there
would be insufficient illumination of thelandmass to produce a so-called ‘falsecolour’ image. That left only themorning pass. The next day I headed forthe beach and dangled my Pita 137 froma palm tree. There was always a brisk
breeze on the beach, which at times

June 2005

Group for Earth Observation

Figure 1 - Raul Fritx Teixeira pictured at his desk at DEMET.

Figure 2 - The weather stationin the courtyard

Figure 4 - The actinograph

GEO Quarterly No 6

Figure 3 - The rain gauge

Figure 5 - The rain intensity meter

Figure 8 - NOAA 17 at 12:33 UT on November 28, 2004, processed in
WXtoImg in MSA mode and Mercator projection.

Figure 6 - The sunshine autograph

Figure 7 - The wet and dry
thermometerscaused my light-weight antenna to fly horizontally like a kitetethered to a string. This strong wind also caused the verticalmeasuring-tape elements to distort and become folded in half or
twisted. Alas, my once-symmetrical antenna with its all-roundradiation pattern had changed into something resembling a
broken, wind-blown umbrella. This ensured that noise bands
spoiled a considerable number of images.

Figure 9- NOAA 17 at 14:10 UT on December 7, 2004, looking south
towards the River Amazon, showing interference

Images taken from the balcony were not much better; half way
through the pass I had to run with my gear from the balcony atthe northeast, through my hotel room, to the gallery in thesouthwest. Additionally, there were occasions when the strong
wind and heavy rain outside sent the antenna toppling to theground, so that the recordings failed. According to Raul a strong
cold front was active during this period. Nevertheless I did

www.geo-web.org.uk

25

GEO Quarterly No 6

manage to produce three images on thebeach, unfortunately with noise bands,
because I had to lower the aerial a few
times to straighten it out following
distortion by the wind. One of theseimages, from NOAA-17 at 12:33 UT on
November 28, is shown in figure 8.
I also made an attempt to produce animage of the Amazon region on
December 7 (figure 9). The maximum
elevation from my location in the hotel
was about 9° above the western horizon.
However some rather high dunes arelocated in close proximity to the hotel,
which meant that the satellite would
only be ‘visible’ from about 4° elevation.
A problem results from the relatively
narrow bandwidth of my Kecil receiver.
For black and white images thisbandwidth is more than adequate (which
was my original design criterion).
However, these days we are looking fornice coloured images in which theinfrared channel is used together withthe visual channel to produce a so-called‘false-colour’ image. For satisfactory
reception of the IR channel, a bandwidthof 28 kHz is required. If this is not thecase, the IR information will be ‘clogged
up’ in the band filter and will not
produce a nice coloured combination
image. Craig Anderson’s WXtoImg
program (which I used for these images)
provides an option to make somecorrections and adaptations to obtainacceptable results when using narrow
bandwidth receivers such as theGroup for Earth Observation

Kecil 137, scanners or FM-narrow bandwidth amateur receivers. However, I do
not as yet have any experience with thisoption but will most certainly explore
this feature at the first available
opportunity.
During the final week of our holidays,
making images on the beach was nolonger possible due to safety concerns.
During our stay at least four robberies
targeted at guests staying at our hotel
took place on the beach (two with guns
and two with knives). The last attack
occurred almost at the entrance of thehotel. There was a low-flying police
helicopter containing a sharp shooting‘gunman’, police cars everywhere withflashing lights and a TV crew in ourhotel, so there was plenty of ‘action’. In
any case it gave me the chance to makesome rather unusual holiday photos of
the resulting commotion and we wereeven able to recognise ourselves in the
coverage from a local TV station.
Brazil is a beautiful country with afriendly population. However there is anenormous gap between the incomes ofdifferent population groups. The
population of Fortaleza is aboutfour million, divided into a small groupconsisting of the rich, a middle class anda large group of poor people who live inslums distributed throughout the city.
Raul and his wife showed us thesurroundings and the natural beauty ofthis city during the four days that wewere there. We had the opportunity to

Do you or anyone you know run aMacintosh computer? GEO reader
Sergei Ludanov does just that, and wasvery much taken by the article on using
HRPT datafiles obtained via theInternet.
But Sergei had one problem. He doesn’t
have a PC, but does all his computing on
a Mac.
After unsuccessfully searching for a
program that would view these HRPT
images, Sergei decided to write his own,
and the result is MacHRPT.
The first version of MacHRPT is now
available for download from:http://homepage.mac.com/kd6cji
At the time of going to press, this was
version 1.1 although regular updates areplanned.

26

www.geo-web.org.uk

June 2005

enjoy many delicacies at a number of
local eateries. My wife and I would liketo take this opportunity to once again
thank Raul and his wife Poliana for thehospitality we were afforded by them. I
would also like to thank Funceme for
their cordial reception.
Also, my thanks also to Chris van Lint
for translating this article into English.
Equipment Details
AerialPITA137 (Home-made Resonant Quadrifilar
Helical Antenna)

ReceiverKecil 137 (Home made)RecorderSharp Minidisk MD-MT88

Decoding Software
WXtoImg (Craig Anderson)

Satellite Track Prediction software
WXtrack (David Taylor)

Reference
1 People are always asking me for plans tobuild the PITA-137 antenna, so I have
prepared a PDF file with instructions,diagrams and photographs. It is available inboth Dutch and English versions. You candownload the file (900 kb) from my websiteat:http://www.jendela.nl
Click on the image ‘Weersatellieten’ andthen on the link ‘Antennes 137 MHz’. Thistakes you to the ‘Antennes’ page with links toboth versions of the document.

This initial release can decode thecurrent NOAA HRP, LAC and GAC
telemetry files from CLASS (SAA). Anyof the individual channels may bedisplayed, and there are options forcreating colour composite images. At
present there are only a few basic image
processing tools, such as histogram
equalisation and geometric correction.
A feature article describing MacHRPT
will appear in the September issue of
GEO Quarterly.
Meanwhile, if you own a Mac, do try out
MacHRPT, and get in touch with Sergei
to let him know what you think of it.
Future enhancements will depend verymuch on user requirements.
Sergei can be e-mailed at:
kd6cji@mac.com

June 2005

Group for Earth Observation

GEO Quarterly No 6

C S Loh
Fanning into the Andaman Sea, not unlike a lotus leaf
floating in a pond, images of the Irrawaddy delta captured
on my RX2, have often fascinated me by the changing cloud
patterns over that region. Images received during theseasonal monsoons also display varied distribution of
sediment silting, towards the east of the Irrawaddy, in the
Gulf of Martaban. In recent years, having the privilege toview HRPT images captured at the Microsatellite Station in
Kuala Lumpur has further heightened my interest inobserving changes in the delta during the monsoon seasons(see figure 1). SPOT images (figure 2) from CRISP (theCentre for Remote Imaging, Sensing and Processing) at the
National University of Singapore present even more
intricate details of the region.
It is estimated that more than 350 million tonnes ofsediment are discharged annually by the Irrawaddy. This
sediment is composed mainly of silt and clay with less than
1% sand (unlike the Mekong and other major Asian rivers).
More than 80% of the annual river and sediment discharge
occurs during the southwest monsoon period between May
and September. During this period, discharged sedimentfrom the Irrawaddy, Sittang and the Salween rivers istransported clockwise along the coast, towards the Gulf ofMartaban.

Figure 1 - NOAA 17 image at 03:51 UT on January 29, 2005
Credit: Meteorological Services Division, National Environment Agency, Singapore

Figure 2 - A SPOT-5 image of the Irrawaddy delta on January 5, 2005
Image and processing: National University of Singapore’s CRISP

low carbonate sands and thick silty clays (illite, kaolinite,chlorite and smectites) with high amounts of mollusks.

Figure 3 - Map showing sediment distribution in the Gulf of Martaban

During the northeast monsoon period between November
and April, sediment plumes have been noted to move
westwards towards the Bay of Bengal, composing mainly ofAt the mouth of the Irrawaddy, broad estuaries meander overshoals and mangrove flats. Grasses and mangroves often clump
on to offshore sandbars, even during high-water levels. The
dendrite channels of the Irrawaddy delta are broad, about
20 km wide nearer to the Andaman Sea, but shallow at no morethan 20 m deep (figure 2).

www.geo-web.org.uk

concluded on page 39 ...

27

GEO Quarterly No 6

Group for Earth Observation

June 2005

Les Hamilton
Every once in a while, when conditions arefavourable, weird snaking cloud patterns
can show up on weather satellite images.
A good example can be seen south-westof the UK in Ruud Jansen’s superb
NOAA-17 image reproduced here.
These unusual cloud formations are ship
trails, a phenomenon that owes its origin
to the exhaust emissions from shipping
plying the oceans of the world.
The Formation of CloudTo understand how ship trails arise, it isnecessary first to detail how ‘normal’ cloudforms in Earth’s atmosphere. Ship trails
are, after all, just one particular form ofcloud, albeit man-induced.
Earth’s atmosphere contains water vapour
but this does not automatically condense
into liquid droplets to form clouds, evenwhen the temperature is well below
freezing. Cloud formation depends on thepresence of aerosols—suspensions oftiny, microscopic solid and liquid particles
dispersed throughout the atmosphere.
Cloud-forming aerosols originate, in themain, from natural sources like sea salt,
volcanic ash, desert dust and biomassburning but also, increasingly, through theburning of fossil fuels by man.
Aerosol particles often contain substancesthat dissolve easily in water (such as sea
salt, sulphur dioxide etc.) and it is thesethat provide the cloud condensation nuclei(CCN) around which water molecules
condense. If the air were devoid of aerosol
particles, cloud, mist and fog would neverform at all and the sky would be foreverclear and cloudless!
When do Ship Trails Form?
Ship trails generally form in the still, moist
air commonly associated with anticyclonicconditions, when the sea is overlain with astable layer of air at a similar temperature
to that of the water itself. This layer may on
occasions already contain thin cloud or
mist but it is in effect supersaturated andlacks sufficient CCNs to generate fullscale cloud.
When ships pass through this region, fineaerosol particles from their exhausts float
up through the moist layer of air where
they become additional CCNs. Thismeans that water vapour in the air now

28

Figure 1 - Ship trails west of Biscay - NOAA 17 APT - 11:48 UT on February 10, 2005
Image: Ruud Jansen

Processing: WXtoImg software

contains many more nuclei upon which tocondense and these produce new cloud
droplets where few may have existed
before. The outcome is that the cloud
becomes more reflective to sunlight.

leave shorter, wider, and more diffuse
trails. It is worth noting that ship trails often
reflect the direction and speed of local
winds as much as the direction and speedof the ship itself.

As a ship crosses the ocean its exhaust
issues a continual stream of CCNs in its
wake. Consequently, its path shows up asa trail of shallow stratus clouds—a 'ship
trail'. This cloud streamer often stretches
for hundreds of kilometres and can extend
tens of kilometres in width.

Ship trails normally persist for many hours
and sometimes remain visible for days on
end provided that the air mass
surrounding them remains relatively
undisturbed.

Generally speaking, the faster a ship
travels, the narrower, longer, and lessdiffuse its ship trail will be. Slower ships
www.geo-web.org.uk

Ship trails show up well in satellite images,
even those from low-resolution APTtransmissions. The trails show up moststrongly in reflected radiation (NOAA
channels 1, 2 and 3) where they appear as

June 2005

Group for Earth Observationbright lines that can be distinguishedclearly from any surrounding clouds. The
same trails are usually all but invisible in
the radiated infrared from NOAA channels
4 and 5.

Temperature
Inversions
Under normal conditions, airtemperature decreases with altitude.
That’s why high mountains retain
snow even during summer. A
temperature inversion is a situation
where this temperature decrease isinterrupted by the presence of alayer of warmer air at higher altitude.

What Conditions Favour Ship trails?
Persistent ship trails often form beneath a
low-level temperature inversion where
humidity is high and low-level stratus or
stratocumulus cloud may already exist.
Such conditions are most likely to occur
during conditions of high pressure when
the lower atmosphere can become
especially calm due to a layer of warmer
air lying approximately 500 meters above
the sea surface. This effectively places a‘cap’ over the cooler moist air below,
trapping pollutants and water vapour alike.
In general, ships vent their exhausts into
still, relatively clean marine air that suffers
minimal convective turbulence and which
is near-saturated and generally depleted
in CCNs. Under these conditions exhaust
fumes are able to rise only as far as the
top of the cool air-mass where particulates
greatly increase the number of CCNspresent (figure 2). The result is theformation of many tiny water droplets, too
small to produce precipitation, but which
form relatively low-elevation clouds that
resemble larger versions of aeroplane
contrails. Unlike contrails, ship trails lastfor many hours. The inside back cover ofthis issue features two more splendid truecolor MODIS images featuring ship trails.

Figure 2
A layer of moist air, relatively depleted incondensation nuclei, is trapped beneath a highpressure inversion. The ship’s exhaust fumes
can rise to the upper reaches of the trapped airmass but no farther, greatly increasing thenumber of condensation nuclei present. The
increased numbers of tiny water droplets
produced in the air-mass makes it morereflective, giving rise to the phenomenon of‘ship trails’ in satellite images.

Aircraft Contrails
Enthusiasts spotting these cloud trails on
their satellite images for the first time often
mistake them for aeroplane contrails.
Contrails (condensation trails) producedby jet aircraft normally form at altitudes ofeight kilometres and more, where the

GEO Quarterly No 6

Figure 3
An exceptional case of ship trails was observed
off the Bay of Biscay during a high-pressure
situation on January 26-27, 2003. The
NOAA-17 channel-2 image above shows many
persistent ship trails along the regular shipping
lanes entering and leaving the English Channel.
There is also clear evidence of how the trails
are modified by the effects of the wind.
GAC Telemetry: NOAA CLASS Library(http://www.class.noaa.gov)
Image: HRPT Reader/GeoSatsignal

temperature is around -40°C. Under these
conditions, water vapour in the exhaust
can change directly into ice crystals(without forming liquid water at all), a
process that does not require nuclei suchas dust particles.
Contrails can be observed in satellite
images, but show up most strongly in
NOAA channels 4 and 5—the very ones
where ship trails are least likely to bevisible. Contrails are much colder than theterrain beneath them and this temperature
differential shows up sharply in the radiantinfrared channels. Of course, contrails(and their shadows) also show up byreflected radiation, but are so narrow (afew hundred metres only) that they rarely
appear in APT images. They can,however, be readily identified in many
HRPT images.
Further Reading• Studying ship tracks
http://earthobservatory.nasa.gov/
Study/Pollution/pollution_2.html• Every cloud has a filthy lining
http://earthobservatory.nasa.gov/
Study/ShipTracks/• Scheepswolken studieobject
http://www.keesfloor.nl/
artikelen/zenit/shiptrail/
www.geo-web.org.uk

An inversion is an extremely stablelayer of the atmosphere which acts
rather like a lid. Rising currents of air
within the lower cool air mass lose
their buoyancy when they reach thewarmer, less dense inversion layer;
they cannot rise any higher and areforced to spread laterally. Any
pollutant particles released into thelower layer become trapped there
because normal convective mixing of
the atmosphere is prevented.
Phenomena associated withtemperature inversions are valley fog(where surrounding mountain peaks
may be bathed in sunshine) and redsunsets (caused by the build-up ofpollution particles).
What causes an Inversion?
Temperature inversions are produced
in a variety of ways. A familiar but
usually short-lived example occurs insecluded mountain valleys where
overnight radiative cooling of theground produces low-level air that iscolder than the air above. If thecooling is sufficient, valley fog may
form although the mountain peaks,
surrounded in the warmer inversion
layer, remain clear. This inversion
ends when the morning sun warms
the lower levels once more.
The type of inversion that results inship tracks is of longer duration, andis found within a region of highpressure. High pressure is caused bydescending air and as the airdescends it becomes compressedand experiences adiabatic warming.
This increases its buoyancy,
eventually arresting its descent andisolating a cooler, denser layer of air
below it. This is known as a‘subsidence inversion’. As highpressure systems often combine
temperature inversion conditions withlow wind speeds, they can persist fora long time, and provide ideal
conditions for the formation of ship
trails.

29

GEO Quarterly No 6

Group for Earth Observation

June 2005

Douglas Deans - douglas@dsdeans.freeserve.co.uk
As many of you will already know, there
have been some fundamental changes in
the way NORAD two-line element sets
(TLEs) can be downloaded anddistributed. The recent history of this iscomplicated and too lengthy to explain indetail in this limited column space. For afull appraisal of the events leading up to
the present situation I strongly recommend
reading the notes provided by Dr T Kelso
on his excellent web site at:

earlier do go to Dr Kelso’s web site for all
the background and up-to-date news.

The Important Notice page has full
explanatory notes dating back to August 3,
2004, outlining the problems, difficulties
and general headaches as events havedeveloped and progressed.

The situation is still changing and as I
prepare this column I have just heard thatDr Kelso has received the necessary
approval from Air Force Space Command
to redistribute TLEs and Space Situation
Reports obtained from the Space-Trackweb site. This means that for the moment
the Celestrak web site is once again
providing up to date element sets. This isindeed excellent news. Nevertheless, theapproval is only valid for one year and so
Dr Kelso is still encouraging all users toapply for a Space-Track account and hehas advised me that he intends to continue
offering his new software.

In simplistic terms the fundamental change
has come about as the Air Force SpaceCommand (AFSC) plans to provide spacesurveillance data, including NORAD twoline element sets, with the NASA OIG web
site closing down. This is further
complicated because public law prohibits
the redistribution of data from the newservice without express approval of theSecretary of Defence. However as I said

In order to help those who rely on element
sets, two items of free software have been
made available to the community at large.
The first of those has been written byDavid Taylor, already well known toweather satellite enthusiasts for his wide
range of excellent software; the other isfrom Dr Kelso. Remember, both sets ofsoftware require that you are a registereduser of the Space-Track web site at:

http://celestrak.com/NORAD/elements/

http://www.space-track.org/perl/login.pl
Registration, however, is free.
Kepler Manager v1.1.4
David Taylor’s program allows you tointerface with the new Space-Track website and greatly simplifies the downloadingof elements. The basic program is free but
for those who have a registered copy of his
WXtrack program there are a number of

GS1 All David Taylor's weather satellite programs and libraries, including the current releases of WXtrack, 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.
WXtrack
Satellite Tracking Programv 3.4.8
SatSignal

Creates images from wave files

HRPT Reader

Converts raw HRPT data files into images

v 4.1.0
v 2.5.6

GroundMap

Rescales satellite images

v 1.3.8

RX2 PassControl

Computer control program for the RX2 receiverv 3.0.2

GS2 A wide range of software for all aspects of weather satellite reception, including tracking, receiving, 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).
Collection D03

Scanner recorder v 1.8 (wave file recorder), *NOAA95/*FENG99 (software for the NOAA 95 HRPT project)

Collection D04

Wxsat (wave file recorder/decoder), Satmon (wave file recorder).

v 2.59AGSatTrack

Satellite tracking programv 1.33

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

Element Manager

2-line element manager

v 1.59

Footprint

Satellite tracking programv 2.10Irfan View

Image/slideshow viewer

v 3.80

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)

Paintshop Pro

Image processing program (30-day evaluation)

Satscape

Satellite tracker and wave file recorderSpace-Track TLE Retriever

Generates TLE files in 'Celestrak' style from data sets recovered from Space Track

Splitter

Utility program for splitting and reuniting large files

WXtoImg

WAV file recording and decoding program with many options.

v 2.02v 2.5.11

GS3 3DEM Package for 3D Terrain Visualisation
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.
GS4 Image CD
A wide selection of high-resolution remote images from a range of satellites, including stunning imagery from the Space Shuttle missions. A full description andsource if provided for each image.
GS5 Mars Rover Panoramics
A chronological account, in panoramic images, of the NASA Mars Rovers' progress across the Martian Terrain

30

www.geo-web.org.uk

June 2005

Group for Earth Observation

very useful additional features. Those include the ability toautomate the program using Windows scheduler, calling the
program directly from WXtrack and adding your own favourite
satellites to download. The use of Windows scheduler ensurescomplete freedom to schedule as you wish. A further bonus is
the ability to build up your own historic kepler data, useful for
programs which process non real-time data. The basic program
is available on GEO software CD GS1 (Program Extras >WXtrack) or, for more information and to download the program
go to :http://www.satsignal.co.uk
Space Track TLE Retriever v1.5.0
This second software offering has been provided by Dr Kelso in
conjunction with his Celestrak web site. The main purpose ofthis program is to allow users who have an active Space-Track

GEO Quarterly No 6

AMSAT-UK will be holding a Space Colloquium at the
University of Surrey in Guildford, England from July 29-31,
2005.
This 3-day event always attracts Radio Amateurs from acrossEurope as well as North America, Africa, Asia and the Pacific.
Over a third of those attending come from outside the UK. It
provides an opportunity to rub shoulders with the designers of
the Amateur Satellites and find out the latest news.
As in previous years there will be special beginners’ sessions toteach newcomers how to get started in the fascinating world of
Amateur Radio Space communications. You can get started
using little more than a standard dual-band FM hand-heldradio.
An antenna-testing range will be available to enable you tocheck out the gain of your latest antenna—not all commercial

account to download Space-Track data sets and use them togenerate data sets in the old Celestrak groupings. The groups
available for download from the Space-Track site have different
names and content which is inconvenient for those who havebeen downloading from Celestrak for a very long time. The
program addresses this issue. It can be run as and whenrequired but can also be set to download automatically,
although this is restricted to starting any time up until
90 minutes from setting, and updates can be set for once, twiceor four times per day. The downloaded data is automaticallyarchived in a file system.
The program is available on GEO software CD GS2 or, for more
information and to download the program go to :http://celestrak.com/SpaceTrack/TLERetrieverHelp.asp
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) for theappropriate amount. Nothing else is required.
The cost includes the CD, packaging, posting and a small
donation towards the cost of overheads. No fee is asked
from overseas members although an exchange of softwareor 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.

Some of the attendees at AMSAT’s 2004 Colloquium

antennas perform as well as you might think! Microwave
experts will be on hand with test equipment covering up to
24 GHz, so you can have your equipment tested and receive
professional advice.
There will be guided tours of the Surrey Space Centre with thesatellite mission control centre and the satellite assembly
facility. These tours are always popular and they provide a
unique opportunity to see satellites in various stages of
construction.
The RSGB GB4FUN van, which contains a fully equipped
satellite station, will be available during the event for visitors
to work the Satellites.
There is an extensive lecture programme ranging from highly
professional technical presentations to basic down-to-earth‘how to do it’ type talks.
Guildford is 40 miles from central London and is easily
reached from both London-Heathrow and London-Gatwick
airports.
Day passes and 2- or 3-day packages covering meals andaccommodation in the University campus are available. For
details contact the secretary, Jim Heck G3WGM
Tel: 01258 453959
E-mail: g3wgm@amsat.org
Website: http://www.uk.amsat.org/

www.geo-web.org.uk

31

GEO Quarterly No 6

Group for Earth Observation

June 2005

Mike Stevens - mikeg4cfz@tiscali.co.uk
Since writing my previous article in GEO Quarterly No 4, I am
now able to pass on my experiences as to how it has all worked
out for me—or not—as the case might be.
Winter has come and gone and we in the Weather Satellite
fraternity have been watching the pictures in awe; and we’vebeen forecasting the coming day’s weather well before the TV
weather-man or -woman has had time
to take breath. And yes: we wereright! It was going to rain, it didsnow, and the sun shone.

When I returned to the house the signal meter was indicating
red and I discovered that I had lost the signal completely. It
was a disaster! Just when I wanted the satellite to see what
was happening it was ‘dead’. It was a good thing that I still had
my Polar Orbiter NOAA APT system operational. I could atleast see the storm that was doing all the damage.

But what did it cost us in time andlabour to achieve all that? Those of us
who have taken the plunge and arereceiving the fantastic pictures from
Meteosat-8 will know the answer.
Since my last article I have had quite
a few e-mails requesting help or
assistance to get systems up andrunning, and most of the problems
seem to centre around the Tellicast
software and setting up the satellite
dish.

After the gale had gone and more
settled conditions returned I started
to repair the damage. Upon
examination, I noticed that the wind
had pushed the dish downward and I
had lost my elevation angle to the
Hot Bird-6 satellite—hence the lackof signal. As soon as I readjusted theelevation of the dish the signal
returned at 70% and, using thesignal strength meter in Setup4PC,
final adjustments to the dish gave mea maximum signal strength of 73%. I
then tightened all the bolts andbrackets to ensure this would not
happen again.

Since carrying out the repairs wehave had several gales in the area
As far as the software is concerned it
and I have suffered only very slightreally is a case of reading ‘Broadcast
loss of segments but as soon as theMeteosat 8 - 13:00 UT on February 19, 2005
System for Environmental Data’,
better weather returns I am going to
Image: © EUMETSAT 2005
EUMETSAT document EUM TD 15. I
try and locate the dish at a lower
stressed last time that you must read this paper through: to level in a more sheltered part of the garden. I have also
inwardly digest it before you attempt to load the software, and acquired a second satellite dish which I am going toto pay particular attention to entering your username and experiment with. That should be quite exciting, and I’ll will let
password by the copy/paste method. Incidentally, I have found you know the results.
the staff at EUMETSAT extremely polite and helpful—aMagnetic Variationdelight in this day and age. Well done to them!
One other question I have been asked was: ‘What is magnetic
Satellite Dishvariation?’
The satellite dish is something quite different. My own
experiences have been fraught with problems caused by the Magnetic variation is the difference between true north andhigh winds in this area of Dorset. When I first installed my magnetic north, and always has to be considered when using aown one I knew that it would be difficult to stabilise a 60 cm magnetic compass. The compass contains a magnetic needle
satellite dish in such a location, and I was right. I first noticed that points to magnetic north, which, in Britain, currently
a problem one weekend while the system was up and running; deviates from true north by 3°. When hiking or walking over
I was experiencing missing segments. At the time the wind long distances it is important to take magnetic variation into
was gusting to gale-force 8 from the west and it was dark and account.
wet. To go outside and see what was happening wasn’t quite
When using a compass to calculate the position of awhat I wanted to do: but I had to!
geostationary satellite, it is important to add 3° to yourSo out I went, with torch in hand and sou’wester on. When I compass reading in order to obtain its true direction. This may
saw the satellite dish I was amazed at its antics. It was not seem important until you consider that Hot Bird-6 andswaying from side to side and vibrating despite all the Astra are only 6° apart.
brackets I had used to secure it to the mast and the fact thatthe unit had been braced against the slope of the garage roof. I have included several pictures from my system to show the
All this just wasn’t enough. As soon as the wind dropped, the results of my labour. All were prepared using David Taylor’s
dish became more stable and the reception improved but that excellent software. I will report again from Dorset in the futurewasn’t the end of it. The next gale came from the north-west to let you know how the experimenting is going. Until thenand was even worse: at one time I thought I was going to lose remember that it is well worth all the effort—and the results
the dish completely as the wind was catching the back of it full are stunning.
on and the vibration was very severe indeed.
Software32

www.geo-web.org.uk

Meteosat 8 - a zoomed section from the 13:00 UT image on April 2, 2005

Image: © EUMETSAT 2005

GEO Quarterly No 6

Group for Earth Observation

June 2005

Les Hamilton
As we become increasingly aware of the
impact of Climate Change on our planet,
more and more satellite enthusiasts aretaking an interest in the production andanalysis of synoptic weather charts.
During the past year, there have been
articles by both Fred van den Bosch [1,2]and Ton Lindemann [3] describing how
they use the program Digital Atmosphereto superimpose synoptic information overtheir weather satellite images.
Digital Atmosphere has been around for along time now and the most recent
incarnation of the software, Digital
Atmosphere Workstation (often referred toas DAWS), launched during 2004, extends
its capabilities considerably.
Installation - Evaluation - Registration
DAWS can be downloaded from theWeather Graphics download centre at:
http://www.weathergraphics.com/dl/
At the time of writing, the current version isversion 1.1i (this is a 12.6 Mb download).
Registration for new users costs $89 forthe standard version. If you have alreadyregistered an earlier version, the fee is $68
to upgrade.
Once the download is complete, doubleclicking the mouse on the installation file,daws11i-std.exe starts the installation
process. You now have the opportunity toevaluate the fully featured program for 30days after which many of the program’s
most useful features such as scripting andthe loading/saving of maps are disabled.
Once you have evaluated the program,the chances are you will wish to purchasea copy. To do so, go to:
http://www.weathergraphics.com/
catalog.htm
As soon as you make payment you will
become a registered user, and be entitledto apply for your software key to fully
enable DAWS. To obtain your software
key you must first open your copy of
DAWS and click <Help → Register> on themenu-bar to open the Register window(figure 1). DAWS will already havecalculated your Serial Number (which isbased on the architecture of your PC) but
the Key Number field is empty.

34

Send an e-mail to:weather@weathergraphics.com
informing them of your Serial Number andrequesting your Key. You will shortly
receive a return e-mail containing the Key.
All you have to do now is type the key into
the blank field and click OK.
If you do not wish to purchase DAWS overthe Internet, you can find full details ofother ways to purchase and register thesoftware in the Help file (manual.pdf)
inside the application folder on your PC.

Figure 1 - DAWS Serial number

Note
Should you for any reason have to reinstall
Windows your Software Key will no longer
function. No major problem! As you are aregistered user, just e-mail your new
Serial Number to Weather Graphics as
before, and a new Key will be sent to you.
You will also need a new Key if you install
DAWS on a new PC.
Creating a Base Map
Although DAWS comes with a default
base map of the USA it is almost certainthat the first thing you will wish to do iscreate one for your own part of the world.
Open <Map → Generate base map>
(figure 2) and insert all the appropriate
parameters (such as latitude, longitude,scale, height and width) and press OK.
The orthographic base map created fromthis screen is shown in figure 3. This map
automatically becomes the default and will
display each time DAWS is loaded (until
you generate a different one). The
positional data entered to create the basemap is also stored by DAWS and used toposition synoptic data over it.

Figure 2 - DAWS Map configuration window

Preferences
Maps initially appear only in outline anduse the program’s default values for thecolours and rendering of features such as
coastlines, national boundaries, rivers,
lakes and so forth. These may all beedited to suit your individual taste byclicking on <File → Preferences → Styles>(figure 4). Here you can select fill colours
for the background (sea), land, lakes etc.
as well as colours for many linear features
such as land boundaries, rivers, andweather fronts. One feature that is‘missing’ in this version of Digital
Atmosphere, though, is the facility to set
www.geo-web.org.uk

Figure 3 - A typical DAWS Base Map

the styles for the multitude of analyticalcontours (isotherms, isobars etc.) from thePreferences menu. These, and indeed theentire Analysis drop-down menu, are now
dealt with through the DAWS scripting
language. The default Analysis menu isactually created by the editable filedigatmos.mnu. This resides inside your
DAWS folder, and can be edited using
Notepad both to modify existing options
and to add new ones.

June 2005

Group for Earth Observation

Temperature
Temperature (deg C) %2
Temperature (deg F) %3
Pressure
Sea level pressure (mb) %1

GEO Quarterly No 6

|CONT CINT=2 COLOR=200:0:0 DASH TEMP|CONT CINT=5 COLOR=200:0:0 DOTS DEGF TEMP|HILO CONT CINT=4 LINE=2 SLPR

Default temperature and pressure scripts as they appear in the digatmos.mnu file
Temperature
2 degree C intervals %2|CONT CINT=2 COLOR=200:0:0 SOLID TEMP
1 degree C intervals %3|CONT CINT=1 COLOR=0:0:0 SOLID LINE=2 TEMP
Pressure
Sea level pressure (4 mb isobars) %1|HILO CONT CINT=4 LINE=2 SLPR
Sea level pressure (2 mb isobars) %1|HILO CONT CINT=2 LINE=1 SLPR
Sea level pressure (1 mb isobars) %1|HILO CONT CINT=1 LINE=1 SLPR

Figure 4 - The Preferences/Styles tab

Modified temperature and pressure scripts.
Both temperature options now draw unbroken lines (SOLID). The Fahrenheit entry has beenedited to yield Celsius temperatures at 1-degree intervals (CINT=1), while the line display has
been coloured black (COLOR=0:0:0), the line thickness has been changed to 2 (LINE=2).
Two additional script lines have been added to display the pressure at 2-mB and 1-mB intervals
while the line thickness has been decreased (LINE=1) to make the display of closely grouped
contours clearer [4].

Obtaining Synoptic Data
Synoptic data files are available from a number of sources, one of
the most useful being the University of Albany site.
www.atmos.albany.edu/
weather/data1/surface/
Whole-world datasets (which are around 3 Mb each) are available
for each synoptic hour (00, 06, 12, 18) and have filenames in theformat yymmddhh_syn.wmo. You can download these directlyfrom within DAWS using <Internet → Retrieve data> and making
sure that the option ‘Synop from Albany’ is checked.
If you choose to download synoptic data manually you will haveto load them into DAWS using <File → Import file>. Data loaded
directly is automatically activated.
Displaying Data
Once you have created your base map and loaded synoptic data
you are ready to create displays using the ‘Analysis’ menu. Hereare some examples using synoptic data for 12:00 UT on March
28, 2005.
Select <Analysis → Temperature → (°C)> to use the default
settings for temperature measured in °C. Figure 5 (page 36
illustrates the situation around Great Britain. Isotherms are drawn
in red, as dashed lines, at 2-degree intervals.
Clear the temperature overlay by pressing <Ctrl+E> on yourkeyboard then select <Analysis → Sea level pressure> to use thedefault settings for sea-level pressure measured in millibars(figure 7). Isobars are displayed as thick solid dark blue lines, at
4 mB intervals.
Clear the map and select <Analysis → Wind → Wind speed (kt)>to display windspeed isopleths (figure 9). Without clearing thedisplay, use <Data → Data plots> or <Ctrl+D> to superimpose
Station Plots. In fact, you can superimpose as many information
displays as you wish in this way.
Editing the Analysis Display
The default settings in the Analysis menu are great for starting out
but it is certain that you will soon wish to alter the colours, line
styles and line thicknesses to improve clarity, specially if you areoverlaying them on actual weather satellite images rather thanoutline maps [1, 3].

Compare the charts in figures 5 and 6 on page 36. These show
the same base chart plotted with the same synoptic data—but
showing clear differences. In the former, isotherms are thin,coloured red and dashed; in the latter they are thick, black andcontinuous. Compare also figure 8 with figure 7, where theisobars have been made thinner, and the display changed from
4 mb to 1 mb intervals.
Just how were these transformations achieved?
To accomplish these alterations you have to modify the Analysis
menu script file, digatmos.mnu, which resides inside your DAWS
folder. The grey panels at the top of this page show the relevant
extracts from this file both before and after editing.
Editing the Analysis Script
It is not the intention in this article, to delve deeply into DAWS
scripting. An in-depth article on this topic by Fred van den Boschwill appear in our September issue (GEO Q7). Here I will detailjust a few simple ideas to help dispel the trepidation that so manyusers feel when faced with a new idea like scripting (theinterested reader can learn more by consulting the DAWS
manual.pdf file, pages 108-121).
The Temperature Menu
Personally, I have no use at allfor the archaic Fahrenheit
temperature scale (so beloved
by the Americans), so my firstinclination was to delete thesecond line from this menu
altogether. However, it soon
The default temperature menu
became apparent that there
were many occasions when thetemperature gradient across achart was very shallow and it
would be useful to be able toplot isotherms at 1°C intervals.
To do so, I edited out the‘convert to Fahrenheit’ code,
DEGF, changed the display
The modified temperature menu
code to SOLID and set the‘contour interval’, CINT, to’1’. I also changed the description. This
now allows me to alternate between the two temperature modes
simply by clicking on the menu. COLOUR=0:0:0 gives black.

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GEO Quarterly No 6

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June 2005

Figure 5 - Temperature isotherms at 12:00 UT on March 28, 2005
(Thin red dashed lines at 2°C intervals)

Figure 6 - Temperature isotherms at 12:00 UT on March 28, 2005
(Thick black solid lines at 1°C intervals)

Figure 7 - Sea level pressure isobars at 12:00 UT on March 28, 2005
(Thick solid lines at 4 mb intervals)

Figure 8 - Sea level pressure isobars at 12:00 UT on March 28, 2005
(Thin solid lines at 1 mb intervals)

Figure 9 - Windspeed isopleths at 12:00 UT on March 28, 2005
(Thin black solid lines at 1 knot intervals)

Figure 10 - Station plots added to figure 9

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The Pressure Menu
When it came to this menu,
rather than modifying what was
already offered, I added two
entirely new lines to allow me
to plot isobars more closely
together. The chart in figure 7
gives little indication of thepressure situation as thegradient across the region isvery shallow. By increasing thesampling from 4 mb to 1 mb,
the situation becomes muchclearer (figure 8).
The original 4 mb line wascopied twice below the original
entry and all three lines given
suitable captions. Because thenew entries would display theisobars closer together, the line
thickness was reduced to ‘1’(LINE=1) and the respective
contour intervals reduced(CINT=2 and CINT=1).

GEO Quarterly No 6

the dreaded ‘No available workchart’ message is displayed.
Not only does the base map fail to appear, but attempts to load
one from disc are thwarted by appearance of a similar message.

The default pressure menu

The solution is to create a new base map (any map will do since
your original base map is actually still intact within the DAWS
folder—no need to worry about parameters). Save this base map,
giving it a name like ‘sparemap’. You will now be able to use<Map → Load base map> to return to your preferred base map—
problem over.
Future Developments
DAWS is such a complex piece of software that its applications
are limited solely by the ingenuity of the user. GEO readers whomake regular use of DAWS, and who have developed their own
techniques to enhance the way that the program displays
synoptic data are encouraged to write to us about their methods
and experiences for the benefit of all (whether full articles or justshort notes).

The modified pressure menu
containing the two new options

Now, depending on prevailing conditions, I can select whichever
setting provides the best chart at the click of a mouse button.
Further Possibilities
The Analysis menu also offers opportunities to plot various
parameters related to atmospheric moisture content, winds andprecipitation. Figure 9 illustrates the windspeed chart that
accompanies the temperature and pressure charts alreadydescribed above. Another useful feature that can enhance any ofthese charts is a Station Plot overlay. An example is shown infigure 10. Just enter <Ctrl+D> to overlay these plots on top of any
displayed chart.
Troubleshooting
I have occasionally found downloaded synoptic data files tocontain corrupt (or inaccurate) data that causes DAWS to ‘freeze’.
Often the program recovers next time it is loaded, but sometimes

At the conclusion of his article in GEO Q5 [2], Fred van den Boschgave us a hint of what is possible by showing us a short
Scheduler Script to fully automate the addition of Fleetcode
overlays to Meteosat-8 images. In the next issue, Fred gets togrips with the whole concept of scripting, including Analysis
Scripting which can greatly enhance your DAWS synoptic charts
in many ways.
Meanwhile, if you wish to learn more about scripting, why not visit
the Weathergraphics on-line forum at:
http://www.weathergraphics.com/forum/and follow the link ‘Digital Atmosphere scripting’.
References
1 Using WXtoImg Images in Digital Atmosphere GEO Q2, page 8
2 My Experiences Setting up an MSG System, GEO Q5, page 44
3 Adding Fleetwood Data to Meteosat-8, GEO Q4, page 25
4 The symbols ‘%1’, ‘%2’ and ‘%3’ in the example scripts enables thesecommands to be called by clicking the ‘SLP’, ‘°C’ amd ‘°F’ short-cut
buttons on the DAWS toolbar.

If you were monitoring the early morning passes fromNOAA-15 around Easter time this year, you would haveobserved several wonderfully evocative examples ofsunglint around the Scandinavian coastlines.
On the immediate left is the 07:59 UT NOAA-15 passfrom March 31 where the still waters of the Skagerrak
and Baltic Sea both reflect strongly. In the 07:36 UT
April 1 image at far right, Denmark is beautifully
framed within a pool of light showing the most subtle
variations in intensity.
APT images - Les Hamilton Processing - Satsignal

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June 2005

Les Hamilton / Peter Wakelin
March 6 this year was a splendid day in
Scotland. Recent snowfalls had salvaged
what was looking to be a dismal wintersports season and the extensive snow
cover over the Grampian Mountains isclearly visible in the NOAA-17 channel-2
image at upper right. Overall, conditions
were calm and clear with high pressure
prevailing but what intrigued me was theprominent, detached cloud plume thatstretched north-south across the country.
Relatively tenuous and unremarkable inthe visible channel, it was the mostprominent feature of the channel-4
infrared image. To investigate this in moredetail I downloaded the HRPT telemetry
from the NOAA CLASS Library (formerly
the SAA - see GEO Q5 page 18) and ran
it through HRPT Reader; this indicatedcloud-top temperatures varying between-22°C and -34°C while surrounding clouds
were registering temperatures in the 0°C
to -5°C range. I wondered if this cloud
might
hint
at
some
significant
meteorological activity and passed thematter to Peter Wakelin for hiscomments.

• the pixel concerned is completely
filled with cloud at the same leveland• the cloud is sufficiently dense thatno radiation from warmer clouds orthe Earth’s surface can penetrate it
and reach the satellite’s sensor.
I doubt if either of these criteria has been
met in this case; indeed, you remarked
that the plume is much less prominent in
the channel-2 visible image. It is so
tenuous that low level cumulus clouds andthe ground can clearly be seen through it.
At the low pressures and temperaturesencountered at cirrus levels, air can holdvery little water in any of its three states so
can rarely, if ever, be dense enough to‘hide’ a warmer radiating source below it.
A good covering of low- level water droplet
cloud on a calm winter’s night prevents the
Earth’s surface temperature from fallingmuch but even the thickest of high levelice crystal cloud has very little effect andthe temperature plummets after dusk. If
that energy is going out through the clouds

Peter wrote:
I don’t think there’s anything
very exciting going on here. I
haven’t looked at any upper air
charts around this date but I
suspect there is a strong NW
flow up at cirrus levels. With
more extensive cirrus further
west over the Hebrides, theair’s water vapour content isclearly close to saturation andthe plume further east isalmost certainly the result ofwind shear creating turbulence
which, in turn, has generated
sufficient uplift for the water
vapour to become saturated
and cloud to form. Note thatthe plume is slightly curved
which would enhance any
turbulence if, as is likely, thecloud is indicative of winddirection.

NOAA-17 channel-2

needed. Sea surface temperatures can bemeasured this way but it is essential toensure that no colder clouds are present.
The sea may be covered with small fairweather
cumuluscloudswhich,
individually, are too small toshow on the images but,collectively, will lower theapparent sea temperature
derived in this way. The
temperature of the top of thickstratocumulus layers, typicallyat around two kilometres
altitude, can also be measured
in this way provided it is known
that there are no holes in thelayer. In the tropics most rain
falls from convective clouds
and their vertical height,
derivedfromcloud-top
temperatures, can be helpful inestimating likely rainfall; butderiving accurate temperatures
is not easy.
These clouds are small in area
so imaging resolution has to behigh and, more importantly,
only at the sub-satellite point
will the sensors be seeing only
the cloud tops.

You
say
the
plume
The NOAA polar-orbiting
temperature ‘varies between satellites have a swath width of
22°C and -34°C’ but you don’t
2700 km and operate fromNOAA-17 channel-4 IR, 11:45 UT, March 6, 2005 - Credit: NOAA CLASS
say how you derived these
850 km orbits which means
figures. If, as I suspect, youthat, near the edges of the
took pixel values from the thermal infrared then it must impinge on any infrared image, an observer would see the satellite
image and somehow converted them to sensors orbiting above.
at below 30° elevation.
temperatures, then your results are almost
certainly far too warm. Cloud-top Infrared pixel values can be reliably Under these conditions, the sensors aretemperatures derived in this way can be converted to temperatures in some more likely to be imaging the warmer sides
reliable only if
circumstances but caution is always rather than the tops of convective clouds.

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GEO Quarterly No 6

Hello Les,
I’ve got as far as page 9 in GEO Q5, Mike
Rowes’s article, and am puzzled. I’ve
never heard of ‘HLS images’ and thearticle offers no explanation, but theimages appear to be from the visible
channel.
Obviously cloud top temperatures canonly be determined from the thermal IR
channel so has Mike derived temperaturesfrom the IR channel and superimposed
them on the visible images? Or, heaven
forbid, has he tried to derive temperaturesfrom the brightness of the visible images,
in which case the results would be
nonsense?
Actually, in general, the correlation
between cloud top temperature andrainfall is poor. It’s not too bad in thetropics where downpours occur fromconvective clouds which don't glaciate(develop fuzzy cirrus tops) but up here
where glaciation is common, the cold tops
can persist for many hours afterconvection has died. For frontal cloud thecorrelation is virtually zero.
If the BBC weather rainfall maps use cloud
top temps at all, then it would be just oneof a number of parameters incorporated.
Peter Wakelin
Reply from David Taylor
SatSignal (and the HRPT Reader) can
map the data from NOAA satellites in a
way which both produces attractive falsecolour images and retains the scientificvalue of the data. They do this by using a
two-dimensional colour lookup table(CLUT) in which the temperature is used
as an index to the X-axis and thebrightness is used as an index to theY-axis. Depending on how many
temperature steps you want, or feel arevalid in the input data, the X-axis (theCLUT bitmap width) may have either 100
intervals from -60°C to +39°C in 1°C steps
or 361 intervals from -120°C to + 60°C in
0.5°C steps, derived from the channel-4
data. The Y-axis indicates the brightness
as derived from the channel-2 data, whichhas 256 values. Thus, with proper designof the CLUT, the colour hue of the image
can be used to indicate temperature while
retaining the more photographic style ofthe visible image.
HLS and HSV simply refer to two different
methods of specifying the colours.

SatSignal offers the choice of both HSV
and HLS-based colour lookup tables. The
choice is a personal preference. HLS_CT
is a special variant of the HLS lookup table
which works in the following way:
• the normal colour lookup table has acontinuous range of brightnesses
and colours, so that the clouds
which appear colder but brighter
than the land may be make to look
“cold”, e.g. by using a purple
colouring for the coldest cloud tops.
Figure 1 in Mike Rowe’s article
shows an image processed in thisway.
• in the cloud-top CLUT, data down toa certain temperature level isprocessed as in a normal CLUT.
However, once the temperature of
the pixel data drops below a certain
level (say -30°C) any variations inbrightness are ignored and theresulting lookup is a constant colour.

that be select frequencies which are in theneighbourhood of the world-wide known
satellites. Is there is any likelihood of achange?
Les. Beeson g3ivb@tiscali.co.uk
Dear Clive
I was delighted to read in GEO Q5 thatyou now have in stock the new PIC for theRX2. Would you please accept a chequefor £7.00 and send me the new PIC.
Thank you all for what you are doing forthe new group and I think GEO Quarterly
is a really good read with lots of
information for all levels of experience.
I am looking forward to the new satellites
and, like all of us, hoping that all goes wellwith the launch. It is so disappointing
when, like the Amateur AO-40 satellite, it
all goes wrong.
Ah well! Here’s hoping.
Regards and thank you

Because these regions of cloud may carry
more precipitation, it is useful to mark theregions with bright colours, going with agiven colour sequence such as cyan,
green, red, yellow, purple, white etc. toindicate progressively colder cloud-tops,
and therefore progressively more
likelihood of precipitation content. Figure 2
shows an example of this CLUT in use,
where a particularly cold cell just off
Ireland is visible as a purple patch.
Thus while the normal CLUTs aredesigned to give an attractive picture, thecloud-top CLUTs are designed to retainthat style of image in most regions, but toallow easy detection of regions with a highprecipitation likelihood.
Hello LesI have installed the new PIC in the RX2 but
I regret that the channels to be used by
NOAA18 are used, around here at any
rate, by bleepers and pagers. These are
not small signals but blast through. I
thought you may like to know and letothers know about it. I have been aware ofthese for a very long time, since my FT847
covers these frequencies.
In theory I can use this setup for the
reception of NOAA satellites but thesevery strong signals just swamp out any
chance. I am wondering if there is any
patch or such. This is the Cambridge area,
for reference. I wonder why the powers
www.geo-web.org.uk

David K. Brierley, Bideford,N. Devon
Silting of the Irrawaddy... continued from page 27

Within the Gulf of Martaban lies thebathymetric Martaban Canyon that
divides the gulf from the Andaman Sea.
The Martaban Canyon has a graben-likestructure featuring faults, slump scars
and eroded wastes from the sea floor.
Having a high SSC (suspended sedimentconcentration), it is not surprising thatturbidity is visible in weather satellite
images. The turbidity front in the Gulf ofMartaban oscillates by about 150
kilometres in phase with the springneap tidal cycles, increasing from lessthan 15 000 km2 (square kilometres) tomore than 45 000 km2 during springtides. Sediments are then transported
from the Gulf of Martaban across the
Martaban Canyon to the Andaman Sea
during this period by the tidal currents.
Acknowledgement
Figure 3 (map showing silting in the Gulf ofadapted from an original
published in:
Martaban)‘Sediment distribution and dispersal on the
Ayeyarwady continental shelf and Gulf ofMartaban, northern Andaman Sea.’ by
V.Ramaswamy, P.S. Rao and Swe Thwin.

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Les Hamilton
Our article in GEO Q5 describing how to
produce HRPT images from telemetry files
downloaded from NASA’s Satellite Active
Archive (SAA) generated a great deal ofinterest. In this issue we continue toexplore the HRPT theme by explaining
how multiple images can be merged tocover an extended geographical area.
Figure 4 was made up from threesuccessive NOAA 16 passes over Europe
combined into a single, larger, image.
Requirements
To prepare the HRPT images you requireregistered copies of two of David Taylor’s
software packages, HRPT Reader and
GroundMap, plus of course, at least two
successive HRPT telemetry files.
NOAA has set up a new facility for
downloading these HRPT files, called theComprehensive Large Array-data Stewardship
System (CLASS). Requests from SAA
have in fact been actioned from CLASS forsome time now and it does seem probablethat the new site will eventually take overfrom SAA. The address for NOAA’s
CLASS site, which is an exact clone of the
SAA site described last time, is
http://www.class.noaa.gov
Once the images have been prepared you
will require Paintshop Pro, probably themost popular image processing package
in use these days, to assemble them.
Everything described below was achieved
using version 6 of PSP—so you don’t
need to rush out and purchase the latest
version.
HRPT Reader
Most of the details concerning the use ofthis package were covered last time.
Three further points are critical, though.
1 You must use a registered version
of HRPT Reader so that you cancreate ‘location’ files in addition to
the actual images. Location files are
required by GroundMap in the nextstage of the process.
2 Your images must be stored using
the <File → Save displayed image>
option. This saves uncorrected
images; the necessary geometriccorrection will be carried out later
using GroundMap.
3 Make sure that the ‘Eq hist’ box at
the upper left of the HRPT Reader
window is unchecked.

40

You will now discover that, every time you
store an uncorrected HRPT image, twofiles will be saved to your hard drive. One
will be a BMP image file, e.g. ‘image.bmp’,
the other its location file, ‘image.lcn’.
GroundMap
Images of the Earth obtained from orbit
always exhibit distortion due to theplanet’s curvature. Whilst features directly
below the satellite are rendered correctly,
those near the margins of the field of view
become foreshortened as a Earth’s
surface curves away from the satellite.
HRPT Reader, like most visualisation
programs, can introduce a degree ofcorrection to improve the overall
appearance of the image but thiscorrection alone is not sufficient to enable
seamless merging of adjacent satellite
passes.

Figure 1 - ‘Atlantic.bmp’

This is where GroundMap comes in. This
software can process uncorrected HRPT
images and map them precisely to anumber of standard projections. Figures 1,
2 and 3 show how the three NOAA-16
images to be merged in figure 4 were dealt
with. Each image frame outlines exactly
the same area on the Earth’s surface, inthis particular instance using the polarstereographic projection option, centredon latitude 53°N, longitude 15°E.

Figure 2 - ‘Arctic.bmp’

Each of the HRPT images has been
positioned on to the appropriate part ofthis frame. As a result, when the three
images are stacked on top of one another,coastlines, rivers and other land features
should be in perfect registration where
they overlap. This, of course, will notnecessarily be true of weather featuresdue to the fact that clouds actually move
during the intervals between successive
satellite passes.
Figure 3 - ‘Blacksea.bmp’

Setting up GroundMap
You really do need a registered copy ofthis program to make the best use of your
HRPT files. The freeware version restricts
the user to a relatively small 800 x 600
pixel working canvas and allows access to
only three predefined geographical areas,‘Europe’, ‘USA’ and ‘Australasia’.
Registration enables the creation of the‘Giant’ 3600 x 2700 pixel images used to
produce the illustrations in this article and,most importantly, makes available thewww.geo-web.org.uk

Options Menu
Output size

Giant - 3600 x 2700

Location

User

Map projection

Polar stereographic

User Setup (General tab)Meridian

15°

Parallel53°

Lat span48°

Picture margin

0

Table 1 - Suggested mapping parametersJune 2005

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GEO Quarterly No 6

Figure 4 - This is a composite image created from three successive NOAA-16 channel-2 images acquired on March 15, 2005.
Telemetry files: NOAA CLASS Library‘User’ item in the <Options → Location>
menu. This option allows you to define
accurately the geographical area in which
you wish to work. The various parameters
used to create figure 4 are listed in Table 1
but everyone is free to create their own.
The user parameters also include options
for the addition of gridlines and country
boundaries to the corrected images, if
desired.
Using GroundMap
Select <File → Open location data> from themain menu-bar and navigate to the folder
containing your uncorrected HRPT
images. Open the first of these:
GroundMap will issue a message-

Processing HRPT Reader, GroundMap and Paintshop Pro v 6

informing you of the name of the mapping
list—just click OK to continue. After a shortdelay (depending on the speed of your PC
and the available RAM) the rectified image
will appear on your screen; save it using ameaningful, easily recognised filename.
Repeat for each of the other images you
plan to merge together.
The Images
LAC files from three successive NOAA-16
passes were requested from CLASS andduly downloaded. Each was processed in
HRPT Reader with the Channel-2 tabselected and histogram equalisation
switched off, then saved using the ‘Savedisplayed image’ option.
www.geo-web.org.uk

Setting up Paint Shop Pro
I find it helpful if all images auto size to fit
the computer screen. From the menu-bar,
open the <File → Preferences → General
Program Preferences → Viewing> window,
and make sure only the ‘New images Auto size’ box is checked.
Merging the Images
First, click <File → New> to create a blank
image the same size as the GroundMap
images (3600 x 2700 pixels in my case)then set the ‘Background color’ to‘Transparent’ and ‘Image type’ to ‘24-bit’. It
is a good idea to save this blank image
immediately with a filename such as‘composite.psp’.

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Figure 6 - Using the ‘Magic Wand’ tool
Figure 5 - Adding the first layer

The images created by GroundMap must
now be stacked as separate layers within‘composite.psp’. Their black backgrounds
must also be removed as we progress.

Figure 9 - The layer palette

Select the Magic Wand tool and, in the
Tool Options Window, set both ‘Tolerance’and ‘Feather’ to zero.
The complete sequence of events is set
out in the following bulleted list.
• The first image, ‘Atlantic.bmp’, wasopened and copied to the clipboard
using <Edit → Copy> (or Ctrl-C).
(figure 5)• The ‘Atlantic.bmp’ window wasclosed.
• The image was pasted as aseparate layer in ‘composite.psp’
using the menu <Edit → Paste → As
new layer> (or Ctrl-L).
• The Magic Wand tool was clicked on
the image’s black background. Aftera few seconds, the entire image
area became highlighted (figure 6).
• <Edit → Clear> was clicked on themenu-bar (or use the Delete key).
This cleared the black background,allowing the checkerboard display of
the transparent canvas to show
through (figure 7).
• The mouse was right-clicked(anywhere) over the image area todisengage the Magic Wand tool
(important step!)• The second image, ‘Arctic.bmp’, wasopened and the entire sequence of
events repeated.
• The third image, ‘Blacksea.bmp’,
was opened and the entire
sequence of events repeated yet
again. The result was figure 8.
At this stage it is advisable to savecomposite.psp as a master copy of yourimage. There is still work to be done and,should you mess up subsequent steps,
you can always return to this saved copy
and start over again.

42

Figure 7 - Clearing the backhroundFigure 8 - The merged image

Note: to preserve the layers in the merged
image, this copy must be stored in PSP’s
native ‘.psp’ format.

Figure 10
Using the Freehand tool to outline a
region in Layer 3 for removal

Final Touching-Up
Although the separate passes are now
successfully combined, the merged image
is marred by several rather intrusive
straight edges where individual passes
overlap (this can be caused by unevensolar illumination across the frames). The
following section explains how to soften
such artifacts using PSP’s Freehand tool.
Removing the prominent vertical division
through Scandinavia will be used as adefinitive example.
Selecting the Working Layer
Figure 8 consists of four layers—thetransparent canvas plus the three
NOAA-16 images. We first of all need to
identify the layer containing the darker,
left-hand portion of Scandinavia—so press
key <L> on your keyboard to reveal theLayer Palette (figure 9).
www.geo-web.org.uk

Figure 11 - Softening a boundaryJune 2005

Group for Earth Observation

GEO Quarterly No 6

Figure 9 shows a zoomed portion of theimage, along with the Layer Palette. There
are two ways to identify a particular layer:• Simply place the mouse cursor overa layer in the list and a small
thumbnail of its image pops up• Successively click each layer’s
visibility toggle (‘spectacles’ icon) tomake the layers flip in and out ofview
When you have identified the layer you
wish to work on, click its name in the Layer
Palette to highlight it. This means that any
modifications you make to a selected areaof the image will affect only this layer.
Cropping and Feathering
Before employing the Freehand tool weneed to be certain that it does not itself
introduce unwanted boundaries on to ourimage. We can achieve this by feathering
the edges of any selections we make.
Feathering theedges of a
selection means
that, instead of
terminating with astraight edge, it‘fades out’ totransparency
across a selected
range of pixels.
Select <View → Toolbars> then place a tickagainst <Tool options window>. Click the‘Freehand’ icon (lasso) on the toolbar (orpress key <A>) and set the ‘Feather’ value
to 20 in the Tool Options window (above).
Removing the Edges
Zoom in to the image and use the Layer
Palette to activate the layer you intend to
modify (the left-hand part of Scandinavia
in this example). Select the Freehand tooland click the mouse at your starting pointon the image. Keeping the mouse button
depressed, drag it around the area you
wish to remove, ending as close as you
can to the starting point. When the mouseis released, PSP automatically connects
the two ends of the line (figure 10). Click<Edit → Clear> or press <Delete> and thejob is done (figure 11).
Move around the merged image, dealing
with all intrusive margins in the same way
until your masterpiece is complete. Again,
save as composite.psp in case you feel
further processing is necessary later. To
complete the job click <Layers → Merge→ Merge all (Flatten)> then save in yourpreferred format (TIFF, BMP, JPG etc.).
Figure 4 was rotated slightly then cropped
before using the <Colours → Adjust> menu
to modify the image brightness, contrast
and gamma to suit my personal taste.

Figure 12 - A composite image stretching the full width of the USA

Troubleshooting• Sometimes you may crop beyond
the region where two layers overlap
and part of the checkered
background canvas shows through.
Don’t worry—just click on<Edit → Undo clear> and start over.
• The degree of feathering is open toexperimentation. But excessive
feathering does lead to blurring in
the image and loss of detail.
• If, when using the Magic Wand to
remove the black background fromeach GroundMap image, black
regions within the image area arealso deleted (revealing thecheckerboard background), this isalmost certainly the result ofapplying histogram equalisation in
HRPT Reader—don’t do it!
• As was mentioned earlier in thisarticle, HRPT images must be
prepared without equalisation. Thisis because Groundmap applies acompletely black background(RGB=0:0:0) to all its output images.
On the other hand, the AVHRR
radiometer aboard the NOAA
satellites transmits even the darkest
colours at a 6% modulation level,
reproducing on (non-equalised)
images as (RGB=16:16:16). It is thisdifference that enables PSP’s Magic
Wand to eliminate the backgrounds
from the images.
• To make image boundaries as‘invisible’ as possible, it is a goodplan to drag the Freehand tool in a
convoluted path that follows closely
any natural, high-contrast features
such as cloud outlines andcoastlines.
Above all, do be mindful that considerable
artistic judgement and patience may berequired to achieve the best results. Part 2of this article will look at ideas that will
improve your composite images evenwww.geo-web.org.uk

more. Meanwhile, do try out this techniqueand submit your results to the editor for
publication.
If we receive a good response from GEO
readers we will publish a gallery of yourbest work.
Acknowledgments
Thanks are due to Ferdinand Valk, whopioneered the merging of HRPT images,
and whose efforts inspired this article. You
can view some of Ferdinand’s work at:
http://www.fvalk.com
SoftwareIf you would like to try out the techniques
described above, you can obtain
evaluation versions of all the necessary
software from Software Showcase(page 39).
Paintshop Pro can be downloaded as a30-day evaluation version from:http://www.corel.com
You can download HRPT Reader and
GroundMap from David Taylor’s websiteat:http://www.satsignal.net
You will find the links under the ‘Satellite
Tools’ section. If you haven’t used David’s
software before you also require his
Runtime Library Bundle (link on the HRPT
Reader page under the section headed‘System Requirements’).
If you would like to sample full versions of
HRPT Reader and GroundMap, David canusually provide time-limited licences whichallow you to experience the programs’ fullfeatures for two weeks or so.
You can e-mail David at:
davidtaylor@writeme.com

43

GEO Quarterly No 6

Group for Earth Observation

June 2005

Doug Thwaites
I have enjoyed a long and wonderfully
adventurous life which could fill a book, so
I will just mention my activities in the fieldof electronics. I was born in London in1916 and at the age of 13 built a threevalve SW Radio and became a SWL. My
wall became covered with QSL cards, mymost prized coming from the then pope,complete with papal seal. Following
technical school, I went into radio
servicing, testing components at the Ultra
factory.
During the war I spent some time in
Scotland as a member of TechnicalTraining Command, flying six hours a day,six days a week training operators inaircraft interception (AI), radar and aircraftto surface vessel (ASV) radar. Later I wastransferred to London where I was chief
instructor of No 7 Radio School where wetrained radar technicians before moving toGreat Malvern where I helped develop
H2S radar.
I came to Australia in 1956 where I trained
radio technicians to cope with the adventof the first television service. After working
for some years in the TV industry, during
which time I set up three companies, I soldout and built and ran a country motel. I
retired at 60 and began to write,
something I have continued ever since.
A friend of mine built weather satellite
receivers and I am fortunate to have oneof them. It scans six channels and stops
when the 2400 Hz tone is found. I use a ‘J’antenna after trying and building all theother types.
Satellite Images
Once summer comes we get the monsoon
clouds building up around the equator. In
the east of Australia, we depend on rainfrom south-east winds off the sea—andalso experience the odd cyclone. We
seem to have been in constant drought
conditions during the last few years as
there have been no cyclones this side ofAustralia. I live in a valley running northsouth with a hill to the south. Not a goodsite, but I can obtain pictures from New
Guinea to Tasmania and if conditions areright and I get a pass from over the Pacific
I can see New Zealand.
Figure 1 shows a scan over a large area of
eastern Australia. You can see themonsoon clouds stretching across the top,
over the Gulf country.

44

Figure 2 - December 28, 2004

Figure 1 - January 1, 2005

On the lower east coast, around Sydney,
you can see cloud on the coast fromstrong south-east winds. At the far south isa weird peninsula shaped like a leg andfoot—the Southern Yorke Peninsula with
Spencer Gulf to its west. At the top of thisgulf, as you look northwards, you can see
the dark mass of Lake Eyre, a huge saltlake system then, north of that, massive
areas of desert. It is hard to believe but,when a cyclone hits Queensland andcauses extensive flooding, it can bemonths later before the water flows down
throughwhat
iscalledtheChannel Country and floods Lake Eyre.

Figure 3 - January 8, 2005

Figure 2 was taken on December 28, thesecond day of the Sydney to Hobart yacht
race, and shows the storm that caused somuch chaos sitting over its path. Figures 3
shows the birth of cyclone `Kerry’, the firstfor about ten years, a category-3 storm at
this point. Figures 4 shows ‘Kerry’ slowly
moving down the coast and weakening toCategory-1. So our drought goes on. All
images are from NOAA 17 on north-southpasses.
About the interference: during the hotsummer months when there are thickclouds and intense lows around, I get one
or more black bands where the signal cuts
out. I have discussed this with othersatellite viewers, and we feel it is due todisturbances in the atmosphere caused by
the conditions. Europeans could not
imagine the summers we get. The
monsoon cloud has descended down the
coast, covering it all the way to Brisbane at
the moment; it is hot and so humid thateverything feels wet. There have been
rainfalls of twelve inches in a day. Rivers
www.geo-web.org.uk

Figure 4 - January 10, 2005

are rising and breaking their banks. But
this is the only way Queensland gets its
rain. The farmers are jumping for joy as
they stand in their flooded fields. But our
winters are paradise where you stand in
the constant sunshine and get tanned.

A true-colour MODIS image from NASA’s Terra satellite taken on January 27, 2003
This ship trail formation, also pictured on page 29, persisted for some 36 hours
Image: MODIS Land Rapid Response TeamA spectacular Terra MODIS image showing ship trails off the Oregon coast of North America on June 28, 2003
Image: MODIS Land Rapid Response Team