Group for Earth Observation

The Independent Amateur Quarterly Publication for

Number 7

Earth Observation and Weather Satellite Enthusiasts

September 2005

Inside this issue . . .
NOAA-18 now in orbit

Are you experiencing pager
problems with this new
WXsat? John Beanland
explains that there is agreat deal you can do tominimise their effect.
For Mac users - newsoftware to decode HRPT
files
Fred van den Boschexplains how to takeadvantage of Digital
Atmosphere’s new scripting
language
Are you looking for a new
APT Receiver? Read ourreview of the German-built
R2FX on page 19.
As the end draws in sightfor WEFAX, John Tellick
has produced a handy
pictorial guide to aligning
your dish antenna on Hot
Bird for the reception of
EUMETCast
Report on GEO’s 2005
Symposium in the National
Space Centre, Leicester
Plus all the regularfeatures ...

CONTACT INFORMATION

several delays due to inclement weather conditions,
After
NOAA-N finally made it into orbit on May 20. The new satellite,

NOAA-18, fills the important early afternoon APT niche that hadremained vacant since NOAA-16’s APT VHF downlink failed in
November 2000. Several early images from the new wxsat are
reproduced opposite (see details on page 18) as well as on some of ourinside colour pages.
operates on a new frequency, 137.91 MHz, which has
NOAA-18
caused many GEO readers problems because of the proximity ofpager transmitters. The scale and scope of this interference were
established in an Internet survey conducted by Nick Hewgil and
Lawrence Harris; you can read about their findings on page 11. We
also have an article from John Beanland, who explains simple
precautions we can all take to minimise the effects of pagers on our
NOAA-18 images.
is perhaps timely to yet again remind those our readers who
Itenjoy
the WEFAX and PDUS data transmitted from Meteosat-7

that these services are due to end in just a few months time. To
continue enjoying geostationary images of Europe you will soon haveto upgrade both hardware and software to capture the Hot Bird-6
DVB transmissions that carry the MSG imagery from Meteosat-8.
You can read more about the impending changeover on page 3.

Contents
GEO Report
The End draws nigh for WEFAX and PDUS
Symposium 2005
Weather Satellite Frequencies
View HRPT Images on your Mac
Earth Imaging NewsNOAA 18 Reception and Pagers
Learning to Live with Pagers
The Twelve Channels of Meteosat-8
NASA’s Aura SatelliteNews in Brief
R2FX APT Receiver
How to Align a Dish on Hot Bird

Francis BellJohn Tellick
Les Hamilton
Sergei LudanovPeter Wakelin
Les Hamilton
John Beanland
ESA Bulletin
Les Hamilton
John Tellick

GEO Shop Page
NOAA Satellite Predictions for the UK
Helplines etc
GEO Membership Form
Weather Down Under
Process your own Images from Feng Yun 2C
Road to Damascus
Using Scripts in Digital Atmosphere Workstation
Coming in the next Issue of GEO Quarterly
Understanding the Weather (book review)
Hurricanes to Intensify as Earth Warms?
Aftershocks
In Tray - members’ letters and comment
Tornado hits Birmingham
Software Showcase
Merge HRPT Images - part 2
An Affordable Radar Service for the UK

2
3
4
6
7
9
11
12
14
16
18
19
22
i
ii
iii
iv

Doug Thwaites
Les Hamilton
Francis BellFred van den Bosch
Robert Moore
C S LohDouglas Deans
Les Hamilton
Douglas Deans

24
26
29
30
35
35
36
38
39
39
41
43
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 7Group for Earth Observation

September 2005

Francis BellI have just returned from three GEO
events so include very brief reports ofthese and other matters; two field
expeditions and the AMSAT-UK
colloquium held in Guildford.
The last three days of July saw GEO at
the AMSAT-UK colloquium in Guildford.
This is a three day event and GEO ran
live demonstrations of Meteosat-8
projected on to a large screen in a room
adjacent to the main lecture theatre. The
60 cm receiving dish, for safety, waspositioned in a garden behind metal
railings but still received perfect images.
We also ran live reception of polar
orbiting satellites. We had two stands
with literature supplied by EUMETSAT
and BNSC as well as our own GEO
Quarterlies on display. As best I canjudge the literature fell into good hands
because, by the end of the third day,most of it had disappeared. John Tellick
was there displaying receiving hardware
while David Taylor was supervising ourlive imaging. David gave a presentationin the main lecture. I’m not sure of theexact delegate numbers, my estimate
was about 100+ from many different
countries. On the third day we werejoined by Clive and Carol Finnis plus
Peter Green. Having dismantled ourstands we then had an informal meetingin the evening to discuss current GEO
issues.

A note about GEO’s management team’s
wives. I am attentive to the support thatthey give to GEO. There were three
wives in Guildford. Whether they aresupporting GEO, their husbands or both
I cannot judge but my thanks to them
anyway, and of course to those others
who support us.

The GEO stand at the AMSAT colloquium
last July
Photo: David Taylor

Meetings
On the subject of meetings, GEO has
now booked the NSC in Leicester for our
next symposium and AGM. The date is
April 29, 2006. Please put this date inyour diary now. The 2005 symposium
was judged to be a success but rather abusy day. For Leicester 2006 I would liketo have presentations about theinterpretation of the weather satellite
images we receive. Previously we havetended to concentrate on the technicalside of signal reception and display; if wewant to know what this informationmeans we must be able to interpret it
correctly. I know Peter Wakelin
contributes regularly to the Quarterly on
this subject but if anybody knows of anadditional person suitable to come to
Leicester next year, please let me know.
NOAA-18 - Field Experiments

GEO at AMSAT
L to R: Peter Green, Francis Bell, Clive andCarol Finnis
Photo: David Taylor

Thanks must go to AMSAT-UK for
inviting us to their colloquium. I hope
GEO made a worthwhile contribution
and also hope we will be invited again in
2006.

2

NOAA 18 is now in orbit and I receive
beautiful APT visible images from thissatellite on 137.9125 MHz from where I
live in SW Surrey. I know that in the UK
the pager frequency allocation overlaps
with the weather satellite band of 137138 MHz. My judgment is that this will
not change for many years so theadjacent pager frequencies and use will
have to be endured.
www.geo-web.org.uk

I have five receivers which can receiveon 137.91 and have been experimenting
with NOAA-18 reception. I also havethree antenna systems. With somereceiver and antenna configurations I
can receive perfect NOAA-18 images
whilst simultaneously listening to thebackground pagers on my scanner.
However, I am sensitive to the fact thatin other locations this is not the case andpager interference is severe.
I have been continuing my experimentsin the field and, at the TCARC rally four
miles west of Petersfield, Hampshire, I
set up a station, literally in a field, andreceived perfect reception. The same wastrue at the AMSAT-UK colloquium site.
My most recent field expedition was atthe Wimbledon Amateur Radio Society’s
week-long expedition on top of the South
Downs, three miles north of Reigate
Surrey. This location is in line-of-sitewith Gatwick airport as well as two
nearby pager transmitters plus manyother RF transmissions in the area. Theinterference was overwhelming, with nochance of realistic NOAA-18 images.
Five seconds of perfect reception then 20
seconds of noise. I even received voiceaudio on a weather satellite channel. If I
lived close to this site I would be very
frustrated. I know that many GEO
members are experimenting and sharing
experiences. Some locations seem okay(thank you at my QTH) while others
experience more difficult reception. I
subsequently learned that there may be
up to 1000 users of the radio services
close to where I had set up my NOAA-18
station on the South Downs.
On the subject of NOAA 18, I will takemy portable station to the USA nexttime I visit. My son and his family have
moved to North Carolina and we visit
them there intermittently. It will beinteresting to try NOAA-18 reception in
the USA and listen for backgroundinterference there.
Subscription to GEO Membership
I reported to our membership at
Leicester the financial position of ourgroup. We do have money in the bank
but we also have liabilities andresponsibilities, so must look at the year

September 2005

ahead. Over the past two years our
income has consisted of membershipsubscriptions, generous sponsorshipfrom some individuals and now
income from the GEO Shop. Our
main expenses are the printing anddistribution of our Quarterly
publication. Nobody within GEO
management has received expenses(forexampletravel,hotels,communication costs and manyother expenses); these have been
supported by our management
team, with no regrets. However, tosecure GEO’s future we must be
realistic about our finances. With
this in mind a decision has beentaken to increase our membershipsubscription from £16 to £18 for our
existing and new memberships.
This will take effect whensubscriptions come up for renewal.
There will be an equivalent increase
for Europe and the rest of the world.
Please do not decline to renew
your membership on the basisof this modest increase insubscription—it still represents
outstanding value for money.
What do you get for yoursubscription?
Our
Quarterly
publication of course, but also,
importantly, shared experienceswith other members and thebenefits of an active management
team promoting the interests of ourmembership to important national
and international agencies. All for£18 a year! Perhaps I shouldn’t
write this but I believe it to be true.
We are fortunate in this country tohave a group such a GEO tosuccessfully lobby for free and easy
access to weather satellite data on
behalf of the amateur, educationaland self-training users. Other
countries are not so fortunate.
If you wish, you can add on any
amount to your annual subscription.
There is no obligation here just an
invitation if you wish.
WEFAX
Many of us will have been receiving
WEFAX
transmissions
from
Meteosats -1 to -7 for many years.
This includes me with accumulated
dishesdown-converters
andreceivers for WEFAX reception. Allusers should note that this Meteosat
service will soon end (see article onright). WEFAX is also being phasedout on NOAA’s GOES geostationary
satellites in favour of LRIT. I was at
the Miami conference in DecemberGroup for Earth Observation

2004 where this was discussed.
Although much of this discussion
was highly technical, I noted thebackground suggestion by a small
group of delegates that thesesatellites continue with WEFAX
because of the many existing usersof the service.
The response from NOAA andtheir consultants wasunambiguous. ‘To continue
with WEFAX is not an option’.
It is clear that image resolution anddata rates are improved by moving
to new formats. WEFAX is on its
way out.
The GEO Shop
Any GEO member who wishes toreceive live images from Meteosat
satellites has to face this reality: if
you have not already done so, takeaction now. The GEO Shop has all
the hardware you need to receive
the Meteosat-8 EUMETcast data
format via Hot Bird-6. If you use theShop to buy a new system or to put
a new chip into your receiver for
NOAA-18 you benefit the group—
because of course, there is a small
margin in sales for GEO. The Shophelps our finances and also offers
the tremendous benefits of help andadvice for our members.
Our thanks to Carol and Clive
Finnis and also John Tellick forestablishing the Shop. Everybody
comes out a winner but I
understand
the
time
and
commitment it takes to run theshop.
I will try to go to Utrecht for thenextmeeting
ofWerkgroep
Kunstmanen, our friends in the
Netherlands. I have just received
my copy of their publication ‘De
Kunstmaan’ with two pages devoted
to a report on our Leicester
symposium, which they supported.
Every Seventh Wave
I have mentioned above that my son
and his family now live in the USA
and we visit them from time to time.
There is a small children's park just
opposite their house which has a
stream running next to it.
My grand-daughter Caroline—three
and a half years old—likes me totake here there to play. One
afternoon we went to this park andCaroline threw a few stones into thestream, which of course createdwaves. I said to her: “it’s always the

GEO Quarterly No 7

John Tellick
At the time of writing (early August), Meteosat7 PDUS and WEFAX services from 0° are due tobe terminated on February 1, 2006 owing to thedelay in launching MSG-2. After that time there
will be no more PDUS/WEFAX services from 0°.
Meteosat-8 (MSG-1) has been providing
EUMETSAT’s prime location dissemination in
HRIT/LRIT format for well over a year now via
EUMETCast, which is transmitted by the Hot
Bird-6 satellite located at 13°E. HRIT imaging
provides a set of 11 whole globe images indifferent spectral channels plus a twelfth
channel which provides a selected area of highresolution visible imagery. All channels are
updated every 15 minutes to provide round-theclock coverage of stunning quality.

EUMETCast, which also includes relays offoreign satellite data, other meteorological data
and NOAA ATOVS sounding data can bereceived using easy-to-install domestic typesatellite TV equipment, all available from the
GEO shop—see our advertisement and price listin the centrefold of this Quarterly.
EUMETCast is a multi service broadcast
system and is the future EUMETSAT
dissemination system for geostationary, polar
orbiting and environmental data services.
This is an exciting development and if you wish
to continue to receive Meteosat data, now atgreatly improved resolution, plus future polar
orbiting imagery over an extended area, youneed to make the transition soon.
You need to register with EUMETSAT in orderto obtain a license from your national Met.
Office and the reception software.
This can take several weeks.
You will also require a suite of display software
such as David Taylor’s Meteosat Data Manager
to process and display/animate the images.
The EUMETCast registration form is available
on the GEO website at
http://www.geo-web.org.uk/eumreg.html
You will also find a guide to help you to fill in
the registration form plus further informationon our website.

Don’t delay - the future is here—now.

... continued on page 10

www.geo-web.org.uk

3

GEO Quarterly No 7Group for Earth Observation

September 2005

Les Hamilton
Following the acclaimed success of GEO’s
inaugural symposium in 2004 there wasalways that niggling doubt as to whether arepeat venture just one year later would bea wise move. Was it too soon to expect somany of our members to return? Could we
provide a suitably varied program without
simply duplicating what had already been
done previously? Was it wise to return tothe same venue at the National Space
Centre for a second successive year?
On April 30 all our doubts evaporated as
GEO members (and one dog) turned up inforce for Symposium 2005. For most of
the day the lecture theatre bulged at theseams with seating very much at apremium; if you were the least bit late forthe start of any of the presentations you
had to stand! We were particularly
delighted to welcome several members of
our sister organisation in the Netherlands,
Werkgroep Kunstmanen [1]. Not only did
they make a big impact by providing threepresentations during the day, but Arne van
Belle and Rob Alblas each set up anddemonstrated his MSG ground station
hardware throughout the meeting.
Proceedings opened with a brief welcome
from Francis Bell after which Peter Greenand Cecilia Taylor chaired the morningand afternoon sessions respectively. Whatfollows is a necessarily brief overview ofthe day.
Mike Grocott
The morning’s first presentation camefrom Mike Grocott, who described various
facets of the work of the Callington Space
Centre [2]. Mike explained how his
personal career outlook had beenchanged following a visit to Florida to viewa Space Shuttle launch and how he hassince devoted himself to ‘inspiring andmotivating’ the next generation of
students. At Callington this has beenachieved with the aid of telescopes andastrophotography and, more recently, by
the introduction of digital satellite imaging
from two Meteosat-8 ground stations
installed with support from Dartcom.
Callington is currently developing aweather satellite module for juniorstudents from 9 to 13 years of age, whichemphasises the influence of satellites on
everyday life. The students are involved
primarily with image processing rather
than under-standing how the hardware

4

operates and they are encouraged to learn
to interpret what the images actually show.
Many students at Callington performparticularly well because they are inspiredby the activities that are available to themoutside the formal classroom, and a groupof 6th form students recently enjoyed a trip
to NASA in the USA.
Gordon Bridge
Gordon opened with a brief overview of
the theory of cloud reflectivity and how thisenergy may be harnessed for interpretative purposes. The 12 channels ofradiation detected by Meteosat-8 provide
unparalleled opportunities for detecting
cyclones, weather fronts, fog etc. and allthese phenomena were illustrated on the
big screen with appropriate movie loops.
In particular, Gordon pointed out how thedifferent reflectances from snow crystals
compared with water droplets—exhibitedin the 1.6 µm infrared (channel-3)—
enabled excellent discrimination between
fog and snow. We were also shown how
the 8.7 µm IR channel was particularly
suitable for the detection of sulphurous
fumes from factories and volcanos.
Gordon continued by describing somenovel channel subtraction techniques
which were paving the way to a moreaccurate means of identifying severe
convection in clouds; this was proving amost valuable ‘nowcasting’ tool in aiding
storm prediction. Varying the colours used
can emphasise where the clouds are attheir most active and makes it possible tofollow the growth and decay stages ofhurricanes—and may eventually prove
useful for tornado forecasting.
Difference techniques were also proving
useful to discriminate clearly between dust
storms and true clouds, even during thenight, and a 24-hour movie sequenceshowing dust blowing off the Saharaemphasised the point. Vegetation showsdifferent reflectance signatures at different
wavelengths, and combining Meteosat-8
channels can be used for the identificationof specific crops—for instance ricepaddies—as well as phytoplankton
blooms in the Earth’s oceans.
David Taylor
David Taylor first described developments
in his own software for Meteosat-8 and theother data streams available overwww.geo-web.org.uk

EUMETCast. Sea-surface temperature
data has already been extended to anumber of regional areas and is expected
to be further increased to include fullnorthern-hemisphere
andAntarctic
coverage. The culmination of the past
year’s software development has been
GeoSatSignal-5 which provides novel
RGB combinations for the 12 channels ofMeteosat-8 data.
David continued by detailing how the
EUMETCast service was to be extended
to carry data from Metop, the forthcoming
European polar orbiting satellite. There
are some exciting new instruments aboard
Metop, including a very high-resolution
infrared spectrometer and a radio
occultation instrument; these will provide
us with new ways to understand theatmosphere.
David showed us some presentationmaterial provided by EUMETSAT which
described how the existing EARS service
is to be extended to cover AVHRR (HRPT)
high-resolution image data from theexisting NOAA satellites, and to provide
pan-European HRPT data without theneed for a complex receiving system ortracking antenna.
All this data will become available over
EUMETCast, resulting in a much higher
data rate, but David described how a new
configuration (based on suggestions fromArne van Belle) had been tested by
EUMETSAT, which showed that both thehigher data rate and co-existence withexisting data were quite feasible.
Ed Murashie
The weather satellite scene in the USA
provided the subject of Ed Murashie’s
eagerly awaited afternoon presentation.
Ed started with an overview of the TIROS
program, originally conceived as far backas 1951, but which did not come to fruition
until TIROS I was launched seven years
later. Much of the delay had been the
result of shifts in responsibility. The US
army was originally in charge of the
project, but this was later handed over tothe air force before finally ending up as theprovince of NASA.
Ed also described in detail the history of
the current NOAA fleet of both polar
orbiting and geostationary weather
satellites, including an animated appraisal

A packed lecture area listens attentively as Ed Murashie from the USA delivers his presentation

Ed Murashie in expansive vein during his talk

Photo: David Taylor

Photo: David Taylor

David Taylor (left) with Gordon Bridge

Demonstration of RGB colour combination

Nigel Evans (left) and Peter Bradley

Photo: Les Hamilton

Image: Gordon Bridge

Photo: Les Hamilton

David Simmons’ setting up the Tellique suite

Tellique setup on the big screen

Tellique software installed—success!

Photo: David Taylor

Photo: Les Hamilton

Photo: Les Hamilton

Demonstrating the satellite signal meter

The RSGB FUN vehicle outside the NSC

Rob Alblas demonstrating his XRIT software

Photo: David Taylor

Photo: Cecilia Taylor

Photo: Les Hamilton

Pointing a Dish towards Hot Bird-6

Customers at the GEO Shop standAntenna discussion with Arne van Belle

Photo: David Taylor

Photo: Les Hamilton

Photo: David Taylor

GEO Quarterly No 7Group for Earth Observationof the ‘NOAA N-prime debacle’, before
detailing with how the civilian (NOAA) andmilitary (DMSP) programmes are soon set
to merge under the NPOESS banner.
‘Is it still worth investing in APT’ asked Ed.
Given that NOAA N (now in orbit as
NOAA-18) and NOAA N-prime (currently
being rebuilt following its accident) eachhas a minimum design life of two years,
there should be an absolute minimum offour years of APT ahead of us. So, yes, it
is definitely worth investing in APT—it willprobably be with us much longer than justthose four years if NOAA-12’s continuing
12-year lifespan is anything to go by.
Ed concluded with a look towards the new
dissemination modes and the equipment
required to receive them. It may well bethat the development of software receivers
could be the way forward—specially inview of the UK’s pager problem. One
approach could be to employ an analog
front-end to convert the signal down to alower base-band frequency and thendigitise it with an Analog to Digital
Converter (ADC). This in turn could feeda Digital Signal Processor (DSP) or Field
Programmable Gate Array (FPGA) which
would contain a ‘brick-wall’ filter to reducethe interfering signals by 60-70 dB. With
all the FM and analogue demodulation
done in the PC it would be much easier to
execute filters. What about forming agroup to develop this as a challenge?
Ferdinand Valk
We were delighted to welcome, from theNetherlands, Ferdinand Valk, whoentertained us with a brief illustrated talkdetailing the history of the B15 iceberg
from its formation up till the present day.

Antarctica composite

After setting the scene with this composite
satellite image of the continent (below),
Ferdinand described events from the initialcalving of the iceberg in 2001 throughvarious phases of movement andgrounding. All this was illustrated by
fascinating movies he had created from
MODIS imagery, which clearly showed thefracturing of the ‘berg in 2003 and its
collision with the Drygalski ice tongue in2005.
Fred van den BoschSatellite
Frequencies

6anumberofsplendid

Workshops
In addition to these speakers, a number ofworkshops operated throughout the day.
One of the most popular was John
Tellick’s demonstration of the use of asatellite signal meter to align a dish on Hot
Bird-6 (see photographs on page 5). The
whole process went flawlessly and took
only two minutes.
In the demonstration room, anotherpopular offering came from David
Simmons who tackled the potentiallyproblematic installation of the Tellique
software on a PC. With each stage of theprocess projected on a large overhead
screen, everything installed smoothly,
culminating in a comforting audio signal
which pulsed as the data was received
from Hot Bird-6. David’s secret here was
the use of a set of radio headphones
which allowed the dish to be pointed
remotely from the PC by reference to thesound volume.

Fred also discussed several usefulsoftware packages he uses: Digital
Atmosphere, Photofiltre and Anaglyph
Maker. Photofiltre was particularly usefulas it allowed both the addition andsubtraction of MSG channel data, onecase in point being to subtract channel-1
from channel-2 to enhance country
outlines.

Once all the presentations were over,Francis Bell presided over a short AGM
where he opened proceedings byreiterating, for the benefit of new
members, the fact that GEO is a limited
company which makes annual returns toCompanies’ House and the Inland
Revenue. GEO represents its members’interests to international agencies, andhas already made its mark.

Rob Alblas
Rob Alblas is well known in the
Netherlands as a weather satellite
software author and his XRIT for MSG
was featured in GEO Q5. Rob had
intended to demonstrate using the LINUX
platform, but his first major computer
malfunction in 15 years occurred justbefore setting out for Leicester, so hedemonstrated with the Windows version
instead.
Rob took us through all the features of his
software, which was used to decode live
Meteosat-8 data throughout the day. He
also explained how additional software
could be used to convert MSG images into
movies (as they were being received) and

Frequencies (MHz)NOAA-12
NOAA-14
NOAA-15
NOAA-16
NOAA-17
NOAA-18
Feng Yun 1C, 1D

showed us
animations.

Another of our Dutch members, Fredstarted with the assertion that ‘basically I
am lazy’, then went on to explain how hehas fully automated his weather satellite
activities by means of batch files. By
setting up an appropriate folder structureon the single PC used for the task he has
fully linked products from MSG DataManager, MSG Animator, GeoSatsignal
and Digital Atmosphere. Images andsynoptic files are all retrieved andprocessed completely automatically to
produce satellite images overlain withfronts, isobars and so forth.

Polar Orbiting Satellites

Weather

September 2005

GEO has recently expanded its management team, with David Painter (Education)
and Peter Green (International Liaison)joining the Group’s founders.
The meeting continued as a question-andanswer session where members posed avariety of queries from the floor, before
David Painter wound up proceedings witha vote of thanks.
References
1 Werkgroep Kunstmanen
http://www.kunstmanen.nl
2 Callington Space Centre

APT

HRPT

Geostationary
Satellites

137.50137.50137.62137.91-

1698.01707.01702.51698.01707.01707.01700.4

GOES-E
GOES-W
Meteosat-5
Meteosat-6
Meteosat-7
Meteosat-8

www.geo-web.org.uk

http://www.callingtoncommunitycollege.co.uk/
spacecentre

Location
USA
USA
INDOEX
EuropeEuropeEurope

75°W
135°W
63°E
10°E
0°
0°

Frequencies
WEFAX (MHz)
1691.01691.01691.01691.01691.0, 1694.5
D VB

September 2005

Group for Earth Observation

GEO Quarterly No 7

Sergei Ludanov - kd6cji@mac.com
Figure 1 - MacHRPT displaying a NOAA channel-4 infrared image

Introduction
It was with great interest that I read Les
Hamilton’s article ‘HRPT images from the
NOAA Satellite Archive’ in issue No 5 of
GEO Quarterly. I almost rushed to theInternet to register with NOAA and request
files to download but suddenly realisedthat I don’t have HRPT Viewer on my Mac
PowerBook. I went to Google to search forsuch a program that runs on Mac OS X
but results were not very encouraging; infact, I found none. Well, to be more exact,
there is a multi-platform program called
GRASS that runs on Mac OS X using X11,
but it is very complicated to install and use.
At any rate I have not figured out how to
use it yet. However, I was so inspired by
Les Hamilton’s article that, by the time mysearch was over, I was on a roll anddecided to try to write a program myself.
MacHRPT
At that point I had no clue about HRPT fileformats or anything else related to them.
Fortunately, the NOAA website contains a
wealth of information, including theinvaluable ‘KLM Users Guide’. After detailsof the image format had become more orless clear, I fired up XCode—Apple’s
development tools and environment—andwas on my way. A couple weeks of busy
late nights at the computer and the firstversion of the program which, having no
poetic talent I called MacHRPT, wasready.
MacHRPT is by no means a mature
program yet and lacks many of thefeatures that users of David Taylor’s
HRPT Reader are accustomed to: but I
am planning to continue working on it,
especially if there is significant interest
expressed in it. I must admit that, before I
started writing MacHRPT, I took a quick
look at HRPT Reader to see what this was
all about (I still have Windows PC at mywork, collecting dust—but in this particularcase it served a useful purpose).
At the time of writing I released version 1.1
but, by the time this magazine reaches
you I hope there will be a newer and better
version to explore.
Program Features
For the initial release I decided to
implement only very basic features with alimited range of image processing
capabilities. So the current version
supports HRPT, LAC and GAC images forv2 datasets, but only HRPT for preNOAA 15 datasets . It can display any of
the five satellite data channels (figure 1)
as well as create false colour images
using RGB and HSB models (figure 2). I
found that the RGB model produces
better, more vivid and colourful images
from daytime passes. Overnight passes,
where channels-1 and -2 are blank, don’t
produce anything interesting, and the HSB
model is marginally better suited to these.
The only image processing tools that are
implemented are ‘Equalise Histogram’ and‘Geometry Correction’. For RGB images,
equalisation works on all three channels at
www.geo-web.org.uk

the same time; with HSB model you canequalise both Hue and Brightness at thesame time or separately, trying to create
something viewable without too much
effort. There is also Saturation adjustment
for the HSB image (figure 3).
When the image for any individual channel
is displayed its histogram is shown on theright panel of the window. An RGB image
has three histograms, one for eachcomponent plus pop-up buttons to selectthe channel for each colour representation. Displayed images can be saved in
TIFF or PDF formats (at both full
resolution and quarter resolution sizes)
and printed. When printing, images are
scaled to fit the page. In future I plan to
add an option to choose multi-page
printing so one can create a wall poster for
displaying proudly in the shack!
While working on this project I ordered anddownloaded a few files from NOAA and it
was a somewhat annoying experience. As
the main rule for writing software is tomake it as user-friendly as possible, I
decided to add a capability to download
files from the NOAA ftp server from within
the program. All that is required is to copy
the filename from the e-mail you receivefrom NOAA, select Download from the Filemenu in MacHRPT, paste this filename
into the File Name field and click the
Download button (figure 4). Then just sit
back, relax and watch the download byte
counter flying (or crawling depending on
your Internet connection speed). Actually

7

GEO Quarterly No 7Group for Earth Observation

September 2005

there is no need to sit back as files aredownloaded asynchronously on a
separate thread, so it is possible to do
image processing while new files arebeing downloaded in the background.
When the download ends it will prompt
you that the file is ready. For now thisworks only with the NOAA ftp server. Asa final touch, just for fun and without
any useful purpose, I added the little
rotating globe icon at the upper rightcorner of the program window.
Performance
After I finished the program I could notresist measuring the performance andcomparing with numbers given by Les
for HRPT Reader on various Windows
PCs. I don’t have a bunch of Macs
sitting around, but I was happy to seethat MacHRPT’s performance on my
1GHz G4 PowerBook with 512 Mb of
RAM was on par with the data reported
for a 2.8 GHz Pentium IV Windows
machine running HRPT Reader.
For further development my plans are
as follows: get ready for the HRPT v3
format change which will happen after
the NOAA N launch and add support for
the level 1f format used by Russianservers. I will also add more file formats
for saving (JPEG, PNG, ?). After I run
out of ideas I hope others will come up
with more suggestions, criticism and soon.

Figure 2 - An equalised and geometrically corrected false colour image

Availability
Meanwhile, the program can be
downloaded from:http://homepage.mac.com/kd6cji
Once the download is completed
Mac OS X will decompress the fileautomatically and you will end up with
the MacHRPT icon on your desktop.
Just drag and drop it to your favourite
applications folder.
On the same web page there is also adownload link for my OrbitaX program,a satellite-tracker for Mac OS X which
may be useful for satellite enthusiasts
as well. Admittedly, it is quite outdated
but by no means obsolete. A newversion will be released after I havecompleted MacHRPT.

Figure 3 - The Saturation adjustment for an HSB image

Contacting the Author
Give these programs a try and let meknow what you think. Both positive andnegative comments are welcomed. I
can be reached by e-mail at:
kd6cji@mac.com
Figure 4 - The Download dialogue

8

www.geo-web.org.uk

September 2005

Group for Earth Observation

GEO Quarterly No 7

Peter Wakelin
NOAA-N Successfully Launched
Earlier NOAA satellites were launched by surplus Atlas E and
Titan II missiles but these have now been retired so a Boeing
Delta 7320 was used for this mission. The rocket lifted off fromSpace Launch Complex 2W at Vandenburg Air Force Base in
California at 1022 UTC on May 20 and the 1442 kg spacecraft
entred the planned 846 x 866 km orbit inclined at 98.8 degrees
to the equator (measured from the east). The spacecraft was
built by Lockheed Martin Space Systems and was launched onbehalf of NASA’s Goddard Space Flight Center’s Polar
Operational Environmental Satellite Program.
At the time of writing, in late July, NOAA 18 (renamed onachieving orbit) is being checked out and some anomalies areunder investigation but it is believed that all instruments areeither operating, or capable of operating, nominally.
NOAAs Galore
NOAA are obliged to keep just two polar-orbiting weather
satellites in the NOAA series operational and two further craftin standby mode. With the recent unexpected resumption ofimagery from NOAA 14’s scanning radiometer there are no
fewer than six spacecraft imaging, though one, NOAA 16, iscapable of transmitting its data on the HRPT frequency only.
Because of perturbations to their orbits, the older craft nolonger maintain precise sun-synchronism and have driftedaway from their original orbital planes. In late July, the local
times of northbound equator crossings were as follows:
NOAA 12 - 16:53
NOAA 14 - 20:49
NOAA 15 - 18:01
NOAA 16 - 14:48
NOAA 17 - 22:25
NOAA 18 - 13:57
Columbia’s Last Flight Formed Clouds over Antarctica
A burst of high altitude cloud activity over Antarctica inJanuary 2003 was caused by the exhaust plume of the Space
Shuttle Columbia during its final flight, reports a team ofscientists who studied ground-based and satellite data fromthree different experiments.
It had been suggested that the increases in brightness,
occurrence and range of these high altitude clouds observed inrecent years may be related to global climate change but it now
seems likely that water released into the high atmospherefrom rocket launches could be responsible.
These Polar Mesospheric Clouds (PMCs) are rare and form ataround 84 km altitude when the temperature is colder thanabout -125°C. Such temperatures occur only at high latitudes
in summer, hence the name. They are also known asnoctilucent clouds as, because of their great height, they can beseen at night when all lower clouds are devoid of sunlight.
The Space Shuttle Columbia released about 400 tonnes ofwater (the product of its hydrogen fuel combustion) into themesosphere at the time it was accelerating to orbital velocity

whilst travelling almost horizontally near 110 km altitude.
The resulting plume was about 3 km in diameter and about
1,000 km long and was detected and tracked by the Global
Ultraviolet Imager on NASA’s Thermosphere, Mesosphere,
Energetics and Dynamics (TIMED) satellite. The images
revealed rapid movement of the plume toward the South Pole.
More on this story, together with images, can be found at
http://www.nrl.navy.mil/pao/PressReleases/2005/36-05r
The writer witnessed a fine display of PMCs from southern
England on the night of 22/23 June this year. They werevisible low in the north throughout the short night and were
probably over Scotland. Can these clouds be detected on
weather satellite imagery? They may be too tenuous for the
lower resolution IR sensors but would a suitably placed HRPT
image show them, or perhaps the new high resolution visible
imager on Meteosat 8?
NASA Opens New Hurricane Web Page
NASA now has a new Internet resource page highlighting theagency’s diverse hurricane research. It was opened just in time
for this year’s North Atlantic hurricane season which has got
off to a busy start with seven named storms before the end of
July. The information is available on the web at:
http://www.nasa.gov/hurricane
Collision in Crowded Sun-Synchronous Orbit
The subjects of a collision which occurred on January 17, 2005
885 km above Antarctica have been identified by the US Space
Surveillance Network. The rocket which launched the military
weather satellite DMSP-5 more than 31 years ago was struck
by one of the several hundred catalogued pieces of debris
which resulted from the explosive break-up of the Chinese
CZ-4 rocket that launched the CBERS-1 satellite in 1999.
The first recognised collision between objects from different
missions occurred in July 1996 when the French CERISE
spacecraft, also in a sun-synchronous orbit, was struck anddamaged by a small fragment from an exploded Ariane rocket.
The sun-synchronous orbit between 600 and 1000 km is a
popular destination for Earth-imaging spacecraft but,
regrettably, several rockets and spacecraft in this region have
exploded as a result of build-up of pressure from unused fuelor within batteries. Even very small fragments travelling athigh speed are hazardous to satellites and it is only a matterof time before an operational spacecraft is destroyed by such acollision.
Japan’s Next Earth-Imaging Satellite Delayed
Japan Aerospace Exploration Agency (JAXA) has announced
that the launch of ALOS (Advanced Land Observing Satellite)
has been delayed. Tests on another Japanese satellite,
ASTRO-F, revealed a faulty transistor of a type that is also
used on ALOS. Although the one on ALOS is working properly,
JAXA have decided to replace it. Launch is still expected thisyear.

www.geo-web.org.uk

9

GEO Quarterly No 7Group for Earth Observation

Cloudsat Arrives at Launch Site
NASA’s Cloudsat spacecraft has arrived at the Vandenberg,
California launch site and, after further testing, will be
integrated on to a Boeing Delta II launch vehicle with its copassenger Calipso (Cloud-Aerosol Lidar and Infrared
Pathfinder Satellite Observation).

September 2005

The Mars Orbiter Camera on Mars Global Surveyor captured
this image of Mars Odyssey on April 21 when the spacecraft
were about 100 km apart and travelling at more than 4 km/s
in different orbits. At this range, the camera’s field of view isabout 800 m so a high pointing accuracy and precision timing
are required to successfully image such a fast-moving target.
An added complication is the time taken for commands totravel the constantly changing distance to Mars.
The image was obtained by the Mars Global Surveyor
operations teams at Lockheed Martin Space Systems,
Denver; California Institute of Technology’s Jet Propulsion
Laboratory and Malin Space Science Systems, the San Diego,
California, company that built the camera.
Every Seventh Wave... continued from page 3

Cloudsat (Image: NASA)

Launch is now expected in late September and will take thetwo craft to a 705 km sun-synchronous orbit where they will
fly about 100 km apart. Both satellites carry revolutionary
measurement technologies that will probe Earth’s
atmosphere in new ways. A detailed account of thesespacecraft will appear in this column after launch.
Martians Emulate Earthlings’ Feat

big waves which come out first”. She challenged me on this:“No, it’s not like that. You get the small waves first”. I thengave her a one minute lecture on waves: their interferencewith each other, the speed of propagation as a function ofwave length and how important this is for the distribution ofenergy around our oceans. I was a little doubtful about her
understanding of the concepts and mathematics involved.
This doubt was confirmed when she smiled at me beguilingly,
took me by the hand and said those magic words. “Can I go
and play on the slide now please”?

From time to time it is claimed that strange streaks or spots
on weather satellite images can be attributed to otherspacecraft but the resolution, sensor characteristics andscanning methods employed make this extremely unlikely.
However, other imaging spacecraft have observed satellites
in Earth orbit and military spacecraft probably do it
routinely. It is likely that the Space Shuttle Discovery, inorbit at the time of writing, has been extensively imaged byother satellites to check for damage.
Now, for the first time, this feat has been achieved by aspacecraft orbiting Mars. NASA’s Mars Global Surveyor has
successfully imaged the European Space Agency’s Mars
Express and NASA’s Mars Odyssey both of which are also inorbit around the red planet.

Quarterly Question

Mars Odyssey imaged from Mars Global Surveyor

Computer drawing of Mars Odyssey

10

The last question related to the interference caused byMeteosat-8 to other satellite reception. The answer was on
page 41 of ESA Bulletin No 121 (February 2005). The answer
is the SOHO satellite which is studying the sun. I received
three correct answers. The ESA Bulletin it is available on
request, free of charge, from:ESA Publications Division
c/o ESTECPO Box 299
2200 AG Noordwijk
The Netherlands.
I did say I wouldn’t set another question myself but, since I
haven’t received one from anybody else, here’s mine. E = mc2
is a famous equation. E stands for energy, m for mass and cthe speed of light. The question is: Why pick a lower caseletter ‘c’ for the speed of light? Answers to me by email or post:
details on page 1.
www.geo-web.org.uk

September 2005

Group for Earth Observation

GEO Quarterly No 7

Les Hamilton
Based on an Internet survey conducted by Lawrence Harris and Nick Hewgill
It had been known for a long time prior to its successful launch on
May 20 (for several years in fact) that NOAA-18 would transmit its
APT on one of two new frequencies in the 137 MHz band. Which ofthese was finally to be used was not however established by NOAA
until the satellite was actually in orbit and, as (bad) luck would
have it, it was 137.91 MHz. Of course, for the World at large, thisis of little consequence. But for APT enthusiasts in Great Britain
this is worryingly adjacent to the pager frequencies which operatefrom 137.975 MHz and upward into the 138 MHz band. It was
widely anticipated that this would cause problems—perhaps
denying UK users access to the NOAA-18 satellite altogether.
In the event the great day arrived and almost at once conflicting
reports started to flood in. Some members were experiencing
perfect reception but by far the majority were reporting pager
intrusions varying from ‘mild banding’ through their images to‘completely unusable’. Interestingly, these were not always inaccord with the generally held belief that reception in urban areas
would be impossible whilst the chances of success in rural locations
would be much greater. Even within Greater London we received a
few reports of ‘perfect’ reception, though most members foundthemselves in the ‘unusable’ category.

Interference Level
ReceiverDartcom
Martelec MSR50
Proscan

None
4
1
1

RX2
OthersScanners (various)
Totals110118

Antennas
Turnstile
QFH

7
11

6
12

Mild
4
0

Moderate
32

Unusable
2
2

2

1

20

11
1
1
19

15
1
3
25

10
5
5
44

9
15

23
24

Table 1
Summary of the main survey results

In an effort to place the matter on a more systematic footing,
Lawrence Harris and Nick Hewgill set up an Internet survey
on the problem. Nick produced a web page where members could
input details of their receiver, antenna etc. and the degree ofinterference experienced with NOAA-18 while Lawrence
summarised the results. Table 1 lists the main findings for themost popular equipment but a more detailed summary,accompanied by charts, can be viewed on Nick’s website at:www.weatherstation.org.uk/tabularresults.html
Lawrence Harris summed up the results thus:‘Almost without exception, non-UK monitors are not experiencing any interference. There is some preliminary evidence that
one or two receivers might be relatively pager tolerant. It has tobe said though that (1) the receiver concerned is very expensiveand (2) those who have done the tests will not wish to buy a newreceiver simply for NOAA-18 reception.

Figure 1 - No pager interference
NOAA 17 channel-2 APT image at 11:20 UT on May 29, 2005,
received on 137.62 MHz using the MSR50 receiver
Image processing: Satsignal and GroundMap‘These data should be interpreted carefully. A low-cost receiverin a radio-quiet environment would probably give better results
than an expensive receiver next to a pager transmitter! The more
receivers of one type that are in operation, the more the results
can vary.... etc. etc.’
From my own location in Aberdeen I have tested three receivers
with NOAA-18, an RX2, a Martelec MSR-50 and a German-built
R2FX, all under identical conditions. Figure 1 comes from a
NOAA-17 pass obtained on May 29 using the Martelec MSR50
tunable weather satellite receiver tuned to 137.50 MHz. The image
is pager-free. Figure 2 was achieved with the same equipment
some two hours later when the receiver was tuned to 137.90 MHz(sic) to capture NOAA-18. Moderate pager intrusions are visible(which are even stronger when operating the MSR50 at thesatellite’s nominal frequency of 137.91 MHz). ... concluded on page 13

Figure 2 - Moderate pager interference present
NOAA 18 channel-2 APT image at 13:24 UT on May 29, 2005,
received on 137.91 MHz using the MSR50 receiverwww.geo-web.org.uk

11

GEO Quarterly No 7Group for Earth Observation

September 2005

John Beanland G3BVU/W1
The arrival of NOAA-18 last May madealmost every weather satellite enthusiast
in Great Britain painfully aware of theexistence of ‘pager’ transmissions. The
new NOAA-18 frequency of 137.9125 MHz
is uncomfortably close to these pagers,which transmit at 137.975 MHz andupward. In some areas the effects areminimal but many GEO members havereported the problem to be so severe as torender NOAA-18 imaging impossible.
Do we simply accept defeat, or can we
actually do something to improve
reception and eliminate or reduce theimpact of the pagers? John Beanlandcertainly believes so, as explained below.
May I offer you some helpful comments inconnection with the current, and future,
RFI problems with ‘pager Interference’ on
the reception of NOAA-18 transmissions at
137.9125 MHz.
The problem is due to the classical ‘low
cost’ design of almost all weather satellite
receivers. Without getting into details, twomajor problems are:
• The selectivity function (the ceramic
IF filter) does not have sufficient skirt
selectivity. More poles (and morecost) are needed.
• The major filtering is in the final IF(455 kHz in most receivers). This is
too late in the receive chain. There is
too much gain ahead of it.
Ideally the channel filtering should be at
RF (which is not really practical without
excessive expense). The alternative is in
the first IF (10.7 MHz). But 10.7 MHz filters
are more expensive than 455 kHz ones forthe same number of poles. Huge
production volume of 455 kHz filters has
resulted in minimum cost.
Additionally most low-cost WX receivers
use the inexpensive Motorola MC3359 ‘doeverything’ integrated circuit for the IF
gain, IF filter location and detector
functions. This is far from the best design
for a robust receiver, but ‘the price is right’.
The above comments are made to define
the problem. I do not propose to offer asolution to the receiver design deficiencies
in this article.

12

But I would like to offer a way to minimise
the pager hazard encountered by manyreceivers. The objective is to reduce theamplitude of the pager signal entering thereceiver without reducing the amplitude of
the NOAA-18 signal.
Antennas
Many WX receive systems (note: I say
receive systems) use a quadrifilar helix
antenna (QFH) for reception of theweather satellite image signals. This is an
excellent choice of antenna for general
purpose use. By rejecting the LH polarised
multipath signal and accepting only the RH
polarised direct signal, the multitude of‘noise bars’ across the image iseliminated. There is no multipath signal(180 degrees out of phase with the direct
signal) to result in a zero amplitude vector
addition of the direct and multipath signals
to cause amplitude cancellation. In certain
locations (like New York City) there areoften ‘double’ reflections which place themultipath signal back in a RH polarisedmode!
It is unfortunate that a QFH antenna
responds very well to both horizontal andvertical linearly polarised signals. Hencethe Quad Helix readily receives the Pager
signal which is, without doubt a verticallypolarised signal, to suit their omnidirectional coverage.
Fortunately there is a simple, low cost
solution: a turnstile antenna! A turnstile
antenna is circularly polarised only at thezenith. As we reduce the elevation angle,
its response becomes elliptically polarised,of varying ratio, until at the horizon it islinear, horizontally polarised. Now thepager signal, as noted above, is verticallypolarised; hence there is the potential
for significant cross-polarised rejectionof the pager signal without attenuationof the NOAA-18 signal!
What are the requirements of the Turnstile
design?
• It must be carefully constructed,
observing symmetry about the axis.
• More importantly, the transmission
line connection must be balanced.
Co-axial cables must have baluns
installed at the feed point to present a
www.geo-web.org.uk

balanced load to the dipoles. Ferrite beads
on the co-axial cable provide a simple andeffective solution. Similarly, ferrite beads
on the co-ax at the receiver end attenuate(pager) signal energy that is induced on tothe outside of the co-axial braid. ‘Ground’
the receiver to an honest earth rod andkeep the rod watered with ‘conducting
water’ (train you hound dog to do this foryou).
Of all the people complaining about
pager interference, how many ofthem have an effective, or even apoor, ground system connected totheir receiver?
Using the turnstile will result in some ‘noisebars’ because the elliptical polarisation will
receive the LH polarised, multipath signal.
This is a small price to pay for providing
significant attenuation of the pager signal,
which may now be of low enoughamplitude for the ‘low cost’ APT receiver
design to produce acceptable NOAA-18
images.
Co-axial Cable
Let us consider a typical 137 MHz APT WX
station’s RF installation.
1. There is an antenna installed ‘high’in the air, probably 20-30 feet above
ground in most installations.
2. A length of co-axial cable between
the antenna and the receiver alsoreaches upward (nominally vertically)
the same 20-30 feet.
3. A receiver, located indoors, with theco-axial cable connected to its input
and a data decoder (either adedicated hardware decoder orconnection directly to the computer’ssoundcard) is connected to thereceiver’s output.
4. The only ground connection isthrough the mains power supply’s
green/yellow earth wire (which leads
to earth). Basically the whole
receiving system is usually floating
way above ground, particularly as
most units are powered by 12 volts
provided by a transformer.
5. In general almost every receiver haspoor selectivity and poor overload
protection.
No wonder most people are in trouble!

September 2005

Group for Earth Observation

Let us consider the co-axial cable. The braid is an excellent
antenna for vertically polarised (pager) signals. RFI EMFs are
induced in the braid (actually within 0.010 inch of the outersurface) and currents flow on the braid both towards the receiverand towards the antenna.
Let us assume that the receiver is built into a metal case and that
it is effectively grounded (which I doubt). In this case the pager
RFI currents will be shunted to earth and no (or little) harm will be
done.
What about the induced pager currents flowing up to theantenna? When these currents reach the (antenna) end of the coaxial cable they will, in general, continue flowing on the innersurface of the braid, down to the receiver and right into it! These
two currents, up on the outside and down on the inside of the coaxial braid ‘know’ nothing of each other due to the ‘skin effect’.
100% effective grounding of the co-axial cable’s braid (and thereceiver) at ground level as the cable enters the house, and at the
input of the receiver, will not stop this pager current from entering
the receiver! This pager current is being input to the receiver justlike that from a satellite signal! It’s what your receiving system isdesigned to do.
Connecting the co-axial cable to a turnstile antenna, in place of a
QFH antenna, will reduce the amplitude of the pager signal
received by the antenna but it will not change the amplitude of thepager signal received on the braid of the co-axial cable. So you
get some reduction of the pager signal amplitude, but not as muchas you expected, since the ‘big, long and vertically polarised
antenna’ (the outer surface of the co-axial braid) is still doing what
it is supposed to do.
What can we do to help ourselves?
1. Stop the pager currents that are flowing on the outer

GEO Quarterly No 7

surface of the co-axial cable’s braid from reaching the
braid’s inner surface. Fit ferrite chokes (ferrite toroids) tothe braid at the antenna connection to attenuate thecurrents flowing on its outer surface as they attempt toreach the inner surface. This is a very good start and canbe very effective.
2. Install an effective balun at the antenna terminals. Anotherimportant feature.
3. Bond the co-axial cable braid to an effective ground as thecable enters the house. Train your faithful hound dog tomaintain the effectiveness of the ground rod.
4. In an extreme case, wrap your receiver in aluminium(kitchen) foil and connect the foil (and the receiver) to aneffective GROUND.
All of the above have the potential to significantly reduce theamplitude of the pager signal entering the receiver. If you’resuffering from ‘pager interference’, do something about it insteadof complaining.
Further steps in reducing pager interference will require changes
to the receiver’s design and are probably not within the reach or
technical competence of most WX enthusiasts. For those who aretechnically competent, consider adding a ‘real’ filter in the10.7 MHz IF of your receiver. An 8-pole KVG crystal filter, model
XF-107-E, is perfect for this job; it was designed for APT receiverapplications. Don’t forget to provide effective screening anddecoupling between the input and output of the crystal filter.
‘Stiffening’ the design of the RF amplifier and the first mixer, totake advantage of a 10.7 MHz crystal filter, are other excellent
attributes.
In Summary
If you are currently using a QFH antenna, change to a turnstile. If
you are already using a turnstile, pay attention to the feed’sbalance, etc.

NOAA-18 Reception and Pagers... continued from page 11

The RX2 receiver provides virtually pager-free reception, theMSR-50 suffers moderate to severe interference (figure 2)
while my R2FX is totally ‘wiped out’. Figure 3 compares theRX2 and the R2FX on the same pass. It must however be
stressed that all these receivers perform flawlessly on both ofthe ‘old’ NOAA frequencies. It is only on the NOAA-18
frequency that any problems with pagers are encountered.

Reference to Table 1 would suggest that the RX2 is distinctly
superior to most other receivers. The figures also back up John
Beanland’s assertion (see article above) that the turnstile
antenna is more likely to provide good results than the QFH.
The survey includes over 100 responses from users across theentire length and breadth of Great Britain. Although thesefindings must be treated with caution they do nonethelessprovide a most illuminating insight into the effect of pagers on
NOAA 18 APT reception nationwide.

Figure 3 - NOAA-18 at 14:03 UT on July 5. Perfection with the RX2 (left) and wipeout with the R2FX (right)
www.geo-web.org.uk

13

GEO Quarterly No 7

Meteosat-8 is the first of the Meteosat
Second Generation (MSG) all-digital
geostationary weather satellites andtransmits twelve imaging channels
every 15 minutes throughout the day.
All this is accomplished by a single
instrument known as the Spinning
Enhanced Visible and InfraRed Imager(SEVIRI). Six of its channels (1, 2, 3, 4, 9
and 10) were specifically selected tocorrespond closely with the channels
disseminated by the AVHRR-3 imager
carried aboard the NOAA-KLM series ofpolar orbiting satellites. But what
exactly do all these diverse imaging
channels tell us?

CHANNEL 1: Visible 0.6(0.56 - 0.71 µm)

Group for Earth Observation

The two visible channels centred on 0.6
and 0.8 micrometres (µm) provide cloudand land-surface imagery during
daylight hours. These particular
wavelengths permit discrimination
between vegetated and non-vegetatedland surfaces and also between the
Earth's surface and different cloudtypes. These channels are also useful in
helping to determine the atmosphericaerosol content.
The 1.6 µm infrared channel can be used
to distinguish low-level clouds fromsnow surfaces and, in combination withthe 3.9 µm and 8.7 µm channels, helps to

September 2005

differentiate between ice and water
clouds. Additionally, when combinedwith the two visible channels, they also
support the determination ofsoil
moisture content and the optical depthof atmospheric aerosols.
The 3.9 µm infrared channel can be used
to detect fog and low-level clouds atnight and to distinguish water clouds
from ice surfaces during the hours of
daylight. It also supports the 10.8 µm
and 12.0 µm channels in making
determinations of surface temperaturesby estimating the tropospheric watervapour absorption.

CHANNEL 2: Visible 0.8(0.74 - 0.88 µm)

These channels are essential for cloud detection, cloud tracking, scene identification andthe monitoring of land surfaces and aerosols. Together with channel 3 they can be used togenerate vegetation indices.

CHANNEL 3: NEAR-Infrared 1.6(1.50 - 1.78 µm)

CHANNEL 4: Infrared 3.9(3.48 - 4.36 µm)

CHANNEL 12: High Resolution Visible(0.6 - 0.9 µm)

Helps to discriminate between snow andcloud, and between ice and water clouds.
Also provides aerosol information.

Primarily for detection of low cloud and fog
at night, but also useful for measurementof land and sea temperatures at night andthe detection of forest fires.

The broadband visible channel, but with an
improved sampling interval of just one
kilometre.

14

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September 2005

CHANNEL 5: Water Vapour 6.2(5.35 - 7.15 µm)

Group for Earth Observation

CHANNEL 6: Water Vapour 7.3(6.85 - 7.85 µm)

Provides continuity of the Meteosat first generation broadband water vapour channel tomeasure mid-atmospheric water vapour and to produce tracers for atmospheric winds.
Also supports height assignment for semi-transparent clouds. Two separate channels
representing different atmospheric layers instead of the single channel on Meteosat.

CHANNEL 8: Infrared 9.7(9.38 - 9.94 µm)

Responsive to ozone concentrationin the lower stratosphere. It will be
used to monitor total ozone andassess diurnal variability. Potential
for tracking ozone patterns as anindicator of wind fields at that level.

CHANNEL 9: Infrared 10.8
(9.8 - 11.8 µm)

CO2 absorption channel, to be used
for the estimation of atmosphericinstability, as well as contributing
temperature information on the lower
troposphere.

CHANNEL 7: Infrared 8.7(8.3 - 9.1 µm)

Used mainly to provide quantitative
information on thin cirrus clouds andto support the discrimination between
ice and water clouds

CHANNEL 10: Infrared 12.1
(11 - 13 µm)

These two channels, termed the ‘split window’ infrared channels, both respond to thetemperature of clouds and the surface. By splitting this part of the thermal infrared,
each channel shows a slightly different response with respect to clouds and theEarth’s surface. Combining them can help to reduce atmospheric effects whenmeasuring surface and cloud top temperatures. They are also used for cloud tracking
for atmospheric winds and for estimates of atmospheric instability.
The two channels in the water-vapour
absorption band, at 6.2 and 7.3 µm
determine the water-vapour distribution
for two distinct layers in the troposphere.
These two channels can also be used toderive atmospheric motion vectors incloud-free areas and will support the10.8 µm and IR-12.0 µm channels in thealtitude assignment of semi-transparent
clouds.

CHANNEL 11: Infrared 13.4
(12.4 - 14.4 µm)

GEO Quarterly No 7

The 8.7 µm channel may also be utilisedfor cloud detection and, in combination
with the 1.6 µm and 3.9 µm channels, canhelp to discriminate between ice clouds
and the Earth's surface. Moreover, the8.7 µm channel may also be used in
combination with the 10.8 µm and12.0 µm channels to determine the cloudphase.
The SEVIRI channel that covers the verystrong fundamental vibration band ofozone at 9.7 µm, will be used to deterwww.geo-web.org.uk

mine the total ozone content of theatmosphere and may also be applied tomonitor the altitude of the tropopause.
The two channels in the atmosphericwindow, 10.8 µm and 12.0 µm, will
mainly be used together with the 3.9 µm
channeltodeterminesurfacetemperatures.
The 13.4 µm channel covers one wing of
the fundamental vibration band ofcarbon dioxide centred at 15 µm, and will
therefore be used primarily foratmospheric temperature sounding in
supportof
air-mass
instability
estimations.
Acknowledgement
Much of the information used in the preparationof this article was obtained from ‘Meteosat
Second Generation Becomes Operational’ by W
Schumann, R Oremus and S Rota, published in
ESA Bulletin No 119, August 2004.

15

GEO Quarterly No 7Group for Earth Observation

As we reported briefly in GEO Q3, ‘Aura’ was launched from
Vandenberg Air Force Base, California aboard a Delta II rocket on
July 15, 2004 thus becoming the third and final satellite in NASA’s
current Earth Observing System. Aura’s view of the atmosphereand its chemistry will complement the global data already being
collected by its forebears, Terra and Aqua. Collectively, thesethree satellites allow scientists to study how life, land, water, andthe atmosphere work together as a unit. Aura’s four instruments
will enable scientists to discern subtle chemical interactions to,and achieve a better understanding of how, Earth’s atmosphereworks: most specifically, whether the stratospheric ozone layer isshowing signs of recovery, discerning the processes that control
air quality and investigating exactly how the Earth’s climate ischanging.
Unlike Terra and Aqua, Aura is not an imaging satellite. Aura’s
objective is to probe the troposphere, that region of Earth’s
atmosphere, up to an altitude of approximately 10 km, which
affects our daily lives the most. Aura will measure greenhousegases such as methane, water vapour and ozone in the upper
troposphere and lower stratosphere; Aura also will also measureboth absorbing and reflecting aerosols in the lower stratosphereand lower troposphere, water vapour measurements inside hightropical clouds and high vertical resolution measurements ofcertain greenhouse gases in a broad swath (down to the clouds)
across the tropical upwelling region. All of these measurements
contribute key data for climate modelling and prediction.
OMI - the Ozone Monitoring Instrument
OMI is a nadir-viewing spectrometer that records total ozone (andother atmospheric parameters) related to atmospheric ozone
chemistry and climate. The instrument measures reflected andbackscattered solar radiation along the satellite track in no fewer
than 740 wavelength bands across a selected range of theultraviolet and visible spectrum. The spectrometer’s 2600 km
viewing swath-width is perpendicular to the satellite’s orbit track
and provides complete daily coverage of the sunlit portion of theatmosphere. OMI was contributed by the Netherlands Agency for
Aerospace Programs in collaboration with the Finnish
Meteorological Institute.
OMI is Aura’s primary instrument for tracking global ozone
change and will continue the high quality column ozone record
begun in 1970 by Nimbus-4 BUV. However, OMI has a broader
wavelength range and better spectral resolution and, additionally,measures column quantities of trace gases important to ozone
chemistry and air quality. OMI can map aerosols and estimate theultraviolet radiation reaching the Earth’s surface. OMI’s horizontal
resolution is about four times greater than TOMS.
HIRDLS - the High Resolution Dynamics Limb Sounder
HIRDLS is an infrared limb-scanning radiometer designed tomeasure trace gases, temperature, and aerosols in the upper
troposphere, stratosphere, and mesosphere to provide criticalinformation on atmospheric chemistry and climate.
TES - the Tropospheric Emission Spectrometer
TES is an imaging Fourier Transform Spectrometer which canobserve the thermal emission from the Earth’s surface and

16

September 2005

atmosphere, by both night and day. TES measures troposphericozone and other gases important to tropospheric pollution withvery high horizontal resolution. TES has a higher resolution than
OMI, but monitors a swath of only 5.3 x 8.5 kilometres.
MLS - the Microwave Limb Sounder
MLS is a limb scanning emission microwave radiometer whichmeasures radiation at millimetre and sub-millimetre wavelengths.
MLS measures important ozone-destroying chemicals in theupper troposphere and stratosphere as well as trace gases in thepresence of ice clouds and volcanic aerosols.
Early Results from the Aura Mission
Figure 1 shows the first publicly released product from the OMI.
Acquired on September 22, 2004. It outlines the dramaticallydepleted levels of stratospheric ozone over the Antarctic. The
lowest ozone concentration includes values of 100 Dobson units
and under, and is shown in purple; the turquoise green and yellow
regions indicate progressively higher concentrations of the gas.
Figure 2 displays data collected by OMI during the first ten daysof March 2005, showing high concentrations of sulphur dioxide
drifting northwest from Ambrym volcano on the island of the same
name in the Pacific nation of Vanuatu. Indeed, at the time, thiswas the strongest point source of sulphur dioxide on Earth.
Ambrym Volcano is not erupting in the traditional sense but isconstantly leaking sulphur dioxide gas from active lava lakes inongoing passive emissions. These gas emissions present a
serious hazard to the local population: the strongly smelling gas
irritates the eyes and nose and makes breathing difficult. Higher
in the atmosphere the sulphur dioxide combines with water tocreate acid rain which, on Ambrym, has destroyed staple crops
and contaminated the water supply.
The Manam volcano erupted explosively overnight on
January 27, 2005, spreading a cloud of ash and sulphur dioxide
across New Guinea (figure 3). The following day Aura’s OMI
measured the cloud of sulphur dioxide drifting westward using thesame Dobson scale as for ozone. Red pixels indicate the areasof highest concentration; the lowest concentrations are
represented by pink pixels. A normal atmospheric column
contains just 1 DU of sulphur dioxide. Following this eruption, theatmosphere over New Guinea contained up to 50 DU (red).
Measuring Total Ozone - the Dobson Unit (DU)
If all the atmospheric ozone on Earth could be concentrated
evenly in a layer, at atmospheric pressure and 0°C, such a layer
would be approximately 3.5 mm thick. This unusual approach
forms the basis of the definition for the Dobson Unit (DU) which
is used for ozone measurement. Put simply, one DU is defined asa notional layer of ozone, 0.01 mm thick, measured under these
conditions.
So the total ozone concentration in Earth’s atmospheric column isaround 350 DU, a value that fluctuates from place to place butlies typically between 200 and 500 DU. The unit was named after
G M B Dobson, one of the first scientists to investigate
atmospheric ozone.

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September 2005

Group for Earth Observation

GEO Quarterly No 7

Figure 1
Aura image of the Antarctic ‘ozone hole’during September 2004.
NASA image courtesy the Scientific Visualisation Studioat Goddard Space Flight Center.

Figure 2

Consequences
Once in the atmosphere, sulphur dioxide (SO2)combines with water to create a highly reflective haze ofsulphuric acid which reflects sunlight away from the
Earth and back into space. Since less sunlight reaches
the Earth, the haze has a cooling effect on the climate.
If an eruption is sufficiently severe it can lead to cooler
temperatures for several years until the sulphuric acid iswashed out of the the atmosphere as rain. In 1991,
Mount Pinatubo in the Philippines emitted millions oftons of SO2 into the atmosphere and global
temperatures, which had been expected to risebecause of the greenhouse effect, actually levelled out.
While large, Manam’s eruption does not compare with
Pinatubo’s in magnitude, and it is not clear if, or how,the current eruption will impact regional climate.

The ongoing passive emissions from Ambrym volcano on the Pacific Ocean
island group of Vanuatu during early March 2005 released clouds of sulphur
dioxide gas into the atmosphere. These were recorded by the OMI instrument
aboard NASA’s Aura satellite, and are shown on the map above.
NASA image and caption information courtesy Simon Carn, Joint Center for Earth
Systems Technology (JCET), University of Maryland Baltimore County (UMBC).

This new view of passive volcanic emissions could leadto significant advances in understanding both volcanic
eruptions and the impact of sulphur dioxide on climate.
Passive emissions can be a precursor of explosive
eruptions, and thus provide a warning signal that the
volcano’s activity may be changing. Scientists building
computer models of the complicated interactions thatmake up Earth’s climate need to understand how muchsulphur dioxide enters the atmosphere and where it
travels. Since most volcanic sulphur dioxide emissions
come from passive degassing, OMI now allows
scientists the means to assess the volcanic contribution
to atmospheric sulphur dioxide concentrations with
unprecedented accuracy. The data should help refine
climate models.
Further Reading
A wealth of further information about Aura, its
instrumentation and results can be found on NASA’s
Aura Mission website at:
http://aura.gsfc.nasa.gov/

Figure 3
Manam volcano in New Guinea erupted explosively during the night of January
27, 2005, spreading a vast cloud of sulphur dioxide over the country.
Concentrations were measured by the OMI aboard Aura and peaked at fifty
times normal (red areas on map).
NASA image and caption information courtesy Simon Carn, Joint Center for Earth
Systems Technology (JCET), University of Maryland Baltimore County (UMBC).

www.geo-web.org.uk

17

GEO Quarterly No 7

Dartcom APT Receiver
As you will read elsewhere in this issue,
NOAA-18 reception in the UK has
proved something of a hit-and-missaffair. However, one particular device,
the Dartcom APT receiver, has proved
particularly pager resistant. John
Tellick, who gave up APT imaging many
years ago because his location in
Greater London was completely
swamped by pager interference,
discovered to his amazement that whenusing the Dartcom receiver tuned to137.91 MHz he obtained perfectcomplete passes from NOAA-18. At thesame location the popular Proscan
receiver, fitted with a new crystal for thesame frequency, was completely‘flattened’ by the pagers. Reports from
elsewhere in the country tend to support
these findings. So if you have a Dartcom
APT receiver gathering dust in the attic,
bring it back into service—you may be infor a pleasant surprise.
New Dartcom Receiver EPROM
Several GEO Readers are still using theold Dartcom APT receiver (sadly now
discontinued) and finding it to beparticularly pager resistant at the
NOAA-18 frequency of 137.91 MHz.

Group for Earth Observation

nothing. There were a few reports fromaround the world of intermittent
transmissions, but often for only part ofa pass. Fortunately it turned out to be asoftware problem whereby the APT wasbeing erroneously commanded off and
NOAA engineers restored normal
service at 14:08 UT on July 5.
NOAA 14 Returns from the DeadAs many readers will recall, NOAA-14
ceased transmitting AVHRR imagery on
April 14, 2004 when its scan motor
seized up. It had been assumed that thisspelled the end of imaging from thissatellite yet, amazingly, more than ayear later on July 16 this year, it
unexpectedly sprang back to life andgood quality HRPT images were once
more transmitted from July 17. There isno sign of a regular resumption of APT
imaging which will probably remain off
due to the likelihood of frequent clashes
with NOAA 17.
There are of course no guarantees as tohow long NOAA-14’s new lease of life
will continue, but it is certainly worth
looking out for if you are an HRPT user.
The HRPT frequency for NOAA-14 is1707.0 MHz.

Although the receiver can of course be
tuned manually to 137.91 MHz theoriginal EPROM did not include the new
frequencies in the scan list.

Cover Colour Images
Front cover - One of the first colour
composite images from the new Chinese
Feng Yun 2C geostationary satellite,
dating from 14:00 UT on December 31,
2004. Image courtesy NSMC, China.
Inside front cover
Milan Konecny from Canada provided
us with a superb NOAA-18 channel 1+2
false colour image from the 19:48 UT
pass on May 21 (upper left) . Milan used
David Taylor’s Satsignal to produce thisimage from a WAV file received by
WxSat.

Joris Prosje, who lives in Harlingen at
the very north of the Netherlands, sentin the APT image from NOAA-18
reproduced at the foot of the page. It is acomposite of the 12:52 UT and 14:34 UT
passes from June 11, 2005, which wereacquired using an R2FX receiver (seepage 19) fed from a turnstile antenna.
Processing was achieved using Craig
Anderson’s WxtoImg software.
Back cover

NOAA 17 APT Scare18

In fact, NOAA did activate APTtransmissions from NOAA-14 between
July 28 and August 2 for test purposes.
Unusually, these consisted not of thefamiliar visible/IR combination ofchannels 2+4, but an intriguing twin
infrared APT combination of channel 3
with channel 4. Channel 3 (3.7µm midIR) is the infrared channel that NOAA
satellites normally switch in to replace
the visible light channel overnight,
while they are flying over the night sideof Earth

The 13:25 UT NOAA-18 image, also
from March 21, is the earliest daylightimage we received (upper right). It wassent in by Ruud Jansen who lives inHaarlem in the Netherlands. Ruud uses
WXtoImg in conjunction with his homebuilt PITA137 receiver and an indoor
home-built QFH antenna located in theroof-space of his house.

If you own one of these receivers andwish to include this frequency in its
automatic scan mode, you require a new
EPROM. GEO has been collaboratingwith Dave Wright at Dartcom to develop
a new EPROM for the Dartcom APT
receiver, which includes both 137.1 and
137.91 MHz in the scan frequency list.
This EPROM is available exclusively
from the GEO Shop as GEO/Dartcom
EPROM v 1.3 (see details in our centre
pages)
APT enthusiasts suffered a major scarewhen NOAA-17 failed to transmit its
137.62 MHz telemetry on July 3. A
report from Nigel Heasman indicatedthat the 08:04 UT pass was received as
normal in Cyprus, but thereafter

September 2005

This channel-2 visible image was taken fromthe 12:52 UT descending pass on July 17, thefirst full day of ‘normalised’ operation and shows
Labrador and Nova Scotia in Canada.
Credit: NOAA CLASS Archivewww.geo-web.org.uk

Hartmut Schaksmeier from Remscheid,
Germany sent in this superb NOAA-18
image captured from the 12:37 UT passon July 22, 2005. The image wasprocessed in vegetation mode using
Craig Anderson’s WXtoImg software.

September 2005

Group for Earth Observation

Les Hamilton
New APT weather satellite receivers do not appear on the scene
very often these days so, when I heard about the R2FX model
manufactured by Holger Eckardt of Hohenbrunn, Germany, I just
had to try one out.
This receiver has beautifully clean lines and is provided in an
attractive aluminium case measuring just 113 x 85 x 31 mm. The
front panel supports just a single ‘select’ button and 12 variously
coloured LEDs (figure 1) while the rear panel boasts twin 50 Ω
BNC antenna sockets, a power supply socket, audio-out jacksocket and RS232 serial interface (figure 2).
Manufacturer’s Specifications
The R2FX receiver is designed for the reception of polar orbiting
weather satellites which transmit in the 137 MHz band. Matched
IF filters and a highly linear demodulator provide optimum image
quality, even with weak signals. An AFC circuit compensates for
Doppler frequency shifts. A novel feature is the ability of theR2FX to utilise two antennas simultaneously: the receiver polls
the antennas constantly and always selects the stronger signal toprovide the cleanest possible image.
The R2FX Package

GEO Quarterly No 7

damage. Personally, I always use a 6-volt supply and this has
proved entirely satisfactory at all times. On the subject of PSU, I
have found that a set of four rechargeable 2300 mAh NiMH ‘AA’
batteries also performs beautifully, providing a minimum of 36
hours supply—useful for trips to the countryside with a laptop.
Setting up the R2FX
Connecting up the R2FX could hardly be simpler. The PSU plugs
into the rear of the unit, the audio lead connects between theaudio-out socket and the line-in (or mic-in) of your PC soundcard
while the antenna attaches to the ‘Antenna 1’ BNC position.
Should you require to adjust the audio output level of the R2FX
there is a small trimming potentiometer inside the unit, close to
the RS232 D-connector, labelled ‘V’ in figure 3. Turning thiscounter-clockwise decreases the output. But be careful, as thedevice does not have a ‘stop’ and rotates a full 360°—so you can
inadvertently set the output back to ‘high’ by turning too far.
To switch on the R2FX you simply supply power—it does nothave an on/off switch. The entire display of LEDs lights up forabout two seconds, then all extinguish except for the the amberantenna LEDs and the red 137.50 MHz channel LED. You willprobably notice the amber LEDs alternating on and off as thereceiver polls between the two antenna BNC connectors.

The R2FX comes complete with a power supply unit.
Unfortunately it is of the continental ‘Shuko’ 2-pin design so you
will require a suitable adaptor if you plan to use it. I used astandard plug-top PSU designed for use in the UK without
experiencing any problems. Also supplied was an audio lead toconnect the R2FX to the soundcard of your computer and a CDbearing a copy of the R2FX manual, Craig Anderson’s WXtoImg
decoding software and some sample images and WAV files.

Repeatedly pressing the ‘Select’ switch briefly steps the receiverthrough the six frequency channels. Holding this switch down for
two seconds or more sets the receiver into scan mode and thesix red LEDs start to flick on and off in turn as each channel isactivated. The R2FX comes with the two new polar satellite
frequencies already installed, and you can program new
frequencies later should the need ever arise through the RS232
port, using your computer.

Power Supply for the R2FXFrequencies currently provided are:Without doubt the single most important aspect of preparing the
R2FX for use is attaching the power supply. This receiver works
well with an input of between 5 volts and 12 volts d.c. but you
must take care with the supply’s polarity.
The power jack feeding the R2FX must have a centrepositive supply (the jack tip must be positive) as thereceiver is not protected against reverse polarity.
The lower limit of 5 volts permits the unit to be powered from a
USB port on your PC. And although it would have been perfectly
feasible to include polarity protection circuitry, this would raise
the minimum voltage to 6 V and prevent USB operation.
The supplied PSU comes ready to use but UK members who
substitute one their own must note the above carefully, speciallyas the R2FX does not possess a power switch: once the PSU isconnected, the device is switched on. Check the voltage of thePSU—exceeding 15 V for even a short period can lead to137.10 MHz 137.40 MHz 137.50 MHz 137.62 MHz 137.91 MHz 134.00 MHz -Metop / NOAA 19 (future)
Okean/Sich
NOAA 12, 15
NOAA 17NOAA 18WEFAX downconverter

Using the R2FX
Once set up the R2FX performed almost flawlessly and images
and WAV files were produced using both Wxsat and WxToImg
software packages. I found the audio output somewhat high for
my notebook PC, so reduced this as explained above. My firstimage is reproduced in figure 5.
I was initially disappointed to note a stepped pattern of short,dark, horizontal lines marching diagonally across the image. As I
was simultaneously decoding the same image with my Proscan
receiver (which did not produce this effect), I initially feared thatwww.geo-web.org.uk

19

GEO Quarterly No 7Group for Earth Observation

September 2005

Figure 1
The front panel of the R2FX showing the various LEDs

Figure 2
The back panel of the R2FX, showing connectors

Figure 5
My first NOAA 17 image received at 10:34 UT on April 26, 2005 using the
R2FX. A stepped pattern of short, dark, horizontal lines mars the image.
The effect is most clearly evident over northern Scandinavia and over themass of cloud at upper left. This effect is easily addressed by converting the
R2FX from ‘antenna diversity’ to single-antenna mode.

Figure 3
The interior of the R2FX showing the audio output adjust potentiometer(V) and the jumper switch (A) used to set/unset the dual antenna facility

Figure 4
My mobile weather satellite ground station, consisting of the R2FX
receiver with 4 x AA battery pack and notebook PC.

20

Figure 6
This image from NOAA 17 was acquired at 11:40 UT on May 15, 2005 after
the R2FX had been adjusted for single-antenna operation.
Processing: both the above images were produced using Satsignal

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September 2005

Group for Earth Observation

my R2FX might be faulty. However, an e-mail to Holger Eckardt
soon solved this. The unit ships in twin-antenna mode (‘antenna
diversity’ as the manual describes it) ... but I only had a single
antenna connected. It turns out that, in this situation, the totallack of signal when the receiver attempts to access the second
antenna results in a brief loss of signal, which places black pixels
in the image. Switching the R2FX to single antenna mode
removed the problem completely (figure 6).
Using Two Antennas
The idea of using twin antennas intrigued me, so I ran a test with
two QFH antennas, deliberately positioned to the north and southof my house in such a manner that the structure prevented me
obtaining a complete horizon to horizon pass from either (neither
QFH was capable of receiving a complete pass because of the
obstruction from my house). Nevertheless, results were superb:
you would not have been able to guess that there was a problem
as the R2FX seamlessly switched antennas at the appropriate
point to maintain the strongest possible signal. For users who
cannot position a single antenna in a location clear of
obstructions this provides a novel way of extending the imaging
range.
Changing to Single Antenna Mode
As my situation does not require me to make use of twin
antennas I decided to switch modes. On opening the case of theR2FX you will see a red jumper next to the push-button on thefront panel (labelled ‘A’ in figure 3). By default this is in the righthand position (twin antenna mode). Just move the jumper to theleft-hand position and the receiver is converted for singleantenna operation. You will find that only the amber antenna LED
labelled ‘antenna 1’ now illuminates. Of course, the antenna must
be connected to the ‘Antenna 1’ BNC connector otherwise you
will not now receive any signal at all.
Performance
I received my R2FX in mid-April. Once the antenna ‘problem’ wasunderstood, I ran a series of tests comparing the R2FX with mycommercial Proscan and Martelec MSR 50 receivers. The R2FX
was tested simultaneously with either the Proscan or MSR 50,
both test receivers being fed from QFH antennas in the loft;
signals were decoded on laptop PCs using WXtoImg software.
Results were identical. Images were all well-nigh perfect, andany imperfections resulting from local interference showed
identically on both. I had initially feared that the R2FX, being
manufactured in Germany, might not possess sufficient filtering
to eliminate pager intrusions but I need not have worried. There
were absolutely no problems in this respect.

GEO Quarterly No 7

some readers have reported good reception using the R2FX.
One final associated problem can arise when pager activity isparticularly severe: if the R2FX is in scanning mode, it can lockon to 137.91 MHz for 30 minutes or more at a time, which meansthat passes of other satellites can be missed.
Satellite Imaging ‘On Location’One of the delights of holidaying in remoter parts of Britain istaking along a mobile satellite ground station in order to check up
on impending weather. This is something I do several times ayear when visiting the Isle of Skye off the west coast of Scotland.
The R2FX adds a new dimension to this pursuit because it canbe operated with a power supply as low as 5 volts—you can evenpower it directly from a USB port on a laptop PC. It is the simplest
task to purchase a set of four rechargeable AA batteries, a cellholder and a 6 mm plug to fit the R2FX. Figure 4 shows mystation shortly after decoding a satellite pass. The battery packcan be seen just behind the R2FX and the entire setup can beused ‘in the field’ without the need for mains electricity.
Reprogramming the R2FX Frequencies
If you purchased your R2FX earlier than May 2005 it will be set
up with with the old Russian APT frequencies rather than the two
new NOAA ones. This is easily rectified by downloading a simple
program called R2FX-config from Holger Eckardt’s website (seebelow). All you require to do is connect the R2FX to the 9-pin
serial port on your computer then run this program.
First select the correct port
(normally COM1) and click‘LOAD’. This recovers thefrequencies held in the
R2FX and displays themas illustrated. Just retypeany of these then click‘STORE’ and the newvalue will be programmed
back into the receiver.
Conclusions
The R2FX is a modern, highly effective APT weather satellite
receiver that performs well even in the UK with its notorious‘pager’ problems. The only significant criticism concerned
imaging from NOAA-18, but in fairness, the R2FX fared no worse
than most other receivers.

NOAA 18 Problems
However, the arrival of NOAA 18 in mid May, transmitting on the
new frequency of 137.9125 MHz, did produce severe problems.
Certainly, at my location in northeast Scotland, the R2FX was
badly affected by pagers (some transmitting on 137.975 MHz),and images were simply awash with horizontal pager intrusions.
But the same was true for the MSR 50 (I cannot comment on the
Proscan here, as mine is not upgraded for NOAA 18, althoughmembers elsewhere in Great Britain have found it impossible toimage from NOAA 18 on the Proscan also)
The NOAA 18 situation does, however, vary a great deal acrossGreat Britain. From some districts I have received reports thatimaging is ‘impossible’ or ‘hopeless’ using both the Proscan and
R2FX; from others, both receivers are performing perfectly. As
expected, most members in the London area (a notorious pager
hot-spot) cannot obtain NOAA 18 images—though even there,

I have received numerous reports from GEO members indicatingthat APT receivers of all types are being affected by pagers at the
NOAA-18 frequency of 137.91 MHz. In some parts of the country
the problem is so severe that imaging is impossible: yet there arelocations where excellent images are being obtained with the
R2FX.
The bottom line is this: if you are looking for a high quality
receiver for APT then the R2FX is as good as any you will get.
And its price of 179 euros (which includes post and packing)equates to just a shade over £120. When you consider that the
UK-designed RX2 receiver now costs £90 in kit form, this readybuilt receiver from Germany, which works ‘straight out of the box’,
becomes a very attractive proposition. As far as I can ascertain,
it is the cheapest ready-built receiver currently on the market, as
well as being one of the best.
... concluded on page 38

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GEO Quarterly No 7Group for Earth Observation

September 2005

John Tellick
Photograph 4

Photograph 1
Many readers have probably set up a
prime focus dish for Meteosat-7 (the white
dish in the photograph) and will know it
points directly at the satellite in elevation
as well as azimuth.

Place the LNB in the
LNB holder and giveit a small twist off thehorizontal, about 5°
to the east, before
tightening. This is tocompensate for thesatellite’s increasing
apparent twist thefurther east or west of south it is located in
the geostationary arc (which twists – or‘skews’ —the V/H transmitted signal). Andof course, for a satellite positioned west ofsouth, the LNB requires a westerly twist.
Photograph 5

The three dishes pictured above are all
pointing at satellites with fairly similarelevations: EUTELSAT W1 at 10 °E (left),
Meteosat-7 at 0° (centre) and Hot Bird-6 at
13°E (right). This last also has a second
LNB for the reception of Astra-1 at 19.2°E.
Notice the shallow elevation angle of theoffset dishes compared with the prime
focus dishExact pointing co-ordinates for yourlocation can be found from EUMETSAT’s
antenna pointing calculator at:
http://www.eumetsat.int/cgi-bin/tools/antennaPointing

Photograph 3
Make sure that thevertical pole on yourwall bracket or patio
stand, on to which
the dish is to be
mounted, is truly
vertical.

Photograph 7
Dish aligned on Hot
Bird at 13°E

Photograph 7 shows the dish lined up on
Hot Bird-6, the satellite position you want,
having panned it westward of Astra-1.
Notice the size of the horizontal angle
through which the dish requires panning
between these two high-level signals.
Note: The camera position remained thesame for photographs 6 and 7.
Peak the dish in both elevation andazimuth then confirm, via a satellite TV
receiver or your SkyStar card, that you areindeed on Hot Bird-6 (via a preprogrammed channel) then make final
peaking of the signal. First adjust thehorizontal axis for maximum signal
strength then tighten the azimuth bolts.

Photograph 2
Use a compass toascertain the direction
where you need to point
the dish and make sure
your mounting point hasa clear view of the sky atabout 28 degrees elevation.

Photograph 6
Dish aligned on
Astra at 19.2°E

Mount your dish on its pole and tighten the
Az/El bolts sufficiently that the dish issecure and doesn’t wobble—but can stillbe panned. Elevate the dish to about 8°.
This, plus the approximate 20 degree
offset of the LNB arm, will give a total
elevation of around 28°.
Point the dish in the direction of your
EUMETSAT calculation—or to between
15° and 20° east. Connecting a metersuch as the TechniSat ‘SatFinder’ or Arne
van Belle’s satellite meter between the
LNB and your receiver will greatly assist in
locating the signal.
Photographs 6 and 7
If you followed the above you may wellalready observe a signal indicating on themeter. You will find two very strong signals
around the 15°E area (Astra-1 at 19.2°E
and Hot Bird at 13°E) by slowly panningthe dish azimuth in this area.

Now peak the elevation and tighten theelevation bolts. You may wish to go backand check both again, individuallytightening each as you do so.
Photograph 8
Now that your dish is aligned and peakedon Hot Bird-6, and all the bolts have beentightened, you may wish to experimentwith multi-satellite reception with one dish.

This is quite easy if you use a ‘SatFinder’
meter. Connect the meter to a second LNB
placed next to and to the west of your fixed
one (as shown in the picture) and you willsoon detect a strong signal. This shouldbe Astra-1 at 19.2°E. Owing to the size ofthe integrated feedhorn, extra LNBs canonly be placed to receive satellites spaced
6 degrees or more apart.
... concluded on page 38

22

www.geo-web.org.uk

September 2005

Group for Earth Observation

GEO Quarterly No 7

Manager: Clive Finnis
e-mail: shop@geo-web.org.uk
FAX: +44 (0) 1202 893 323

PRICE LIST

TechniSat SkyStar 2 PCI Card

EU

RoW

TechniSat SkyStar 2 PCI Card49.50 51.00
Technisat Skystar USB box
109.50 121.50
Telestar 80 cm dish with LNB
49.00
Telestar Ku band universal LNB
11.00 12.50
Technisat Satfinder alignment meter 21.50 24.50
Dartcom high quality QFH antenna 259.00 279.00
Turnstile APT antenna
36.00
GEO-PIC 1.0
7.00
7.40
GEO/Dartcom EPROM v 1.3 NEW 10.00 10.75
GEO 2004 CD (back issues)
8.00
8.40

UK

8.30
11.25
9.30

Printed Back Issues
GEO Quarterly No 2
GEO Quarterly No 3
GEO Quarterly No 4
GEO Quarterly No 5

5.10
5.10
5.10
5.10

3.50
3.50
3.50
3.50

4.20
4.20
4.20
4.20

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.

TechniSat SkyStar USB Box
If you do not feel confident about
installing cards inside your computer
you can use the external USB version.

Telestar 80 cm dish (or similar model)
and Ku-band LNB

All prices are in £ sterlingand include postage and packaging

HOW TO PLACE YOUR ORDER
Orders should clearly state your name and address, including
postcode, and contact telephone number and e-mail addressin case we need to contact you about your order. Items orderedshould be clearly described and quantified.
It is preferred that you submit your order on a copy of the official
Shop Order Form, which you can download from the GEO
website at:
http://www.geo-web.org.uk/Orderform.pdf(Of course, we will also accept handwritten or typed orders)TechniSat SatFinder
Alignment Meter
A very useful and sensitive
meter which is a great help insetting up and aligning the dishfor maximum signal. The metercomes with full instructions

GEO PIC 1.0 for
RX2

GEO/Dartcom
EPROM v 1.3

This PIC comes
programmed withthe two new
frequencies to be
utilised by theforthcoming NOAA18 and NOAA-19
satellites.
Note: Check yourRX2 synthesiser
chip before ordering(see GEO Quarterly
No 5, page 16)

Recent tests haveshown the Dartcom
APT receiver to be
one of the best
regards pager
immunity in the UK.
This NEW EPROM
for the Dartcom
APT receiver adds
the two new NOAA
frequencies to thescan list in memory
page 0.

Please mail your orders to:
GEO ShopPO Box 1375
Christchurch BH23 9AS
EnglandIf you are paying by credit card, you can FAX us your order to:+44 (0) 1202 893 323
Turnstile APTantenna

TERMS AND CONDITIONSPayment Methods

Payments from UK Members can be accepted by Personal
Cheque, Postal Order, Credit Card and Debit Card. Paymentsfrom EU and Rest of World members can be accepted by Credit
Card or Debit Card.
Cheques and Postal Orders must be made payable to ‘Group for
Earth Observation’

Dartcom
QFH antenna

GEO 2004 CD
Back issues in PDF
format - so that new
members can catchup on last year.

All credit cards are authorised before goods are despatched.
Please include your e-mail address or telephone number in case
we need to contact you about your order. In the event ofproblems with items purchased from GEO-Shop, please contact
Clive Finnis (contact details at top of page).
Ordering and Shipping

VISA, Mastercard, Switch and Switch Solo are all accepted, butplease note that you must state

We will ship by post, so please allow 28 days for delivery although wehope UK and EU orders will take just a few days; orders to the Rest of
the World may take a few weeks.

• the cardholder’s signature• the type of card, card number and expiry date
• the issue number (for Switch and Switch Solo only)

Items from the GEO shop are available only to
paid up GEO members

www.geo-web.org.uk

i

NOAA 12NOAA 15NOAA 17NOAA 18NOAA 12NOAA 15NOAA 17NOAA 18

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Nov 04 05:33 07:13 15:19 16:59
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Oct 08 05:00 06:40 14:47 16:26
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Dec 01 04:26 06:05 15:52 17:32
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Dec 03 05:16 06:56 15:03 16:42
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Dec 05 04:27 06:07 15:53 17:34
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Dec 07 05:17 06:57 15:04 16:43
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Dec 15 05:19 07:00 15:06 16:45
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Dec 19 05:21 07:01 15:07 16:47
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05:44 07:24 15:32 17:10 10:14 11:54 20:03 21:41 02:30 04:11 12:22 14:03
05:20 07:00 16:47 18:28 09:52 11:31 21:18 22:59 02:20 04:01 12:12 13:53
06:36 08:17 16:23 18:03 11:09 12:49 20:56 22:36 02:09 03:50 12:02 13:43
06:13 07:53 16:00 17:39 10:46 12:26 20:33 22:13 01:59 03:40 11:52 13:32
05:49 07:29 15:37 17:15 10:23 12:03 20:11 21:50 01:49 03:30 11:42 13:22
05:25 07:05 16:52 18:33 10:00 11:40 21:27 23:08 01:39 03:20 11:32 13:12
06:41 08:22 16:28 18:08 09:37 11:17 21:04 22:44 01:29 03:09 11:23 13:01
06:18 07:58 16:05 17:44 10:54 12:34 20:42 22:21 01:18 02:59 12:51 14:33
05:54 07:34 15:42 17:20 10:31 12:11 20:19 21:58 01:08 02:49 12:41 14:23
05:30 07:10 16:57 18:38 10:08 11:48 21:35 23:17 02:39 04:20 12:31 14:12
05:07 06:47 16:33 18:14 09:46 11:25 21:12 22:53 02:28 04:10 12:21 14:02
06:23 08:03 16:10 17:49 11:03 12:43 20:50 22:30 02:18 03:59 12:11 13:51
05:59 07:39 15:47 17:26 10:40 12:20 20:27 22:07 02:08 03:49 12:01 13:41

Nov 01 05:07 06:47 14:54 16:33 06:23 08:03 16:10 17:50 10:13 11:53 20:02 21:40 02:16 03:57 12:09 13:49
Nov 02 04:42 06:22 14:30 16:08 05:59 07:39 15:47 17:26 09:50 11:30 21:17 22:58 02:06 03:47 11:59 13:39
Nov 03 04:18 05:57 15:44 17:24 05:36 07:16 17:02 18:44 11:07 12:47 20:54 22:34 01:56 03:37 11:49 13:29

ii

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

September 2005

Group for Earth Observation

GEO Quarterly No 7

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 8

Monday, October 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

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Please note that your subscriptioncommences with the issue of GEO
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iv

www.geo-web.org.uk

September 2005

Group for Earth Observation

GEO Quarterly No 7

‘A Tale of Two Cities’: This superb NOAA 12 channel-2 visible image submitted by Marciano Righini form Ravenna, Italy clearly shows the cities of
London, England and Paris, France in this near-cloudless view captured at 15:45 UT on June 18, 2005.

Von Karman vortex streets shed by the Kuril Islands drift across the Sea of Okhotsk in this ENVISAT ‘MERIS’ image taken on June 3, 2005.
Image: European Space Agency (ESA) - produced from ESA remote sensing data by Brockmann Consult (http://www.brockmann-consult.de/)www.geo-web.org.uk

23

GEO Quarterly No 7Group for Earth Observation

September 2005

Doug Thwaites
Australia is a vast and beautiful country. It
is the world’s largest island with an area of
7,618,493 square kilometers, yet it is only
thinly populated. Water, or lack of it, is thereason.
The Great Artesian Basin
The only source of potable water is fromrain, although there is a water source
underground: the Great Artesian Basin,
which has an area of 1,711,000 square
kilometres and consists of layers of waterbearing sandstone aquifers. At its deepest
point, the Basin, which contains about
64.9 quadrillion (6.49 x 1016) litres ofwater, is 3,000 metres below ground. It isestimated to have been formed about 200
million years ago. More than 1,500 bores
use it, with a flow rate of about 1.5 billion
litres a day per bore. The Basin isreplenished from rainwater falling on thewestern side of the great dividing ranges
in the east of Australia, but not enough tomaintain the original quantity. The pH of
the water is high and it contains a highsodium level which makes it unsuitable for
irrigation, but stock drink it and survive.

interior of Australia. But there are otherways that rain can find its way inland. A
warm stream of water, rather like the Gulf
Stream in the Atlantic, flows down thenorthern West Australian coast. During thesummer months this breeds cyclones
which cross the coast to become
depressions. Due to the prevailing west toeast movement, heavy rain is carried
inland, sometimes all the way to the east
coast.
Occasionally cyclones also form in the
Coral Sea, to the northeast of Australia.
These normally travel southwards over theocean where they weaken and disperse;
but if they cross the coast there are floods
and the farmers are happy. For somereason Coral Sea cyclones are very rare
nowadays, although ten years ago they
were quite common.

A coastal belt of fertile land runs all aroundthe coasts of Australia due to onshore
winds. This is where the majority of people
live and where all the big cities lie.
Weather systems move slowly across thecontinent from west to east, alternate lows
and highs producing changes in the winddirection and thus to the chances of rain.
During the year the weather systems
move slowly up and down the country,
causing the north to have wet summers
and the south to have wet winters. You
can see this effect in the summer (figure 1)
and winter (figure 2) rain record maps.
Because the rain-bearing winds do notreach far inland there are deserts in the24

The Southern Oscillation Index
Is the current lower rainfall going tocontinue? Where have our wet seasons
with the accompanying floods gone?
There is yet another reason why the rain
patterns vary. Sometimes our television
weather forecast mentions the Southern
Oscillation Index (SOI), which is
calculated from the monthly variations in
the mean sea level pressure difference
between Tahiti and Darwin. The index,
which has a range from -35 to +35, isexpressed by a formula used by theAustralian Bureau of Metrology.
Sustained negative values of the SOI
often indicate what is called an El Niño
event. Such an event is accompanied bywarming of the central and eastern tropical
Pacific Ocean. This causes the Tradewinds to weaken bringing reduced rainfall
to eastern and northern Australia. The last
bad El Niño was in 1997-1998. Withdrought all over the central and easternareas at the present time we are possibly
heading for another an El Niño period.

Rainfall
To obtain potable water we need rain,
which is produced by evaporation from thesaltwater which surrounds Australia. To
get this over land needs onshore winds tostart with followed by conditions whichcause precipitation. On the east ofAustralia is a range of mountains called
the Great Dividing Range, which causes adivision in the rainfall, though most falls tothe seaward side. So we have a fertile
green belt running all down the east coastand drier regions inland.

collected by these instruments and, bycomparing these with the weather at thetime, we hope to learn more about how
our weather is affected and what causes
the changes.

Australia
Map provided by www.worldatlas.com

The Oceans
Scientists are sure that our weather isaffected by the two massive oceans oneither side of Australia. During the summer
months two pools of warm water exist—in
the western Pacific and the eastern Indian
Oceans. Because of different tide times,
water flows between the oceans throughthe Torres Strait to the north of Australia.
Five countries have banded together toresearch the effects of this flow of warm,
low salinity water between the two oceans.
In order to do this, sub-surface monitors
have been placed at strategic points
throughout the Lombok, Ombai, and Timor
passages through which this water flows.
Over the next few years, data will be
www.geo-web.org.uk

If, however the SOI becomes positive, theopposite applies. The waters of theeastern and central Pacific Ocean become
cooler and eastern and northern Australia
will become wetter. This is called ‘La Nina’
and results in stronger trade winds during
our summer months. Our last La Nina wasin 1999 and carried over to the southern
autumn of 2000.
I live in the SE of Queensland, an areamuch favoured by retirees because of its
lovely weather. The summers are not as
hot and humid as further north, and its
winters are not cold or wet like thesouthern states. Because of this people
are flocking north putting the services atrisk
We are now in a water crisis. We haveseveral large dams, but the evaporationeach week is much higher than the rainfall.
The dams are at 40% capacity and water
restrictions are in force. To refill them weneed a cyclone, and it is winter here, so
there is no hope at present (figure 3).

September 2005

Group for Earth Observation

GEO Quarterly No 7

Figure 1 - Rainfall analysis for winter (June 2005)

Figure 2 - Rainfall analysis for summer (January 2005)

Credit: Australian Bureau of Meteorology (www.bom.gov.au)

Credit: Australian Bureau of Meteorology (www.bom.gov.au)

Figure 3 - Drought in Australia - NOAA 17 at 00:03 UT on July 29, 2005, processed using WXtoImg
www.geo-web.org.uk

25

GEO Quarterly No 7Group for Earth Observation

September 2005

Les Hamilton
China’s Feng Yun 2C (FY2C) geostationary satellite is now in service andproducing hourly images in five frequency
channels, including visible, infrared andwater-vapour. The website of China’s
National Satellite Meteorological Centre(NMSC) [1] makes available both 185 kb
infrared images measuring 572 x 592
pixels as well as full 5-channel datasets inthe form of HDF files which weigh in at ahefty 133 Mb apiece. The embedded
images are all 2280 pixels square. The
front cover of this Quarterly displays thefirst colour composite image from FY2C
released by NSMC.
If you wish to view the entire range ofimages at full resolution you must first
download an HDF file [2]: and therein lies a
problem. Download speeds from the
NSMC server vary enormously. On a good
day my 512 kb/s Broadband retrieves a filein just under 40 minutes. But the rate canwither to almost zero—considerablyslower than a standard dial-up
connection—so you just have to keep
trying (7am is often a good time to try).
The HDF File Viewer
HDF files contain huge quantities of datain addition to the images, and specialised
software is required for their retrieval.
Fortunately, the National Center for
Supercomputing Applications (NCSA) at
the University of Illinois, provides HDF
View [3], a visual tool for browsing HDF
files. This is available free of charge as a
15 Mb download.

Figure 1
HDF View menu tree

Figure 2
Dataset selection window

The image now appears in the main
window (figure 3). You can zoom in andout of the image using the +/- buttons at
the top left of the window.

you have upgraded to the new version,
GeoSatsignal5, you can extract FY2C
images from HDF files and produce
monochrome, false-colour, thermal falsecolour and remapped products (seeopposite).

Note 1: The visible image is only 6-bits
deep and appears very dark indeed. It canbe brightened by clicking the ‘Image’button at upper left on the window,
selecting ‘brightness’ from the fly-out
menu, then inserting a suitable value (e.g.
100).
Note 2: Members who use David Taylor’s
GeoSatsignal have an alternative way ofviewing HDF images from FY2C. Provided

References
1 National Satellite Meteorological Centre

http://nsmc.cma.gov.cn/indexe.html
2 HDF and JPG Image download site

http://nsmc.cma.gov.cn/SCB/F2C
3 HDF Viewer

http://hdf.ncsa.uiuc.edu/
hdf-java-html

After you load an HDF file into the viewer
a list of its contents appears in a panel at
the left-hand side (figure 1). The only
items that concern us are the five entries‘NOMChannelIR1’ ... ‘NOMChannelVIS’,
which contain the image data.
Producing an image is not at all intuitive,
but is straightforward enough once you
know how!
• Load an HDF file
• Right-click on any one of the fiveimage entries to highlight it andopen the sub-menu (figure 1)• Select ‘Open As’ from this menu toreveal the dataset selection window(figure 2)• Click on the ‘Image’ button at theupper right of this screen• Click the ‘OK’ button
Figure 3 - Displaying an FY2C image using HDF View

26

www.geo-web.org.uk

Super Typhoon ‘Haitang’ dominates the gibbous Earth
as it tracks across the Pacific Ocean to the northeastof the Philippines on July 16, 2005 in this
00:00 UT image from Feng Yun 2C
Processing: GeoSatsignal 5
Image: National Satellite Meteorological Centre (NSMC) - China

GEO Member Hartmut Schaksmeier from Remschied, Germany sent us these images
relating to NOAA-N. Above is a detail of the Great Lakes region from the 18:55 UT pass on
July 15, 2005, prepared using David Taylor’s HRPT Reader software.
Credit: NOAA CLASS Archive ()http://www.class.noaa.gov)

At upper left is a photograph of the early morning launch of NOAA-N from Vandenberg Air
Force Base on May 20 while below is a photo of the Delta II launch vehicle on its launch pad.
Photos: NASA/NOAA

September 2005

Group for Earth Observation

GEO Quarterly No 7

Francis BellMy thanks to Wimbledon and District
Radio Society for inviting me to their
one-week field expedition in earlyAugust 2004. I could only stay one night
but others from the society were there
for the entire week. I admired the skillsof the people there; operating amateur
radio and contesting in different modes
on various bands. Although I can do this,my main interest lies in satellite
communication, particularly weather
satellites.
I camped overnight on one of the highest
locations on the North Downs, near
Reigate, Surrey. Others more organised
than myself had comfortable mobile
homes but I was happy under canvas.
Camping expeditions with the family inFrance have made me quite resourcefulinside a tent.
My arrival was shortly after midday. I
quickly set up my tent followed by the
installation of a Meteosat-8 receiving
station. I used my 60 cm dish and asmall computer. It worked well and I
demonstrated live Meteosat reception
for 24 hours. My thanks to Graham
Seale for providing me with 230 V fromhis generator.
I’m not sure how many people were
there: 20 to 30 perhaps. Sitting around atable in the evening with some of themembers I casually asked: ‘Are there
any satellites coming overhead soon?’With the aid of a computer somebody
said yes: ‘ECHO and NOAA-17 in a few
minutes.’ With my hand-held receiver, I
demonstrated the live downlink audio
from both satellites. I thought it was agood demonstration with only ten
minutes notice.
The point of writing this article relates
to 8.00 a.m. the following morning.
Following my night under canvas I
awoke to a beautiful sunny morningwith a crystal clear sky. One of myfriends said to me: ‘One of our members
has a telescope to look at the sun’. Just a
few minutes later I was on the receiving
end of a demonstration.
The next sentences should beread with care. This is notadvice—it is an absolute
instruction. NEVER look at thesunthroughany
opticalinstrument unless you are 100%
confident that you know what
you are doing. Otherwise you
may finish up blind. Don’t do it!
I could scarcely believe what was
happening! A WDARS member brought
out his very special telescope with itsvery expensive filters and pointed it at
the sun. ‘There!’ he said: ‘Look at that’
Being ultra cautious I had watched him.
‘Are you sure this is okay?’ I asked twice.
‘Yes’... so I looked.
Wow! If there was ever a road toDamascus this was it for me. I could see
our sun in real time using its hydrogenalpha emission line. No other radiation
was being allowed through the telescope.
The sun was visible as a dark red disc.
The details were staggering. Not only
could I see the sun’s surface (with adistinctive granular appearance generated
by convective cells): dark spots,
prominences and great arching loops
above the surface—like magnetic
rainbows—were visible.
This was real time: not archive material.
I was looking at our local star and in the
30 minutes of my observation I could seethat it changed. Our sun is not a stable,
friendly glowing ball of fire. It is
dynamic ... a bubbling, heaving, pulsing,magnetically varying ball of fusion. If
anybody thinks our sun is constant try
observing it for 30 minutes (but notwithout a specialist instrument please).
It changes minute by minute.
Of course I understand the intensescientific research that goes into thestudy of the sun. I have seen and respect
the published papers and images from
Earth-based observations and from thesatellite SOHO (there is a clue here).
But for me there is no substitute forseeing it myself in real time.

A typical hydrogen-α image of our sun

Tenting on the North Downs

The Meteosat-8 station inside the tent

I guess that’s why I’m interested inweather satellites. Live reception or live
observation—that’s what gives me abuzz. My eyeball on something new.
That’s what I like.
Our sun. A hot tennis ball in my sitting
room. Constant? Certainly not! Science
just does the best it can to explore whatis ultimately our Earth’s energy life
support system.
WADS meeting on the North Downs

www.geo-web.org.uk

29

GEO Quarterly No 7Group for Earth Observation

September 2005

Fred van den Bosch
Introduction

Coding the Script

I am lazy! So I work very hard to automate as much as
possible. For GeoSatSignal you can do that by using batch
jobs. I do this to decode images in a format that I can use for
Digital Atmosphere Workstation [1]. Digital Atmosphere (often
called DAWS) can also be automated, by means of scripts [2]. A
script is a combination of commands which are executed insequence. A DAWS script is prepared with a simple text-editor
like Notepad. DAWS has two types of script:

The hardest part of the exercise, deciding what the script mustdo, is now behind us. Now we have to start with the coding:writing the separate commands. For this you often require tosearch through the scripting chapters in the manual to see
which commands can be used (the file manual.pdf is inside
your DAWS folder). And then it’s often a matter of trial anderror to see if your script will do what you intended. In theexample below, the scripting commands are capitalised forclarity (but this is not essential).

• Scheduler scripting is used for letting DAWS dovarious tasks while unattended.
• Analysis scripting is used to build products in a very
flexible way.
In practice both types can be combined into a single script thatruns at predefined times and gives predetermined products.
Many people find scripting to be somewhat vague and difficult.
In this introduction I will try to demystify it a bit.
Making a script takes three stages:

Each of these stages will now be described in detail.
Designing a Script
Before you make a script you must think of what you want toperform in it. You can do that thinking in Notepad in the formof comments. A comment is plain text with, in the first
position, a ‘#’ character. This line will be ignored when thescript is read by DAWS. So open Notepad and start by keying
in the first few lines describing the purpose of the script. Hereis an example ...
## Show an MSG image with a fleetcode overlay#

This is one of the most difficult commands to understand. It
says: “Download the file ‘ASXX21’, with the latest day andtime, from the internet address ‘http://ftp.hb-yacht.ch/’.”The second part of the command means: “Write this file to thefolder ‘C:\Data’ under the name ‘fleet.dat’.” This folder nameis your own choice but it must exist—you have to create it
yourself before running the script! I created the folder ‘Data’on my ‘C:\’ drive specially for storing my scripts.
The first command wrote the fleetcode data file to the harddisc. But you need to load the information into DAWS itself, so
you must now import it. This is done with ...
INGEST,C:\Data\fleet.dat

OK, this is the beginning. Now think of the different tasks thatmust be executed to achieve this. The main one is that I want
to show the fleetcode so ...
# Show fleetcode
And I want to do that on the latest MSG image, so I must getthat image ...
# Import image
And, oh yes, I want to display the latest data, so I add ...
# Retrieve data
Now give the comments a logical sequence. This results in ...

30

DOWNLOAD,http://ftp.hb-yacht.ch/ASXX21.@D@S00,C:\Data\fleet.dat

Scripts use tokens like ‘@D’ (for the day) and ‘@S’ (for thesynoptic hour). When the script is run by DAWS, the program
will substitute the correct day and hour for these tokens andend the filename with ‘00’. So if you ran the script on March 27
at 12.00 hours, the file downloaded would be ‘ASXX21.271200’.

• designing• coding• testing## Show an MSG-image with a fleetcode overlay## Retrieve data
# Import image# Show fleetcode

The first comment line: ‘Retrieve data’. Searching the manual
under ‘Scheduler scripting’ we find the DOWNLOAD
command ...

This means: “Retrieve the datafile ‘fleet.dat’ from ‘C:\Data\’
and load it into DAWS.”
Next we must load a DAWS base map generated to have thesame dimensions as the Meteosat-8 image to be used [5]. I
called this map (Map-Europa.dmf) and stored it in the folder‘C:\Map’. This is loaded with the command ...
LOAD,C:\Map\Map-Europa.dmf
This will ensure that all the necessary georeferencing dataneeded by DAWS to position synoptic data correctly over theimage are also loaded. After this we can import the Meteosat-8
image (Image-Europa.jpg) that I created in GeoSatSignal ...
IMPORT,C:\Map/Image-Europa.jpg
This command replaces the DAWS base map with theMeteosat-8 image from GeoSatSignal. If you want to see thecountry boundaries you can add the command ...
BASEMAP
to your script.

www.geo-web.org.uk

September 2005

Group for Earth Observation

GEO Quarterly No 7

So the result up to now is that we have an image with country
boundaries on the screen.

described above could be called fleet.dsf. You can save this in
the DAWS folder, or even better, a sub-folder called ‘Scripts’.

The final step is to show the fleetcode. Searching in the list ofcommands we find ...

Automatic Scheduling

FLEETF
This will display the fleetcode over the satellite image. And
finally we add ...

Click the ‘Scripting’ tab at the upper left of the DAWS screen
and then the ‘Scheduler is off...’ button. The following window
appears.

STAMP
This adds a datestamp in the upper left corner of the image toindicate the date and time when you made this image.
The whole script now looks like this:## Show MSG-image with Fleetcode## Retrieve data
DOWNLOAD,http://ftp.hb-yacht.ch/ASXX21.@D@S00,C:\Data\fleet.dat
INGEST,C:\Data\fleet.dat# Import image
LOAD,C:\Map\Map-Europa.dmf
IMPORT,C:\Map/Image-Europa.jpg
BASEMAP# Show fleetcode
FLEETF
STAMP
This completes the coding of the script. But is it OK? It’s time
for the final step.
Testing the script
Whole books are written about testing so I can give here just a
few hints.
Test your scripts carefully!
And keep in mind: you often read what you think you havewritten. This means that if you cannot find the problem,
explain it to someone else or let another person check thescript.
Comment out Commands for Test Purposes
If you are not sure about a certain command you can add a ‘#’in front of it so that it is (temporarily) ignored so you can see
what happens.
Check the Input Files
If your script is not giving the result you expect, check not only
your script, but also the input files. When I was working on ascript for fleetcode, no output was being generated. After sometrials I checked the files on the Internet site.
Normally there exist 31 groups of 4 files (for a 31-day month),
for 0000, 0600, 1200 and 1800 hours, e.g. ‘ASXX21.271200’ as
explained above, where ‘27’ is the day of the month.
At the beginning of each day, or possibly later that day, eachof the previous month’s files for that day are cleared and ‘noentry’ is written into them. As soon as the synoptic information
is available it is written into the file but this can be up to acouple of hours later than the time indicated by the filename.
When DAWS reads a file with ‘no entry’ in it the script
performs without errors. Only, it does not plot the fleetcode.
Save your Script
Once your script is working correctly, save it with ameaningful name, and the filename extension ‘.dsf’. The fileIn the right-hand panel, enter the time you wish to run thescript in 4-digit UTC format (hhmm). By using ‘*’ wildcards, I
can make this script run automatically at 12 minutes past
every hour, all day long. Finally, check the ‘Enable scheduler’
box and click ‘Save’. The window closes and the scheduler
button at upper left now says ‘Scheduler is on’.
You can also make the scheduler run at a predefined interval(in minutes) by using ‘M’ followed by the minute interval
expressed as three digits. For example, to run the script every
12 minutes use ‘M012’ as the time. A new interval begins
immediately after the prior one has ended, rather than after
the completion of any task at hand, so the time accuracy isreliable and predictable [3].
A Simple Temperature Script
Many of the overlay maps created in Digital Atmosphere canbe improved by adding colour fills, for example, to areas witha particular temperature range. Figure 2 is a temperature
chart for Europe. Isotherms are drawn every 5°C, and each 5°
range is coloured differently. The script for this was ...
# Displaying temperature in 5-degree steps
ERASE# Fill the temperature zones
ANALYZE,OVER FILL COLOUR=064:128:255 FILS=0 LSTN=0 TEMPANALYZE,OVER FILL COLOUR=064:160:192 FILS=0 GRTN=0 TEMPANALYZE,OVER FILL COLOUR=096:192:128 FILS=0 GRTN=5 TEMPANALYZE,OVER FILL COLOUR=128:160:000 FILS=0 GRTN=10 TEMPANALYZE,OVER FILL COLOUR=192:192:000 FILS=0 GRTN=15 TEMPANALYZE,OVER FILL COLOUR=224:160:000 FILS=0 GRTN=20 TEMPANALYZE,OVER FILL COLOUR=255:160:000 FILS=0 GRTN=25 TEMP
# Now draw the isotherms
ANALYZE,CONT CINT=5 COLOUR=100:100:100 LINE=1 TEMP
STAMP

Explanation
The first comment is ERASE, which clears the screen.
The ‘ANALYZE’ lines are more difficult, particularly as DAWS
executes them from right to left. Let’s take the first example
one term at a time to explain what is happening.

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September 2005

Figure 2 - Temperature zones - April 7

Figure 3 - Temperature zones - April 7

Figure 4 - TT chart created by the TT script opposite for May 22, 2005

Figure 5 - The Meteosat-8 image from 16:00 UT on May 22, 2005 with a TT index script overlay (using a hatched fill)
Image: © EUMETSAT 2005

32

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Group for Earth Observation

TEMP
take the temperature in °C
LSTN=0
if this temperature value is less then 0
FILS=0use fill-style 0 (solid)
COLOUR=R:G:B select colour red, green, blue
FILL
fill the entire area (temp<0) with this colour
OVER
overlay translucently on the basemap
ANALYZE
make all the above commands happen
The next six lines are similar except that they operate fortemperature values greater than (GRTN) specified values.
The final ‘ANALYZE’ line draws the actual isotherms.
TEMP
LINE=1COLOUR R:G:B
CINT=5CONTANALYZE

take the temperature in °C
set the thickness of the lines (isotherms)
select the line colour
select the contour (line) interval (5°C)
draw the contours (isotherms)
make all the above commands happen

Finally, if you wish, you can add the ‘STAMP’ command to add
a timestamp in the upper left corner of each image.
A Script to Handle Negative Temperatures
If you look carefully at figure 2, you will notice that all
temperatures below zero are the same colour. This is because
a DAWS script cannot (at present) handle negative numbers,so everything ‘less than 0’ is treated equally. But a little
trickery can solve the problem, as in this script.
# Displaying temperature in 5-degree steps
ERASE# Set a temperature offset of 15 degrees
ANALYZE,SADC=1:15 STOR=1 TEMP# Apply fills in 5° steps
ANALYZE,OVER FILL COLOUR=000:064:255 FILS=0 GRTN=0
ANALYZE,OVER FILL COLOUR=000:096:255 FILS=0 GRTN=5ANALYZE,OVER FILL COLOUR=064:128:255 FILS=0 GRTN=10
ANALYZE,OVER FILL COLOUR=064:160:192 FILS=0 GRTN=15
ANALYZE,OVER FILL COLOUR=096:192:128 FILS=0 GRTN=20
ANALYZE,OVER FILL COLOUR=128:160:000 FILS=0 GRTN=25
ANALYZE,OVER FILL COLOUR=192:192:000 FILS=0 GRTN=30
ANALYZE,OVER FILL COLOUR=224:160:000 FILS=0 GRTN=35
ANALYZE,OVER FILL COLOUR=255:160:000 FILS=0 GRTN=40
ANALYZE,CONT CINT=5 COLOUR=100:100:100 LINE=1 TEMPSTAMP

The first ‘ANALYZE’ process increases the values of all
temperatures by 15. This ensures that -15°C is converted to
0°C (a positive number) and so on, so that it can be handled by
DAWS. These terms are:
TEMP
STOR=1
SADC=1:15

take the temperature in °C
store this value (in storage slot No 1)
add 15 to the number stored in slot No 1

This calculated value (rather than the actual temperature) is
next passed to each of the following statements in turn todetermine the appropriate fill colour; everything else is thesame as before. You can see the result in figure 3 where there
are now additional 5-degree colour bands for negative
temperatures.
There are numerous tricks that you learn as you create more
scripts. One useful one is that once a parameter has been
selected (e.g. TEMP), it applies to all following ‘ANALYZE’commands until a new parameter is chosen. So in the example
in the previous column, the ‘TEMP’ parameter could in fact beomitted from every ‘ANALYZE’ line after the first one. To run
this script you must first load suitable synoptic data into
DAWS using the <Internet → Retrieve data> menu and selecting‘SYNOP from Albany (worldwide)’.

GEO Quarterly No 7

A Script for the Total Totals Index (TT).
The so-called ‘totals totals index’ is an index of atmosphericinstability and uses temperature parameters at two different
levels in the atmosphere to determine the potential forthunderstorms. It is expressed by the formula
TT = (Td850 - T500) + (T850 - T500)
where T850 and T500 are the temperatures at the 850 mb and
500 mb levels in the atmosphere and Td850 is the dewpointtemperature at the 850 millibar level.
The predicted risk of severe weather activity is as follows:
TT>30 Showers and thunderstorms become increasingly likely
44-45 Isolated moderate thunderstorms
46-47 Scattered moderate / few heavy thunderstorms
48-49 Scattered moderate / few heavy / isolated severe
thunderstorms
50-51 Scattered heavy / few severe thunderstorms andisolated tornadoes
52-55 Scattered to numerous heavy / few to scattered severe
thunderstorm / few tornadoes
TT>55 Numerous heavy / scattered severe thunderstorms andscattered tornadoes
In this script we will use different colours, lines and coloured
areas. First the whole script is presented and then follows an
explanation.
ERASE
STOR=1 DWPT H850
STOR=2 TEMP H500
STOR=3 SDIF=1:2
STOR=4 TEMP H850
STOR=5 TEMP H500
STOR=6 SDIF=4:5
ANALYZE,SSUM=3:6
ANALYZE,OVER FILL COLOUR=224:255:224 FILS=0 LSTN=44
ANALYZE,OVER FILL COLOUR=255:255:100 FILS=0 GRTN=44
ANALYZE,OVER FILL COLOUR=255:240:000 FILS=0 GRTN=46
ANALYZE,OVER FILL COLOUR=255:204:000 FILS=0 GRTN=48
ANALYZE,OVER FILL COLOUR=255:161:000 FILS=0 GRTN=50
ANALYZE,OVER FILL COLOUR=255:097:000 FILS=0 GRTN=52
ANALYZE,OVER FILL COLOUR=255:014:014 FILS=0 GRTN=55
ANALYZE,CONT CINT=2 LSTN=53 GRTN=44 DASH COLOUR=100:100:100
ANALYZE,CONT CINT=5 GRTN=55

The first lines introduce some new terms which are required
to make the TT calculations.
H850
set the 850 mb level
DWPT
take the dewpoint (Td850, °C)
STOR=1store in slot No 1
H500
set the 500 mb level
TEMP
take the temperature (T500, °C)
STOR=2store in slot No 2
SDIF=1:2
subtract the values in slots 1 and 2
STOR=3store the result in slot 3 (Td850 - T500)
H850
set the 850 mb level
TEMP
take the temperature (T850, °C)
STOR=3store in slot No 3
H500
set the 500 mb level
TEMP
take the temperature (T500, °C)
STOR=4store in slot No 4
SDIF=3:4
subtract the values in slots 1 and 2
STOR=5store the result in slot 5 (T850 - T500)
ANALYZE,SSUM=3:6
Make an analysis based on the sumof the contents of slots 3 and 6
The next seven ‘ANALYZE’ lines are similar to those we met
earlier and apply selected colour fills to areas.

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GEO Quarterly No 7Group for Earth Observation

Now we draw dashed contour lines at 2-TT intervals when
the index is less than 53 but greater or equal to 44.
ANALYZE,CONT CINT=2 LSTN=53 GRTN=44 DASH COLOUR=100:100:100

COLOURDASH
CINT=2
GRTN=44
LSTN=53
CONT

set the line colour (see below)
draw a dashed line
do this with an interval of 2
do this for every value greater than 44 ...
... and less then 53
draw contour lines

Finally, we draw dashed contour lines at 5-TT intervals
when the index is greater or equal to 55.
ANALYZE,CONT CINT=5 GRTN=55

To run the TT script you must first load suitable data into
DAWS using the <Internet → Retrieve data> menu.
‘Radiosonde from COD (worldwide)’ is a good place to start.
Figure 4 shows the DAWS chart produced using the noon
data for May 22, 2005 while figure 5 displays it over a
Meteosat-8 image. Note that, in the latter case, ‘FILS=0’ hasbeen replaced by ‘FILS=1’ to produce a cross-hatched fillwhich allows the satellite image to show through better.
Note
The first time I did this I wrote ‘CINT=2 GRTN=55’ and to
my surprise obtained a contour line at 54! After playing
with the values it turned out that the starting point is thenearest, lower, multiple of ‘CINT’ (in this case 54). So
asking ‘GRTN=55’ with ‘CINT=5’ starts at 55. In fact,using ‘CINT=11’ is perhaps a better solution as there will
be no more lines until 66.
How to Produce Colours
Each colour is made by a combination of Red, Green andBlue (RGB). Each RGB triplet is defined by three numbers
from the range 0 to 255. For example, red has an RGBvalue of 255:0:0, green 0:255:0 and blue 0:0:255. A nicelittle program to find RGB-values is Colour Cop, which canbe downloaded from:http://www.datastic.com/tools/colorcop/download.php
When you start it, click on ‘Custom’ to open the colour
palette. When you click the cursor on a colour, you see inthe lower right corner the RGB-value of that colour. So foreverything you want to plot you can look for a suitablecolour in the palette, note the RGB-value and use it in yourscript. When you have decided on all your script colours,
run it and see how it looks. If some colours are not exactly
as you planned, you can return to Colorcop and change thevalues a little. This is definitely a matter of trial and error.
But if you know how this works you can change every
script to your own wishes.
At this moment it is perhaps a good idea to play a bit withthis script: change the value of COLOUR and FILL to see
what happens. And then it’s time to make your own script.
Tips and Tricks• Practice, practice, practice. This is the most important
tip. You can only learn scripting by doing! You canfind some good script examples by following the linkto ‘Digital Atmosphere scripting’ in the Digital
Atmosphere on-line forum at:
http://www.weathergraphics.com/forum/• Try them and see what happens, then use theinformation for your own scripts. We have a Dutch
proverb: ‘beter goed gejat dan slecht verzonnen’
which, translated, means ‘better to copy well theninvent badly’.

34

September 2005

• When DAWS performs an analysis, it reports each activity
in the ‘Legend block’ at the lower left side of the image.
This can become very intrusive with complex scripts.
Unfortunately, there is no way at present of disabling thisfeature. The best that can be done is to display it in thesmalleststyle
possible.
Do
this
from
<File → Preferences → Styles> by changing the entry under‘Legend block’ to SIZE=1, FONT=Arial.
• If a command line is followed by one or more trailingspaces the command does not work.
• The command GRTN (greater than) in fact means ‘greaterthan or equal to’.
• Negative values cannot be included in commands.
• Beware! At the time of writing this article the scripting
language still has some bugs. If your script is not doing
what you expect, the fault is not always yours!
Digatmos.mnu
Make a print of this file, which you can find in the DAWS folder.
This file contains all the menu commands that drive the DAWS
‘Analysis’ drop-down menu, and you can use them in yourscripts. Just add ‘ANALYZE,’ at the start of each line. You canmake any line into a comment by making the first character thehash (#) symbol.
Write in Parts
Don’t write a long and complex script in one try. Divide theproblem into several parts, write and test them separately andfinally combine them to one script.
One Script or Many Scripts
Think carefully about the way you want to make the scripts.
You can write• one big script with a lot of tasks in it, or• many small scripts
The advantage of a big script is that it’s easy to run. Run asingle script and everything happens. The disadvantages arethat it is difficult to maintain and you can never use thecommands separately (for debugging) and view the result on thescreen.
For a set of small scripts it is the opposite. They take longer toanalyse and run but, since each executes just one task,
debugging is easier (you can comment out commands easily to
see their effect). This is my personal preference.
I hope that, in the future, there will be a possibility to combine
small scripts in an easy way and I have already added this wish
to the forum.
Comments
Write comment lines in the script. This will help you later if you
want to change things. And believe me, if you don’t, then after
just a short time you will think when you look at a script: “Whaton Earth was my intention when I did this?’
Different Folders
In the folder where DAWS is installed make a new folder with
the name ‘Scripts’ and put all the scripts in it. This prevents a
lot of searching. If you want you can do the same with maps: all
the different maps you are generating as base maps. And finallymake another folder where you can store all the maps withoverlays generated by your scripts (the place is not important).
Analysis commands
In the manual (manual.pdf) is a list of commands grouped by
type. On the forum I have placed a list of analysis commands

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September 2005

Group for Earth Observation

GEO Quarterly No 7

sorted by name. This is very useful if you look at scripts
written by others.
KISS
And last but not least: Keep It Simple S..… For instance,
you can combine a lot of commands into one statement of up
to 255 characters. Although a script with a couple of theselong lines performs a bit quicker, it is very difficult to readand understand. Personally I always write one command on
one line. See the above example and some of my examples
on the DAWS-forum.
Good luck with creating new scripts and, if you develop anice script, please put it on the DAWS forum.
References
1. Digital Atmosphere Workstation
http://www.weathergraphics.com
2. Digital Atmosphere User Manual, Tim Vasques and Shannon Key
3. Digital Atmosphere forum
http://www.weathergraphics.com/forum/
4. Use ‘Fleetwood’ data to add synoptic details to Meteosat images,
Ton Lindemann, GEO Q4, page 25 (2004)
5. My experiences setting up an MSG-1 System, Fred van den Bosch,
GEO Q5, page 44 (2005).

• Fred van den Bosch demonstrates how easy it is tocreate 3D colour images from your APT (and HRPT)
weather images.
• Fred has also kindly written up the talk he gave at
Symposium 2005: ‘POVIM - A Framework for Product
Orientated Video, Images and Maps’. This deals withthe systematic organisation, on the PC, of all the files
relating to a fully automated MSG data retrieval
system.
• We will also be reviewing a new, complete, APT station
called WEATHERMAN, produced by the German
company Vierling. This consists of a computer
controllable APT receiver, operating software and a
QFH antenna.

A book review by Robert Moore
This book is a very usefuladdition to the shelves ofweather observers who makeuse of satellite data and forsatellite hobbyists. The book iswell in advance of the‘beginners guide’ but you do
not need a degree in physics
or maths to learn a great deal
from it. It fills an important gap
in the literature available tosupportamateurearthobservers (see ‘Some Useful
Titles’ at the end of Observing
the Weather with MSG-1 in
GEOQ 3). As soon as you turnthe pages you will recognisefamiliar images—indeed you may have received the sameimages and have them stored in your archives.
In chapter 4 for example there is an extremely useful discussionof reflection, absorption and scatter accompanying a clear
account of why particular frequencies are used for weather
satellite operations. The authors force you to ask what exactly itis that you see in an image and why you see it. The discussion
largely confines itself to the use of visible, infrared and watervapour imagery, only mentioning briefly some of the more
complex atmospheric soundings that are now becoming
available. Discussion of the latter would have lengthened thebook and detracted from the clarity of the discussion.
The book is copiously illustrated and includes boxes in which
particular topics are expanded. Unfortunately, the illustrations
become somewhat separated from the relevant text, requiring theuse of fingers and thumbs to follow the argument. It is hard to
avoid this happening in a book of this nature but the publishers
really should have tried harder. There is also a slight tendency forthe authors to repeat themselves in ways which may be useful forsome readers but confusing to others.
One really nice feature of the book is that the authors discuss
what we do not know: the uncertainties and controversies
amongst scientists. No science is about Truth with a capital ‘T’
and this is no less the case in meteorology. Mayes and Hughes
draw our attention to this rather than skirting around the issues.

If you would like a sneak preview, go to:
http://www.vierling.de/www_vierling/
weatherman-en_667_340_6_f.htm?query=• We will also be evaluating APTDecoder, a newsoftware offering that promises to rival current APT
decoding favourites such as WXsat and WXtoImg.
If you would like to try out this new package, it can be
downloaded from:http://www.ptast.com/apt/decoder• Have you ever wished that you could power yourweather satellite receiver from just 4 rechargeable ‘AA’
batteries so that you could image satellites when awayfrom home? Richard Osborne describes a simple
construction project that will help you do just that.

Most books dealing with the analysis of satellite imagery discuss
Northern American weather systems. This volume concentrates
on the UK and Europe, with shorter discussions of the USA andother regions. So if you are not already a weather expert but wish
to extend your understanding of the images you receive fromNOAA satellites and Meteosat-8 then you need this volume foryour book shelf. It will certainly make all readers look at theirsatellite imagery with even greater care and interest.
Understanding Weather : A visual approach (188 pages)
Authored by Julian Mayes and Karel Hughes
Published by Arnold (London), 2004
ISBN 0 340 80611 7

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35

GEO Quarterly No 7

The sustained hurricane onslaught
endured by North America’s Atlantic
coastline during 2004 has served tohighlight recent arguments that humaninfluenced environmental changes may
be increasing both the severity andfrequency of such storms. Humanactivities are changing the compositionof the atmosphere and global warming,
which is manifested in unexpected ways,
is one of the consequences.

Group for Earth Observation

numbers vary so greatly on a regional
level from year to year and also fromdecade to decade, it is difficult to use

September 2005

statistical techniques to extract longerterm trends in the number of hurricanesthat form and where they move.

World-wide sea surface temperatures
have risen by approximately 0.5°C
during the past 100 years and thequantity of water vapour over the oceans
has increased by about 2% since 1988.
Most hurricanes that strike the U.S.
coastline are born in the tropical North
Atlantic Ocean, where sea-surface
temperatures over the past decade havebeen the warmest on record. Increased
ocean surface temperatures means thatthe environment in which hurricanes
form is changing and one notablemanifestation was the March 2004
hurricane in the South Atlantic, off thecoast of Brazil—the first and only such
hurricane to be recorded in that region.
The warmer sea surface and moister
atmosphere furnish potential energy forthe showers and thunderstorms that
fuel hurricanes: the additional water
vapour will tend to produce heavier
rains within the hurricanes and anincreased risk of flooding at landfall.
The evidence strongly suggests more
intense storms and risk of greater
flooding events for the future, so that
the North Atlantic hurricane season of2004 may well be a harbinger of things
to come.
The effect on hurricane numbers is lesscertain as models disagree on how global
warming might affect the wind shearthat can either support or discourage
hurricane formation.
Globally, the number of hurricanes andtyphoons tends to hold relatively steadyfrom year to year. When activity
increases in the Atlantic, it often
decreases in the Pacific and vice versa,
based in part on the El Niño and La
Niña phenomena. Because hurricane

36

Hurricane Dennis, imaged approaching Cuba by the MODIS instrument
aboard NASA’s Terra satellite on July 7, 2005
NASA Image courtesy Jeff Schmalz, MODIS Land Rapid Response Team at NASA GSFC

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September 2005

Group for Earth Observation

GEO Quarterly No 7

Hurricane Emily as imaged at 18:15 UT on July 18, 2005 by GOES 12
Image NOAA/NESDIS (http://www.nnvl.noaa.gov/)

Super Typhoon Haitang to the northeast of the Philippines, as seen by GOES 9 at 03:25 UT on July 16, 2005
Image NOAA/NESDIS

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GEO Quarterly No 7Group for Earth Observation

September 2005

The R2FX APT Receivercontinued from page 21 ...

How to Obtain the R2FX ReceiverC S LohYou can find full details concerning the
R2FX receiver by visiting Holger
Eckardt’s website at:

Following the 2004 Boxing Day tsunami inSoutheast Asia, aftershocks havecontinued to propagate through the Indian
Ocean basin as Earth’s interior readjuststo the surface changes.

http://www.df2fq.de
Although the site is in German, an R2FX
manual in English can be downloaded
as a PDF file fromThe Nias Quake
At 16:09 UT on March 28, 2005, a
powerful magnitude 8.7 aftershock took
place on the same fault line, 69 km to thesoutheast, and was felt in Sri Lanka, theAndamans, Thailand, Malaysia andSingapore. The epicentre lay 12 km deep
between the islands of Nias and Simeulue
off western Sumatra (Figure 1). A 3-metrehigh wave swept into Simeulue and at
Nias the sea surged at least 400 m inland
destroying 70% of the buildings in the
town of Gunungsitoli. Farther away thewaves were much smaller: just 25 cm in
Colombo, Sri Lanka and 10 cm in the
Cocos Islands. At Malé in the Maldives,
the tide gauge measured a wave height of
20 cm, compared with a 2 m tsunami
following the December quake.
As a result of this quake the coastline in
Simuele was reported to have been
uplifted by a metre; at Sarangbaung, anisland 20 km north of Nias, there wasabout 1.7 m subsidence. At Nias itself,
uplift exposed offshore coral as illustrated
in Figure 2a/b.
The aftershock originated south of the
December earthquake and was of shorter
duration and lower magnitude, leading tosmallerwaves.
Furthermore,theDecember earthquake had a higher
average slip, ruptured a longer section of
the interplate thrust fault and occurredunder a greater depth of water (up to 4 km
compared with just 1 km) than the March
event. It was this greater depth that
produced the tsunami that lashed theIndian Ocean shorelines last December.
Another factor is that there was a 5 mvertical sea-floor displacement in
December compared with 3 m in March
resulting in a greater overburden of water
being pushed upwards. Finally, the waves
from the March aftershock spread mainly
to the southwest across the Indian Ocean,
avoiding any landmass where they could
have created a major tsunami.
The Padang Quakes
Between March 28 and April 10 theMeteorological Services Department,
Malaysia recorded more than 190

38

http://www.df2fq.de/
res/R2FX-Engl.PDF
To purchase an R2FX you must send
179 euros to:Holger Eckardt
Kirchstockacherstrasse 33
D-85662 Hohenbrunn
Germany
Figure 1 - Location of the March 28 quake
Credit: USGS

Unfortunately, there is no facility for acredit card payment, so you have toeither arrange a bank transfer or send
cash. I sent euro banknotes in a jiffybag.
If you have any questions about theR2FX, do not hesitate to e-mail Holger
Eckardt. Communication is not a
problem as Holger speaks excellent
English. Holger can be contacted at:holger@df2fq.deFigure 2a - Offshore coral - July 13, 2000
Terra ASTER Image courtesy NASA

How to Align a Dish on Hot Bird
continued from page 22 ...

You can purchase 6° spacing LNB
holders from satellite TV stockists but,
as you will see, the position has quite a
bit of ‘play’ and any DIY enthusiast
could knock up a support arm from parts
available at your local DIY store.
Figure 2b - Offshore coral uplift - April 6, 2005
Terra ASTER Image courtesy NASA

aftershocks culminating in a magnitude
6.3 quake southwest of Padang in
Sumatra. This was followed by increased
activity in Gunung Talang, one of Sumatra
many volcanoes as grey ash rose 250 m
above its summit.
On May 14, another earthquake, of 6.9 on
the Richter scale, was felt in Penang,
Kuala Lumpur and Malacca during
Saturday lunch hour, the epicentre
reportedly 50 km northwest of Padang.
Since the March tremor, seismological
data indicate earth rupturing to haveprogressed southwards, accentuating
future risks in other towns in Sumatra.
www.geo-web.org.uk

If you now place your LNB farther roundto the west and pointed back into thedish you should find another strong
signal. This is a combination of Astra-2
at 28.2°E and EUTELSAT EUROBIRD
at 28.5°E. This is the location for all the
Sky TV services as well as FTA BBC-1
and BBC-2 national and regional optouts, BBC-3, BBC-4 and BBCinteractive streams as well as several
other English language services.
You could therefore mount two
additional LNBs on to a DIY arm forextra FTO TV channels.
This will not interfere with your receptionof EUMETCast via Hot Bird-6 as yourdish and primary LNB is already aligned
to the Hot Bird 13°E location.

September 2005

Dear Editor,
I do agree with Peter Wakelin's niceconclusion on page 21 of the last issue of
GEO Quarterly, but some of his statements
are incorrect. His conclusion about thetightening of isobars shown in Digital
Atmosphere Workstation (DAWS) is not
the result of air moving around hills but aconsequence of the internal calculation
methods used in DAWS itself.
Readers should be warned not to use
too small maps in DAWS. It would bebetter to use programs such as GrADS
for in-depth analyses of the weather, or
to use one of the on-line archived
mapping sites/tools from NOAA.
Anyway, these hills are too small for thiskind of effect. Air can move over hills toform mountain waves, or lengthwise(partly) along the hills to create eddies ason the images. In the latter case, it neverresults in pressure changes of several
hPa. As we shall see, there was aninversion at 1700 m and the highest of thehills in question are around 400 m. Most of
the air is just hopping over the tops.
Reports from weather stations are always
in Mean Sea Level, meaning that they are
reduced to 45° latitude at 0°C on sea level.
This is resulting in a smoothed map where
the effects of mountains and hills are fadedout. I checked this with the on-line FNL
archived analyses on the site of the Air
Resources Laboratory/READY and there
were no hill-tightening effects at all.
Peter suggests that there is a cloud layer
with waves above the stratocumulus
clouds. First: the cloud tops on the image
are not stratocumulus, but just stratus in avaried density. Stratocumulus on satellite
imagery looks like so-called ‘closed cells’:
bright oval spots with a darker border.
Stratus is smoother but can show avariation in thickness as darker andbrighter lanes. Synoptic reports did indeed
report stratocumulus cover on thecloudbase, but this was not visible bysatellite as they are overlain by the stratus.
The types of the cloud layers can bechecked by soundings. The nearest
sounding, from Trappes (near Paris) at 12
UTC indicated a cloud layer from nearsurface up to 1.700 m. There were no
clouds at higher levels (as Petersuggested) because of an inversion at
1700 m. At the inversion the relative
humidity (RH) dropped down from around

Group for Earth Observation

95% to less as 10% at higher altitudes.
Scattered clouds are possible if the air ismore saturated than 70%, and it canbecome completely overcast if RH
exceeds 90%. I made a double check witha hypothetical sounding calculated fromthe gridded FNL data for 50°N and 2°E, inthe centre of the cloudmass, for 6 UTC,and found an identical inversion with astratocumulus base with stratus on top anda cloud-free upper level up to 10 km.
About the waves: sometimes we can see
them on the boundary layer of the stratus
where wind is blowing over the cloud tops
at the inversion level (like wind overwater). This was the cause of the waves
on these images.
Ton Lindemann, Meteo Maarssen
Netherlands

Hello Les,
Many thanks for the GEO June issue, I am
enjoying it very much. Particularly thearticle of “Introducing Digital AtmosphereWorkstation”, which was very timely to me
since I was just considering learning
DAWS at that time.
I am including a NOAA-18 APT image ofSouth East Asia (see page 40) dating from04:55 UTC on July 17, which depicts
Typhoon Haitang. The image was received
by an RX2 receiver with a rotor controlled
Yagi-Uda antenna and processed by
WxToImg and Photoshop Elements.
Cheers,Jiro JQ2LMG, Japan.

Hello Les,
Thank you for your great effort with themagazine—it is superb; and thank you inparticular for your recent article on the
production of HRPT Images from the‘NOAA Satellite Active Archive’.
Presently I'm preparing for the reception of
NOAA 1.7 GHz signals (using Sam
Elsdon's HRPT Receiver and hopefully
Rob Alblas' Decoder.)To help become familiar with David
Taylor's Runtime Library Bundle and
HRPT Reader Program, I could think ofnothing better than the opportunity ofdownloading some NOAA passes overwww.geo-web.org.uk

GEO Quarterly No 7

Australia: maybe the same passes that I
already have in APT format. This would
enable a direct comparison.
Ken Morgan
Brighton,
Victoria, Australia.

Tornado hits
Birmingham
If you lived in the United States, aheadline like this might not seem out ofplace. But Birmingham England?
On the afternoon of July 28 this year afreak mini tornado hit the Sparkbrookand Kings Heath districts of the UK’s
second largest city. The entire episodelasted no more than 10 minutes as thesudden storm cut a kilometre-longswathe through the city, blocking manyroads by fallen trees and causing trafficchaos.
Following a spell of torrential rain it
became very dark, the sky turned dull
brown and powerful winds whipped up,
felling hundreds of trees, overturningcars, toppling walls and stripping entire
roofs from buildings. Rows of rooflesshouses were left with gaping windows.
One observer noted ‘.. all of a sudden it
got dark and the front door blew open.’
Weather experts judged the storm tohave been a tornado with a rating of T3T4, implying that windspeeds could havebeen as high as 200 km/hour.
Twenty people were injured andrequired hospital treatment, three of themore serious cases involving fractures,
while hundreds who were left
temporarily homeless were forced tospend the following night in emergency
shelters.
Although nowhere was affected for morethan a minute or so the streets wererapidly littered with broken glass,bricks, roof tiles and furniture before thestorm cleared as quickly as it hadarrived, giving way to warm sunshine.
Although there are upward of 30 tornado
reports annually in the UK, these rarely
impact on built-up areas.

39

GEO Quarterly No 7Group for Earth Observation

September 2005

Alan Woodcock received this excellent NOAA-18 image at 13:12 UT on
May 30 from Twickenham, west London using a Chris van Lint Quad
Helix antenna feeding into a Dartcom pre amp and then into a slightly
modified Cirkit receiver. The Image was processed with WxtoImg using
the vegetation option (channels 1+2).

Ken Morgan from Brighton, Victoria, Australia sent us this NOAA-17
image dating from 00:49 UT on March 9. It shows Cyclone ‘Ingrid’ off
the east coast of Cape York peninsula.

Jiro Yamamoto from Nishio City, Japan sent us this superb NOAA-18
APT image of South East Asia which includes Typhoon Haitang. It dates
from 04:55 UT on July 17, 2005.

Tony Le Page sent us this NOAA-18 image received from St Peter Port,
Guernsey at 13:21 UT on June 18. Tony uses a Dartcom receiver, Paul
Hayes QFH antenna and WXtoImg software.

40

www.geo-web.org.uk

September 2005

Group for Earth Observation

GEO Quarterly No 7

Douglas Deans - douglas@dsdeans.freeserve.co.uk
Let me start this quarter with some news
on updates to the Mars Rover Panoramics
CD, GS5. The two Rovers, Spirit andOpportunity, have astounded everyone
with their performance and, having
completed their three month planned
mission in April 2004, are still going strong
in their second mission extension. So far,
the two rovers have together covered anamazing total of 6.2 miles. GS5 is now
filled to capacity with their panoramic
images.
Despite the continued missions of theRovers, it is not my intention to produce
any further CDs for the GEO library,
primarily because GS5 contains about
every possible image topic you could
expect from Mars and a few you would not
anticipate: plains, views of craters somefrom inside, rocks of all types, views fromhills, clouds—yes there are clouds on

Mars, and even dust devils. Many are in
full colour and there is a good selection of
3D. If you want to save yourself nearly
700 Mb of downloads and have an image
description provided, then this is the CD
for you.
Orbitron v 3.60
This is not a brand new tracking program
but one that was brought to my attention
by a GEO member. There are many
tracking programs available to the radio
ham and weather satellite enthusiast alikebut that in itself does not constitute a valid
reason for not reviewing new ones.
Although
Orbitronisextremely
comprehensive it does not offer much
more than many of the other programs
already on the market. However it has onevery attractive feature in that it iscompletely free with no facilities held backwww.geo-web.org.uk

for paying options. The author, Sebastian
Stoff from Poland, has called his software‘Cardware’, a new word for my computer
vocabulary ! This means that you may use
it free of charge but, if you have found it
useful and think he has done a good job
creating it, then you are encouraged tosend a traditional (snail mail) postcard withyour city/region view (Ham QSL cards arealso accepted). Sebastian treats thesending of a postcard as a form ofsoftware registering and in turn provides alist of all users who have ‘carded’.
Installation is very straightforward but dobeware of a couple of choices which areincorporated into the installation window.
One option is to run a screensaver, theother the to auto-update TLEs’: both are
selected by default. I missed this first timeround (too hasty) and was most annoyedwith both the screensaver (which I

41

GEO Quarterly No 7Group for Earth Observation

normally do not use) and the dial-up connection box popping up
every time I loaded the program.
The main screen, shown here, incorporates the usual cylindricalequidistant type map but an unusual touch is the ability to centre
the map anywhere by simply pressing the mouse button anddragging it; and there is a further option to zoom into the map. The
satellite list is provided at the right side of the map, with thoseavailable being dependent on which TLE group is loaded. Tochange the list just select ‘Load TLE’ and you are given the option
to select another TLE group from the program files. All the usual
tracking program options are provided and are too numerous tomention here. Orbitron is certainly worth a look and is probably
the most comprehensive program of its type available free ofcharge. The program is still evolving.

September 2005

features being accessed though a simplified menu. Navigation is
automated with single clicks of a mouse as well as the ability totype in any location and automatically zoom into it.
I do not intend to review the program in this column as I am
hopeful of a more detailed article, as merited by a program of thismagnitude, in a future issue of GEO quarterly. However due it islarge download size (over 180 MB) I have added it to CD GS2 tohelp those without a broadband connection.
For further information and to download the program go to :-Orbitron is available on GEO software CD GS2 or, for more
information and to download the program go to :http://www.stoff.pl/
World Wind v 1.3
World Wind, produced by NASA, is an incredible program whichallows the user to zoom from satellite altitude into any place on
Earth, utilising high resolution LandSat imagery and SRTM
elevation data to experience Earth in visually rich 3D, just as if
you were really there. It has to be seen to be believed.
Particular focus was put into the ease of usability so people of allages could enjoy World Wind. All that is needed to control the
program is a two button mouse, with additional guides andhttp://worldwind.arc.nasa.gov/
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
the appropriate 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.

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 3.5.0
SatSignal

Creates images from wave files

v 4.2.0

HRPT Reader

Converts raw HRPT data files into images

v 2.6.0

GroundMap

Rescales satellite images

v 1.3.8

RX2 PassControl

Computer control program for the RX2 receiverv 3.0.6

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)

OrbitronSatellite Tracking Program

Paintshop Pro

Image processing program (30-day evaluation)

v 3.60

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

v 2.02

World Wind (NASA)

View anywhere on Earth from satellites

v 1.3

WXtoImg

WAV file recording and decoding program with many options.

v 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

42

www.geo-web.org.uk

September 2005

Group for Earth Observation

GEO Quarterly No 7

Les Hamilton
Last issue I explained how to combine
two or more HRPT images to display amore extensive geographical area. This
tends to be particularly straightforward
for regions such as Europe and North
America where the NOAA CLASS
Library [1] makes all the necessary
satellite passes available.
But what about more distant regions of
the planet: Australia for example? Mostdays only a single HRPT file covering
most of the central and eastern parts ofthe continent is made available. On
those days when two successive passes
over Australia can be downloaded theimages are usually centred on the major
land regions only. Extremities andsurrounding oceans are ‘clipped’ and theresulting composite image, with its
ragged outline, tends to be singularly
unappealing, as illustrated below.

pixel—and often less as a result of thenecessary rectification in GroundMap.

Composite of three NOAA-16 channel-2 GAC
images from March 19, 2005
GAC files: NOAA CLASS Library

The resulting composite GAC image
could be cropped neatly around
Australia as shown above.
Of course, the downside is that thisimage provides a maximum ground
resolution of just 4 kilometres per

But of course, the two HRPT images
covering most of Australia are alsoavailable. These can now be loaded into
Paint Shop Pro as additional layers
above the GAC ones (i.e. load them after
the GAC images) so that they aredisplayed above the GAC ‘background’.
The result is a high resolution image ofmost of Australia with the ‘missing’
extremities and oceans rendered insomewhat lesser detail. Indeed, because
the eye is drawn to the detail of the
HRPT segments, you are scarcely awarethat the margins of the image aresomewhat less sharply defined.
References
1 NOAA CLASS Library

http://www.class.noaa.gov
2 The NOAA Satellite Active Archive
GEO Quarterly No 5, page 19.

Composite of two NOAA-16 channel-2 HRPT
images from March 19, 2005
LAC files: NOAA CLASS Library

The question is: ‘can we do anything to
improve the overall appearance of thisimage?’GAC Images
While HRPT images may not always be
available, it is almost certain that lower
resolution GAC images for the region ofinterest will be. A quick check throughthe CLASS Library for March 19, 2005
revealed that three of these files (which
covered Australia in its entirety) wereavailable for downloading. Using the
CLASS area selection tool [2], segmentsfrom each GAC file stretching from 20°
north of Australia to 20° south wereordered. This selection ensured thatsufficient of the surrounding oceans was
included to provide an attractive
background.

The final composite, with the two HRPT sections superimposed on a ‘background’ framed fromthe three GAC segments.
All original telemetry files: NOAA CLASS Library

www.geo-web.org.uk

43

GEO Quarterly No 7Group for Earth Observation

September 2005

Douglas Deans

Good quality radar imagery is difficult to come by, even in thismodern day of Internet access. There are a number of sources
but the imagery is usually of poor resolution and often timelagged. Either one of those problems makes the data of little
benefit for local nowcasting; both make it almost impossible.
To receive a service of good value and one which can contribute
positively to other meteorological data we (by which I mean
amateurs) have to consider registering for a paying service.
This need not be financially onerous.
There are a number of paying services but there is one I havefound that offers excellent value for money whilst providing
good resolution data of the whole UK, updated every fifteen
minutes, and available within 15 minutes of actual time. I
have now been using it for several years.
The service is provided by AvBrief.
http://www.avbrief.com/
AvBrief is as site primarily dedicated to offering a wide rangeof services for pilots, in particular for flight briefing. As you
would expect, there is a large selection of data available
including weather, Airfield Information, Route Briefing,
NOTAMS and many other services. There are a number ofdifferent packages to suit everyone’s needs but what I really
liked about this site is the ability to register only for the 15
minute radar service. Full marks to AvBrief for recognising
the interest of meteorology without having a pilot’s licence !
Let me say from the outset that I have no association
whatsoever with AvBrief other than I have been a registereduser of their radar data for several years. I must say that theservice has been excellent and any communication I have had
has been dealt with promptly and courteously. As an exampleof that, there was one recent (and very rare) occasion when theservice was down for nearly two days over a weekend.
Everyone registered had a week added on to their registration
period. At the moment a full year of 15 minute radar imagery
can be obtained for £25.85.
What do you get for your money?
A typical radar image is shown opposite, alongside thecorresponding Meteosat-8 segment showing the UK forcomparison. Please note, however, that the coloured Rainfall
Radar Key, normally accessed separately, has been added tothe image by myself to save space. These images are updated
every 15 minutes, with the latest and the previous ten
available for access at the click of a mouse (more are available
from archive). Whilst it would be a simple matter to make yourown animations there are five preset animations available at aslightly lower resolution on the web page: quarter-hourly
frames over a 2, 4, 6 and 8 hourly periods and half-hourly
frames over an 8 hour period. I find those perfect for most of
my purposes and only rarely make up an animation from my
own individual frames.
The composite rainfall radar image uses colours to represent
the approximate rainfall rate, with blue as lightest, throughgreen, yellow, orange and reds which represent very heavy
rainfall. Although it may not be clear from the article image,44

the full resolution radar image is bigger than my web page
screen and my monitor is run at a resolution of 1280 x 1024.
I don’t intend, nor am I able, to give an in-depth analysis ofradar imagery. For those who may be interested there is an
excellent book called Images in Weather Forecasting [1] which
devotes a full chapter to radar imagery. I have had this bookfor some time and it contains a wealth of knowledge for thoseinterested in weather satellite imagery and radar
interpretation.
Can I also say that the AvBrief site itself provides some
excellent help both in interpreting weather radar and detailingits usefulness although the latter is understandably aimed atpilots.
However, a word of caution as interpretation of radar imagery
is not always straight forward. There are many things which
can influence readings including topography local to the radar
station partially blocking the beam and showing no return
when in fact there may be rain.
Droplet size can affect the radar and in some cases givemisleading precipitation rates. The angle of the radar beam issuch that it is measuring precipitation closer to the ground inproximity to the device and progressively higher from theground the further the beam travels. Consider theconsequence of this in a condition of light rain falling andperhaps evaporating before hitting the ground. There may also
be situations where very narrow bands of precipitation are
missed due to the resolution of the radar.
Whilst it is possible to make some assessment of rainfall frominterpretation of satellite images in different wavelengths, it is
not an exact science. Access to 15 minute radar is extremely
useful and, used in conjunction with satellite imagery andother meteorological data, can be an excellent learning tool.
The Images
The images opposite date from Friday, June 24, 2005, whensevere storms struck the West Country. Many minor roads
were flooded, and there were major traffic delays on the M4
motorway in Wiltshire. At Poole in Dorset, a teenager was
fortunate to survive after lightning blasted a hole through theroof of his home. He had been playing a video game, and wasthrown across his bedroom by the strike, which also caused firedamage to the house.
The opening day of the Glastonbury music festival was aspectacular washout. The 100 000 participants were wakened
in the early hours of the morning by crashing thunder,
lightning and torrential rain. Tents were flooded, stages werestruck by lightning and nearby streams burst their banks,
inundating parts of the site under knee-deep floodwater.
Power to the stages had to be disconnected on safety grounds
and all the morning’s entertainments postponed.
Reference
1 Images in Weather Forecasting by Bader, Forbes, Grant, Lilley andWaters, published by Cambridge University Press.

www.geo-web.org.uk

Severe storms course across England on June 24, 2005,
caused widespread thunderstorms and flooding.

The morning radar map from AvBrief illustrates the extent of thestorms, the colours indicating rainfall in millimetres per hour.

Image © EUMETSAT 2004

Chart courtesy AvBrief (http://www.avbrief.com/)

Just a few days prior to the thunderstorm event of June 24, anotherband of thunderstorms, accompanied by torrential rain, swept
across England. Parts of Yorkshire experienced an entire month’s
rainfall in just three hours and helicopters had to rescue a numberof people who had sought refuge from the floodwaters on roofs andin trees.

Robert Moore submitted these two Meteosat-8 images detailingthe situation at 18:00 UT on June 19. The false-colour HRV image(left) displays the cloud mass positioned over northeast England
while the false colour IR frame clearly picks out the coldest cloud
tops, the areas most likely to experience the heaviest rainfall (red).

Images © EUMETSAT 2005