Met Office College - Course Notes
Meteosat Second Generation
Contents
1.
Introduction
2.
Equipment onboard MSG
3.
MSG Channels and Resolutions
3. Products
4. Summary
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Principal, Met Office College, Fitzroy Road, Exeter, Devon. EX1 3PB. UK.
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1. Introduction
“Meteosat Second Generation … should be able to advise us with
considerable accuracy about whether to take an umbrella or avoid a
particular stretch of road because of bad weather..”
- European Space agency. The media has suggested that MSG will herald a revolution in weather
forecasting
Meteosat Second Generation (MSG) is a joint project between ESA
(European Space agency) and Eumetsat (European Organisation for the
exploitation of Meteorological Satellites). Four MSG satellites, launched in
stages, will replace the current Meteosat geostationary series giving
geostationary cover up until 2018. Total cost for project is 1.3 billion Euros
(£0.8 billion), with the Met Office contributing £20 million to the project.
The first MSG satellite was launched 28th
August 2002 from French Guyana, into a
geostationary orbit at 35800 KM (6 times the
Earth radius).
Eumetsat have decide to name this first MSG
satellite as ‘Meteosat 8’, to continue the name
convections from the ‘old’ Meteosat series.
In late January 2003, Meteosat-8 was being
decontaminated (when launched the satellite
picks up water vapour through the
atmosphere– this degrades the image as it
freezes as a very fine film). Decontamination is
carried out by heating the optics up from their
very cold temperature in space. During
decontamination the imaging stops. Afterwards
some of the water vapour may re-freeze over
time - hence new satellites usually need
decontaminating 4-5 times, with each decontamination taking 3-4 days.
Figure 1. The first MSG launch
onboard Ariane 5, 28th August 2002.
The two likely limits on the life of a satellite are the harsh conditions and the
amount of fuel required to keep its orbit. Meteosat 9 (MSG 2) is due for
launch/operation at the end of 2005, but this will be dependant on the life of
the other Meteosat satellites currently in orbit. MSG-3 will be built and put
into storage until it is required.
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Meteorological Satellites
2. Equipment onboard MSG
The MSG satellite contains the SEVIRI imager (Spinning Enhanced Visible
and Infra-red Imager - pronounced “sevry”) which is a multi-wavelength
camera which allows imaging in 12 channels.
The satellite is ‘Spin stabilised’, similar to a gyro. As a by-product this
spinning is used to allow the east - west scanning of the globe. The SEVIRI
radiometer takes images at twelve different wavelengths, focussing
radiation onto the detectors within the SEVIRI. The mirror onboard is
‘stepped’ south to north giving the full image. Imaging and data
transmission takes place over a 15 minute cycle.
SEVIRI
Spinning Enhanced
Visible and Infrared Imager
Figure 2. Image scanning, using the SEVIRI and stepping mirror.
Also on board is the GERB instrument (Geostationary Earth Radiation
Budget) designed to measure the amount of radiation incident on the Earth
and the amount leaving (as heat or scattered / reflected radiation). This
instrument has been designed primarily for research, particularly with
global warming in mind. The GERB experiment is provided by the
Rutherford Appleton Laboratory.
MSG also carries a transponder for search and rescue / SOS activities.
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3. MSG Channels and resolutions
Meteosat First Generation
(MFG)




3 Channels
Images every 30 Min
5 km resolution SSP
Best resolution 2.5 km
SSP (Vis)
Meteosat Second Generation
(MSG)




12 Channels
Images every 15 Min
3 km resolution SSP
Best resolution 1 km
SSP
(HR Vis)
Figure 3. Comparison of Meteosat First Generation and Meteosat Second Generation satellites.
The images received via Darmstadt are calibrated (also known as normalised
– images must be consistent with no sudden changes in brightness) and
navigated (correct positioning, adding coastlines). Eumetsat have also
developed a new ground processing system and satellite control system.
Channel 01:
VIS 0.6 m
Channel 07:
IR 8.7 m
Channel 02:
VIS 0.8 m
Channel 08:
IR 9.7 m (Ozone)
Channel 03:
NIR 1.6 m
Channel 09:
IR 10.8 m
Channel 04:
IR 3.9 m
Channel 10:
IR 12.0 m
Channel 05
WV 6.2 m
Channel 11:
IR 13.4 m (CO2)
Channel 06:
WV 7.3 m
Channel 12:
HRV (High
Resolution Visible)
Figure 4. MSG channels, All wavelengths will have a resolution of 3 km except the HRV
(High Resolution Visible) which has a resolution of 1 km SSP (Sub satellite point).
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Meteorological Satellites
Figure 5. SEVIRI multi-spectral image ground
resolution. The resolution deteriorates as you move
further away from the sub satellite point. 3.1 km (inner
circle), 4 km, 5 km, 6km , 8 km and 11 km (outer band).
This data is transmitted to Darmstadt for processing,
above 55 deg North / South images are little use due to
curvature, they need to be processed and projected to be
useful for lats up to 65 deg.
4. Products
Rapid Scan
Rapid scan imagery is produced using
the ‘hot spare’ satellite. Rapid scan
currently shows satellite images
for every 10 minutes. When
Meteosat 9 is launched
(2005/2006) there will be two
MSG satellites in orbit, it is likely
that this will become every 5
minutes.
It is possible to decrease the times
between frames further, but this
would require decreasing the area
scanned.
Figure 6
During the transition from Meteosat First Generation (MFG) to MSG the Met
Office has elected to replicate the products that are already available. So
although there will be no new products for ‘Day 1’ these products will
benefit from improved spatial resolutions, temporal resolutions and more
information from the additional wavelengths. It is hoped that more products
will become available over time.
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Figure 7. Day 1 products: Products generated on Autosat – available through NIMROD.
a) Cloud mask b) Cloud Top Temperature
c) Cloud Top Height
d) Fog product
e) Volcanic ash product
Autosat is the Met Office software used to generate products based on
Satellite imagery. Many other products are available to Eumetsat members
through MPEF (Meteorological Products Extraction Facility) and the
specialised SAFs (Satellite Application Facilities).
Although many similar products are produced using polar orbiting data,
with better resolutions, MSG offers a much greater frequency, with some
products being updated every 15 minutes.
Although MSG data can be assimilated into the model, most of the data
comes from the polar orbiters which provide more detail due to their lower
orbit and better resolutions. More information could be assimilated from
MSG, but it is unclear if this will increase NWP scores.
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Meteorological Satellites
Figure 8. Eumetsat SAFs are spread across Europe, each with it’s own
specialism. Examples of products can be found through the Eumetsat website
www.Eumetsat.de
5. Summary:
Meteosat Second Generation will bring many advantages to the Meteosat
series of satellites most notably;
 Higher temporal sampling (15 min)
 Better resolution (3 km IR / WV / VIS, 1 km HRVIS)
 more channels (12)
 Better discrimination of surfaces/clouds
 More information on vertical structure of the atmosphere
- Soundings
- Water vapour at two levels
- Ozone information
 Higher capacity of data collection
 GERB instrument for climatological studies
 Search and Rescue package for emergencies
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