In order to be able to observe the whole earth (except for the
polar areas) at least five geostationary satellites are necessary,
each lying around 70 degrees of longitude from one another. Currently
there are 7 such satellites available: the European Meteosat, the
Indian INSAT, the Japanese GMS, the American GOES (O) and GOES (W),
the Chinese and the Russian GOMS (the latter still are not fully
The first European geostationary weather satellite, Meteosat 1,
was launched on November 23rd 1977. Meteosat 7 was operational before
the turn of the century, sending us every 30 minutes a weather picture
covering virtually the whole of Europe, Africa, and the eastern
part of South America and the Atlantic Ocean. Like most geostationary
satellites, Meteosat 7 (1998) is active in 3 channels (visible,
IR and water vapour). It furnishes images on which cloud cover and
special atmospheric conditions can be distinguished.
The spatial resolution of Meteosat 1 through 7 amounts to 2.5 km
in visible light and 5 km in the infrared and water vapour spectrum.
In January 1994, the EUMETSAT programme for Meteosat Second Generation
(MSG) was established. The new-generation Meteosat satellites, which
are scheduled to be launched after the year 2000, will not only
deliver the conventional images of clouds and the underlying earth's
surface (Imagery Mission), but also measure the temperature, moisture
and ozone in the atmosphere (Airmass Mission).
The new satellites will have 12 spectral channels and an image
will be provided every 15 minutes. The resolution will be 3 km for
the infrared channel, and 1 km for the visible channel.