METOP-AVHRR

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2.2 METOP-AVHRR

2.2.1 Main principles

The series of METOP satellites is constructed by the European Space Agency (ESA) and managed by the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT). METOP1 was launched in October 2006, METOP2 will follow in 2012 and the program is guaranteed to continue via METOP3 until the mid-twenties. METOP complements the European geostationary meteorological satellites (MSG, MTG), in the same way as NOAA does for GOES-East and -West. On the other hand, METOP also represents the European counterpart of the NOAA-platforms, because amongst the wide range of different sensors its payload also comprises the same AVHRR-instrument as installed on NOAA. In a joint European-US initiative, METOP assumes since 2007 the "morning orbit" (overpasses at around 08h|20h LST), while NOAA remains responsible for the "noon orbit" (14h|02h.

Contrary to NOAA, the METOP platform is well stabilized and protected against orbital drift. Moreover, it contains advanced on-board data storage capacities, so all the registered 1 km imagery of the last orbit is systematically transmitted to a single antenna in Svalbard (Norway) and further channelled to EUMETSAT (Germany). After some first but crucial adaptations, EUMETSAT distributes the "raw" data freely and in near-real time via its EUMETCAST broadcasting service. The resulting data stream is cut into segments of 3 minutes (1080 scanlines) which are distributed in near-real time via the EUMETCast broadcasting system in the form of EPS-formatted Level1B-files.

Just like NOAA, METOP-AVHRR still lacks on-board calibration standards for the shortwave bands (Red, NIR, SWIR). But EUMETSAT uses the same "vicarious" calibration methods for METOP as NASA does for NOAA. This approach guarantees an optimal agreement between the AVHRR measure¬ments on both platforms.

EumetSatSystem.png