The Advanced High Resolution Picture Transmission (AHRPT) system on EUMETSAT’s Metop-A has operational service resuming over a limited area across the North Atlantic and Europe. This follows the onboard failure of the system in July of 2007, whose cause has been identified and for which corrective measures have been taken. This is good news for users who have invested in antennas to receive the data via AHRPT, who can once again benefit from their investment. It will also enable Metop data and products to be delivered as part of the EUMETSAT Advanced Retransmission Service (EARS) services, as originally planned, and allow the use of existing HRPT stations located around the North Atlantic and in Europe.
The trial focused on providing highly timely data covering passes by Metop-A over the North Atlantic and European areas. For southbound passes, AHRPT has been activated for all orbits over the North Atlantic and Europe starting at 60 degrees North. For northbound passes, a Fast Dump Extract will provide data for a number of instruments: the Advanced Scatterometer (ASCAT), Advanced TIROS Operational Vertical Sounder (ATOVS) and Advanced Very High Resolution Radiometer (AVHRR). Data from ASCAT, ATOVS and AVHRR will be available in due course from the EARS network of stations. The data is already available from the French Centre de Météorologie Spatiale’s Lannion HRPT station; the Athens AHRPT station run by the Hellenic National Meteorological Service; and the Maspalomas HRPT station operated by INTA, the Spanish National Institute for Aerospace Technologies.
Regional products generated from the Fast Dump Extract and the AHRPT will be made available via EUMETCast, EUMETSAT’s near-real-time broadcast system for environmental data. The AHRPT on Metop-A failed last year when its Solid State Power Amplifier stopped working, due to heavy ion radiation affecting a power transistor. The probability of this incident occurring again has been greatly reduced by excluding the North and South polar regions (high in heavy ion flux) and the so-called South Atlantic Anomaly area (high in proton flux) from the new operating area. However, there are no totally safe operational areas and a further failure cannot be completely ruled out during the lifetime of Metop-A. Furthermore, the units on Metop-B and -C are being modified to cope with the radiation environment. The AHRPT sub-system on these satellites is being fully re-engineered to ensure the continued availability of AHRPT data once they are launched in 2012 and 2016, respectively.
