Role of the European Operational Meteorological Satellites in the Space-based Global Observing System

The paper addresses the European contribution to global operational meteorological satellite observing system. EUMETSAT currently contributes with the geostationary Meteosat satellites and the polar Metop-A satellite in a mid-morning orbit. Both satellite systems provide unique information to operational numerical weather prediction (NWP) and to Nowcasting. It is shown that satellites have an increasingly important role in NWP and that they help making Nowcasting more objective and quantitative. For the latter the advanced imagers (SEVIRI) on Meteosat-8 and -9, respectively, are important with their high temporal repeat cycle of 15 minutes and the twelve spectral channels. The role of the individual instruments on Metop will be discussed, notably the hyperspectral sounder (IASI), the radio-occultation instrument (GRAS), the continued ozone and trace-gas observations with GOME-2 and the scatterometer observations (ASCAT) which extended the original mission to observe ocean surface winds to also include soil moisture. It is also demonstrated that Meteosat and Metop are well-suited to provide good information on volcanic ash, a threat to air traffic that emerged drastically with the recent eruption of the Eyjafjallajökull on Iceland. The role of the satellites in climate monitoring is discussed with emphasis on the Global Space-based Intercalibration System (GSICS) where IASI is considered one of the reference instruments for the intercalibration in the thermal Infrared. Finally it is argued that a coherent international planning of the future Global Space-based Observing System from the outset will be necessary in order to meet the evolving needs of the global user community. The cooperation between NOAA/NESDIS and EUMETSAT is an example of a realization of complementary planning and operations.