Height assignment of atmospheric motion vectors with Meteosat 8

摘要

Atmospheric Motion Vectors (AMVs) are one of the most important products generally derived from all geostationary satellites, and especially from Meteosat at EUMETSAT, because they constitute a very important part of the observation data fed to Numerical Weather Prediction. The resolution of the current operational products is 160 km at the sub-satellite point. The height assignment is currently the most challenging task in the AMV extraction scheme. The main approach used for Meteosat was the so-called 'WV-IRW intercept method' for semi-transparent cases. Opaque cloud heights are calculated from the representative Equivalent Black Body Temperatures derived from the AMV target area. The advent of Meteosat 8 provides many new opportunities for improve height assignment of AMVs. Existence of a CO2 absorption channel at 13.4 μm on SEVIRI instrument enables to use simultaneously the IR/CO2 ratioing methodology in addition to the semi-transparency technique. Due to the existence of several Water Vapour and Infrared channels on SEVIRI, each method can be implemented in slightly different configuration, and finally, there are 15 cloud top pressure schemes implemented in the MSG-MPEF. This paper presents a comparison of some of these methods using Meteosat 8 data.