|Title||SSMI/S radiances over land in the all-sky framework: one year report|
|Series/Collection||EUMETSAT/ECMWF Fellowship Programme Research Reports|
|Authors||Baordo, F, Geer, AJ, English, SJ|
|Event Series/Collection||EUMETSAT/ECMWF Fellowship Programme|
|Place of publication||Shinfield Park, Reading|
This report summarises a feasibility study investigating the possibility to assimilate SSMI/S humidity sounding observations over land in the all-sky framework within the ECMWF system. The use of these channels might bring additional information to that already available by the assimilation of other microwave sounders radiances and helps to enhance and constrain the humidity analysis. The findings show that first guess departures of SSMI/S and MHS humidity sounding channels not only have very similar distribution in shape and intensity, but the standard deviations computed over the whole sample are also comparable. This result is very important as a Gaussian and unbiased distribution of first guess departure is the necessary 4D-Var assumption that must be satisfied before any sample of observations can be considered for an assimilation experiment.