All-sky assimilation of SSMI/S humidity sounding channels over land: second year report

TitleAll-sky assimilation of SSMI/S humidity sounding channels over land: second year report
Publication TypeReport
Date Published09/2013
Series/CollectionEUMETSAT/ECMWF Fellowship Programme Research Reports
Document Number30
AuthorsBaordo, F, Geer, AJ, English, SJ
Event Series/CollectionEUMETSAT/ECMWF Fellowship Programme
Place of publicationShinfield Park, Reading

The all-sky assimilation of SSMI/S humidity sounding channels over ocean has been recently introduced within the ECMWF operational system, benefiting winds and humidity analysis and forecasts. The upgrade over ocean was based on better scattering radiative transfer calculations which, using discrete dipole simulations to represent optical properties of snow hydrometeors, improve the simulated microwave radiances. Taking advantage of such improvements, the all-sky package over ocean has been extended in order to have an equivalent framework to also assimilate SSMI/S humidity sounding channels over land. This paper not only describes the necessary technical changes to develop the over land framework, but also scientifically evaluates, through different assimilation experiments, the impact on analysis and forecast. The findings of this investigation show that the all-sky assimilation over land is reliable and it brings positive improvements into the system which can be seen in term of both forecast scores and fits to conventional and other satellite observations. These results encourage additional investigations to widen the application of the all-sky approach over land to other microwave humidity sounding sensors such as MHS.

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