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The assimilation of Cross‐track Infrared Sounder radiances at ECMWF
Author(s) -
Eresmaa Reima,
LetertreDanczak Julie,
Lupu Cristina,
Bormann Niels,
McNally Anthony P.
Publication year - 2017
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1002/qj.3171
Subject(s) - radiance , remote sensing , environmental science , data assimilation , meteorology , atmospheric infrared sounder , satellite , numerical weather prediction , water vapor , physics , geology , astronomy
The operational assimilation of theCross‐track Infrared Sounder (CrIS) radiances in a fourdimensional variational framework at the European Centre for Medium‐range Weather Forecasts (ECMWF) is presented. Currently onboard the Suomi National Polar‐orbiting Partnership (S‐NPP) satellite, CrIS provides radiance data on 1305 channels in three spectral bands. Based on the experience of radiance assimilation using earlier infrared sounders, the use of CrIS radiances relies strongly on CO 2 ‐sensitive channels in the 15 μm absorption band. The overwhelming majority of data is assimilated assuming no significant contamination from cloud or aerosol, and use of data over land is limited to channels with primary sensitivity in the stratosphere. Observation‐error covariance specification is based on diagnostic methods and inter‐channel error correlations are explicitly accounted for. The use of CrIS radiances is demonstrated to have a consistent beneficial impact on shortand medium‐range forecasts, especially in the Extratropics.