Data assimilation of IASI radiances over land
Vincensini, Anaïs ; Fourrié, Nadia ; Rabier, Florence ; Guidard, Vincent
Observations from satellite infrared measurements have large atmospheric and surface information contents and are known to improve Numerical Weather Prediction. However, the use of these observations is still not optimal over land because of uncertainties about land emissivity and skin temperature. Currently, radiances are assimilated only when they are not affected by the surface. Previous studies on microwave and infrared observations have shown that the use of land emissivity climatologies together with land surface temperature retrievals improves the assimilation system. As a first step toward the assimilation of Infrared Atmospheric Sounding Interferometer (IASI) data over land, the aim of this study is the improvement of the simulation of the IASI data over land in the ARPEGE model of Météo-France. The provision of spatial and temporal variations in emissivity is studied. The impacts on simulation of a constant emissivity, emissivity climatologies from the IASI Level-2 products from EUMETSAT and atlases computed from MODIS (Moderate Resolution Imaging Spectroradiometer) emissivity products are compared.
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