Assimilating GPM/GMI and TRMM/TMI Microwave Radiance Data With GEOS-5

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Wednesday, 7 January 2015
Jianjun Jin, NASA/GSFC, Greenbelt, MD; and M. J. Kim, W. McCarty, S. Akella, and W. Gu

The Global Precipitation Mission (GPM) Core Observatory satellite was launched on February 27, 2014. Observations from its two instruments, the GPM Microwave Imager (GMI) and the dual-frequency radar, aim to advance scientific understandings of Earth's water and energy cycle. GMI conically scans 13 channels between 10 183 GHz between 65 S 65 N latitude. This instrument is in many ways a successor to the Tropical Rainfall Measurement Mission (TRMM) Microwave Imager (TMI). The TMI has been observing 9 channels at frequencies ranging 10 85 GHz between 40 S 40 N latitude since 1997. Information about clouds, rain, snow, and sea surface temperature can be extracted by assimilating GMI and TMI level 1 brightness temperatures. The Global Modeling and Assimilation Office (GMAO) has developed procedures to incorporate these radiance data into its Goddard Earth Observation System model, version 5 (GEOS-5) atmospheric analysis via an all-sky radiance data assimilation methodology. Initial experiments have shown that clear-sky GMI and TMI data assimilation lessens the model's precipitation, moving it towards retrieved rainfall products. The GEOS-5 atmospheric data assimilation algorithm now has the capability to assimilate near-real-time GMI radiance observations and is under testing. The procedures of assimilating these observations and the impact of these data on GEOS-5 atmospheric analysis will be presented in this talk.