An Evaluation of the Use of Satellite-Derived Winds in NAVGEM

FSOI (Forecast Sensitivity Observation Impact) for satellite-derived winds in the U.S. Navy’s global numerical weather prediction system NAVGEM (Navy Global Environmental Model) indicates a greater benefit for these winds than is typically seen in other NWP systems.  The processing of satellite winds in NAVGEM differs from that at other centers primarily in two ways—the use of superobs instead of thinning, and the use of two datasets for each geostationary satellite, one from CIMSS (University of Wisconsin) and one from the operational provider (NESIDS, EUMETSAT, or JMA).  This paper will present results from a series of experiments using NAVGEM to investigate the degree to which superobbing and the use of two datasets contributes to the increased FSOI.  The experiments include: 1) control—operational configuration; 2) thinning rather than superobbing; and 3) one dataset for geostationary winds rather than two.  The results will be presented in terms of FSOI as well as analysis increments and analysis differences.