Recent MODIS data assimilation experiments in the NCEP GFS

Through collaboration with NCEP personnel, as well as substantial NOAA hardware support, the JCSDA has obtained the capability to run impact studies of all data types used in the Global Data Assimilation system (GDAS). Such studies have allowed a better understanding of how to utilize current and future in-situ and remotely sensed data types in NCEP's present-day 3-DVAR data assimilation systems.

These global GDAS studies have identified results of interest about existing data types. They also have the ability to provide impact studies of new data types coming on-line before they are merged into the operational data stream. Finally, perhaps the greatest advantage of these global studies is that they are undertaken at the operational resolution of the model (which until very recently was T254L64 to 84 hours, T170L42 to 180 hours and T128L28 to 384 hours).

Results will be shown which demonstrate positive impact from high-latitude MODIS winds in both the extratropics and hurricane track forecasts. These results use a newly derived assimilation quality control procedure for MODIS polar winds during both the northern hemisphere winter and summer of 2004. These previously tested MODIS polar wind techniques have now entered final testing at NCEP and are planned for acceptance into operations in late 2005.