WSR-88D Radar Data Assimilation at NCEP

The radar radial winds and reflectivity from WSR-88D network are assimilated within the operational NDAS (North American Model Data Assimilation System) and North American Mesoscale Rapid Refresh system (NAMRR). The radial winds are directly analyzed by NCEP's grid-point statistic interpolation (GSI) analysis system, while a cloud analysis package, developed by the NOAA Earth System Research Laboratory's Global Systems Division, is modified and used to analyze reflectivity. Surface observations, satellite products and radar reflectivity are used to update hydrometeors and derive a temperature tendency in GSI. The hydrometeors and temperature tendency are used during the forward integration of the Digital Filter Initialization (DFI) step to establish convective storms in the model. The impact of radar data assimilation on the forecast and challenges encountered during implementation will be presented.