Improving very-short-term storm predictions by assimilating radar and satellite data into a mesoscale NWP model

A high-resolution data assimilation system is under development at the Naval Research Laboratory for mesoscale NWP models. The objective of this development is to assimilate high-resolution data, especially those from Doppler radars and satellites, into the Navy's Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPS" ) to improve the model's capability and accuracy in very-short-term prediction of severe weather events. A variational approach is used to retrieve three-dimensional wind fields from radar observations of radial velocity from multiple radars in a limited area and the thermodynamic perturbations associated with the retrieved winds. In parallel, techniques are also developed to combine satellite, radar reflectivity, and surface observations to update the model 3D cloud forecasts. The retrieved wind and thermodynamical fields are then assimilated into the model together with the cloud information. The system has been tested with severe storm cases. Studies have been conducted to investigate the impacts of the assimilated data on model forecasts with the help from a verification system specially designed for radar data assimilation. The results show some notable improvements in storm location and strength predictions during the first few hours after the data assimilation.