The Impact of Assimilating Aircraft Observations in the Tropical Cyclone Core with HEDAS, the HWRF Ensemble Data Assimilation System

The HWRF (Hurricane Weather Research and Forecast) Ensemble Data Assimilation System has been developed to address the tropical cyclone vortex initialization problem for regional models using high-resolution aircraft data transmitted in real time by the National Oceanic and Atmospheric Administration and Air Force Hurricane Hunters. The system has been run on more than 80 cases from 2008 to 2011 when aircraft data are available. Two sets of data assimilation and forecasts have been run, one using all the aircraft data available and the other using all the data except the airborne Doppler radial wind data. A control set of model forecasts using the standard model vortex initialization was also performed. Assessments of the impact of the standard aircraft (dropwindsonde, flight-level and stepped-frequency microwave radiometer) data over the standard vortex initialization, and the further impact of the Doppler radial wind data will be presented.