Ting-Chi Wu, Colorado State University
Assimilating Satellite Precipitation Observations in Applications to Analysis and Predictions of Tropical Cyclones using the NOAA HWRF System
CoauthorsMilija Zupanski, Lewis Grasso, Paula Brown, Christian Kummerow, and John Knaff
Abstract: With more precipitation observations available through the global satellite networks, numerical weather forecasting skills of high-impact weather events such as tropical cyclones (TC) may be improved via data assimilation. In this presentation we address the assimilation of satellite precipitation observations using NOAA hybrid variational-ensemble Gridpoint Statistical Interpolation (GSI) data assimilation system within NOAA Hurricane Weather Research and Forecast (HWRF) modeling system.
The NASA Goddard PROFiling (GPROF) algorithm, that produces hydrometeor retrievals from the Tropical Rainfall Measuring Mission (TRMM) and Global Precipitation Measurement (GPM), has been customized for hurricanes/TCs applications. To assimilate the Hurricane GPROF retrieved solid- and liquid-water contents, new observation operators are developed and implemented in GSI/HWRF system.
Single observation experiments were conducted to assimilate a single integrated solid-water content and single integrated liquid-water content observations. Results suggest that the new observation operators are capable of extending information from integrated solid- and liquid-water contents observations in a physically consistent way. Hurricane Gonzalo (2014) is selected to perform data assimilation experiments within HWRF. In general, the assimilation of Hurricane GPROF retrieved hydrometeors results in the analysis that is moister, cooler, and slightly more intense in the mid to lower hurricane core region. However, the impact of assimilating the Hurricane GPROF retrieved hydrometeors on the TC forecast is not obvious.
In addition to assimilating novel satellite-retrieved quantities in HWRF, techniques to utilizing cloudy or precipitation-affected radiances from microwave satellite instruments are also under development. Preliminary results from HWRF experiments that assimilate all-sky radiances from the Advanced Technology Microwave Sounder (ATMS) will be also presented.