2020-9-30 0:0:0
Hurricane 3-D Wind Structure Analysis Using Stepped-Frequency Microwave Radiometer Surface Wind Measurements
The Stepped-Frequency Microwave Radiometer (SFMR) is the primary tool used for collecting aircraft-based estimates of the surface wind speed in tropical cyclones (TCs), which are used as input to numerical models and by National Hurricane Center TC forecasts that are critical to protect life and property. While the SFMR has proven to be reliable over the past 15 years, areas for further improvement to the accuracy of the observations have been identified, some of which this project addressed. Completed were the development of new guidance for the SFMR on the impacts of aircraft angle with respect to the surface; identification of rain-related aspects that were being attributed to wind speed, which were previously unknown; and comparisons of SFMR data to surface wind speed measurements from other instruments (dropsondes and aircraft-based radar systems), which revealed much larger variability in techniques than had been previously understood. The radars also depicted several features in the TCs that may explain discrepancies between the SFMR and wind speed data collected at the height of the aircraft. These findings provided forecasters at the National Hurricane Center with additional guidance for interpreting the SFMR surface wind speed and will be incorporated into an upcoming update to the SFMR observation processing to further increase the accuracy of the observations.