Hurricane wind speed and rain rate measurements using the airborne Hurricane Imaging Radiometer (HIRAD)

Microwave remote sensing of surface wind speed and rain rate in hurricanes is critical to predict their growth and movement as they develop and make landfall. The Hurricane Imaging Radiometer (HIRAD) is an experimental airborne microwave radiometer developed by NASA Marshall Space Flight Center (MSFC) to provide ocean surface wind speed and rain rate measurements in hurricanes. It is intended to expand the current NOAA and US Air Force hurricane surveillance capability, particularly by extending the operational Stepped Frequency Microwave Radiometer (SFMR) measurement to a large swath. HIRAD also has potential for space applications. This paper will describe the HIRAD instrument and its flight history, to date, and present wind speed and rain rate retrievals from observed brightness temperatures (Tb's) in a flight over Hurricane Earl in 2010 as part of NASA's GRIP mission. A comparison between HIRAD and SFMR retrievals will be shown.