Improved microwave remote sensing of hurricane wind speed and rain rates using the Hurricane Imaging Radiometer (HIRAD)

The Hurricane Imaging Radiometer (HIRAD) is a new imaging technology microwave remote sensor for hurricane observations that is currently under development by NASA Marshall Space Flight Center in partnership with the NOAA Hurricane Research Division, the University of Central Florida and the University of Michigan.

HIRAD is designed using passive microwave Synthetic Thinned Array Radiometry (STAR) technology to provide wide-swath images of ocean surface winds and rain rates in hurricanes. HIRAD is a next generation instrument that is derived from the operational airborne Stepped Frequency Microwave Radiometer (SFMR) that measures wind speed and rain rate along the ground track directly beneath the aircraft. This paper presents an overview of this sensor and compares its measurement capabilities with SFMR. The presentation includes an instrument description, discussion of the hurricane retrieval algorithms and examples of hurricane measurement capabilities from high-flying aircraft and low-earth-orbit satellites.

Details will be presented for two candidate airborne platforms, operating at 11 km and 20 km altitudes and a satellite HIRAD operating from a low inclination 450 km orbit. Simulated measurement scenarios will be presented for these aircraft and satellite, which illustrate wind speed and rain rate measurement dynamic range and accuracies, spatial resolutions and swath coverage.