The Hurricane and Severe Storm Sentinel (HS3) Hurricane Imaging Radiometer (HIRAD) was collected by the Hurricane Imaging Radiometer (HIRAD), which was a multi-band passive microwave radiometer operating between 4-6.6 GHz. It used a novel interferometric aperture synthesis technique to produce high resolution wide swath observations without any mechanical scanning of the antenna. The instrument was designed to measure ocean surface wind speed in tropical storms and hurricanes. Developed in collaboration between scientists and engineers at National Aeronautics and Space Administration Marshall Space Flight Center (NASA MSFC), the University of Central Florida, and the University of Michigan, the instrument was first flown on a NASA high altitude aircraft in the Genesis and Rapid Intensification Processes (GRIP) Experiment in 2010 and was then flown for the Hurricane and Severe Storm Sentinel (HS3) in 2012-2014.