The Hurricane Imaging Radiometer (HIRAD) is an innovative technology development designed to provide the operational and research communities with hurricane intensity information that cannot be observed by other sensors. HIRAD will produce imagery of ocean surface wind speed and rain rate during strong wind and heavy rain hurricane conditions that hamper the observational capabilities of existing instruments. HIRAD ocean surface wind observations will significantly contribute to the low altitude wind information needed for the NOAA observational requirement for three-dimensional tropical cyclone wind profiles, identified by the NOAA Hurricane Forecast Improvement Project as a high priority need.
HIRAD is a passive microwave remote sensor which incorporates the observing frequency range of the NOAA Stepped Frequency Microwave Radiometer (which is the only active or passive remote sensing technique that has successfully measured surface wind speeds and rain rates in tropical cyclones) and a unique, technologically advanced array antenna and other technologies successfully demonstrated by the NASA Instrument Incubator Program. HIRAD will be a compact, lightweight, low-power instrument with no moving parts that will produce wide-swath imagery from aircraft or spacecraft platforms.
The HIRAD development team includes scientific and engineering personnel from the NASA Marshall Space Flight Center (MSFC), NOAA’s Atlantic Oceanographic and Meteorological Laboratory (AOML) Hurricane Research Division (HRD), the University of Alabama in Huntsville, the University of Central Florida, and the University of Michigan. The Von Braun Center for Science & Innovation collaboration will capitalize on an initial NASA MSFC technology investment to finish the development of two critical subsystems and to test-fly the integrated aircraft instrument in partnership with NASA MSFC. This partnership will expedite the overall development of the HIRAD ocean wind sensor as a prototype for a NOAA Unmanned Aerial Systems (UAS) component of the Global Earth Observing Systems of Systems (GOESS) for research and operational tropical cyclone applications.
After multiple flights over two named Atlantic storms, Earl and Kyle, the single polarized sensor instrument Hurricane Imaging Radiometer (HIRAD) was successful in measuring meteorological parameters that will aid in the understanding and prediction of tropical storms. Chamber tests and science test flights on NASA aircraft were first successfully completed and HIRAD flew aboard the WB-57 during NASA Genesis and Rapid Intensification Processes (GRIP) missions in August and September 2010.
HIRAD is a compact and light weight passive microwave synthetic thinned aperture radiometer which operates on multiple frequencies (4, 5, 6 and 6.6 GHz) at the C-band. It was able to successfully produce imagery of ocean surface wind parameters and rain rate during a high wind and heavy rain conditions associated with a hurricane. Other higher frequency passive microwave radiometers are unable to do this due to scattering and absorption of the microwave energy and the imagery of ocean surface wind parameters produced by HIRAD is a necessary component for the NOAA three-dimensional tropical cyclone wind profiles. With HIRAD’s ability to accurately measure sea surface temperatures during overcast and light rain events, there is also no longer a need for thermal infrared imagers. By incorporating the observing frequencies of the NOAA Stepped Frequency Microwave Radiometer (SFMR), advanced array antenna and other NASA Instrument Incubator Program technologies, the HIRAD instrument produces wide-swath imagery from aircraft with a potential for spacecraft.
The Von Braun Center for Science & Innovation collaboration capitalized on the initial NASA MSFC technology investment and finished the integration of the full aircraft prototype of the HIRAD sensor, provided testing of the system in a test chamber and also participated in the conduct of engineering and science test flights on NASA aircraft. The HIRAD team includes scientific and engineering personnel representing the NASA MSFC, NOAA Atlantic Oceanographic and Meteorological Laboratory (AOML) Hurricane Research Division (HRD), University of Alabama Huntsville, University of Central Florida, University of Michigan, Georgia Technology Research Institute, and the Universities Space Research Association (USRA). This partnership expedited the overall development of the HIRAD ocean wind sensor as a prototype for a NOAA Unmanned Aerial Systems (UAS) component of GEOSS for research and operational tropical cyclone applications. The potential future of HIRAD (HIRAD II)could include an addition of polarmetric capability which would allow the sensor to measure wind direction and wind speed.