Researchers contribute to instrument for remotely measuring hurricane intensity

A device designed by engineers at the Georgia Tech Research Institute (GTRI) is part of the Hurricane Imaging Radiometer (HIRAD), an experimental airborne system developed by the Earth Science Office at the NASA Marshall Space Flight Center in Alabama.

Known as an analog beam-former, the GTRI device is part of the radiometer, which is being tested by NASA on a Global Hawk unmanned aerial vehicle. The radiometer measures microwave radiation emitted by the sea foam that is produced when high winds blow across ocean waves. By measuring the electromagnetic radiation, scientists can remotely assess surface wind speeds at multiple locations within the hurricanes.

HIRAD could provide detailed information about the wind speeds and rain intensity inside hurricanes without the need to fly manned aircraft through the storms. In addition to the beam-former design, GTRI researchers also provided assistance to NASA with improvements aimed at a potential future, more advanced version of the radiometer.

''Improved knowledge of the wind speed field will enable the National Hurricane Center to better characterise the storm's intensity,'' explained Timothy Miller, research and analysis team lead for the Earth Science Office at the NASA Marshall Space Flight Center. ''Better forecasts of storm intensity and structure will enable better warnings of such important factors as wind strength and storm surge. That would allow businesses and residents to prepare with more confidence in their knowledge of what is coming.''

HIRAD was flown above two hurricanes in 2010 and a Pacific frontal system in 2012. The data it gathered on wind and rain will be provided to the scientific community for use in numerical modelling, and could also guide development of a next-generation system that would provide information on wind direction in addition to measuring wind speed and rain intensity.

''We have verified the instrument concept in terms of sensitivity to wind speed and rain rate,'' Miller said. ''We have also learned a lot about the factors that need to be considered in developing calibrated images from the flight data. That work is still ongoing.''