{"177121":{"#nid":"177121","#data":{"type":"news","title":"Researchers Contribute to Instrument for Remotely Measuring Hurricane Intensity","body":[{"value":"\u003Cp\u003EA device designed by engineers at the \u003Ca href=\u0022http:\/\/www.gtri.gatech.edu\u0022\u003EGeorgia Tech Research Institute\u003C\/a\u003E (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.\u003C\/p\u003E\u003Cp\u003EKnown 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.\u003C\/p\u003E\u003Cp\u003EHIRAD 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.\u003C\/p\u003E\u003Cp\u003E\u201cImproved knowledge of the wind speed field will enable the National Hurricane Center to better characterize the storm\u2019s intensity,\u201d explained Timothy Miller, Research and Analysis Team Lead for the Earth Science Office at the NASA Marshall Space Flight Center. \u201cBetter 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.\u201d\u003C\/p\u003E\u003Cp\u003EHIRAD was flown above two hurricanes in 2010 and a Pacific frontal system in 2012. Data it gathered on wind and rain will be provided to the scientific community for use in numerical modeling, 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.\u003C\/p\u003E\u003Cp\u003E\u201cWe have verified the instrument concept in terms of sensitivity to wind speed and rain rate,\u201d Miller said. \u201cWe 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.\u201d\u003C\/p\u003E\u003Cp\u003EGTRI researchers supported development of the radiometer with design of the beam-formers, which are part of the radiometer\u2019s array antenna. The array antenna gathers microwave signals from the ocean and the GTRI-designed devices \u2013 several of which are required \u2013 form \u201cfan\u201d beams of electromagnetic energy across the ground path of the aircraft\u2019s travel. The resulting signals are then fed into sensitive receivers developed by researchers at the University of Michigan and ProSensing, Inc., a Massachusetts company.\u003C\/p\u003E\u003Cp\u003E\u201cThere are different ways to build antennas to solve this problem, but array antennas provide multi-channel capability and greater sensitivity,\u201d said Glenn Hopkins, a research engineer who headed up the GTRI design work. \u201cBecause this system is passive \u2013 it doesn\u2019t send out radiation \u2013 we need to have maximum sensitivity and a focus on minimizing noise in the system.\u201d\u003C\/p\u003E\u003Cp\u003EThe HIRAD system, also known technically as a microwave synthetic aperture radiometer, is designed to operate in the microwave spectrum, from about 4 gigahertz to 7 gigahertz. Discrete parts of that range are used to enable discrimination between ocean surface emission and that from the rain located between the instrument and the surface.\u003C\/p\u003E\u003Cp\u003E\u201cOn the aircraft, the instrument would be flying a track over the storm, with a multitude of simultaneous beams,\u201d explained Hopkins. \u201cWe would be pixelating the surface and could determine what radiation is coming from each area to generate a map of the intensity of the wind speeds as we fly over the storm.\u201d\u003C\/p\u003E\u003Cp\u003EBeyond supporting the radiometer\u2019s need for high sensitivity and low noise, the component also had to be as small and light as possible to be part of the Global Hawk payload. The GTRI design was manufactured by an outside company, and integrated directly onto the back of the instrument\u2019s antenna. The circuitry is just 20 one-thousandths of an inch thick, printed on flexible circuit materials.\u003C\/p\u003E\u003Cp\u003E\u201cThis project is an example of the kinds of work we have been doing for the Department of Defense, and we\u2019re pleased that this technology can be transitioned to assist with weather prediction and research,\u201d Hopkins said.\u003C\/p\u003E\u003Cp\u003EAs part of a small business innovation research (SBIR) project with Spectral Research, Inc., GTRI researchers also participated in an effort to increase the capability of the HIRAD array by designing a dual polarized array to replace the single polarized array that is part of the existing test system. The dual polarized array operates at the same 4 to 7 gigahertz range as the single polarized array, but provides both polarization channels in the same area.\u003C\/p\u003E\u003Cp\u003EThe dual polarized design exploited fragmented antenna technology developed at GTRI to support this broad range of frequencies.\u003C\/p\u003E\u003Cp\u003E\u201cOne key challenge in the array study was to use the same footprint as the single polarization array,\u201d said Jim Maloney, a GTRI principal research engineer. \u201cPrototype dual polarization arrays were built and measured to confirm the ability of GTRI\u2019s fragmented antenna technology to meet the bandwidth and form factor requirements.\u201d\u003C\/p\u003E\u003Cp\u003EThe Global Hawk can fly at altitudes of more than 60,000 feet, and can stay in the air for as long as 31 hours, allowing it to remain in the hurricane area as much as four times longer than piloted aircraft now used for monitoring hurricanes. It provides data that is more detailed than what satellites could provide.\u003C\/p\u003E\u003Cp\u003E\u201cA UAV is able to stay over the storm for much longer,\u201d Miller noted. \u201cCompared to a satellite, the UAV observations are of much higher spatial resolution, and depending on the satellite\u2019s orbit, generally of a much longer time period. A satellite instrument would be able to observe storms continually, over a much larger area, but would provide much coarser spatial resolution.\u201d\u003C\/p\u003E\u003Cp\u003EDevelopment of HIRAD was supported by NASA and the National Oceanic and Atmospheric Administration (NOAA). The project involved partnerships among NASA\u2019s Marshall Space Flight Center, NOAA\u2019s Unmanned Aerial Systems Program, the University of Michigan, the University of Central Florida and NOAA\u2019s Hurricane Research Division.\u003Cbr \/\u003E\u003Cbr \/\u003E\u003Cstrong\u003EResearch News\u003C\/strong\u003E\u003Cbr \/\u003E\u003Cstrong\u003EGeorgia Institute of Technology\u003C\/strong\u003E\u003Cbr \/\u003E\u003Cstrong\u003E177 North Avenue\u003C\/strong\u003E\u003Cbr \/\u003E\u003Cstrong\u003EAtlanta, Georgia\u0026nbsp; 30332-0181\u003C\/strong\u003E\u003Cbr \/\u003E\u003Cbr \/\u003E\u003Cstrong\u003EMedia Relations Contacts\u003C\/strong\u003E: John Toon (404-894-6986)(\u003Ca href=\u0022mailto:jtoon@gatech.edu\u0022\u003Ejtoon@gatech.edu\u003C\/a\u003E) or Lance Wallace (404-407-7280)(\u003Ca href=\u0022mailto:lance.wallace@gtri.gatech.edu\u0022\u003Elance.wallace@gtri.gatech.edu\u003C\/a\u003E).\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EWriter\u003C\/strong\u003E: John Toon\u003Cbr \/\u003E\u003Cbr \/\u003E\u003C\/p\u003E","summary":null,"format":"limited_html"}],"field_subtitle":"","field_summary":[{"value":"\u003Cp\u003EA 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.\u003C\/p\u003E","format":"limited_html"}],"field_summary_sentence":[{"value":"A device designed at Georgia Tech is part of the Hurricane Imaging Radiometer being tested by NASA."}],"uid":"27303","created_gmt":"2012-12-12 14:54:23","changed_gmt":"2016-10-08 03:13:22","author":"John Toon","boilerplate_text":"","field_publication":"","field_article_url":"","dateline":{"date":"2012-12-12T00:00:00-05:00","iso_date":"2012-12-12T00:00:00-05:00","tz":"America\/New_York"},"extras":[],"hg_media":{"177101":{"id":"177101","type":"image","title":"Hurricane 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