Four former researchers from the UMass Electrical and Computer Engineering (ECE) Department recently received a special Group Achievement Award from the National Aeronautics and Space Administration (NASA) “for engineering team excellence and dedication to developing the advanced weather radar HIWRAP.” HIWRAP stands for High-altitude Imaging Wind and Rain Airborne Profiler. ECE Professor Emeritus Dan Schaubert, his former doctoral student Justin Creticos (now at MITRE), Lihua Li (former Ph.D. student of Robert McIntosh now at NASA), and former research faculty member Jim Carswell were all on the HIWRAP Radar Team of 18 scientists. The HIWRAP system was developed for use on NASA’s Global Hawk drone aircraft, used during hurricane season to gain many scientific insights into tropical storms.
As Professor Schaubert, who is a Fellow of the Institute of Electrical and Electronics Engineers, said about his ECE colleagues on the NASA team, “Justin Creticos did his Ph.D. thesis on the design, development, fabrication, and testing of the antenna system for the HIWRAP radar. The radar was designed by Remote Sensing Solutions, specifically by Jim Carswell, former research faculty in MIRSL [Microwave Remote Sensing Laboratory]. Lihua Li oversaw system design and integration flights on the Global Hawk.”
NASA describes HIWRAP as “a dual-frequency (Ka- and Ku-band), dual-beam (30° and 40° incidence angles), conical scan, solid-state transmitter-based Doppler radar system. HIWRAP utilizes solid state transmitters along with a novel pulse compression scheme. This results in a system that is considerably more compact in size, requires less power, and ultimately costs significantly less than typical radars currently in use for clouds and precipitation observation. HIWRAP is able to image the winds through volume backscattering from clouds and precipitation, enabling it to measure the tropospheric winds above heavy rain at high levels. It was designed for operation on the high-altitude (20 km) Global Hawk UAV.”
In 2007 NASA acquired a pair of pre-production Global Hawks and entered a partnership with Northrop Grumman to modify, operate, and maintain the airplanes as scientific and research platforms and began using them to study hurricanes in 2010.
An article written earlier this summer on the Science Codex website noted that HIWRAP and the Global Hawk were being prepared for heavy use during the 2013 Atlantic hurricane season. “Most aircraft carrying Doppler radar look like they've grown a tail, developed a dorsal fin, or sprouted a giant pancake on their backs,” the article explained. “But when the unmanned Global Hawk carries a radar system this summer, its cargo will be hard to see. The autonomous and compact High-altitude Imaging Wind and Rain Profiler, or HIWRAP, a dual-frequency conical-scanning Doppler radar, will hang under the aircraft's belly as it flies above hurricanes to measure wind and rain and to test a new method for retrieving wind data.”
As the article noted, HIWRAP is one of the instruments that flew in this summer's mission to explore Atlantic Ocean hurricanes. NASA's Hurricane and Severe Storm Sentinel, or HS3, airborne mission investigated tropical cyclones using a number of instruments and two Global Hawks. The HS3 mission operated between Aug. 20 and Sept. 23.
"Radar is an important remote sensor for atmospheric research," said Li. "Radar signals penetrate clouds and precipitation, allowing scientists to detect information on raindrops or ice particles."
That information, he said, is one piece of the puzzle toward improving scientists' understanding of weather events.
Among other flights, the HIWRAP radar was used in an unmanned Global Hawk aircraft flying over Hurricane Leslie in the Atlantic Ocean on September 7, 2012, before landing at NASA’s Wallops Island Test Facility in Virginia. The mission targeted the processes that underlie hurricane formation and intensity change. The aircraft helped scientists decipher the relative roles of the large-scale environment and internal storm processes that shape these systems.
HIWRAP measured cloud structure and winds, providing a three-dimensional view of these conditions, and was used in conjunction with several other sophisticated sensing instruments as part of the Global Hawk’s payload to sample the environment around hurricanes. (September 2013)