NASA to field UAVs to monitor hurricanes

NASA Global Hawk 871

The National Aeronautics and Space Administration (NASA) will field two unmanned aircraft capable of high altitude, long duration observation, to fly over hurricanes during the peak of hurricane season in September.

The two surplus Northrop Grumman Global Hawks, said NASA on Aug. 15 in a post on its Website, are part of the agency’s Hurricane Severe Storm Sentinel Mission, or HS3.

Both Global Hawks will be flying out of NASA's Wallops Flight Facility in Virginia in September, too late for Hurricane Isaac, which is currently lashing the Gulf Coast, but in time to monitor the peak of the hurricane season in the Atlantic Ocean.  The hurricane season lasts from June 1st to November 30^th, with the most active period usually falling in September, when wind shear that can tear storms apart is low and ocean temperatures are at their warmest.

The unmanned Global Hawks, which NASA calls "severe storm sentinels," are operated by pilots located in ground control stations at the agency’s Wallops Flight Facility in Wallops Island, VA, and NASA's Dryden Flight Center on Edwards Air Base, CA. The NASA Global Hawk, said the agency, is well-suited for hurricane investigations because it can over-fly hurricanes at more than 60,000 feet and can stay aloft up to 28 hours at a time.

NASA said the unmanned aircraft can also take the severe beating that hurricanes can mete out and cover thousands of square miles of territory in high winds and heavy rain. The can also penetrate storm turbulence and debris to see down into a storm to monitor ground conditions.

"Several NASA centers are joining federal and university partners in the Hurricane and Severe Storm Sentinel (HS3) airborne mission targeted to investigate the processes that underlie hurricane formation and intensity change in the Atlantic Ocean basin," said Scott Braun, principal investigator for the HS3 Mission and research meteorologist at NASA's Goddard Space Flight Center in Greenbelt, MD.

The two NASA Global Hawks that will be flying during the HS3 mission have different payloads to measure winds, temperature, humidity (water), precipitation, and aerosol (particle) profiles from the surface to the lower stratosphere, said the agency.

The payload installed on NASA’s Global Hawk No. 872, will consist of three instruments that sample embedded conditions in a storm. According to the agency, the aircraft will carry a laser system called Cloud Physics Lidar (CPL) developed at NASA Goddard in its nose. CPL measures cloud structure and aerosols such as dust, sea salt particles, smoke particles by bouncing laser light off of those particles and clouds. Located in the aircraft’s belly will be an infrared instrument called the Scanning High-resolution Interferometer Sounder or S-HIS from the University of Wisconsin in Madison. The system can be used to remotely measure or remotely sense the temperature and water vapor vertical profile along with the sea surface temperature and some cloud properties. A dropsonde system from the National Center for Atmospheric Research and National Oceanic and Atmospheric Administration will be located in the tail of the aircraft. The dropsonde system ejects small sensors tied to parachutes that drift down through the storm measuring winds, temperature and humidity.

The second aircraft, Global Hawk No. 871, will also carry a trio of instruments, said the agency. Global Hawk 871’s prime responsibility will be to sample the cores of hurricanes. According to NASA, a microwave system called the High-Altitude MMIC Sounding Radiometer or HAMSR, created by NASA's Jet Propulsion Laboratory in Pasadena, CA, will be located in the aircraft's nose. HAMSR measures temperature, water vapor, and vertical precipitation profiles.

A High-altitude Imaging Wind & Rain Airborne Profiler or HIWRAP radar system from NASA Goddard will be located in 871’s belly, it said. The system is similar to a ground radar system but pointed downward. HIWRAP measures cloud structure and winds. The Hurricane Imaging Radiometer (HIRAD) from NASA's Marshall Space Flight Center in Huntsville, AL, will be located in the aircraft's tail section. HIRAD measures microwave radiation emitted from the surface and atmosphere. The HIRAD observations yield surface wind speeds and rain rates.