NASA is preparing to deploy a pair of unmanned aircraft above stormy skies to help forecasters improve their understanding of hurricane formation and intensity changes.
Dubbed "severe storm sentinels," the unmanned Global Hawk aircraft will fly missions along the Atlantic Ocean basin. The Hawk is particularly well-suited for monitoring hurricanes, as it is capable of over-flying hurricanes at altitudes greater than 60,000 feet with flight durations of up to 28 hours - something piloted aircraft would find nearly impossible to do.
"Hurricane intensity can be very hard to predict because of an insufficient understanding of how clouds and wind patterns within a storm interact with the storm’s environment," explained Scott Braun, HS3 mission principal investigator and research meteorologist at NASA's Goddard Space Flight Center in Greenbelt, Md.
"[This mission] seeks to improve our understanding of these processes by taking advantage of the surveillance capabilities of the Global Hawk along with measurements from a suite of advanced instruments."
According to Braun, one aircraft will sample the environment of storms while the other measures eyewall and rainband winds and precipitation. Both aircraft are expected to help scientists further their understanding of the large-scale environment that tropical storms form in and move through, as well as how environment affects the inner workings of the storms.
For example, the study will address the controversial role of the hot, dry, and dusty Saharan Air Layer in tropical storm formation and intensification, as it may both favor and suppress intensification. Researchers are also slated to examine the extent to which deep convection in the inner-core region of storms is a key driver of intensity change or just a response to storms finding favorable sources of energy.
As noted above, NASA is planning to deploy a range of advanced instruments on the Hawk aircraft, such as the scanning High-resolution Interferometer Sounder (S-HIS), the Advanced Vertical Atmospheric Profiling System (AVAPS) also known as dropsondes, and the Cloud Physics Lidar (CPL). The Tropospheric Wind Lidar Technology Experiment (TWiLiTE) Doppler wind lidar will likely fly in 2013.
Other instruments include the High-Altitude Imaging Wind and Rain Airborne Profiler (HIWRAP) conically scanning Doppler radar, the Hurricane Imaging Radiometer (HIRAD) multi-frequency interferometric radiometer and the High-Altitude Monolithic Microwave Integrated Circuit Sounding Radiometer (HAMSR) microwave sounder.