Initial assessment of NASA Global Hawk Unmanned Aircraft remote sensing observations

Understanding tropical cyclone (TC) upper-level warm core evolution and how it relates to storm intensity change remains a challenge in both operations and research. The height and intensity of the warm core anomaly, and how it evolves with variations in TC intensity and structure will be revisited. NASA's Global Hawk (GH) unmanned aircraft can fly to an altitude of ~18 km (~11 miles) with endurance of up to 24 hours. The observations from Global Hawk enable unique upper-level atmospheric measurements.

The NOAA Unmanned Aircraft Systems (UAS) program began conducting its Sensing Hazards with Operational Unmanned Technology (SHOUT) mission in 2015. This program utilizes the GH to investigate tropical cyclones in the North Atlantic and follows the success of the 3-year (2012-2014) NASA Hurricane and Severe Storm Sentinel (HS3) field campaign. The unmanned GH is equipped with a suite of instruments capable of collecting both TC inner-core and environmental measurements. The HS3 environmental GH was equipped with the Scanning High-resolution Interferometer Sounder (S-HIS), GPS dropwindsondes, and the NASA Cloud Physics Lidar (CPL), while the NOAA SHOUT Global Hawk payload included GPS dropwindsondes, the NASA High-Altitude Imaging Wind and Rain Airborne Profiler (HIWRAP) conically scanning Doppler radar, and the High Altitude MMIC Sounding Radiometer (HAMSR) cross-track microwave sounder.

Although GPS dropwindsondes have been actively used to collect data in both research and operational missions into TCs, less attention has been focused on utilizing remote sensing instruments that provide retrievals of atmospheric temperature and water vapor profiles. Remote sensing measurements of wind profiles from GH instruments such as HIWRAP and HIRAD can also provide additional value that can supplement tail Doppler radar (TDR) radial wind observations that are routinely collected by the NOAA P-3s and the G-IV jet. The current study will demonstrate some unique features of TCs observed by remote sensing instruments onboard the GH during the NASA HS3 and NOAA SHOUT field campaigns. To examine these GH data, NOAA's Hurricane Weather Research and Forecasting (HWRF) modeling system will be used in conjunction with NOAA/AOML/HRD's Hurricane Ensemble Data Assimilation System (HEDAS), which combines a state-of-the-art square-root ensemble Kalman filter and a storm-relative processing capability for a variety of TC observation types. An initial assessment of the impact of the GH remote sensing observations on TC analysis and prediction will be presented.