Impact of NASA Global Hawk Unmanned Aircraft Observations on Tropical Cyclone Track, Intensity and Structure: A Perspective from the NOAA SHOUT Program

The NOAA Sensing Hazards with Operational Unmanned Technology (SHOUT) program aims to demonstrate and test prototype Unmanned Aircraft Systems (UAS) concept of operations that could be used to mitigate the risk of diminished high impact weather forecasts and warnings in the case of observing gaps in conventional data. As part of the SHOUT program, NOAA and NASA are collaborating to deploy NASA's Global Hawk unmanned aircraft to investigate how to maximize the impact of UAS observations for the analysis and prediction of tropical and extratropical weather systems in global and regional numerical models. The current study focuses on tropical cyclones and utilizes NOAA's Hurricane Ensemble Data Assimilation System (HEDAS) and Hurricane Weather Research and Forecasting (HWRF) modeling system.

HEDAS was developed as a research tool to assimilate high-resolution observations in tropical cyclones. It combines a state-of-the-art square-root ensemble Kalman filter, NOAA's HWRF modeling system, and a storm-relative processing capability for a variety of observation types. In 2013 and 2014, HEDAS was run in near real time on the NOAA Hurricane Forecast Improvement Project's Jet supercomputer to assimilate observations from NOAA and Air Force Reserve research and reconnaissance flights (dropwindsonde, flight level, Stepped-Frequency Microwave Radiometer, and Doppler radar data), satellite Atmospheric Motion Vectors, retrieved thermodynamic profiles from the Atmospheric InfraRed Sounder (AIRS) and Global Positioning System Radio Occultation (GPSRO), nearby rawindsondes, and Aircraft Communications Addressing and Reporting System (ACARS) on commercial aircraft.

In addition to the standard observation platforms assimilated in HEDAS mentioned above, the impact of three sounding platforms on the Global Hawk aircraft is investigated here for their impact. These platforms of interest are GPS dropwindsondes, retrieved thermodynamic profiles from the High Altitude Monolithic Microwave integrated Circuit (MMIC) Sounding Radiometer (HMSR), and retrieved thermodynamic profiles from the Scanning-High Resolution Interferometer Sounder (S-HIS). Results from data denial experiments from cases in 2013 and 2014 will be presented to illustrate the potential impact of these Global Hawk sounding platforms along with some preliminary ideas as to how to optimize their assimilation for tropical cyclones.