OSSE Evaluation of Global Hawk Dropsonde Sampling Strategies in a Tropical Cyclone

The Global Hawk uncrewed aircraft system (UAS) has the unique capability of sampling tropical cyclones (TCs) from a high altitude for a length of time that exceeds the capabilities of existing crewed reconnaissance aircraft. In addition to a variety of remote sensing instruments, the Global Hawk’s research payload includes up to ~90 dropsondes. Christophersen et al. (2017) has shown in case studies from Edouard (2014) that vortex-scale assimilation of Global Hawk dropsonde observations in the inner core of the storm tends to have a positive impact on the intensity forecast, while observations further from the center tend to have more of an impact on the track forecast.

This study will further investigate how Global Hawk dropsonde data targeting the inner core vs. the near environment of a TC impacts the vortex-scale analysis and forecast in an observing system simulation experiment (OSSE). Observations are simulated from the Nolan et al. (2013) hurricane nature run and assimilated into NOAA's HWRF model using NOAA/AOML/HRD’s Hurricane Ensemble Data Assimilation System (HEDAS). Results will be shown for multiple cases as the simulated storm intensifies from tropical storm to major hurricane, along with discussion of possible implications for future flight planning.