Anticipated Benefits of Gulfstream-550 Tail Doppler Radar Measurements on Tropical Cyclone Prediction

Tail Doppler radar (TDR) observations account for the majority of data collected using reconnaissance aircraft within the tropical cyclone (TC) and nearby environments. Typically assimilated into numerical models as radial velocity measurements, the TDR captures a three-dimensional representation of the wind field within range of its host NOAA hurricane hunter aircraft. TDR data often provide the only means of thoroughly characterizing a storm’s current state including its position, intensity, and structural features. While TDR has proven beneficial on NOAA’s WP-3D aircraft, NOAA’s Gulfstream-IV (G-IV) TDR only recently began collecting substantial amounts of data due to changes in operational flight planning.

In anticipation of the TDR’s installation on NOAA’s next generation Gulstream-550, data impact experiments were conducted to suggest advantages to hosting a TDR on this high-altitude platform. Hurricane Florence reconnaissance provided the best TDR coverage using NOAA’s current high-altitude aircraft and the only suitable set of missions for such a study. For more robust results, additional experiments were performed using a subset of P-3 TDR observations as a proxy for G-IV TDR coverage. Proxy experiments include TDR data collected in high-impact tropical cyclones such as 2017 hurricanes Irma and Maria. This presentation focuses on the benefits of assimilating these observations into NOAA’s operational Hurricane Weather Research and Forecasting (HWRF) Model, especially in the prediction of metrics that represent hazards associated with landfalling TCs. In addition to verifying track and intensity, this study features a structure-based verification using wind field extent and precipitation characteristics. Potential improvements to the TDR assimilation process are also discussed.