Evaluation of the Impact of CYGNSS Wind Speed Data on Tropical Cyclone Structure Analyses and Forecasts in a Regional OSSE

The Cyclone Global Navigation Satellite System, or CYGNSS, is a constellation of micro-satellites planned for launch in October 2016. It utilizes reflected signals from existing GPS satellites to retrieve surface wind speed near the satellites' ground tracks over the ocean, and the orbits are designed such that there is excellent coverage of the tropics and subtropics, resulting in better sampling intervals over tropical cyclones than is possible with current scatterometers. Furthermore, CYGNSS will be able to retrieve data under a wide range of precipitating conditions and wind speeds.

Realistic CYGNSS wind speed data have been simulated from a high-resolution tropical cyclone "nature run". A regional Observing System Simulation Experiment (OSSE) comprised of the Gridpoint Statistical Interpolation (GSI) for data assimilation and the Hurricane Weather Research and Forecast (HWRF) system for forecasts is used to evaluate the potential impact of CYGNSS surface wind speed data on analyses and forecasts of tropical cyclone structure and critical wind radii.

Previous work by the authors demonstrated that CYGNSS observations can have a positive impact on tropical cyclone intensity and track analyses and short-term forecasts provided the spatial coverage of the data is fairly symmetric about the storm center.