Impact of CYGNSS Data on Tropical Cyclone Analyses and Forecasts in a Regional OSSE Framework

The Cyclone Global Navigation Satellite System, or CYGNSS, is a planned constellation of micro-satellites that utilizes existing GPS satellites to retrieve surface wind speed near the satellites' ground tracks. 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 winds under all precipitation conditions, and over a large range of wind speeds.

Using output from a high-resolution tropical cyclone nature run as truth, synthetic CYGNSS wind speed data have been created. The tropical cyclone nature run spans 13 days and is nested within the European Center for Medium-range Weather Forecasting's (ECMWF) joint Observing System Simulation Experiment (OSSE) global nature run. In addition, the Variational Analysis Method (VAM) is utilized to supplement the wind speed data with wind direction. Using a regional OSSE system, the impact of synthetic CYGNSS surface wind data on Gridpoint Statistical Interpolation (GSI) analyses, Ensemble Kalman Filter (EnKF) analyses, and Hurricane Weather Research and Forecast (HWRF) system forecasts will be evaluated.