he Impact of Assimilating Cygnss Ocean Surface Winds on Numerical Simulations of Tropical Cyclones and Tropical Convection

The NASA Cyclone Global Navigation Satellite System (CYGNSS) was launched in December 2016, providing an unprecedented opportunity to obtain ocean surface wind speeds (OSWS), including wind estimates over the hurricane inner-core region. This study first demonstrates the influence of assimilating CYGNSS observations of OSWS on numerical simulations of hurricanes in recent hurricane seasons (e.g., these in 2017 and 2018) over the Atlantic basin and mesoscale tropical convective systems over the Maritime Continent region. The NCEP Grid-point Statistical Interpolation (GSI)-based hybrid ensemble-variational data assimilation system is used. A research version of the NCEP operational Hurricane Weather Research and Forecasting (WRF) model and a mesoscale community Weather Research and Forecasting (WRF) model are employed to study the hurricane and mesoscale convective system (MCS) cases, respectively.

Early results found that the assimilation of CYGNSS data results in improved track, intensity, and structure forecasts for hurricane cases, especially for the weak phase of a hurricane, implying potential benefits of using such data for future research and operational applications. Further studies evaluated and compared the impacts of assimilation of CYGNSS data from the different versions and various retrieved data sources on numerical forecasts of hurricanes.

Recent work emphasizes examining impacts of CYGNSS OSWS on numerical simulations of mesoscale convection systems over the maritime continent (MC) region during the international Years of the Maritime Continent (YMC) campaign. The influence of CYGNSS data on numerical simulations of the diurnal cycles of precipitation and their interaction with MJO over the MC region is evaluated.

Detailed results, progress, and development will be presented at the conference.