The Cyclogenesis and Typhoon Predictions with the GNSS RO Data Assimilation over the Northwestern Pacific Ocean

The Cyclogenesis and Typhoon Predictions with the GNSS RO Data Assimilation over the Northwestern Pacific Ocean

Shu-Ya Chen^1,2, Quan Pham Xuan^1,2, Hsiu-Wen Li¹, and Ching-Yuang Huang^1,2

¹ GPS Science and Application Research Center, National Central University, Taiwan

² Department of Atmospheric Sciences, National Central University, Taiwan

It has been confirmed that the intensity of hurricanes/typhoons has increased in recent decades. Such intense, severe weather events with strong wind speeds and heavy rainfall could result in a hazard. Early prediction of cyclogenesis would gain more time for disaster prevention. Since cyclogenesis and development of a tropical cyclone mainly occur over the ocean, where sparse observations are available, Global Navigation Satellite System (GNSS) radio occultation (RO) data, especially the FORMOSAT-7/COSMIC-2 data, cover the tropical region and have better penetration depth close to the surface, could be much more helpful.

In this study, we utilize hybrid data assimilation systems and conduct experiments with and without GNSS RO data, including conventional observations, to detect the impact of the RO data on cyclogenesis and typhoon prediction over the northwestern Pacific. For cyclogenesis simulations, ten cases in 2020-2022 are picked up. Assimilations with RO data show higher predictability on the prediction of tropical cyclone formations and have smaller location errors. The positive influence of GNSS RO data can be found in the simulations from the regional Weather Research and Forecasting (WRF) model and the global Model for Prediction Across Scales (MPAS). Assimilations with an appropriate observational error show further improvements in the track prediction.