Impact of GPS Radio Occultation Data on the Prediction of Tropical Cyclogenesis

Tropical cyclones are one of the most devastating severe weather systems that are responsible for huge loss of lives and properties every year. Accurate prediction of tropical cyclogenesis by numerical models has been a significant challenge, largely because of the lack of observations over the tropical oceans. The GPS radio occultation (RO) technique can provide valuable water vapor and temperature observations for the analysis and prediction of tropical cyclogenesis. In this paper, we examine the impact of GPS RO data on the prediction of ten tropical cyclones over the Western Pacific from 2008 to 2010. Using the WRF modeling and data assimilation system, we show that the assimilation of GPS RO data can increase the probability of detection from 30% to 70%. To gain insight on the impact of GPS RO data assimilation, we perform a detailed analysis of the formation process of Typhoon Nuri (2008), and examine how the assimilation of the GPS RO data enables the model to capture the cyclogenesis. We perform additional experiments to study the impact of observation operator (i.e., local versus nonlocal operators) and RO data distribution on the prediction of genesis. The Taiwan-U.S. COSMIC-II mission launched in June 2019 will provide 5,000 GPS RO data per day over the tropics and offer a great opportunity to study tropical cyclogenesis. We will also present preliminary results based on COSMIC-II data.