Impact of Radio Occultation Data on Tropical Cyclone Intensity Forecasts at Different Development Stages over the Western North Pacific

This study explores the impact of radio occultation (RO) data on tropical cyclone (TC) intensity forecasts at different TC development stages over the western North Pacific using a regional model. This study also assesses the relative importance of RO data for the improvement of TC intensity forecasts under different moisture environments. Preliminary results show that the assimilation of RO data increases the mid- and low-level moisture and low-level vorticity around the TCs compared to no assimilation of RO data. It reduces the underestimation of TC intensity forecasts by 15 kt during TC intensification and by 5 kt for TC maximum intensity. The intensity improvement is more significant for TCs developing in drier environments than those in moister environments. Moreover, the improvement of TC intensity forecasts is more sensitive to RO data at the initial TC stage, while less sensitive at the matured TC stage. In summary, the assimilation of RO data highly improves the intensity forecasts of TCs in drier environments at the initial formation stage. The impact of vortex dynamic processes may be more crucial for TC intensity forecasts at the maximum intensity stage compared to the impact of environmental improvement by RO data.