A Tropical Cyclone Warm-Core Retrieval Algorithm for the Microwave Temperature Sounder of FY-3E

Microwave observations have become the primary means of acquiring internal information on typhoons because microwave radiation can penetrate clouds and precipitation. By exploiting the strong relationship between the observed microwave brightness and atmospheric temperature, it is possible to derive a 3-D temperature structure within typhoons. However, these retrievals are limited by the consistent overestimation of warm cores and excessive intensity of cold centers at lower levels. Through the optimization of clear-sky and cloudy data classification and the incorporation of a latitude zone regression algorithm, this study successfully established an improved algorithm for the retrieval of typhoon inner atmospheric temperature using Microwave Temperature Sounder-III (MWTS-III) on China’s FY-3E, the first civil dawn-dusk polar orbit satellite. The analysis of the actual retrieved results for typhoons Bolaven and Doksuri at different stages demonstrates that the new algorithm effectively reduces errors in the low cold center and provides a more reasonable position for the warm core. Further analysis indicated that the accurate separation of quasi-clear-sky and cloud data is crucial for adjusting the warm-core position and mitigating errors in the low-layer temperature bias. In addition, fitting within latitudinal bands helps minimize the overall warm-core bias resulting from latitudinal temperature gradients, allowing for better characterization of real-time changes in typhoon intensity through temperature retrieval. The optimized 3-D air temperature retrieval product for typhoon regions holds great promise for advancing research on typhoon mechanisms and forecasting.