Performance evaluation of IMERG precipitation products during typhoon Lekima (2019)

It is of great significance to evaluate satellite precipitation products performance for short-duration heavy precipitation in typhoon events. In this study, the performance of GPM (Global Precipitation Measurement) IMERG (Integrated Multi-satellitE Retrievals for GPM) with different run products (early run (IMERG-ER), late run (IMERG-LR), and final run (IMERG-FR)) were evaluated when typhoon Lekima landed in the eastern coastal area of China in 2019. Taking the rain gauge data as the reference, we carried out the study by comparing precipitation characteristics, verifying evaluation indices, and analyzing the heavy precipitation process. The differences between IMERG products in different stages and affected areas of the typhoon Lekima were compared. On the whole, the correlation coefficient (CC) of IMERG products was 0.51-0.56, and the IMERG-FR had the best probability of detection (POD, 0.88), followed by IMERG-LR (POD, 0.84) and IMERG-ER (POD, 0.81). With an increase in release latency, the precipitation retrieved by IMERG products increased and gradually approached the rain gauge observations. The evaluation indices result showed that IMERG products tend to underestimate precipitation and failed to show good performance for high-intensity precipitation. The error was positively related to the precipitation intensity. The performance of IMERG-LR was very close to that of IMERG-FR during the typhoon short-duration heavy precipitation, although IMERG-FR had higher latency and more processing.