Ground validation of GPM IMERG rainfall products over the Capital Circle in Northeast China on rainstorm monitoring

Obtaining accurate satellite precipitation data is crucial for monitoring flood and flood disasters and analysing climate change. As a new generation of satellite precipitation product, global rainfall observation program GPM is integrated with advanced microwave detection technology and data correction algorithm, providing more choices for studying precipitation in global regions. The main purpose of this paper is to evaluate the adaptability of GPM three-stage precipitation product IMERG (Final Run mode) at different temporal resolutions in the Beijing-Tianjin-Hebei region. After screening, the precipitation data of 107 national meteorological stations in the Beijing-Tianjin-Hebei region was used as the verification data, and the detection capability of GPM satellite precipitation data in different time scales of day, month and season as well as extreme precipitation events was analysed. The following conclusions were obtained: (1) Compared with the IMERG products with half -hourly and daily temporal resolution, the IMERG satellite precipitation data with 1month temporal resolution has a strong correlation, reaching 0.90. It can reflect the precipitation event accurately in the Beijing-Tianjin-Hebei region. The poor performance of IMERG satellite is concentrated in the north-western and south-eastern edges of the Beijing-Tianjin-Hebei region.(2) The performance of IMERG precipitation data in the humid season on the monthly scale is better than that in the dry season, and GPM satellite precipitation data are generally overestimated.(3) In the process of extreme precipitation event detection using 0.5h temporal resolution data, the tendency of IMERG satellite precipitation data to accumulate precipitation is roughly consistent with that of the station, but the phenomenon of overestimation still exists, especially in places with large precipitation, overestimation is more obvious. In view of this precipitation event, satellite precipitation data covers almost the entire precipitation process, and some values are still high. Although the data has good detection capability for extreme precipitation events, the monitoring of precipitation peak is not accurate enough. According to the comprehensive analysis, its Final GPM product has a strong ability to detect rainfall events, which can provide data support for the long time series analysis in the Beijing-Tianjin-Hebei region.