Evaluation of the GPM-IMERG V06 Final Run products for monthly/annual precipitation under the complex climatic and topographic conditions of China

The new-generation multi-satellite precipitation algorithm, namely, Integrated Multi-satellitE Retrievals for Global Precipitation Measurement (GPM-IMERG) version 6, provides a high resolution and large spatial extent and can be used to offset the lack of surface observations. This study aimed to evaluate the precipitation detection capability of GPM-IMERG V06 Final Run products (GPM-IMERG) in different climatic and topographical regions of China for the 2014-2020 period. This study showed that (1) GPM-IMERG could capture the spatial and temporal precipitation distributions in China. At the annual scale, GPM-IMERG performed well, with a correlation coefficient (R) >0.95 and a relative bias ratio (RBias) between 15.38% and 23.46%. At the seasonal scale, GPM-IMERG performed best in summer. At the monthly scale, GPM-IMERG performed better during the wet season (April-September) (RBias=7.41%) than during the dry season (RBias=13.65%). (2) GPM-IMERG performed well in terms of precipitation estimation in Southwest China, Central China, East China and South China, followed by Northeast China and North China, but it performed poorly in Northwest China and Tibet. (3) The climate zone, followed by elevation, played a leading role in the GPM-IMERG accuracy in China, and the main sources of GPM-IMERG deviation in arid and semiarid regions were missed precipitation and false precipitation. However, the influences of missed precipitation and false precipitation gradually increased with increasing elevation. Despite the obvious differences between the GPM-IMERG and surface precipitation estimates, the study results highlight the potential of GPM-IMERG as a valuable resource for monitoring high-resolution precipitation information that is lacking in many parts of the world.