The Changing Morphology of Global Precipitation Systems during the Last Two Decades

Abstract The morphology of global precipitation systems can enhance our comprehension of precipitation patterns and the underlying physical processes. However, several unresolved issues remain in the existing studies of precipitation system morphology. This study employs Integrated Multi-satellitE Retrievals for Global Precipitation Measurement (GPM) (IMERG)-derived precipitation system dataset to investigate the climatological and changing characteristics of global precipitation system morphology from 2001 to 2022. The results show that precipitation systems with larger scales tend to be more flattened in morphology, while no clear differences in morphological characteristics are observed across systems with different intensities. In terms of geographic distributions, a notable land–sea contrast is observed, with land systems more circular than those over oceans. Due to the impact of the Coriolis force, the orientation distribution of precipitation systems shows obvious hemispherical contrast. Precipitation systems over tropical regions are more regular in shape and more likely to be organized convective systems. During the period of 2001–22, there is a significant trend of global precipitation systems becoming more flattened and are more likely to manifest as organized convective systems. Our results also indicate that the precipitation system morphology is under combined influence of subtropical highs, lateral stretching influences of wind, and the organizing effects of moisture transport and convergence. Moreover, the increasing flattening of precipitation systems could be attributed to enhanced atmospheric stability which constrains vertical expansion and increased moisture availability which favors wider horizontal extension. This study could provide new insights into precipitation changes under global warming. Significance Statement Precipitation systems exhibit distinct morphological characteristics due to varying formation mechanisms. The morphology of global precipitation systems can enhance our existing understanding of the response of precipitation to global warming, which is primarily based on time series analysis using observations collected from weather stations that are sparsely distributed. By using the latest merged satellite precipitation dataset, this study systematically explores the changing morphology of global precipitation systems. The results indicate a significant trend toward more flattened precipitation systems, which could be vital indicators of the broader impacts of global warming on atmospheric processes. Future research could be conducted regarding the specific regional effects of these morphological changes, which will be crucial for improving weather forecasting and climate adaptation strategies.