Enhanced moisture uptake and recycling contributing to increased summer precipitation over the monsoon region of China

Abstract Moisture transport is a key driver of mass and energy transfer in the climate system, and its role is increasingly amplified under global warming as enhanced atmospheric moisture alters source–sink dynamics. Yet, the mechanisms by which the atmospheric hydrological cycle controls summer precipitation in the densely populated and disaster-prone monsoon region of China (MRC) remain poorly understood. Here, we apply the Lagrangian model FLEXPART to quantify changes in the atmospheric water cycle associated with MRC summer precipitation from 1979 to 2020. Evaporation from MRC contributes ∼35% of summer rainfall on average due to dense air parcel convergence, strong uptake, and relatively low transport loss. Long-term trends indicate a strengthening of the summer water cycle, with total precipitation increasing at a rate of 2.5% per decade, and the moisture originating from MRC accounting for ∼71% of this increase. This intensification is closely caused by increased atmospheric moisture uptake of air parcels during transport, which is associated with both higher air parcel density and intensified surface evaporation. The higher parcel density over the northern MRC and Northeast Asia is tied to an anomalous anticyclonic circulation over Northeast Asia that favors southward transport, partially compensating for the weakened oceanic moisture influx from the South. Intensified surface evaporation over the MRC is linked to vegetation-controlled evapotranspiration. These findings highlight the importance of integrating moisture transport dynamics and land–surface interactions to understand regional hydrological variability under a warming climate.