Dynamic and thermodynamic mechanisms of precipitation efficiency variations in China under global warming

Study region China. Study focus This study investigates the spatiotemporal evolution of precipitation efficiency (PE) over China (1979–2022) using ERA5 reanalysis and CHM_PRE precipitation data. Combining the moisture budget and moist static energy frameworks, we quantify the thermodynamic and dynamic controls on PE variability and assess how climate warming influences moisture transport and atmospheric stability, leading to distinct regional and temporal responses. New hydrological insights for the region PE exhibits pronounced regional contrasts, with the highest values over the Tibetan Plateau and the lowest in humid southern China. Over the past four decades, PE has generally increased across China, with the strongest rise in arid regions (0.25 % yr⁻¹) and weaker trends in semi-arid (0.12 % yr⁻¹) and humid regions (0.11 % yr⁻¹). As temperature rises, the increase in precipitation lags behind the rapid growth of precipitable water, leading to a decline in monthly PE. Vertical moisture advection dominates PE variability, exerting far stronger influence than horizontal transport. Further decomposition reveals that thermodynamic moistening tends to enhance PE nationwide, whereas dynamic changes determine its regional differences. In humid regions, weakened upward motion limits PE growth; in contrast, strengthened ascent and enhanced thermodynamic effects jointly increase PE in arid and high-altitude regions. These findings clarify the physical controls of precipitation efficiency under a warming climate and provide a process-based understanding of regional hydrological responses in China.