Change in the relationship between daily mean precipitation and temperature over the East Asia summer monsoon region

The relationship between daily mean precipitation and surface air temperature (mean P-T) over the East Asia summer monsoon land region for 1979–2022 and its decadal change are investigated using binned scaling analysis and the Clausius–Clapeyron equation. Mean P-T scaling analysis produces a peak-shaped scaling curve that roughly follows the Clausius–Clapeyron constraint below a threshold temperature at which precipitation reaches its peak and shows negative scaling due to a saturation deficit above the threshold temperature. This feature is similar to the scaling behavior for extreme P-T relationships observed in many previous studies for mid-latitudes, execpt for a different magnitude of precipitation and the C-C scaling rate. It is found that there is distinct regime shift of mean P-T relationship before and after 2000, which is clearly seen in all the parameters such as the threshold temperature, mean precipitation, and scaling rate. The threshold temperature has increased after 2000, indicating that the hydrological response to warming can be explained by C-C scaling prediction at further high temperature. However, the precipitation peak has decreased after 2000, which contradicts well-established increasing and linked tendencies for temperature and precipitation in a warmer world. We therefore conclude that the dependency of daily mean precipitation on daily mean surface temperature may be influenced by hydrological changes in the East Asian monsoon in summer. This poses a concern for the spatio-temporal variability of regional monsoon systems and suggests that localized responses to global warming need to be considered to understand the mean P-T relationship over the East Asia summer monsoon region.