ABSTRACT The Lower Reaches of the Yangtze River Basin (LYRB) are highly vulnerable to summer extreme precipitation (EP). Understanding the long‐term intensification of such events has become a critical issue with both scientific and societal relevance. Although EP events can be categorised as either associated with atmospheric rivers (ARs) or not, the specific characteristics of AR‐associated EP (AR&EP) remain inadequately understood. By integrating gauge observations, Lagrangian modelling and moisture uptake diagnostics, this study investigates the drivers behind the intensification of high‐impact AR&EP events from the perspective of upstream evaporative moisture sources. Results show a significant intensification of AR&EP from 1991 to 2022. This trend is decoupled from changes in AR characteristics but aligns strongly with a concurrent increase in regional moisture uptake. Although remote oceans remain the ultimate moisture source for the LYRB, terrestrial regions contribute 94% of the total increase in moisture supply, far exceeding the oceanic contribution of 6%. Thus, the widespread increase in evaporative moisture uptake, rather than changes in AR dynamics, serves as the primary driver of the intensifying AR&EP events. These results highlight the crucial role of regional land–atmosphere interactions and are essential for predicting future hydrological risks and managing water resources under a changing climate in the LYRB.
Liu et al. (Thu,) studied this question.