The Influence of Precipitation Phase Changes on the Recharge Process of Terrestrial Water Storage in the Cold Season Over the Tibetan Plateau

Abstract

AbstractClimate warming has affected the land surface and atmospheric temperature over the Tibetan Plateau (TP), resulting in a series of hydrological changes, such as atmospheric wetting and decreasing terrestrial water storage (TWS). According to Gravity Recovery and Climate Experiment data, TWS higher than 2,500 m over the TP significantly decreased during the 1979–2019 period, with a more enhanced trend in the cold season. Previous studies have mainly focused on the influence of global warming on the discharge process in the warm season, such as glacier melting, increasing runoff and decreasing snow cover. The changes in atmospheric moisture recharge in the cold season and its contribution to decreasing TWS remain unclear. Based on the time scale, the hydrological process can be divided into slow (snowfall and evaporation) and fast (rainfall and runoff) processes. Our results suggest that the TWS changes in the cold season are dominated by slow processes. Cold‐season warming over the TP can increase the atmospheric melting level height (MLH), leading to a transition from snowfall to rainfall. Consequently, the decreasing snowfall and increasing evaporation induced by warming result in a net decrease in atmospheric recharge to the TWS. A quantified contribution of the fast and slow processes to the TWS changes in the cold season indicates that the slow processes play a dominant role over most of the TP, except for the Hexi, Inner, Qaidam, Yangtze, and Yellow Basins. Decreasing atmospheric recharge could accelerate the decrease in TWS, which motivates further investigation to better predict the hydrological response.