Warming of Tibetan Plateau and continual winter-spring drought in Southwest China in the background of global warming

Abstract

In the context of global warming, the Tibetan Plateau, as the “third pole”, is still unclear about the impact of climate warming on the climate anomalies in the surrounding areas. Using mathematical statistics and climate diagnosis, we compared the anomalies of thermal and dynamic field caused by plateau warming during winter-spring with the continuous drought events in Southwest China from 1991 to 2020. Here we show that, there is a three-year lagged correlation between the plateau climate warming and southwest China precipitation. The correlation coefficient between sensible heat and drought degree exceeds -0.498 and confidence level is greater than the 95%. The warming of the Tibetan Plateau leads to the positive vorticity change around the plateau, which strengthens the westerly circulation of the southern branch, weakens the westerly (cold) wind of the northern branch. Thus, the Southwest China is controlled by a single dry and warm air mass,  and eventually leads to continual winter-spring drought events. When the plateau warming is accompanied by the La Niña event, the drought will last longer and be stronger. The results are of  reference value for the prediction of extreme climate under the action of special terrain, and have certain significance for local disaster prevention.