What caused the drought in China in 2009?

Ma Zhenfeng said that the current climate warming is the background, and under this premise, extreme weather and climate events are more likely to occur. Sichuan, however, is located at the intersection of East Asian monsoon, South Asian monsoon, plateau monsoon and other monsoon circulation, and is affected by various monsoons, so its climate is complex.

Why did Sichuan do this this year? Ma Zhenfeng put forward three important reasons. First, the influence of plateau thermal factors on the Qinghai-Tibet Plateau. Our province and other provinces in southwest China are greatly influenced by the "roof of the world". Last winter, there was little snowfall on the Qinghai-Tibet Plateau, and the thermal conditions on the plateau were good, which led to weak troughs in India and Myanmar, weak monsoon in South Asia, and insufficient transportation of water vapor to southwest China. In addition, the cold air from the north to the south moved eastward and northward, which led to drought in our province and southwest China. The second is the influence of El Nino phenomenon. Under this influence, the SST in the equatorial Middle East Pacific is warmer, the subtropical high is stronger as a whole, and the water vapor carried by the East Asian monsoon meets the cold air from north to south, resulting in more precipitation in the east of China and frequent snowfall in the north. On the contrary, the southwest of China is dominated by downward flow, which is often sunny and rainy. Third, the timing of cold air is not well grasped. Although the cold air has affected our country many times this winter, most of the cold air began to move eastward in the north and "slipped" directly from the edge of our province. Coupled with the Qinling Mountains, if the cold air is not "strong" enough to cross the mountains, it will still not affect the basin. Even if sometimes cold air enters the basin, it forms the first condition of rainfall with warm air: convective weather. However, if the second condition "water vapor" that forms rainfall is not rich, it still cannot form good precipitation. "This is a process that requires cooperation."