Analysis of a Large-Scale Heavy Precipitation Weather Process in Northern China from September 17 to 20, 2021

摘要

In the autumn of 2021, China’s precipitation appears the distribution characteristics of “more in the South and less in the north”. Compared with the same period in history, the precipitation is more. The analysis is based on a large-scale heavy precipitation weather process in the middle and late September. The atmospheric circulation situation and weather situation of this precipitation process are mainly discussed. The results show that the low-pressure trough between the Balkesh Lake and Baikal Lake area made the cold air move eastward, and the warm and humid air flow extending westward was conducive to the enhancement of precipitation. The anticyclone circulation in the Sea of Japan transported the cold and humid air to the northeast of China. The southeast air flow around the subtropical high in the Western Pacific, the southwest air flow in the bay of the Bengal Bay and the South China Sea met in the southwest to produce precipitation and continued to move northward. They merged with the cold and humid air flow in the Northeast in the north of the Yangtze River, resulting in large-scale precipitation in northern China.