Analysis of the July 2020 Atmospheric Circulation and Weather
The main characteristics of the general atmospheric circulation in July 2020 are shown as follows. The polar vortex splits into multiple centers distributed around the polar which were stronger than normal in the Northern Hemisphere. Compared to the normal, the western Pacific subtropical high was stronger and the position of which was further west and south. The western Pacific subtropical high was located in the middle and lower reaches of the Yangtze River and south of the Yangtze River during the first and middle dekads, and obviously extended westward and northward shifting between north and south during the last dekad of this month. The monthly mean precipitation of China in July was 125.7 mm, more than the normal by 4.2%. The positive anomaly of precipitation was significantly more than 1 to 2 times in northern part of Jiangnan, Jianghuai, Jianghan, Huanghuai, and the Southwest China. However, the negative anomaly of rainfall was 50% in the Northeast China and the South China. There were seven regional torrential rain processes in this month, seen mainly in the middle and lower reaches of the Yangtze River, Huanghuai and Southwest China. The daily precipitation of 103 stations reached or exceeded the extreme values of the same period. Severe flood disaster occurred in the middle and lower reaches of the Yangtze River and the Huaihe River Basin. The monthly mean temperature of China was 22.1℃, slightly higher than the usual. The mean maximum temperature in southern Fujian, Guangdong, and eastern Hainan was 2-4℃ higher than normal. During middle and last dekads, largescale persistent high temperature weather occurred in Jiangnan and South China, where 81 stations located in the coasts of Fujian and Guangdong, southern Hunan, and central and eastern Sichuan experienced extreme high temperatures. In terms of typhoon, it was the first time that there was no typhoon event in July 2020, which is the first time since 1949, so it is called “typhoon absence”.