Analysis of the November 2011 Atmospheric Circulation and Weather
The following are the main characteristics of the general circulation of atmosphere in November 2011: there is one polar vortex center in the Northern Hemisphere with the same strength as normal years. The circulation presents a fourwave pattern in middlehigh latitudes. The European trough is stronger and further east than the same period of normal years. The East Asian major trough is weaker and further east than the same period. This kind of circulation is not favorable for the outbreak of cold air southward. There are five cold surge processes affecting China, and the monthly mean temperature is 3.9℃，which is 1.8℃ higher than the same period of normal years. In this month, the southern branch trough is strong and the subtropical high is to west, which is favorable for transportation of the southwest warmmoist air to China. There are 6 main precipitation processes, and the mean precipitation (28.3 mm) is 57.3% above normal, which is the most in the past 20 years. The precipitation over most parts of the northern China is more than the same period of normal years, among them the precipitation over east of Northwest China, south of Inner Mongolia, west of North China, southeast of the Jiangnan region, centraleastern of South China is over three times more than the same period of normal years.