2011年11月大气环流和天气分析

2011年11月大气环流主要特征是：北半球极涡呈单极性分布,主体位于北极圈内,强度和常年同期接近。中高纬呈4波型,其中欧洲大槽强度较常年偏强,位置偏东;东亚大槽强度偏弱,且位置偏东,这不利于引导冷空气影响我国,月内我国出现了5次主要的冷空气过程,11月全国平均气温为3.9℃,比常年同期（2.1℃）偏高1.8℃。南支槽位于100°E附近,强度接近常年,副高的位置偏西,有利西南暖湿空气向我国的输送。11月,我国出现6次主要的降水过程,全国平均降水量为28.3mm,较常年同期（18.0 mm）偏多57.3%,为近20年来的最大值。北方大部地区降水较常年偏多,其中西北地区东部、内蒙古南部、华北西部、江南东南部和华南中东部较常年同期偏多2倍以上。

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 four-wave pattern in middle-high 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 warm-moist 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,central-eastern of South China is over three times more than the same period of normal vears.