The Weather and Its Circulation in Summer of 2005
2005年夏季的主要天气及其环流分析

The main weather processes and the related circulations are discussed.The total precipitation amount over most of China is almost equal to or more than climatologic one.The flooding occurred over Xinjiang Autonomous region and South China,but typical Meiyu over the Yangtze River valley did not occurred.The severe heavy rainfall over South China was caused by the shear line at lower troposphere and stationary front at surface,which was associated with the convergence of cold air from northwestern and northeastern China and warm-wet air from South China Sea.The comparison of summer monsoon circulation between 2005,1994 and 1998 shows that the summer monsoon in 1994 and 2005 was stronger than that in 1998.In the Meiyu season of 2005,the blocking high located to the east of Lake Baikal,small trough in westerlies was relatively active in middle latitude area.Comparing with the circulation in 1998,the westerly jet at upper troposphere and southwesterly jet at lower troposphere moved north farther about 10 latitudes.The landing tropical cyclones with high intensity were more than the normal and resulted in serious disasters.The heavy rainfall in North China was related to the activities of tropical cyclones over mainland or western Pacific Ocean.The vortices were very active over northeast China in the summer of 2005.The hot weather days over southern China and North China in the summer of 2005 are relatively more than that in the summer of 2004,and swelter weather also occurred over North China.In addition,hot weather days did not happen over northeast China.The hot wave occurred in southern and North China,which was associated with subtropical high of West Pacific and continental high,respectively.