Climatological Characteristics of Evolution of East Asian Winter Monsoon

Characteristics of evolution of East Asia winter monsoon and cold surge were discussed and compared with those in South Asia. It is found that there exist an abrupt change of meridional circulation in East Asia during middle October, which represents the onset of East Asia winter monsoon circulation. Three abrupt changes of temperature occur in lower troposphere in the early September, middle November and late January. However, the change of the circulation in South Asia is not as strong as in East Asia. The change of meridional wind in upper troposphere is earlier than that in lower troposphere. There exist two abrupt changes of the temperature in lower troposphere, which are weaker than in East Asia longitudinally. Furthermore, in East Asia, the frequency of cold surges has its maximum in South China Sea in December, but in west Pacific in January. On the other hand, in South Asia, the cold surges occur most frequently still in December, but much less than in East Asia, and they decrease quickly with time. Another different aspect is that the clod surge frequencies decrease upward in East Asia, but increase in South Asia