2006年北半球大气环流及对中国气候异常的影响

2006年，赤道中东太平洋经历了一次从La Nina状态到El-Nino事件的过程。500hPa高度场上，欧亚中高纬度地区前冬为经向型环流，后冬亚洲地区盛行纬向环流；夏、秋季，亚洲高纬度地区为经向型环流而中纬度为纬向环流，这种环流形势不利于冷空气南下，导致我国2006年的夏、秋季变得异常暖。2006年西太平洋副热带高压面积偏大、强度偏强且西伸脊点异常偏西。夏季没有出现持续性的较强的阻塞形势，从而使长江中下游地区降水较常年同期偏少，梅雨较弱。东亚夏季风异常偏强。2005／2006年冬季，青藏高原温度异常偏高，各季的高度场也较常年同期偏高，这有利于副高的加强西伸，而7-8月、10月太平洋暖池区对流活动强盛，为热带气旋的生成发展提供了有利的动力条件，并在副高的引导下多为西行路径。

General Circulation in the North Hemisphere in 2006 and Its Impact on Climate Change in China

In 2006,sea surface temperature(SST)in Central-East Pacific of equator was undergoing from cold phase(La-Nina condition)to warm(El-Nino).At 500hPa geopotential height,it prevail meridional circulation in the mid-high latitude over Euro-Asian area in early winter,but zonal circulation was mainly exhibited over Asian area in late.In summer and autumn,the circulation appeared meridional in the high latitude and zonal in the middle latitude over Asian continent,to result in the most warming in summer and autumn in China.In summer 2006,subtropical high was stronger,and the position was northward and westward than normal.Asian summer monsoon was stronger than normal.There was no obvious and persist blocking in the northeast Asia.The Meiyu in the mid-lower Yangtze River was weaker.Heating resource over Qinghai-Xizang Plateau was higher from winter to autumn.Convective activity in warm pool of west equator Pacific is stronger in July,August and October.