1994年北半球环流特征及其影响

General Circulation over the Northern Hemisphere in 1994 and Its Impact

１９９４年北半球主要环流特征表现为：５００ｈＰａ副高明显偏强西伸，盛夏位置异常偏北；欧亚地区盛行纬向环流，北半球极涡向极地收缩，强度偏弱；盛夏东亚中纬地区维持稳定的高压脊，西风带锋区位置偏北；夏季１００ｈＰａ南亚高压强度偏强、位置偏北、东伸明显；热带海洋出现明显异常，一次新的厄尔尼诺事件形成。北半球大气环流和热带海洋的异常对我国天气气候产生了明显影响。

General circulation features over the Northern Hemisphere in 1994 are analysed. It is shown that the subtropical high over the west Pacific is stronger than normal and extends to the west,in mid-summer it moves northward abnormally. Zonal circtilation is dominant in Eurasian 9 and Polar vortex in the Northern Hemisphere is smaller in area and weaker in strength than normal. In midlatitude of the East Asia,high pressure systems keep stable in summer,and frontal zone in westerly moves northward. At 100hpa, the South Asia high is stronger in strength, further to the north and eastward than normal. A new El Nino event is forming over the tropical Pacific. The anormaly of both the atomspheric circulation and the tropical ocean exerts a significant impact on the weather and climate in China.