2000年北半球平流层、对流层质量交换的季节变化

Diagnosed Seasonal Variation of Stratosphere-Troposphere Exchange in the Northern Hemisphere by 2000 Data

用 2 0 0 0年NCEP资料 ,P坐标下Wei公式诊断北半球平流层、对流层交换的季节变化。主要结论 :( 1 )热带西太平洋是物质由对流层向平流层输送的主要通道 ,并有明显的季节性东西移动。由于 2 0 0 0年赤道辐合带偏弱 ,因此秋季通量最大。 ( 2 )中高纬度地区同时存在向上、向下的通量 ,大尺度槽区伴随着平流层向下的输送。一年中冬春季向下的输送强 ,夏秋季较弱 ,其季节变化与大尺度环流的季节性变化一致。 ( 3)东亚地区存在很强的平流层向下输送 ,且中心位置移动不大。只占北半球 5 6%面积的东亚其年净交换量竟占北半球的 2 9% ,这说明东亚地区的平流层与对流层之间的质量交换对北半球平流层。

The seasonal variation of stratosphere-troposphere mass exchange in 2000 year is diagnosed by Wei formula in pressure coordinate. The main results are as follows: (1) The west Pacific in the tropic is the main channel of the upward transport from the troposphere to the stratosphere with the obviously seasonal shift. The largest net flux from the troposphere to the stratosphere appears in autumn due to the weak of equator convergence belt in 2000. (2) The upward and downward transport of mass in the middle and high latitude accompany with each other. Downward transport from the stratosphere to the troposphere mainly appears near the large-scale trough. The stronger transport into troposphere appears in winter and spring, the weaker in summer and autumn. The seasonal variation of upward transport is consistent with the variation of the large scale circumfluent. (3) Strong downward fluxes of air mass from the stratosphere appear in eastern Asia. Although its area accounts 5.6% of the Northern Hemisphere (NH), the net exchange value reaches 29% of the total mass exchange in NH. This means the STE in the eastern Asia is important for the Northern Hemisphere.