全球对流层顶气压场的季节变化特征分析

Analysis on seasonal variation of global tropopause pressure

利用经验正交函数分解（EOF）方法对1948--2004年全球对流层顶月平均气压场进行分析，讨论57a来气压场的空间载荷向量场及其对应的标准化时间系数的演变，并且利用小波分析方法分析各个季节对流层顶气压周期变化特征．结果表明：春季和夏季整个时段内全球大部分地区对流层顶气压降低趋势比秋冬季明显，对应对流层顶高度有升高趋势，特别是东亚及北美等地在春季具有对流层顶气压升高的显著趋势，对应对流层顶高度可能降低；对流层顶气压场各个季节的标准化时间系数变化具有多时间尺度特征，在各个季节都有明显的3～5a的周期振荡，春季还具有明显的准2a周期特征．

The monthly average global tropopause pressure data in recent 57 a （from 1948 to 2004） is analyzed with EOF （empirical orthogonal function） method to discuss the spatial loading vector field and corresponding temporal variation. Then, the periods of tropopause pressure in every season are investigated by using wavelet analysis method. The results show that the decreasing trend of tropopause pressure in spring and summer is more distinct than that in autumn and winter in the most regions, and the corresponding tropopause height shows an increasing trend in spring and summer. It is distinct that the tropopause height might descend relative to the increase of tropopause pressure in East Asia and North America. The temporal variation of tropopause pressure in every season shows the muhi-timescale feature. There is the significant period of 3 -5 a in every season＇s tropopause pressure, also a quasi-biennial oscillation in spring.