北半球50 hPa位势高度距平场的EOF分析及其与对流层的比较

本文以EOF方法为基础对北半球50 hPa高度月平均距平场进行了分析，指出北半球50 hPa场存在着几种定常的环流型，且它的距平场的EOF展开精度具有相当好的稳定性。另外，北半球50 hPa高度月平均距平场高、中纬之间存在着远远超过α=0.001信度检验的“跷跷板”式振荡。功率谱分析发现，北半球50 hPa环流场有着显著的准2—3年及准4个月振荡周期，赤道平流层QBO现象在高度场上也有清楚的反映。通过与对流层的EOF分析比较得到，500 hPa与50 hPa第一、第二特征向量场有相似的空间分布，但对于EOF展开无论是从拟合精度的稳定性还是收敛性看，平流层都远远优于对流层。

The EOF Analysis of 50 hPa Potential Height Anomaly Field in the Northern Hemisphere and Its Comparison with the Tropospheric Field

In this paper, we analysed the 50 hPa potential height anomaly field in the Northern Hemisphere using the EOF method. It is indicated that (1) there are several stationary circulation patterns in 50 hPa field of the Northern Hemisphere, and the stable fitting precision of EOF, (2) there is a obvious “see-saw” phenomenon between high latitude and middle latitude in the 50 hPa potential height anomaly field of the Northern Hemisphere, (3) the quasi-biennial to quasi-triennial oscillation and quasi-four month oscillation of 50 hPa circulation field in the Northern Hemisphere exist obviously, and the QBO phenomenon of equatorial stratosphere is also verified, and (4) as compared between the 500 hPa and 50 hPa field, the first and second characteristic vectors of potential height anomaly field have the similar spatial distribution, but EOF expansion in the stratosphere whether the stability of fitting precision or the convergence is better than that in troposphere.