北半球冬季环流的特征纬向波数及其时空演变

Characteristic Zonal Wavenumber of Winter Circulation in Northern Hemisphere and Its Temporal and Spatial Evolutions

应用三维数据的纬向空间小波变换方法,分析了北半球冬季环流的特征纬向波数及其与特征纬向波数相对应的北半球冬季环流的时空演变特征和规律。结果表明,北半球冬季环流的特征纬向波数分别是3,2和1。北半球冬季环流的3波活动主要在中纬度,2波活动主要在高纬度,1波活动则主要在低纬度。中纬度3波环流的槽脊线走向是东北-西南向,高纬度2波环流的槽脊线走向是西北—东南向,低纬度1波环流的槽脊线走向则又是东北—西南向。对应于各特征纬向波数,北半球的冬季环流从1949—1999年均表现出一种显著的系统东移特征,初步估计,北半球的冬季环流在过去50年中已大约向东移动了近5个经距。

Using the zonal spatial wavelet transform method for three-dimensional data, the characteristic zonal wavenumber of winter circulation in Northern Hemisphere and its temporal and spatial evolutions corresponding to the characteristic zonal wavenumber are investigated. The results show that there are three characteristic zonal wavenumbers of 500 hPa potential height in Northern Hemisphere winter,they are wave number 3, 2 and 1 respectively. For 500 hPa circulation in Northern Hemisphere winter, the main 3-wave activity are in the middle latitude regions, the main 2-wave activity are in the high latitude regions and the main 1-wave activity is in the low latitude regions. The orientations of the trough and ridge lines of the 3-wave circulations in the middle latitude regions are from northeast to southwest, the orientations of the trough and ridge lines of the 2-wave circulations in the high latitude regions are from northwest to southeast, and the orientations of the trough and ridge lines of the 1-wave circulation in the low latitude regions is from northeast to southwest. Corresponding to the characteristic zonal wavenumbers, the eastward migration features of winter circulation in Northern Hemisphere are very significant from 1949 to 1999. It has been estimated that the distance of the migration is about 5 longitudes in the past 50 years.