热带OLR异常准二年周期的初步研究

A PRELIMINARY STUDY OF QUASI-BIENNIAL PERIOD OF OLR ANOMALIES IN THE TROPICS

本文用带通滤波、单点相关和EOF研究了热带(40°N—40°S)OLR异常准二年周期的水平结构。指出其空间模态具有纬向偶极结构,它同热带行星波数2相联系。印尼—赤道中太平洋偶极型的准二年周期变化同赤道QBO有一定关系。后延相关和交叉谱分析揭示出赤道低纬OLR异常准二年周期在东非—赤道中太平洋(30°E—150°W)为驻波振荡,而在赤道东太平洋—赤道大西洋巴西海岸(140—40°W)则为向西传播。

The horizontal structure is examined of the outgoing longwave radiation (OLR) anomalies in the tropics on the quasi-biennial period time scale during 1974-1986. The techniques of the band pass filter and multiple statistics are used. The primary results show that : (1) the band of high relative variance is found stretching from Indonesia to the equatorial Atlantic coast of Brazil along the equatorial Pacific; (2) The horizontal structure in the 15°N-15°S zone takes up the pattern of zonal dipole, which coincides with the planetary wavenumber 2 in the tropics; (3) the dipole in OLR anomalies between the maritime conth and the equatorial central Pacific is related to the equatorial QBO; (4) there exists the quasi-stationary wave oscillation for an area from East Africa to the equatorial central Pacific (30°E-150°W); and (5) zonal phase propagation is westward for an area from the equatorial eastern Pacific to the equatorial Atlantic coast of Brazil (140-40°W).