OLR资料所揭示的热带地区低频振荡的变化特征

本文使用1979年1月至1984年12月射出长波辐射(OLR)资料,对热带地区低频振荡的一些特性进行了研究,认为正常年份30—60天振荡的合成功率谱最强,El Nino年最弱。低频波活动冬夏差异较大,其年际变化大值区冬季在赤道地区,夏季位置偏北,位于印度洋和西太平洋。就六年平均而言,低频波在西太平洋及印度洋地区有明显的经向传播,赤道地区低频波的纬向传播主要集中在北半球夏季。此外,30—60天OLR滤波场的强弱与印度季风的爆发和减弱有较好的对应关系。 

VARIATION CHARACTERISTICS FOR THE LOW FREQUENCY OSCILLATION IN THE TROPICAL REGION AS REVEALED FROM OUTGOING LONGWAVE RADIATION

In this paper, We have made a preliminary study on the variation features for the Low -Frequency Oscillation.(LFO) in the tropical region. The results ave as follows;1. The activity areas for the 30-60 day oscillation of the OLR data are located in North Indian Ocean, subtropical and tropical Western Pacific Ocean. The integrated power spectra for the 30-60 day period range is large during the normal years,and small during the El Nino years.2. There exists large difference for LFO between summer and winter with its large inter annued variability being mainly confined to the equatorial region during winter and to the Indian Ocean and western pacific during summer.3. The meridional propagation of LFO over the western pacific and Indian Oceans is obvious and the zonal propagation of LFO over the equatorial region is mainly concentrated in northern summer.4. The intensity of filtered 30-60 day OLR field can reflect the "active" and "break" phases for the Indian Monsoon.