【摘要】 本文根据FGGE Level Ⅲb资料详细分析了1979年夏季大范围内(30°S—30°N,30°E—150°W)40—50天周期振荡的空间分布及其传播特点。结果证实了早先关于“这些低频振荡主要表现为纬向风振荡”的究研结果,且它们向东向北传播。而季风区域850毫巴经向风的振荡周期却小于10天,这或许反映了这一地区季风扰动的活跃。在赤道,40—50天周期的纬向风的扰动系统地向东(600公里/天)和向上(0.7公里/天)传播。纬向风、位势高度和大尺度的“视热源”场之间的位相关系表明这些扰动确实不象大气中的开尔文波。与赤道地区不同,沿着15°N的纬向风的位相虽然也向东传播但不很系统。在这一纬度,纬向风的振荡在季风地区是低层显著,而西太平洋地区是在高层显著。这两个系统的相互作用导致西风或东风在阿拉伯海地区向下传播。西风(东凤)向下的位相对应着南亚和东南亚地区季风活跃(中断)的开始。更多还原

【Abstract】 On the basis of FGGE Ⅲb data, the spatial distribution of 40 - 50day oscillations and features in their propagation over an extensiveregion (30°S--30°N, 30°E -- 150°W) during the summer of 1979 are dis-cussed in detail. The results confirm earlier investigations that theselow frequency modes are primarily associated with the zonal windoscillations. These 40--50 day perturbations propagate eastward and northward. However, the monsoon region is characterized by promi-nent spectral peaks in the 850 mb meridional winds with periodsshorter than 10 days, probably reflecting the activities of monsoondisturbances. At the equator,the 40-50 day zonal wind perturbationspropagate systematically eastward (600km/day) and upward (0.7km/day).The phase relationship between the zonal winds, geopotential heights,and large-scale apparent heat sources indicates that these equatoriallow frequency oscillations do not resemble atmospheric Kelvin waves.In contrast to what happens at the equator, the phase propagationof zonal wind perturbations along 15°N, although also being directedeastward, is not so systematic. At this latitude, zonal-wind pertur-bations are pronounced in the lower troposphere over the monsoonregion and also in the upper troposphere over the western Pacific.As an integral part of E--W interaction between these two regimes,there occurs downward progression of westerly (or easterly) pertur-bations over the Arabian Sea region. The downward phase of wes-terly (or easterly)modes corresponds to the commencement of "active"monsoons (or monsoon "breaks") over South and Southeast Asia更多还原