摘要
通过对 COADS1950—1979年海面经向风和海温资料的分析,本文探讨了印度洋—太平洋近赤道地区经向风的长期变化特征及其与厄尼诺发生发展间的关系。结果表明:(1)热带太平洋辐合带系统与海温具有相同的季节变化趋势,冬季赤道辐合带和高海温位于南半球,夏季位于北半球。厄尼诺年经向风发生异常,近赤道地区出现强烈的经向风辐合。(2)近赤道经向风存在准2年(QBO),准3.5年(SO)和准5年(FYO)3种年际低频振荡。QBO对厄尼诺年经向风异常起着重要作用,SO 对厄尼诺年和冷水年的经向风变化均十分重要,这两种振荡可以很好的拟合经向风的实际变化,FYO 则起着加强的作用。(3)经向风年际低频振荡起源于印度洋—海洋大陆和东太平洋沿岸地区,南北半球冬季风异常和东太平洋沿岸地区信风异常是其主要原因。(4)季风—信风(V)相互作用表现为当异常经向风扰动从季风区东传到信风区时明显增幅,这与信风区海气系统之间时间尺度约1年的自我正反馈有关。
Based on analysis of the meridional winds over oceanic areas and sea surface temperaturefor 1950—1979 extracted from the data sets of COADS,the long-term variability of the merid-ional winds over the equatorial Indian—Pacific Oceans and its relationship to the onset and de-velopment of E1—Nino events have been studied.The major results are as follows:1.There is a great similarity betwen Intertropical Convergence Zone(ITCZ) over the Pacific andSST in the seasonal trend,with ITCZ and high SST found in Southern Hemisphere in winter andin Northern Hemisphere in summer.During E1—Nino years,unusual meridional winds were oftenobserved,with significant convergence of meridional wind occurring over near-equatorial re-gions.2.For the near-equatorial meridional winds,there are three types of interannual low-frequencyoscillations——QBO,SO,FYO.QBO plays an important role in the unusual behavior of meriodi-onal wind for E1—Nino years,while SO is very important for both E1—Nino and cold wateryears.These two oscillations may fit well to the observed variation in the meridional wind.FYOmay enhance the variation of meridional wind.3.Interannual low—frequency oscillations of meridional winds originate in the Indian Ocean—Maritime Continent and coastal area of the east Pacific.Unusual activities of winter monsoon inboth hemispheres and trade wind off the coastal area of the east Pacific are believed to be theirmajor cause.4.Monsoon-trade interaction shows up in the significant amplification of the disturbances ofmeridional wind while they propagate eastward from monsoon area to trade wind area.
出处
《应用气象学报》
CSCD
北大核心
1990年第1期2-11,共10页
Journal of Applied Meteorological Science
