热带大气对EI Nion和La Nina的动力响应  

THE DYNAMIC RESPONSE OF TROPICAL ATMOSPHERETO EL NINO AND LA NINA

作　　者：杨 燕[1] 朱抱真[1] 杨 辉[1] 张瑞雪[2] 

机构地区：[1]中国科学院大气物理研究所,北京100029 [2]中国气象科学研究院

出　　处：《热带气象学报》2002年第1期10-18,共9页Journal of Tropical Meteorology

基　　金：国家自然科学基金项目49675211的资助

摘　　要：利用1951－1992年的热带太平洋每月海表温度资料，采用3－5年带通滤波，得到SSTA在这种时间尺度的低频振荡（LF），SSTA的LF振荡的经验正交分析第1主分量的时突变化突出地表现了E1 Nino和La Nina循环的特征。对热带大气环流850hPa月风场异常进行3－5年带通滤波，再对纬向风作经验正交分析，得到第1主分量明显地表现了热带大气环流在纬向上不均匀分布的循环特征。为了探讨上述两个循环的物理关系，建立了一个简单的热带大气模式，其中包括蒸发，感热和风场之间的反馈以及凝结潜热和流场的反馈作用。当E1 Nino和La Nina所形成的SSTA为定常已知的分布时，模拟了热带大气纬向风和降水对海表温度异常的响应。In the 1st part of this paper an observational study is given. We choose 3~5 year low frequency (LF) period range for the band-pass filter and EOF analysis to the data set of SSTA over tropical Pacific, 1951~ 1992. We then apply the LF band-pass filter to the global belt 850 hPa wind variables and the link between the leading mode EOF-1 of LF oscillation of SSTA and circulation anomalies is investigated.In the 2nd part of this work a simple equatorial model for one baroclinic mode with explicit moisture evolution equation is developed. The interaction between convective condensational heating and large-scale flow as well as the feedback between evaporation, sensible heating and perturbation wind are included. Also, the realistic underlying surface temperature field and sea-land contrast are introduced.By introducing typical SST anomalies in El Nino or La Nina years, respectively, into the lower boundary, the anomalous tropical circulation is simulated. The model experiments show that during a warm episode, the convection center is situated further east, convective activities over eastern Pacific are strengthened and there is anomalous westerly over central Pacific Ocean. On the contrary, during a cold episode, the eastward propagation of the disturbances is much prohibited, the convective active region are confined to the west of the date line.

关 键 词：3-5年循环 热带大气 厄尔尼诺 拉尼娜 热带太平洋 经验正交分析 

分 类 号：P732[天文地球—海洋科学]