初夏东亚环流对厄尔尼诺的两种响应过程及其对中国降水的影响  

The two responses of the East-Asian atmospheric circulation in early summer to the preceding El Nio event and their influence on the rainfall over China

作　　者：王亚非[1] 李琰[1,2] 丁一汇[3] 

机构地区：[1]中国气象科学研究院灾害天气国家重点实验室,北京10081 [2]国家海洋信息中心,天津300171 [3]国家气候中心,北京10081

出　　处：《气象学报》2012年第1期39-49,共11页Acta Meteorologica Sinica

基　　金：国家重点基础研究发展计划973项目(2012CB417205);国家自然科学基金面上项目(41075068);中国公益研究专项(GY-HY201006009)

摘　　要：利用NCEP/NCAR提供的月平均850、500 hPa位势高度场和风矢量场资料及NOAA气候诊断中心的海温扩展重建资料,同时利用NCEP的CAM3.0模式对厄尔尼诺气候效应进行了分析。外强迫为赤道东太平洋的异常海温,从9月积分至次年6月,对此进行了模拟,结果表明:(1)冬季厄尔尼诺达到强盛后对次年东亚初夏的环流有明显的影响,表现在低层菲律宾附近反气旋环流的增强和中高纬度OKJ类波列(主要为鄂霍次克海—日本东部—日期变更线以西副热带高压北部的波列)的活跃,而后者更容易被模拟,这两种环流方面的影响都能在资料中检测出来。当这两种异常环流的发展被模拟出来时,长江以南地区的多雨状态也能够被模拟,表明厄尔尼诺发生后,其对夏季风的发生、发展有滞后作用,从而加强向中国南方的水汽输送,但至6月由于OKJ波列的发展使波活动通量在北太平洋中西部产生大面积强烈散射使副热带高压偏南,因而又抑制了夏季风的进一步向北推进,从而只停留在长江及其以南地区,这可能是致使降水南多北少的原因之一;(2)中国南方降水多寡受到鄂霍次克海高压及菲律宾反气旋的共同影响,两者任何一方加强时南方降水增多,反之亦然。近年来受鄂霍次克海高压的影响更为突出,鄂霍次克海高压、南北方降水、厄尔尼诺事件以及菲律宾反气旋都存在相近似但又各自不同的年代际变化规律,其共同影响与中国南涝北旱的年代际降水格局变化有密切关系。Using the monthly mean geopotential height,wind vector at 850 hPa and 500 hPa of the NCEP/NCAR reanalysis data,the sea surface temperature（SST） of the CPC and the Community Atmosphere Model V3.0,we examined the impact of the preceding El Nio event on the East Asian circulation.The results are：（1） The climate simulations show that there are two kinds of major impact of El Nio in the mature phase on the atmospheric circulation over East Asia in next early summer.The two ways of the impacts are embodied in the development of the low level anticyclonic circulation around the Philippines and the active mid-level Okhotsk-Japan wave-train-like pattern（OKJ pattern） that accompanies the development of the Okhotsk High.The latter one has been more easily simulated by the climate model.Both the two kinds of anomalous circulation were observed from the reanalysis data.The positive rainfall in the southern part of China with the two anomalous circulation patterns in next June was also simulated after the positive SST anomaly in the Nino-3 region was added in autumn,which indicates a delayed impact of El Nio on the East Asian summer monsoon.The anomalous circulations resulted in the strong southerlies in the area to the south of the Yangtze River.On the other hand,the northward progress of the summer monsoon which is characterized by the movement of the subtropical high was significantly suppressed by the wide scope of scattering wave activity flux over the sea area from Japan to the dateline of North Pacific in the middle latitudes.This suggests that the delayed impact of the ENSO event is one of the major factors that cause the climate pattern of the flooding in the southern China and drought in the northern China.（2） The statistic analysis indicates that the more rainfall occurring in South China is strongly influenced by the development of the Okhotsk high and the anticyclone around the Philippines in early summer.Either of them can result in flooding in the southern China and vice versa.The Okho

关 键 词：厄尔尼诺 菲律宾反气旋 鄂霍次克海高压 波列 

分 类 号：P461.21[天文地球—大气科学及气象学]