2—4月北极涛动对中西太平洋ITCZ活动的可能影响  

POSSIBLE INFLUENCE OF FEBRUARY-APRIL ARCTIC OSCILLATION ON THE ITCZ ACTIVITY OF WESTERN-CENTRAL PACIFIC

作　　者：胡淼[1,2] 龚道溢[1] 毛睿[1] 

机构地区：[1]北京师范大学地表过程与资源生态国家重点实验室,北京100875 [2]北京师范大学减灾与应急管理研究院,北京100875

出　　处：《热带气象学报》2013年第1期55-65,共11页Journal of Tropical Meteorology

基　　金：863重点项目(2008AA121704);国家科技支撑计划课题(2007BAC29B02);ESPRE课题(2010-ZY-01)共同资助

摘　　要：利用1979—2008年逐日向外长波辐射(OLR)资料以及北极涛动(AO)指数,从日尺度上分析了中西太平洋上赤道辐合带(ITCZ)的类型及活跃程度,并研究其与AO的关系。结果表明:在日尺度上ITCZ存在不同的强对流中心,依据中心位置可以划分为北、南、赤道、双、全和弱等六种型态,其中北、南和弱型ITCZ在日尺度上频次最高,分别占总天数的30.98%、31.11%和24.05%,而赤道、双和全型ITCZ出现频次较少。AO与西北太平洋ITCZ活动的相关分析表明,2—4月AO指数与北型ITCZ频次存在显著正相关,相关系数达到0.49,而与弱型ITCZ频次存在显著负相关,相关系数为-0.42。当AO处于正(负)位相时,从同期至8—10月北型ITCZ活跃程度偏强(弱),而弱型ITCZ偏弱(强),在滞后1～2个月时相关达到最高。此外低层环流场以及SST也存在显著变化。当AO为正位相时,中西太平洋上赤道至15°N范围内存在异常西风气流,SST异常偏暖。这也加大了南北向SST梯度,导致赤道以北辐合加强,对流活跃,北型ITCZ频次增多。这表明AO可能是通过风场和SST来影响北型ITCZ的活动,这种海气相互作用产生的影响具有较长的持续性。The daily pattems and activity of Intertropical Convergence Zone（ITCZ） in the Western-Central Pacific Ocean are analyzed using NOAA interpolated Outgoing Longwave Radiation dataset during the period from 1979 to 2008, and the relationships between ITCZ pattems and Arctic Oscillation（AO） is investigated in this paper. In accordance with the central activity region the daily ITCZ can be divided into six pattems--north, south, equator, double, full and weak pattem, respectively. The statistic result shows that the north （30.98%）, south （31.11%） and weak （24.05%） ITCZ patterns are the most active daily patterns within a 30-year period, while the other three ITCZ pattems occur infrequently. Results show that the Feb.--Apr. AO index has a pronounced positive （negative） correlation with the frequency of the north （weak） ITCZ pattem from Mar.--May to Aug.--Oct., with the strongest correlation in Apr.--Jun. （Mar.--May）. At the same time, the lower tropospheric atmosphere circulation （850 hPa wind field） and SST anomalies corresponding to the AO change significantly in the tropical Pacific Ocean. When AO is in the positive phase, there is an anomalous westerly from Equator to 15 °N and warmer SST in the critical north ITCZ active region, while there is an anomalous easterly and insignificant change of SST from Equator to 15 °S. The wind and SST anomalies share the same characteristics of the equatorial asymmetry and thus enlarge the gradient between the south and north of Equator, which can result in the reinforced convection in the north of the equator, as well as a more frequent north ITCZ pattern.

关 键 词：气候学 统计特征 赤道辐合带(ITCZ) 北极涛动(AO) 太平洋 

分 类 号：P434[天文地球—大气科学及气象学]