冬季东亚副热带急流与温带急流的比较分析：大尺度特征和瞬变扰动活动  

Diagnostic comparison of the East Asian subtropical jet and polar-front jet:Large-scale characteristics and transient eddy activities

作　　者：任雪娟[1] 杨修群[1] 周天军[2] 房佳蓓[1] 

机构地区：[1]南京大学大气科学学院,灾害性天气气候研究所,南京210093 [2]中国科学院大气物理研究所LASG,北京100029

出　　处：《气象学报》2010年第1期1-11,共11页Acta Meteorologica Sinica

基　　金：国家自然科学基金项目(40775044,40730953);中国科学院知识创新工程领域前沿项目(IAP07303)

摘　　要：使用ERA40再分析的月资料和逐日资料,从大尺度特征和瞬变扰动活动两个角度对冬季东亚副热带急流(EASJ)和东亚温带急流(EAPJ)进行了比较分析。结果表明,使用月资料分析的EASJ与EAPJ在高层风场上没有清晰的地理分界区,而使用逐日资料计算得到的冬季逐日急流发生数则以高原北部上空所处的纬度带为分界岭,存在两个急流中心集中区,分别对应于EASJ和EAPJ区域。通过分析东亚上空天气尺度瞬变扰动活动(STEA)表明,与强盛的冬季EASJ相伴随的是较弱的南支STEA,而与较弱的EAPJ相伴随的北支STEA却十分活跃,显示出EAPJ是与瞬变活动相伴而存的急流。进一步的诊断分析揭示了冬季东亚温带急流的两种主要异常模态,一种是EAPJ区域反气旋性/气旋性异常环流型,另一种是局地西风的减弱/增加。与第1种异常模态相关的北半球大尺度环流异常主要集中在欧亚中高纬地区,其形成受中高纬大气环流以及东亚上游大气环流异常的共同影响。当EAPJ局地西风减弱/增加时,EASJ东段至西太平洋上空的西风急流呈现出与之相反的变化型,北半球大气环流异常表现为大气遥相关的欧亚(EU)型。冬季EAPJ的两种异常模态还与东亚上空STEA异常密切联系,其中在北支STEA区域出现的瞬变异常以波列的形式沿STEA北支轴线传播到达东亚沿海上空,然后东传入洋面上空,而对于靠近STEA南支轴线的异常扰动活动则只能存在于东亚东部及其沿海上空的200 hPa层上。A diagnostic comparison of the East Asian subtropical jet（EASJ） and polar-front jet（EAPJ） in winter season is carried out by using ERA 40 monthly mean and daily reanalysis dataset.The comparison is based on the large-scale characteristics and the transient eddy activities.It is demonstrated that the EASJ and the EAPJ shown by the monthly mean data have no clear geographical boundary at upper levels.The distribution of the numbers of jet core extracted from the daily data exhibits distinct boundary mark at the latitude of the northern part of the Tibetan Plateau.There exist two areas with large numbers of jet cores,corresponding to the EASJ and EAPJ regions,respectively.The analysis of the synoptic-scale transient eddy activities （STEA） over the East Asian region shows a spatial match among STEA,EASJ,and EAPJ.The strong EASJ is accompanied by the weak south branch of the STEA,while the weak EAPJ is accompanied by the north branch with more active STEA,indicating that the EAPJ is a jet existing with the STEA.Further analysis shows two anomalous modes of the winter EAPJ：One is the anti-cyclonic/cyclonic anomalous circulation pattern,and the other is the weakened/strengthened local westerly wind. The large-scale circulation anomalies related with the first mode are mainly concentrated in the European-Asian mid-high latitudes. It is influenced by the anomalous circulation in both the mid-high latitudes and the upstream area.When the local westerly wind over the EAPJ region is weakened/strengthened,the westerly jet from the east part of the EASJ to the western Pacific region shows an opposite variation.The atmospheric circulation anomaly shows the Eurasian（EU） pattern.The two major modes of the winter EAPJ are also closely linked with the STEA anomaly over East Asia.The STEA anomalies in the north branch of the STEA region propagate as wave train along the axis of the north branch of the STEA and cross the East Asian coastal areas to the oceanic region.However,the ones near the south branch of the STE

关 键 词：东亚副热带急流 东亚温带急流 比较分析 天气尺度瞬变扰动活动 

分 类 号：P421.32[天文地球—大气科学及气象学]