中高纬Rossby波活动对盛夏东亚/太平洋事件中期演变过程的影响  

Impacts of Mid-and High-latitude Rossby Wave Activities on the Medium-range Evolution of East Asia/Pacific Events during the Mid-and Late Summer

作　　者：施宁[1] 布和朝鲁[2,3] 纪立人[2,3] 王盘兴[1] 

机构地区：[1]南京信息工程大学大气科学学院,南京210044 [2]中国科学院大气物理研究所灾害性气候研究与预测中心,北京100029 [3]中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室,北京100029

出　　处：《大气科学》2009年第5期1087-1100,共14页Chinese Journal of Atmospheric Sciences

基　　金：国家重点基础研究发展计划项目2006CB403601;国家自然科学基金资助项目40523001;40575024

摘　　要：在中期时间尺度上探讨了Rossby波活动对盛夏东亚太平洋(EAP)事件的影响。正负EAP事件的形成过程不是简单的反位相过程,但这一时期的气候平均流波导结构决定了两者在Rossby波能量频散特征上有许多相似之处。在对流层中上层,源自上游东北大西洋或东欧平原的Rossby波能量经巴尔喀什湖附近向东北方向频散,它对东北亚异常中心的形成和维持起重要作用。由于盛夏东亚急流位置偏北,我国华北-东北地区成为波导区,Rossby波能量从贝加尔湖附近向该波导区频散,形成了EAP事件的东亚中纬度异常中心。在EAP事件的三个异常中心中,东北亚异常中心最先形成,西太平洋副热带异常中心则最后出现。在对流层上下层波导结构有明显差异,它导致了Rossby波能量在东亚沿岸中高纬地区的反向经向传播特征。在负事件的对流层低层,西太平洋副热带异常中心和中纬度两个异常中心间的经向Rossby波链接较为明显。在东亚地区,盛夏月平均尺度上EAP型的Rossby能量频散特征与中期EAP事件基本一致。Impacts of Rossby wave activities on the evolution process of the East Asia/ Pacific （EAP） events during the post-Meiyu period are investigated on the medium-range time scale. The life cycles of positive and negative EAP events cannot be simply regarded as ＂mirror＂ each other, but the same structure of westlies waveguide makes them bear some similarities in terms of the dispersion of Rossby wave energy. In the upper and middle troposphere, Rossby wave packet, which is originated from the upstream northeastern Atlantic or East European plateau, propagatesthrough Lake Balkhash, and then turns northeastward to northeastern Asia. It plays an important role in the formation and maintenance of the northeastern Asian anomaly center of the EAP event. Due to the northward shift of the East Asian jet during this period, North China-Northeast China becomes the waveguide area. As a consequence, Rossby wave packets emanating from Lake Baikal propagate to this waveguide area, leading to the formation of the East Asian mid-latitude anomaly center. Among the three anomaly centers, the northeastern Asian one appears foremost, while the western Pacific subtropical one is lattermost. Along the East Asian coastal region, the reversed meridional propagation of Rossby wave packets in the upper and lower troposphere results from the distinct difference between the westerly waveguide structures of the upper and lower troposphere. The northward propagation of Rossby wave packets from the western Pacific subtropical anomaly center, via the East Asian mid-latitude anomaly center, to the northeastern Asian anomaly center is apparent only in the negative event and in the lower tropospher~ During the midand late summer, the characteristic of Rossby wave activity over East Asia for the EAP teleconneetion pattern on a monthly-mean time scale is basically similar to that for the EAP event on the medium-range time scale.

关 键 词：EAP事件 中期过程 ROSSBY波 

分 类 号：P433[天文地球—大气科学及气象学]