东亚地区夏季阻塞过程的研究进展

ADVANCES ON THE RESEARCH OF EAST ASIA BLOCKING HIGHS IN SUMMER

阻塞过程是一种大尺度的大气环流持续性异常现象 ,它一旦出现会造成大范围的天气和气候异常。对阻塞过程的定义多种多样 ,有根据阻塞的气候特征进行定义的 ,也有根据阻塞的天气特征进行定义的 ,研究时根据不同的情况应选择不同的定义。人们用平衡态理论、外源强迫下的共振理论、非线性孤立波理论、斜压性及波流相互作用等理论对阻塞过程进行了研究 ,得到了许多有意义的研究结果。东亚夏季的阻塞过程对中国的天气气候有重要影响 ,东北地区的夏季低温、华北地区的干旱、长江中下游和江淮地区的梅雨和洪涝灾害等都与东亚阻塞过程有关。人们对东亚夏季的阻塞过程形成原因的研究很多 ,发现乌拉尔山阻塞高压崩溃后 ,Rossby波的传播。

Blocking high is a phenomena of persistent anomaly of atmospheric circulation, w eather and climate anomaly could be aroused in the close areas under the backgro und. Many kinds of definition of blocking high are given in the past studies, mainly in two categcries: the first definitions base on the cl imatic characteristics, attention were pald to the anomaly of geopotential height field; the second base on the synoptic features, such as center of high appear or not, how long the high persist, etc. Appropriate definitions could be selected according to the purpose of research and the place of your study.Blocking high is stability nonlinear system of forced dissipation, most of resea rches applied to the multi equilibrium states theory, the forced resonance theor y, the nonlinear solitary Rossby waves theory, the baroclinic property theory an d the wave flow interaction theory to explain the formation of blocking high, m o st important results were obtained. The farther studies about mechanism of block ing high would be continued. The East Asia blocking high plays an important role in summer synoptic and cli mati c anomaly in China, it not only causled low temperature in East China and dro ugh t in North China, but also bring Meiyu and floods in mid lower reaches of Yangt z e River and Huaihe River basin, and impact on the weather and climate of far eas t of Russia and Japan. Therefore, in addition to pay attention to SST, subtropical high and monsoon of low mid latitude, the summer short term climatic forecast of o ur country would consider much of blocking high of mid high latitude.Most of blocking high over Atlantic and Pacific occured in winter, but most o f East Asian blocking high occurred in summer. This characteristics show the imp ortant of dynamical forces of terrain and heat forces of diabatic heating in the forming and keeping of blocking high. The formation of East Asian blocking high not only connect with dynamical forces and heating forces of Qinghai Tibetan p l ateau, but also has a good relation with the heat differences between ocean and continent in the far east of Russia. It is another important causes of Asian blo cking high that anomaly of SST over east equatorial Pacific bring atmospheric an omaly over west equatorial Pacific through the Walker circulation, and then exci tated PNA atmospheric teleconnection. The studies on the formation mechanism of East Asia blocking high show that the propagation of Rossby waves accompanying w ith the collapse of Ural blocking high, the influence of Qinghai Tibetan platea u and the PNA teleconnection pattern are the major factors which cause the forming, development and breakdown of East Asia blocking high in summer.