Influence of the Mascarene High and Australian High on the Summer Monsoon in East Asia: Ensemble Simulation
By using a nine-level atmospheric general circulation model developed at the Institute of AtmosphericPhysics (IAP 9L AGCM), two sets of numerical experiments are carried out to investigate the influenceof the Mascarene high (MH) and Australian high (AH) over the southern subtropics upon the East Asiansummer monsoon circulation and summer precipitation in East Asia. The use of ensemble statistics isadopted to reduce the simulation errors. The result shows that with the intensification of MH, the Somalilow-level jet is significantly enhanced together with the summer monsoon circulation in the tropical Asiaand western Pacific region. Furthermore, the anticyclonic anomaly in the tropical western Pacific to theeast of the Philippines may induce a weak East-Asia-Pacific teleconnection pattern. In the meantime,geopotential height in the Tropics is enhanced while it is reduced over most regions of mid-high latitudes,thus the northwestern Pacific subtropical high at 500 hPa extends southwestward, resulting in more rainfallin southern China and less rainfall in northern China. A similar anomaly pattern of the atmosphericcirculation systems is found in the experiment of the intensification of AH. On the other hand, because thecross-equatorial currents associated with AH are much weaker than the Somali jet, the anomaly magnitudecaused by tihe intensification of AH is generally weak, and the influence of AH on summer rainfall in Chinaseems to be localized in southern China. Comparison between the two sets of experiments indicates thatMH plays a crucial role in the interactions of general atmospheric circulation between the two hemispheres.
作 者： 薛峰 姜大膀 郎咸梅 王会军 作者单位： LASG, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029 刊 名： 大气科学进展(英文版) ISTIC SCI 英文刊名： ADVANCES IN ATMOSPHERIC SCIENCES 年，卷(期)： 2003 20(5) 分类号： P4 关键词： mascarene high Australian high East Asian summer monsoon