江淮持续性暴雨前期热带印度洋海温影响初析  

Influence of preceding tropical Indian ocean SST on persistent heavy rainfall over the vicinity of Yangtze-Huai River valley

作　　者：刘会军[1] 汤燕冰[1] 

机构地区：[1]浙江大学地球科学系,浙江杭州310027

出　　处：《浙江大学学报（理学版）》2014年第1期113-122,共10页Journal of Zhejiang University（Science Edition）

基　　金：国家自然科学基金资助项目(41075033)

摘　　要：热带印度洋是最强最稳定的江淮持续性暴雨中期海温信号区．在此基础上，利用28年气候逐候资料，根据该信号区海温与后期0LR（OutgoingLongwaveRadiation）场和环流场的相关分析以及典型持续性暴雨过程的合成分析，初步探究了其对江淮持续性暴雨形成的中期影响机制．研究结果表明，前期信号区海温异常可通过以下3种途径对江淮持续性暴雨过程的发生产生影响．过程发生前5候至前4候热带印度洋偏高的海温及其引起的热带对流异常，导致热带偏北印度洋至热带西太平洋上异常的准纬向环流形成，削弱印度洋上的walker环流和西南季风，有利于西太平洋副高偏强．偏高的海温有利于过程发生前4候北大西洋急流出口区右侧脊发展，还可影响此异常波动的东传，对欧亚波列的发展作出重要贡献．过程发生前3～2候，该波列东传所伴随的环流调整导致南亚高压加强、中国东部槽发展、西太平洋副高加强．另外偏高的海温还有利于过程发生前2～1候110～140°E经向异常环流的形成，该异常环流削弱热带季风经圈环流，使南海一西太平洋热带辐合带偏南，有利于副高西伸．Correlation and composite analysis show that tropical Indian Ocean （TIO） is the strongest medium-range signal region of Sea Surface Temperature （SST） for persistent heavy rainfall （PHR） events over the Yangtze-Huai River valley. Based on climate pentad data for 28 years and the correlation analysis between SST of the signal region and later Outgoing Longwave Radiation fields as well as circulation fields, along with composite analysis of strong PHR cases, the physical processes connecting the signals and large scale circulation condition favoring the occur- rence of PHR events are investigated. The results show that the SST signal may affect the occurrence of PHR e- vents by three procedures. The warm mode in the TIO for 5~4 pentad before the onset of events and associated a- nomalous convection lead to the generation of the anomalous quasi-zonal cell. The cell weakens Indian summer mon- soon and the Walker circulation over the TIO. Besides, it favors the development of WPSH. The warm mode in the TIO favors the development of the ridge at the right side of the exit of North Atlantic jet. Also it can affect the east- ward dispersion of the abnormal wave, making a great contribution to the development of Eurasia wave train. With the eastward dispersion of this Rossby wave train, the large scale circulation undergoes a major modulation, resul- ting in the development of SAH, WPSH, and anomalous low over eastern China. At 2 to 1 pentad before the onset of events, due to the effect of warm mode in TIO, anomalous meridional cell forms between 110 ~E and 140 ~E, which weakens the tropical monsoon meridional cell, making the position of South China Sea-Western Pacific inter- tropical convergence zone （ITCZ） further south, and then it leads to the westward extension of WPSH.

关 键 词：江淮流域持续性暴雨 中期 热带印度洋 海温 

分 类 号：P461[天文地球—大气科学及气象学]