【摘要】 利用NCEP再分析资料,分析了影响2011年春夏季长江南部中下游地区发生旱涝急转的异常大气环流特征及影响因素。发现:长江南部中下游地区旱涝急转发生与西北太平洋副热带高压的变化有密切关系。副热带高压由弱到强的变化为降水提供了水汽条件,高空急流的变化则为降水提供了上升运动条件。进一步分析表明,西太平洋副热带高压西伸加强的原因与副热带高压加强前一候时间内孟加拉湾地区的异常对流加强有密切的关系。急流的变化则与陆地气温的季节变化和中纬度西太平洋强经向海表面温度(SST)梯度异常存在密切的联系。本文的研究表明:2011春夏季长江中下游地区旱涝急转现象的发生,是局地大气环流变化,南北半球大气相互影响以及海洋对大气环流影响的共同作用造成。更多还原

【Abstract】 Using NCEP Reanalysis data,the characteristics of anomalous atmosphere circulation and its influential factors during the period of droughts-floods switch at lower and middle reaches of the Yangtze River in Late Spring and Early Summer of 2011 are studied.It is found that the droughts-floods switch is related to the change of Western Pacific Subtropical High.Water vapor conditions are provided by strengthen of Western Pacific Subtropical High during the floods,while convectional conditions are provided by the change of up level jet.Further study shows that Western Pacific Subtropical High westward extension and strengthen is related to the anomalous convection over the Bay of Bengal about a pentad before,while change of upper jet is related to temperature changes with seasons on land and large meridional SST gradients over sea in mid-latitude west Pacific.Research shows that droughts-floods switch in the lower and middle reaches of the Yangtze River of year 2011 is the common-effects of local circulation changes and interactions between north and south hemisphere as well as the effect of influence from the ocean.更多还原