热带扰动与远距离暴雨关系的统计分析与数值试验
投稿时间: 2014-09-25  最后修改时间: 2014-11-19  点此下载全文
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丁治英 南京信息工程大学 气象灾害教育部重点实验室/大气科学学院, 江苏 南京 210044 dingzhiying@nuist.edu.cn 
朱静 南京信息工程大学 气象灾害教育部重点实验室/大气科学学院, 江苏 南京 210044  
邢蕊 南京信息工程大学 气象灾害教育部重点实验室/大气科学学院, 江苏 南京 210044  
基金项目:国家重点基础研究发展计划(973计划)资助项目(2013CB430103);国家自然科学基金资助项目(41375058)
中文摘要:对2006-2011年5-9月90~150°E、0°~50°N范围内远距离暴雨进行统计与合成分析,并选取典型个例进行诊断分析与数值试验,研究结果表明:1)在有利的大气背景下,强度较低的热带扰动也可以与中纬度系统共同作用引发远距离暴雨,对统计得出的21例依据水汽通道的类型分为3类:S型水汽通道、双水汽通道和西北向型水汽通道,其中S型水汽通道发生次数最多。2)低空急流合成分析表明,不论扰动强弱,热带扰动东侧的偏南低空急流是形成远距离暴雨的关键,是联系中低纬度系统的纽带和桥梁,对S型的个例进行诊断分析与数值试验也进一步显示,热带扰动东侧低空急流是中纬度暴雨区水汽输送的主要通道,偏南低空急流的强弱是影响远距离暴雨强度的主要因子之一。3)敏感性试验结果表明,热带扰动也可以引起Rossby波能量向东北方向传播,其强度与扰动强度成正比,从而改变远距离降水分布;去除热带扰动则无法形成波列,不利于能量的传播与远距离降水发展。
中文关键词:热带扰动  远距离暴雨  水汽通道  能量频散
 
Research on the relationship between tropical disturbance and distant rainstorm by statistical analysis and numerical simulation
Abstract:A study of the relationship between tropical disturbance and distant rainstorm events in the region of 0°-50°N,90°-150°E during May to September in the period 2006-2011 was performed,while typical cases were selected for statistical analysis and numerical simulation.The results are as follows:(1)Under the background of favorable atmospheric conditions,a tropical disturbancewhose intensity is lower than a tropical depressioncan also cause distant heavy rainfall combining with the effect of mid-latitude systems.The statistics suggest that 21 events can be divided into three categories according to the type of moisture channel on 850 hPa:"S" pattern moisture channel,double moisture channel and northwestward moisture channel.The distant heavy rainfall events with "S" pattern moisture channel occur most frequently and the distant heavy rainfall events occur most frequently in July.The composite analysis of the three types shows that the formation of the remote heavy rainfall is closely related to the atmospheric circulation formed by the mid-latitude systems,tropical disturbance and subtropical high.The mid-latitude systems provide a favorable background of atmospheric circulation and the distant heavy rainfall occurs in the area with high moisture flux,which indicates the importance of moisture transportation.(2)The composite analysis of low-level jet of having or not having distant heavy rainfall shows that the southerly low-level jet located in the east of the tropical disturbance plays an important role in the formation of the distant heavy rainfall and is the key to make a connection between the low-latitude and mid-latitude systems regardless of the tropical disturbance intensity.The diagnosis and numerical study of a case with "S" pattern moisture channel further indicates that the southerly low-level jet is the main channel of transporting moisture to the mid-latitude rainstorm area and its intensity is one of the main factors affecting the distant rainstorm intensity.(3)The diagnosis of a case with "S" pattern moisture channel also indicates that the low-level jet between the tropical disturbance and subtropical high is the main energy channel that transports abundant energy to the distant rainstorm area.So the low-level jet not only contributes to the northward moisture transport but also the energy transport to the distant rainstorm area.(4)Sensitivity experiments show that the tropical disturbance can also induce the propagation of Rossby wave energy towards the northeast,the intensity of which is proportional to the intensity of the tropical disturbance,thus affecting the distant rainfall distribution.Wave trains can not form after removing the tropical disturbance,which is not beneficial to the dispersion of wave energy and the development of the distant rainfall.
keywords:tropical disturbance  distant rainstorm  moisture channel  energy dispersion
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