中文摘要：

对2008年我国南方持续性雨雪、冰冻灾害天气的影响系统及层结特征做了研究,集中对第3次过程,即1月25～29日期间的天气形势、水汽条件、高原对流系统东移的影响以及地面和大气层结条件进行了分析。研究表明：位于长江或江南地区的准静止锋（或切变线）是雨雪冰冻天气的重要影响系统,锋面西段的逆温层和暖层强,有利于冻雨的形成;水汽在锋前的对流层低层辐合,沿锋面爬升凝结,锋面的东段低层辐合比西段强,造成锋面东段的降水强度大于西段;高原对流系统活跃,且频繁东移影响我国东部,在第3次过程共有3次高原对流的东移过程;最有利于冻雨产生的层结条件应有中层冻结层、暖层、逆温层,且这些层结的强度和厚度要适当;最有利于冻雨出现的地面温度在-1～-3℃,变化非常小,温度、露点差都在1～3℃,接近饱和,风速较弱。最后,提出了适合于我国南方雨雪、冰冻天气的锋面结构与大气层结的物理模型。

英文摘要：

The weather pattern,moisture flux,the eastward propagating convective systems from Tibetan Plateau and surface temperature,stratification conditions for severe freezing rain and snow storm process during 25—29 January 2008 is diagnosed.The results show that,the east-west oriented quasi-stationary front（or shear line） located along Yangtze River Basin was the most important system producing freezing rain and snow storm.The warm layer and inversion of western part of front was stronger than its eastern part,the former was very favorable for the formation of freezing rain.The strongest moisture convergence occurred ahead the front at low-level and then climbed slantly along the front to middle level.The low-level moisture convergence in eastern part of the front was stronger than that in western part.It is maybe the main reason why the precipitation amount in eastern part of the front was relatively large.The convections were very active over the Tibetan Plateau during January 2008,propagated eastward and impacted East China several times.There were three times eastward propagation of convective systems from the Tibetan Plateau during 25—29 January 2008.The favorable condition for freezing rain was ground surface temperature at-1—-3 ℃ and weaker wind.The middle level frozen layer,warm layer and inversion layer existed while freezing rain occurred,at the same time,the formation of freezing rain was sensible to the thickness of the warm layer and frozen layer.Base on these,the physical model of quasi-stationary front and stratification condition related with freezing rain has been proposed.