夏季江淮气旋结构的比较分析

A COMPARATIVE STUDY ON THE STRUCTURES OF SUMMER CYCLONES OVER THE CHANGJIANG-HUAIHE VALLEY

通过考察两个个例的经向、纬向剖面,对夏季江淮气旋的结构做了比较分析。结果表明:(1)这两个气旋波皆位于低层锋区向北弯曲处,随锋区向北倾斜。但东西方向上倾斜不明显。(2)两个个例在南北方向的结构,分别表现为较明显的温带特征(斜压结构)和热带特征(相当正压结构),后者较有利于气旋发展。(3)这些气旋波的结构与湿大气中的对称不稳定扰动类似,其活动可能与静止锋附近的条件性对称稳定度有关。

Comparative study was conducted between two summer cyclone waves over the Changjiang-Huaihe Valley in terras of their structure. By investigating zonal and eridional cross sections'. The results are as follows: (l)Both waves are located at a place where (the low level front curves norwards. Their axes tilt northwards at the same angle as the frontal zone. On zonal sections , the waves have nearly vertical axis. (2)The two waves have quite different meridional structure: One is a baroclinic structure typical of mid-latitudes, and the other is an equivalent barotropic structure, frequently seen in the tropics, (3)The waves are quite similar to symmetrically unstable disturbances in a moist atmosphere and their apoearecne may be related to the conditional symmetric instability near the stationary front.