摘要
分析了 2 0 0 1年华西秋雨的时空分布特点和大尺度环流背景及天气系统的主要特征 ,并对秋雨形成的主要物理机制进行了诊断和分析。结果显示 ,2 0 0 1年秋季 ,华西地区阴雨日数多 ,雨区集中 ,强降水时段集中在 9月份。该月 ,巴尔喀什湖地区 50 0hPa呈准稳定的低压槽 ,其上不断有短波分裂东移 ,携带冷空气经高原东移 ,与强大的副热带高压西南侧的东南暖湿气流和来自孟加拉湾的西南暖湿气流交汇于四川盆地、陇南、陕南一带 ,致使该地区持续阴雨天气。诊断分析表明 ,9月 ,青藏高原地区对流旺盛 ,水汽凝结释放潜热 ,使其成为一个强大的热源中心 ;而江淮、江南一带多受西北太平洋副热带高压控制 ,盛行下沉气流 ,为热源低值区 ;四川盆地处于高原高能量带与盆地以东低能量带之间的能量锋区。此能量锋区的存在促使从巴尔喀什湖低压槽分裂东移的短波槽在该地区发展。同时 ,东路冷空气的渗入进一步加大了能量锋区的强度 ,激发不稳定能量释放 。
The space time distribution features of autumn rains in West China in 2001, the related large scale atmospheric circulation, and the main features of the weather systems are analyzed to study the physical mechanisms of autumn rains. The results show that there were more rainy days than normal in 2001, and the strong raining processes were concentrated around Sichuan Basin in September. The circulation analyses show that there was a quasi stationary trough near the Oz.Balchas, from which short waves were split one by one, moved southeastward, passed Tibet Plateau and reached the area near Sichuan Basin. Here the cold airs taken by the short waves were combined constantly with the warm and humid southeast air in the southeast side of the strong subtropical high and with the wet warm southwest air from the Bay of Bengal. The physical analyses show that there was a strong energy frontal zone between the high energy center in Tibet Plateau and the low energy center to the east of Sichuan Basin. So the short waves were developed strongly in the Basin. The intensity of the energy frontal zone was strengthened because the cold air from the east area entered so that the instability energy burst out, which triggered the rainstorm in Sichuan Basin.
出处
《应用气象学报》
CSCD
北大核心
2003年第2期215-222,共8页
Journal of Applied Meteorological Science
