1991年梅雨锋暴雨与锋生环流的诊断分析

DIAGNOSIS OF RAINSTORM AND FRONTOGENESIS CIRCULATION NEAR MEIYU FRONT FOR JULY 1991

摘要:

利用原始方程模式锋生环流诊断方程对1991年7月一次梅雨锋暴雨过程进行诊断分析。计算结果表明,锋面横向次级环流在低层是一个热力正环流,低空急流出口区的次级环流使锋面附近的上升运动得到加强;100hPa青藏高压东侧的偏北风与中层的偏南风耦合形成对流层上层的反环流叠加在锋面横向环流上形成深厚的上升气流区是暴雨发生的动力条件;西风急流出口区的横向环流对暴雨的加强有间接贡献。

Abstract:

Diagnosis has been done of the July 1991 Meiyu front torrential rainfall event by using the diagnostic equation of frontogenesis circulation in the primitive equation model. Results suggest that the frontal lateral secondary circulation (SC) at lowerlevels was a thermally positive circulation; the SC at the exit region of low-level jet enhanced the ascenting near the frontal surface; the negative circulation in the upper troposphere formed through coupling of the northerly on the east side of the 100 hPa Qinghai-Tibetan with the mid level southerly resulting in an anti circulation superimposed on the frontal lateral circulation, thus responsible for a deep ascending motion as one of the dynamic conditions for the rainstorm; the lateral circulation at the exit of the westerly jet contributed indirectly to the enhancement of the rainfall.