长江三峡区间初夏大～暴雨的物理量场分析

A DIAGNOSTIC ANALYSIS OF THE MAIN PHYSICAL QUANTITIES OF HEAVYTORRENTIAL RAINS IN THE AREA OF THE THREE-GORGES OF THE CHANGJIANG RIVER

本文采用σ坐标系,分析计算三峡区间初夏出现大～暴雨的31个个例的物理量场,并计算了平均场,得出三峡区间初夏出现大～暴雨当日08时的物理量场的主要特征:①降水发生在低层正涡度带南侧100～200km处,即在0.7与0.55等σ面上的零涡度线之间;②降水发生在低空急流迅速建立或增强后0～24小时,个别发生在24～48小时;③降水发生在θ_(se)密集区南侧;④降水发生在零等αθ_(se)/ασ线之南100～200km处;⑤在没有冷空气直接参与下,也有大～暴雨出现,此时主要受低空急流和切变线低涡影响。

In this paper the σ-coordinates system was used for the analysis of the main physical factors in 31 samples of heavy-torrential rains happening in the area of the Three-Gorges of the Changjiang River in early summer. The mean value fields of each factor were calculated and then the main features of the physical fields at 08 hour on the day when heavy-torrential rain occurred were obtained.