【作者】 张弘； 孙伟；

【Author】 Zhang Hong , Sun Wei (Shaanxi Meteorology Observatory, Xian, Shaanxi 710015)

【机构】 陕西省气象台；

【摘要】 对2002年初夏发生在高原东侧一次特大暴雨的分析认为:这次暴雨的成因是新疆低槽与高原槽合并东移并引导较强冷空气在高原东侧与四川至陕西的西南暖湿气流交汇而形成的。高空西风急流增强、我国东部东阻高压建立及低层偏南暖湿气流的加强、北伸为发生暴雨提供了有利条件。冷锋前暖区内中β尺度对流系统(MβCSs)的活跃直接导致了特大暴雨的发生。低层中尺度辐合系统与中β尺度对流云团的活动、大暴雨出现的时间和落区等密切相关。中尺度对流系统(MCSs)散度垂直分布的特殊结构,即从对流层低层到高层存在的辐合～辐散“双重结构”对大暴雨时强烈上升运动和深对流形成有着重要作用。更多还原

【Abstract】 After analysis of an extreme heavy rain in east of plateau at early summer in 2002, the following conclusion can be drawn: The cause of heavy rainfall is unite movement eastward for low trough in Xinjiang and plateau trough, then lead converge for strong cold air and southwest airflow of warm and moist from Sichuan to Shaanxi at east plateau . The strengthen of westerly jet in high lever , form of east blocking high in east China, strengthen and movement northward of southwest airflow of warm and moist in low lever , provide advantageous conditions for heavy rainfall. The activity of meso-β-scale convective system(MβCS)in front of cold front within warm area directly causes local heavy rainfall, mesoscale convergence system in low lever has a nearly correlativity with motion of meso-β-scale convective cloud cluster, time and precipitation region of heavy rainfall. The especial structure of divergence vertical distributing in mesoscale convective system(MCS), which divergence distribute shows “ double structures” of convergence-divergence from low lever of troposphere to high lever, has an important role to intense ascending motion and deep convective form in heavy rainfall.更多还原