摘要
通过使用低频天气图上大气低频系统(低频气旋和低频反气旋),分析上海地区(长江下游)的暴雨(≥50 mm)过程发生时段低频系统的地理位置和相互配置,并根据近年75次暴雨过程中每次暴雨过程的低频系统演变,归纳合成得到低频预测模型:一种是长江下游北—西北方为低频反气旋,南—东南方是低频气旋(A型);另一类与A型相反,北—西北方是低频气旋,南—东南方是低频反气旋(B型)。最后分析了低频预测模型的物理意义,表明暴雨发生期有西北向东南同时有东南向西北的低频波列(位势高度和水汽通量)在30°N、120°E附近汇合,引起降水。同时低频系统的维持也与扰动动能有关。
The geographical position and configuration of low-frequency systems including low-frequency cyclones and anticyclones during rainstorm processes( ≥50 mm) were analyzed by using low-frequency synoptic map in Shanghai or the lower reaches of the Yangtze River( LRYR). Then two low-frequency prediction models were proposed and applied in operation based on the evolution of low-frequency systems of 75 rainstorm processes in recent years. One is that low-frequency anticyclone exists in the north-northwest of LRYR and low-frequency cyclone exists in the south-southeast( type A),the other is the opposite of type A,which means low-frequency cyclone stands in the north-northwest of LRYR and low-frequency anticyclone exists in the south-southeast. Finally,the physical meaning of low-frequency prediction models was discussed and the results demonstrated that the rainstorms occurred when low-frequency wave trains of geopotential height and water vapor flux from northwest to southeast and southeast to northwest converged over the location of 30°N,120°E and its vicinity region. And the maintenance of low-frequency systems had relation with the intensity of perturbation kinetic energy.
出处
《干旱气象》
2017年第5期784-790,796,共8页
Journal of Arid Meteorology
基金
中国气象局公益性行业(气象)科研专项(GYHY201306030)
国家自然科学基金项目(41205060)"江淮梅雨季节10~30天延伸期降水过程可预报性研究"共同资助
关键词
低频气旋
低频反气旋
暴雨过程
水汽通量
low-frequency cyclone
low-frequency anticyclone
rainstorm process
water vapor flux
