Analysis On Characteristics And Chysical Mechanism Of The Rainstorm Over Tongren In Guizhou

In this paper,using 1985 to 2014,including 10 station daily meteorological observation data,the comprehensive analysis including time and space distribution,storm frequency characteristics of heavy rain.And 49 times heavy rain weather process of 2005-2005 years,and 10 times continuous heavy rain weather process of circulation type characteristics and the characteristics of physical quantity of convective cloud cluster evolution is analyzed.Draw typical circulation model and forecast on seasonal rains,including points season rainstorm forecast physical diagnosis model is established and landing area judgement probability model;Finally based on special terrain sudden or extreme rainstorm circulation background and characteristics of small and medium scale in analysis.The main conclusions are as follows:(1)including overall spatial distribution of heavy rain is much less south north,northwest,northeast,southwest,southeast and less;Torrential rain has focused on August 5-(about 90%),among them 6-July most(27%).And the frequency of the torrential rain in early and late.Tongren precipitation mainly concentrated in the night 23:00 until 09:00,the morning hours of short-time strong rainfall is greater than or equal to 10 mm precipitation mainly concentrated in the surf-07:00 is short-time strong rainfall peak time.(2)the tongren torrential rains are divided into five categories: low trough cold front rainstorm(34%),the Yangtze river cross the heavy(meiyu front type,25%),low(22%),the heavy typhoon trough type heavy rain(12%),projects the weather process of the heavy(7%).(3)the rainstorm convective clouds there are mainly four generation ground: one is the north north or east the area effect tongren city zunyi(60%),2 it is northwest of chongqing east the area effect tongren most(16%),3 it is generated in northern hunan devastated the eastern influence tongren accounted for 8%,four is ChuanDongNa merger with northwest guizhou convective cloud east affect tongren most(11%),also have individual affected by terrain autochthonous development,then east relatively few alone.Thus affect the tongren area of convective cloud cluster mostly from zunyi and chongqing area.(4)quantity statistics,the occurrence of heavy rain and the relative humidity,water vapor flux,vapor flux divergence,specific humidity,temperature,dew point and relative vorticity,vertical velocity,the divergence,SI,K index,Ky index such as 11 parameters correlation is higher.With false quite potential temperature and total temperature(TT),the correlation coefficient of convection effective potential energy(CAPE)is low.To physical quantities to establish local rainstorm quantity diagnosis model is applied to the actual forecast effect is better.(5)in view of the extreme rainstorm tongren special terrain,to explore the forming reason,it is concluded that the terrain effect on heavy rain fall area is larger,heavy rain occurs mostly in low-lying areas in the mountains near or higher zone near the windward side of dongfeng airflow.