The Numerical Simulation Of A Hailstone Strong Convection Weather Process Form Mechanism In Shenyang

A hailstone severe convection taken place, observed over Shenyang area on 28 June 2003, was successfully simulated by MM5 and analysis model. The configuration, evolvement rule and mechanism of the severe convection weather system provided for applying and value ways and means. Based of Stat. the hailstone appearing rule from 1951 to 2002, summarizing the season and time rule in Shenyang area. There are more parts set forth in the numerical simulate result and coming into being mechanism. The first part is middle measure system evolvement analysis. High 500hPa% 700hPa and 850hPa in the three levels weie simulated. Height and low profundity whor! system provide superiority momentum and middle-level dry and cold atmosphere for the hailstone convection. The ground pressure field and wind field provide low layer warm and humid condition. The second part is simulating water vapor combine conditions. Analyze 1000hPa stream field evolvement chart, a southwest-northeast combine strap was forming in Liaoning province by southwest air current and northwest air current. Level combine induce the combine strap cyclone bend, whorl degree intension increase. Boundary layer friction combine bring to ascend and come into being small measure cumulus convection pyrogenation. It hasten the middle scale circumfiuence strengthen. The temperature and humidity field station of low-level warm and wet, middle-level dry and warm, high-level dry and cold, which made potential instability energy reserve, up to break out. The third part is the analysis to uprightness instability condition. It is made that there was the ascending air current about Shenyang, the hailstone forming height is between 700hPa and 400hPa, die water vapor coagulating height is between 950hPa and 900hPa from the simulated TlogP evolvement chart. CAPE is in favor of severe convection development. It is the important mechanism that middle-level dry and cold air current sunk, low-level warm and wet air current ascended. Level direction energy sharp section is important to blaze middle scale hypo-circumfluence. Severe convection weather was brought by layer-knot latent instability. There were strong wind uprightness shear before severe convection occurred. Low-level riffle play an important role in water vapor energy transportation and combine ascending. High-level riffle is propitious to ascend current maintain and strengthen.