A Simulation Of Impact Of Vegetation Cover Characteristics On Severe Convective Weather

This article use meteorological element data about Loess Plateau in summer at 2008 providing by micaps3.0, and global reanalysis data FNL providing by the NCEP. We use the new generation WRF mesoscale numerical model simulation to analyze a regional heavy precipitation in the Loess Plateau. In the simulation, we know the impact of the different land surface vegetation characteristics on the convective weather. The Control test of the simulation, analyze the distribution of rain, the process of evolution and circulation patterns are better shows the simulation performance. Sensitive test of the simulation, get the impact of vegetation characteristics on convective weather by analyzing the water balance on the ground, heat flux, water vapor flux, the temperature field, atmospheric stability, the horizontal and vertical circulation changes and so on.We analyzed the process of vegetation change on the possible impact of convective weather are:when the vegetation increased, (1)the surface roughness and vegetation height are also increased, then underlying surface dynamic heterogeneity is increased and inspire out of a certain intensity of secondary circulation superimposed on the weather system, weather system has been deepened. (2) the increasing of the surface roughness and vegetation height enhances the ability of canopy interception. (3)when the vegetation improved, water vapor and sensible heat, latent heat flux and surface heat flux are increased, and the thermal heterogeneity of underlying surface is also increased, lower surface albedo, the lower atmosphere tends to instability, is conducive to strong convection weather occurred. (4) the improvement of land surface vegetation can make the location of the main rain belt shifts, and the range of rainfall has been expansived. (5)The improvements in vegetation shift cyclonic disturbances, causing rain bands are moved, resulting in the cyclonic disturbances superimposed on large-scale weather systems and, strengthening the vertical movement, the depth of the system has been strengthened. (6) Warming effect and the instability stratification are conducive to strong convection weather occurred.Vegetation degradation is generated with the opposite effect.