Abstract:

A severe convective rainstorm on July 29, 2007 in the western mountain area of He’nan province was simulated by a WRF3.3.1 mesoscale numerical model, and topographic sensitive tests were carried out at the same time. The results show that the model could simulate this process better, and simulated precipitation area and its center are coincident with the observed. A comparison of control test and topographic sensitive test shows that topographical change can affect both horizontal and vertical circulations as well as falling area of precipitation and its central rainfall level. When terrain height and gradient of windward slope rise, convergence of horizontal flow near the surface and lifting movement in middle level become stronger, and water vapor flux in low level increases, which increase the area and amount of rainfall. However, under the contrary conditions, strong precipitation center in the front of windward slope weakens or disappears. Also, precipitation in the lower reaches of mountain slightly increases. Analysis of relationship between topography height and precipitation of windward slope suggests that the latter rises or falls with the former changes correspondingly, while both are not an absolutely linear positive correlation.

Key words: Mesoscale numerical mode, Simulation of severe convective rainfall, Topographic sensitive test