中文摘要：

运用MM5V3．5模式成功模拟了辽东半岛2004年8月3日的大暴雨过程，并模拟出了产生大暴雨的中尺度低压．敏感性试验比较了渤海、沙漠、城市和地形高度产生的地面温度、湿度、不同高度的水平风速、垂直速度的变化，研究了不同下垫面造成的边界层结构特征和局地环流，揭示出渤海和辽东半岛地形使降水大幅度增强．湿位涡诊断分析表明，此次大暴雨是在低层强对流不稳定和斜压不稳定条件下发生的，改变渤海地表和降低辽东半岛地形高度都使低层不稳定减弱．

英文摘要：

By using MM5V3.5 mesoseale model, a torrential rain event caused by mesoscale depression over Liaodong Peninsula on 3 August 2004 was successfully simulated. Numerical experiment compared the influence of Bohai Sea, desert, city and Liaodong Peninsula on surface temperature, humidity, horizontal velocity at different levels and vertical velocity, and investigated the effects of different underlying surface in the local thermal and dynamical structure of the PBL and corresponding circulation. Therefore, it revealed that Bohai Sea and Liaodong Peninsula topography increased the rainfall remarkably. Diagnostic analysis of moist potential vorticity showed that the torrential rain occurred in strong convective instability and baroclinic instability conditions. Changing the underlying surface and lowering the terrain altitude weakened the instability of low troposphere and resulted in the decrease of rainfall.