AREM模式对“05.7”四川大暴雨的敏感性试验

Sensitivity Experiments of AREM Model on "05.7" Rainstorm over Sichuan Basin

利用AREM中尺度数值模式,对2005年7月8日四川盆地大暴雨天气过程进行了数值模拟,比较分析了AREM模式提供的不同降水方案、地表通量方案、地表辐射参数化方案对此次降水过程的模拟,以及对该过程中西南低涡活动特征的模拟。试验结果表明:各方案较好地反映了四川盆地西南部强降水,对其东北部的强降水模拟存在较大偏差;各方案模拟的涡度场和流场分布决定了降水区域分布;采用降水的显式云微物理过程和大尺度饱和凝结过程模拟的降水强度、低涡强度和低空急流有一定差异,后者模拟的偏强,与实况更接近;不同地表通量过程和地表辐射过程对降水、低涡和低空急流的模拟无明显差异。

The rainstorm process, which happened on 8^th Jul., 2005, over S.C. basin, has been simulated by using AREM mesoscale model. Precipitation process and activity character of south-west vortex simulated by different precipitation schemes, surface flux schemes as well as surface radiation schemes provided by AREM model have been analyzed. The results show that various schemes have better prediction capabilities to the south-west precipitation of S.C basin, but there are great differences over north-east heavy rainfall compared with the real. The distributions of simulated vortex fields and stream fields decide on the distributions of precipitation areas. The simulated precipitation intensity, vortex intensity and jet stream in lower atmosphere have some difference when adoptng explicit cloud micro-physics process and large scale saturation-condensation process, and the latter better simulates the precipitation so that it is more closed to the real. Different surface flux process schemes and surface radiation process schemes have no obvious differences in the simulations of precipitation, low eddy and jet stream in lower atmosphere.