次网格对流参数化效果对水平分辨率的敏感生试验

使用单向嵌套的五层有限域模式进行了次网格对流参数化效果对水平分辨率的敏感性试验.使最细网格覆盖主要降水区,并依次嵌套.设计了四种水平分辨率不同的网格,其水平格距分别为381,190.5,95.25及47.625km.对同一降水个例使用上述各种网格分别作了24小时累计降水量预报(积分48小时)试验.结果表明:(1)总降水量(降水最大值及等面积平均最大值)随网格距的减小而增大.当水平格距减小为50km左右时,便可以很好地预报出一般天气尺度降水的落区及雨量分布;(2)随水平分辨率的提高,次网格对流凝结对总降水的

A Sensitivity of Sub-Grid Scale Cumulus Parameterization Effects to Horizontal resolution

The sensitivity of the parameterization of sub-grid scale convective effects to the horizontal resolution were tested with a 5- level nested limited area model. The results show that the contribution of sub-grid scale convective condensation to precipitation decreases remarkably with the increase of horizontal resolution . The convective precipitation is 60- 70% of the total precipitation in the 381km grid model, and only 10% in the 47.625km grid model . It seems that a numerical model , whose grid length is much smaller than the scale of the forecast system , would satisfactorily simulate the precipitation amounts only by the resolvable scale condensation.