GRAPES中尺度模式中不同对流参数化方案模拟对流激发的研究

STUDY OF DIFFERENT CUMULUS PARAMETERIZATION SCHEMES OF GRAPES-MESO MODEL IN SIMULATION OF CONVECTION PROVOCATION

针对GRAPES中尺度数值模式的三种积云对流参数化方案,对华南2005年6月17～25日的降水过程进行模拟,研究了不同参数化方案中对流激发的时间和空间特征,讨论对流的激发状态和预报降水量的关系以及模式预报降水偏少的可能原因。21日的24小时降水量模拟结果显示,总体上雨带与实况接近,但中尺度暴雨中心位置不同。各方案的初始对流激发的状态及演变存在显著不同,并与各自24小时模拟降水量的分布和雨量紧密相关;同时预报对流激发的时间也不同。综合来看,SAS方案能较好地模拟对流的触发,但激发的降水在实况出现小雨和大雨的时段没有太大的区别。用KFETA方案探讨模拟降水偏少的可能原因之一是,对流层中层垂直速度偏小。

With three different cumulus parameterization schemes in GRAPES-Meso model, a rain process lasting from June 17, 2005 to June 24 in south China is simulated, with the focus on temporal and spatial feature of convection provocation and the relation between rain forecast and the status of convection provocation. The reason why forecasted rain is less than observation is discussed. In the 24-hour rain simulation of June 21st, the rain belt is very close to observation, but the simulated meso-scale torrential centre differs a lot from each of the parameterization schemes. Initial provocation status and time change of convection in three schemes are quite different and relate closely to their 24-hour precipitation simulations. Convection provocation time is not the same as the three schemes. Generally speaking, SAS scheme predicts the convection better, but the shortcoming is that the triggered rain mount is nearly the same while the observed rain amount differs much. In the simulation with KFETA scheme, the fact that the vertical velocity in the centre of the troposphere tends to be smaller than normal is one reason for the less predicted rain