次网格地形动力效应参数化及其对降水模拟效果的影响  

A Parameterization Scheme for the Dynamic Effects of Subgrid Topography and Its Impacts on Rainfall Simulation

作　　者：沈玉伟[1] 张耀存[1] 钱永甫[1] 

机构地区：[1]南京大学大气科学系,江苏南京210093

出　　处：《高原气象》2007年第4期655-665,共11页Plateau Meteorology

基　　金：国家自然科学基金项目(40333026)资助

摘　　要：地形对气流的动力抬升作用是地形降水的重要产生机制之一,为了在模式中考虑地形对气流的动力抬升作用,改进模式对复杂地形区域的降水模拟效果,本文提出了一个次网格地形动力效应参数化方案。在模式中首先利用高分辨率的地形高度资料计算出次网格格点处的地形坡度、坡向,这些微观地形参数可以较为精细地描述次网格尺度地形信息;然后再根据地面气压与地形对气流动力抬升作用的关系,对地面气压倾向进行次网格修正;最后利用p-σ区域气候模式进行了三个数值试验,检验该方案对模式模拟降水能力的影响。结果表明,次网格地形动力效应参数化方案的引入,对中国区域的降水模拟有明显改进,尤其对冬、春季的降水模拟,无论是分布范围还是中心最大强度都与实况比较接近。The dynamic uplift effect of airflow over a mountain is one of the important mechanisms for generation of orographic precipitation. In order to improve rainfall simulation in a regional climate model over complex terrain areas, a parameterizationscheme for the dynamic uplift effect of subgrid topography is proposed in this study. In this scheme the subgrid topographic slope and orientation are calculated based on higher resolution surface elevation data, and then the tendency of surface pressure is modified according to the relationship between surface pressure and the dynamic effects of subgrid topography on airflow. Thereafter, three numerical experiments are conducted to evaluate the impacts of the parameterization scheme on rainfall simulation in the P-σ regional climate model. The modeling results show that this parameterization scheme for the dynamic uplift effect of subgrid topography can improve the rainfall simulation over China, especially during winter and spring seasons.

关 键 词：次网格地形 地形坡度 坡向 参数化方案 降水的数值模拟 

分 类 号：P458.121[天文地球—大气科学及气象学]