次网格地形坡度坡向参数化及其对区域气候模拟的影响

Parameterization of Subgrid Topographic Slope and Orientation in Numerical Model and Its Effect on Regional Climate Simulation

随着数值模式水平分辨率的提高, 模式下垫面特征的描述更加仔细, 针对东亚地区复杂的地形和植被特征, 发展适合非均匀下垫面的地表通量参数化方案, 对改进数值模式和刻画高原附近地区复杂地形动力和热力效应的能力非常必要。本文通过计算次网格地形坡度、坡向参数及其对到达地面短波辐射通量的影响, 提出次网格地形热力效应的参数化方案, 改进数值模式中复杂地形区域地面热量平衡的计算。利用p-σ区域气候模式的数值试验结果表明, 次网格地形热力效应参数化方案的引入, 对东亚地区夏季气候尤其是降水的模拟有明显的改进。

It is a very important and difficult problem to deal with complex terrain effectively in numerical weather forecast and climate models. A parameterizationscheme of subgrid topographic slope and orientation in a %p-σ% regional climate model developed in Nanjing University has been proposed to improve the calculation of surface energy balance in the regional climate model over complex terrain areas. Numerical experiment results by using %p-σ% regional climate model show that the parameterization scheme of subgrid topographic slope and orientation can improve the simulation of 500 hPa geopotential height and especially the summer rainfall over East Asia.