模式水平扩散参数化的数值分析与试验  

NUMERICAL ANALYSIS AND EXPERIMENT FOR THE MODEL HORIZONTAL DIFFUSION

作　　者：葛孝贞[1] 雷孝恩[2] 

机构地区：[1]南京大学大气科学系,南京210093 [2]中国科学院大气物理研究所,北京100029

出　　处：《气象科学》1997年第3期213-220,共8页Journal of the Meteorological Sciences

基　　金：国家自然科学基金!49675266

摘　　要：为了研究整个对流层中水平扩散系数（Ky）随高度变化的参数化形式以及平流格式的数值扩散对物质浓度分布的影响及二者对模式结果影响的相互关系，本文用“高分辨对流层物质交换模式”（EM3）对三种不同Ky参数化型能对行星边界层（PBL）内受下垫面影响的高频湍流和PBL以上整个对流层受水平风切变产生的切变湍流分层结构具有良好的描述能力；模式采用几乎无数值扩散二阶矩守恒的Prather平流差分格式（以下简称PRS格式）代替模式Smo－larkiewic格式（以下简称SMO格式），比较模拟结果，可减小一个量级的数值扩散，并能很好地描述物质中心的水平平均运动；在区域尺度污染模式中，与平流作用相比，水平扩散的作用显然是不能忽略的，但是模式只有选用数值扩散小，高精度的平流格式（如本文引进的PRS格式）能才使实际大气的Ky对物质分布的贡献更重要，尤其是对流层上半部。In order to study effect of parameterization forms about variation of horlzontal eddy dif-fusivity (Ky or Kx) with height in the whole troposphere (TL) on species distribution, con-trastive numerical simulations for three kinds of Ky Patterns and two advection differencescheme are made with' A high resolution model for species exchange in TL: (EM3)'. The re-sults show that layering structures on high frequency turbulence influenced by the relativemotion of the earth's surface in planetary boundary layer(PBL) and shear turbu1ence derivedfrom horizontal wind shear in TL 3bove PBL are very well described by JKy pattern; by sub-stituting Prather's scheme on conservation of second-order moments for Smolarkiewicz's pos-itive definite advection scheme,the numerical diffusion can decrease by one order of magni-tude,and horizontal mean motion of the species centers can very well described ; in the region-al pollutant motlel, comparing horizontal diffusion with both the horizontal advection and thenumerical diffusion,its role is not neglected,after Prather's scheme is introduced,the true at-mospheric Ky makes more important contribution to species transfer,especially in the upperhalf part of TL.

关 键 词：水平扩散系数 切变湍流 污染物 数值分析 对流层 

分 类 号：X16[环境科学与工程—环境科学] P435[天文地球—大气科学及气象学]