地表热力非均匀性对近地层相似理论适用性影响的大涡模拟  

Large Eddy Simulation of the Impacts of Surface Heating Heterogeneity on the Applicability of Similarity Theory in the Surface Layer

作　　者：黄慧珊 刘少锋 刘锐 HUANG Huishan;LIU Shaofeng;LIU Rui(School of Atmospheric Sciences,Sun Yat-sen University,Zhuhai,Guangdong Province 519082;Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai),Zhuhai,Guangdong Province 519082)

机构地区：[1]中山大学大气科学学院,广东珠海519082 [2]南方海洋科学与工程广东省实验室(珠海),广东珠海519082

出　　处：《气候与环境研究》2022年第4期480-494,共15页Climatic and Environmental Research

基　　金：国家自然科学基金:41875128;国家重点研发计划项目:2017YFA0604300;南方海洋科学与工程广东省实验室(珠海)创新团队建设项目:311021009。

摘　　要：利用非均匀地表加热的大涡模拟试验,研究了不稳定条件下地表热力非均匀性对近地层相似理论适用性的影响。结果发现,边界层的平均廓线基本不受地表热力非均匀性的影响。进一步分析发现,较大尺度的地表非均匀加热可以激发出有组织的大尺度次级环流,冷暖斑块的通量直到边界层上部才混合均匀;而当地表非均匀尺度较小时,次级环流难以形成有组织的结构,冷暖斑块的通量很快就可以混合均匀。然而,不管是哪种尺度的非均匀地表,非均匀斑块间的平流都对各斑块近地层结构产生重要影响,进而斑块近地层通量—梯度关系与相似理论产生偏差,其中风速梯度关系的偏差更为明显。最后,对目前大气模式中常用的基于相似理论的次网格非均匀地表通量参数化方法——Mosaic方法提出了改进思路。The impacts of surface heating heterogeneity on the applicability of similarity theory in the unstable surface layer are investigated using idealized Large-Eddy Simulation(LES)experiments with prescribed heterogeneous surface heat flux forcing.It is found that the mean profiles in the boundary layer are hardly affected by surface heterogeneity.However,heterogeneous surface heating on a relatively large scale can induce organized large-scale secondary circulations.In this case,the fluxes between COLD and WARM patches are distinct up to the upper boundary layer.On the other hand,there is no such organized secondary circulation developed in smaller heterogeneous scales,and the fluxes are mixed quickly in the low boundary layer.For all heterogeneous cases(from small to large heterogeneous scales),the inter-patch advection greatly impacts the surface layer structure of patches.Therefore,the flux-gradient relationship in those surface layers deviates from the similarity theory,with the deviation more for momentum than for heat.Finally,an improvement to the Mosaic approach based on the similarity theory and widely used for estimating subgrid heterogeneous surface fluxes in current atmosphere models is proposed.

关 键 词：地表非均匀性 相似理论 通量—梯度关系 大涡模拟 地表通量参数化 

分 类 号：P404[天文地球—大气科学及气象学]