A Closure for Updraft–Downdraft Representation of Subgrid-Scale Fluxes in Cloud-Resolving Models
A Closure for Updraft–Downdraft Representation of Subgrid-Scale Fluxes in Cloud-Resolving Models
复制标题
云解析模型中亚网格尺度通量的上升-下降表示的闭包
DOI：
10.1175/mwr-d-13-00166.1
复制
发表时间：
2014
影响因子：
3.2
通讯作者：
C. Moeng
中科院分区：
文献类型：
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作者：
C. Moeng
基于对深对流大涡模拟(LES)资料的分析，提出了次网格尺度(SGS)升、降气流差与可分辨尺度(RS)变量之间的封闭关系，并对云分辨模式(CRM)进行了检验。使用与典型的CRM网格分辨率相对应的截止尺度将LES流场划分为CRM-RS和CRM-SGS。这项研究首先证明了上升气流-下沉气流模式框架在描述整个深对流层上的SGS热量、水汽和动量通量的能力。然后建立了一个闭合方案，将SGS升降气流差与RS变量的水平梯度联系起来。闭合是基于这样的想法，即最大的SGS和最小的RS运动在光谱上是相关联的，因此它们的水平波动必须被强烈地传达出来。这种关系导致了一种SGS方案，它用RS变量的水平梯度来表示垂直SGS通量，这与传统的SGS方案不同。
AbstractA closure relationship between subgrid-scale (SGS) updraft–downdraft differences and resolvable-scale (RS) variables is proposed and tested for cloud-resolving models (CRMs), based on a data analysis of a large-eddy simulation (LES) of deep convection. The LES flow field is partitioned into CRM-RS and CRM-SGS using a cutoff scale that corresponds to a typical CRM grid resolution. This study first demonstrates the capability of an updraft–downdraft model framework in representing the SGS fluxes of heat, moisture, and momentum over the entire deep convection layer. It then formulates a closure scheme to relate SGS updraft–downdraft differences to horizontal gradients of RS variables. The closure is based on the idea that largest SGS and smallest RS motions are spectrally linked and hence their horizontal fluctuations must be strongly communicated. This relation leads to an SGS scheme that expresses vertical SGS fluxes in terms of horizontal gradients of RS variables, which differs from conventional ...