Higher-Order Turbulence Closure and Its Impact on Climate Simulations in the Community Atmosphere Model
Higher-Order Turbulence Closure and Its Impact on Climate Simulations in the Community Atmosphere Model
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DOI：
10.1175/jcli-d-13-00075.1
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发表时间：
2013-12-01
影响因子：
4.9
通讯作者：
Schanen, David P.
中科院分区：
文献类型：
--
作者：
Bogenschutz, Peter A.;Gettelman, Andrew;Schanen, David P.
本文介绍了社区大气模式，版本5（CAM 5）的气候模拟，再加上高阶湍流封闭被称为云层统一的Binormals（CLUBB）。CLUBB是行星边界层和浅层对流的统一参数化，以三元概率密度函数为中心，取代了CAM 5中传统的边界层、浅层对流和云宏观物理方案。与CAM 5相比，CAM-CLUBB改善了基态气候的许多方面。其中最主要的是副热带海洋中层积云向信风积云区的转变。在这些地区，CAM-CLUBB提供了一个更加渐进的过渡，与CAM 5相比，它太突然了，与观测分析更吻合。在CAM-CLUBB中看到的改进可以在很大程度上归因于模拟湍流的逐渐演变，这在一定程度上是参数化的统一性质的结果，以及与CAM 5相比，浅积云的一般改进表示。此外，CAM-CLUBB和CAM 5在海洋边界层云的表现和结构上也有很大的差异。CAM-CLUBB也被证明是更强大的，在边界层云，在全球模拟的垂直分辨率的变化在初步测试。
This paper describes climate simulations of the Community Atmosphere Model, version 5 (CAM5), coupled with a higher-order turbulence closure known as Cloud Layers Unified by Binormals (CLUBB). CLUBB is a unified parameterization of the planetary boundary layer (PBL) and shallow convection that is centered around a trivariate probability density function (PDF) and replaces the conventional PBL, shallow convection, and cloud macrophysics schemes in CAM5. CAM-CLUBB improves many aspects of the base state climate compared to CAM5. Chief among them is the transition of stratocumulus to trade wind cumulus regions in the subtropical oceans. In these regions, CAM-CLUBB provides a much more gradual transition that is in better agreement with observational analysis compared to CAM5, which is too abrupt. The improvement seen in CAM-CLUBB can be largely attributed to the gradual evolution of the simulated turbulence, which is in part a result of the unified nature of the parameterization, and to the general improved representation of shallow cumulus clouds compared to CAM5. In addition, there are large differences in the representation and structure of marine boundary layer clouds between CAM-CLUBB and CAM5. CAM-CLUBB is also shown to be more robust, in terms of boundary layer clouds, to changes in vertical resolution for global simulations in a preliminary test.