Statistically Steady State Large‐Eddy Simulations Forced by an Idealized GCM: 1. Forcing Framework and Simulation Characteristics
Statistically Steady State Large‐Eddy Simulations Forced by an Idealized GCM: 1. Forcing Framework and Simulation Characteristics
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DOI：
10.1029/2019ms001814
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发表时间：
2020-02
影响因子：
6.8
通讯作者：
Zhaoyi Shen;K. Pressel;Zhihong Tan;T. Schneider
中科院分区：
文献类型：
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作者：
Zhaoyi Shen;K. Pressel;Zhihong Tan;T. Schneider
系统地使用大涡模拟（LES）有可能为一般环流模型（GCMs）中的次网格尺度过程（如湍流、对流和云）的参数化提供信息。在此我们展示如何运行LES来模拟GCM的网格柱，从而在动态机制的横截面上生成LES。LES的设置大致复制了GCM网格柱中的热力和水分收支。来自GCM的热量和水分的可解水平与垂直输送以及大尺度压力梯度在LES中被设定为强迫项。LES由规定的地表温度驱动，但大气温度和湿度可自由调整，从而减少了GCM场对LES的影响。在GCM和LES中，辐射传输都以统一但理想化的方式处理（无水蒸气反馈或云辐射效应的半灰体大气）。我们表明，在此设置下的LES在不趋近于GCM热力学廓线的情况下达到统计上的稳定状态。这些稳定状态为开发GCM参数化提供了训练数据。同样的LES设置也为研究云对全球变暖的响应提供了良好基础。
Using large‐eddy simulations (LES) systematically has the potential to inform parameterizations of subgrid‐scale processes in general circulation models (GCMs), such as turbulence, convection, and clouds. Here we show how LES can be run to simulate grid columns of GCMs to generate LES across a cross section of dynamical regimes. The LES setup approximately replicates the thermodynamic and water budgets in GCM grid columns. Resolved horizontal and vertical transports of heat and water and large‐scale pressure gradients from the GCM are prescribed as forcing in the LES. The LES are forced with prescribed surface temperatures, but atmospheric temperature and moisture are free to adjust, reducing the imprinting of GCM fields on the LES. In both the GCM and LES, radiative transfer is treated in a unified but idealized manner (semigray atmosphere without water vapor feedback or cloud radiative effects). We show that the LES in this setup reaches statistically steady states without nudging to thermodynamic GCM profiles. The steady states provide training data for developing GCM parameterizations. The same LES setup also provides a good basis for studying the cloud response to global warming.