A Modified Dynamic Framework for the Atmospheric Spectral Model and Its Application
A Modified Dynamic Framework for the Atmospheric Spectral Model and Its Application
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DOI：
10.1175/2007jas2514.1
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发表时间：
2008-07
影响因子：
3.1
通讯作者：
Tongwen Wu;R. Yu;Fang Zhang
中科院分区：
文献类型：
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作者：
Tongwen Wu;R. Yu;Fang Zhang
提出了大气环流谱模型的动力学框架，在控制方程中引入参考分层大气温度和参考表面压力，以改进压力梯度力以及表面压力和温度梯度的计算。参考大气温度的垂直剖面大致对应于美国中纬度标准大气对流层和平流层内的垂直剖面，参考表面压力是表面地形位势的函数，并且接近观测到的平均表面压力。温度和表面压力的预测变量被来自规定参考的扰动所取代。详细给出了涡度的显式时差格式和散度、扰动温度和扰动表面压力方程的半隐式时差格式的数值算法。修改后的数值框架在国家大气研究中心 (NCAR) 开发的社区大气模型版本 3 (CAM3) 中实施，以测试其验证和对模拟气候的影响。原始模型和修改后的模型都以相同的光谱分辨率（T42）、相同的物理参数化以及与 1971 年至 2000 年观测到的月平均海面温度和海冰浓度相对应的相同边界条件运行。这使得人们能够与常用的动态框架相比来评估新动态框架的性能。结果表明，区域和全球尺度的模拟气候总体有所改善，特别是温度和风。
This paper describes a dynamic framework for an atmospheric general circulation spectral model in which a reference stratified atmospheric temperature and a reference surface pressure are introduced into the governing equations so as to improve the calculation of the pressure gradient force and gradients of surface pressure and temperature. The vertical profile of the reference atmospheric temperature approximately corresponds to that of the U.S. midlatitude standard atmosphere within the troposphere and stratosphere, and the reference surface pressure is a function of surface terrain geopotential and is close to the observed mean surface pressure. Prognostic variables for the temperature and surface pressure are replaced by their perturbations from the prescribed references. The numerical algorithms of the explicit time difference scheme for vorticity and the semi-implicit time difference scheme for divergence, perturbation temperature, and perturbation surface pressure equation are given in detail. The modified numerical framework is implemented in the Community Atmosphere Model version 3 (CAM3) developed at the National Center for Atmospheric Research (NCAR) to test its validation and impact on simulated climate. Both the original and the modified models are run with the same spectral resolution (T42), the same physical parameterizations, and the same boundary conditions corresponding to the observed monthly mean sea surface temperature and sea ice concentration from 1971 to 2000. This permits one to evaluate the performance of the new dynamic framework compared to the commonly used one. Results show that there is a general improvement for the simulated climate at regional and global scales, especially for temperature and wind.