中尺度模式中的三维变量配置
THREE-DIMENSIONAL VARIABLE ALLOCATION IN MESOSCALE MODELS
-
摘要: 由于中尺度模式中采用不同的三维变量配置,必将产生不同的预报和模拟效果。怎样的三维变量分布,才能产生最佳的模拟效果呢?一直没有人从事这方面的研究。为此,在线性非静力滞弹性方程组的基础上,从频率、水平群速和垂直群速方面将中尺度模式中常见的四种三维网格的计算频散性与解析解的情况进行了对比,主要采用图示比较的方法。结果表明:总的来看三维网格C/CP计算频散性能最好,Z/LZ和Z/LY网格次之,C/L网格最差。因此设计非静力斜压模式时,应尽量采用C/CP网格。但C/CP网格对水平波长较短的波,误差相对要大些。如果模拟的波动水平尺度较小时,为减少误差,水平格距要减小。另外C/CP网格主要用在有限差分模式中;要考虑谱模式中的变量配置时,应把C/CP网格和Z/LZ网格或Z/LY网格结合起来使用。Abstract: Forecasts and simulations are varied owing to different allocation of 3-dimensional allocation in mesoscale models. No attempts have been made to address the issue of optimizing the simulation with a 3-dimensional variable distribution that should come to be. On the basis of linear nonhydrostatic anelastic equations, the paper hereby compares, mainly graphically, the computational dispersion with analytical solutions for four kinds of 3-dimensional meshes commonly found in mesoscale models, in terms of frequency, horizontal and vertical group velocities. The result indicates that the 3-D mesh C/CP has the best computational dispersion, followed by Z/LZ and Z/LY, with the C/L having worst performance. It is then known that the C/CP mesh is the most desirable allocation in the design of nonhydrostatic baroclinic models. The mesh has, however, larger errors when dealing with shorter horizontal wavelengths. For the simulation of smaller horizontal scales, the horizontal grid intervals have to be shortened to reduce the errors. Additionally, in view of the dominant use of C/CP mesh in finite-difference models, it is should be used in conjunction with the Z/LZ or Z/LY mesh if variables are allocated in spectral models.
-
[1] WINNINGHOFF F J. On the adjustment toward a geostrophic balance in a simple primitive equation model with applicationto the problems of initialization and objective analysis[M].Ph. D. thesis, University of California, Los Angeles. 1968. [2] ARAKAWA A, LAMB V R. Computational dynamical processes of the UTLA general circulation model. Methods inComputational Physics[M].J. Chang, Ed., Academic Press, 1977. 173-265. [3] 刘宇迪,桂祈军,李昕东,等. 水平网格计算频散性的研究[J].应用气象学报,2001,12: 140-149. [4] 刘宇迪. 水平网格对Rossby波的影响[J].气象学报,2002,60: 76-84. [5] LIU Yudi, WANG Bin, JI Zhongzhen. Research on atmospheric motion in horizontal discrete grids[J].Advances of Atmospheric Sciences,2003,20: 139-148. [6] 王举,刘宇迪. 水平变量配置对地转演变模拟的影响[J].热带气象学报,2003,19: 323-328. [7] 刘宇迪,朱红伟. 垂直网格计算频散性的研究[J].应用气象学报,2001,12: 348-357. [8] 刘宇迪,季仲贞,桂祈军,等. 几种垂直跳点网格计算频散性的比较研究[J].大气科学,2001,25: 523-535. [9] 刘宇迪,程小平. 垂直变量配置与惯性重力波的模拟[J].解放军理工大学学报,2001,2(6): 86-89. [10] LIU Yudi, JI Zhongzhen, WANG Bin. Study on computational properties of several vertical grids with a nonhydrostatic model in comparison to analytical solutions[J].Advances of Atmospheric Sciences, 2002, 19: 528-543.
点击查看大图
计量
- 文章访问数: 931
- HTML全文浏览量: 0
- PDF下载量: 708
- 被引次数: 0