Balanced Models and Dynamics for the Large- and Mesoscale Circulation
Balanced Models and Dynamics for the Large- and Mesoscale Circulation
复制标题
大尺度和中尺度环流的平衡模型和动力学
DOI：
--
复制
发表时间：
1997
期刊：
影响因子：
--
通讯作者：
Jian Wang
中科院分区：
文献类型：
--
作者：
M. Mundt;G. Vallis;Jian Wang
通过数值模拟检验了一个结合准地转方程和行星地转方程动力学的平衡模型。该模型是有效的科里奥利参数和层厚度，典型的动态在环流尺度和更大的变化，以及中尺度动力学中，相对涡度的平流不能忽略。对于远大于变形半径的长度尺度，模式方程中的主要平衡是行星地转方程，而对于天气尺度，模式的动力学渐近接近准地转方程。该模型包括平流的地转位涡，因此是概念简单，数值容易实现，只需要一个线性椭圆方程的解决方案，每个时间步。它是比较浅水方程和其他各种近似模型，以评估其有效性建模中尺度和大尺度动力学。模拟在一个周期性的通道，也在一个封闭的域与风应力强迫。该配方被发现产生一个实质性的改进，在定性性质的环流模式，并在定量的准确性，在行星地转和（特别是）准地转方程，同时仍然保留了这些方程的概念简单。
A balanced model that incorporates the dynamics of both the quasigeostrophic and planetary geostrophic equations is examined via numerical simulations. The model is valid for large variations in the Coriolis parameter and layer thickness, typical of dynamics at the gyre scale and larger, as well as for mesoscale dynamics in which the advection of relative vorticity cannot be neglected. For length scales much larger than the deformation radius the dominant balances in the model equations are those of the planetary geostrophic equations, whereas for synoptic scales the dynamics of the model are asymptotically close to those of the quasigeostrophic equations. The model consists of the advection of a geostrophic potential vorticity, and is is therefore conceptually simple and numerically easy to implement, requiring the solution of just one linear elliptic equation each time step. It is compared to the shallow-water equations and various other approximate models in order to assess its validity for modeling meso- and large-scale dynamics. Simulations are performed in both a periodic channel and also in a closed domain with wind stress forcing. The formulation is found to yield a substantial improvement in the qualitative nature of the circulation patterns, and in quantitative accuracy, over the planetary geostrophic and (especially) the quasigeostrophic equations, while still retaining much of the conceptual simplicity of those equations.