The regional oceanic modeling system (ROMS): a split-explicit, free-surface, topography-following-coordinate oceanic model
The regional oceanic modeling system (ROMS): a split-explicit, free-surface, topography-following-coordinate oceanic model
复制标题
DOI：
10.1016/j.ocemod.2004.08.002
复制
发表时间：
2005-01-01
期刊：
影响因子：
3.2
通讯作者：
McWilliams, JC
中科院分区：
文献类型：
--
作者：
Shchepetkin, AF;McWilliams, JC
本研究的目的是为适用于高分辨率、自由表面、地形追随坐标海洋模型的时间步长和模态分裂找到一种最优数值算法组合。由于斜压动量和示踪物方程之间以及类似地正压动量和连续性方程之间存在数学反馈，对两种模态进行处理是有利的，这样在动量方程的一个时间步长之后，计算出的速度立即参与示踪物和连续性的计算，反之亦然，而不是同时推进所有方程一个时间步长。这导致了一类新的时间步长算法，它将前向 - 后向反馈与最著名的同步算法相结合，由于内部稳定性增强，允许增加时间步长而不牺牲其准确性。基于这些算法，我们为一个实际的海洋模型设计了一个分裂显式水动力内核，它解决了与模态分裂相关的多个数值问题。这个内核通过一个专门设计的滤波函数利用正压模态的一致时间平均，以保证示踪物的精确守恒和恒定性保持特性，并产生更准确（高达二阶）的、可分辨的正压过程，同时防止未分辨的正压信号混叠到缓慢的斜压运动中。由于重新定义了正压压力梯度项以考虑密度场的局部变化，它具有更准确的模态分裂，同时保持了分裂模型的计算效率。它自然地与各种中心和上游偏向的高阶平流算法兼容，并有助于降低混合过程和子模型昂贵的物理参数化的计算成本。（c）2004爱思唯尔有限公司。保留所有权利。
The purpose of this study is to find a combination of optimal numerical algorithms for time-stepping and mode-splitting suitable for a high-resolution, free-surface, terrain-following coordinate oceanic model. Due to mathematical feedback between the baroclinic momentum and tracer equations and, similarly, between the barotropic momentum and continuity equations, it is advantageous to treat both modes so that, after a time step for the momentum equation, the computed velocities participate immediately in the computation of tracers and continuity, and vice versa, rather than advancing all equations for one time step simultaneously. This leads to a new family of time-stepping algorithms that combine forward-backward feedback with the best known synchronous algorithms, allowing an increased time step due to the enhanced internal stability without sacrificing its accuracy. Based on these algorithms we design a split-explicit hydrodynamic kernel for a realistic oceanic model, which addresses multiple numerical issues associated with mode splitting. This kernel utilizes consistent temporal averaging of the barotropic mode via a specially designed filter function to guarantee both exact conservation and constancy preservation properties for tracers and yields more accurate (up to second-order), resolved barotropic processes, while preventing aliasing of unresolved barotropic signals into the slow baroclinic motions. It has a more accurate mode-splitting due to redefined barotropic pressure-gradient terms to account for the local variations in density field, while maintaining the computational efficiency of a split model. It is naturally compatible with a variety of centered and upstream-biased high-order advection algorithms, and helps to mitigate computational cost of expensive physical parameterization of mixing processes and submodels. (c) 2004 Elsevier Ltd. All rights reserved.