A Proposed Modification to the Robert-Asselin Time Filter*
A Proposed Modification to the Robert-Asselin Time Filter*
复制标题
对 Robert-Asselin 时间滤波器的拟议修改*
DOI：
10.1175/2009mwr2724.1
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发表时间：
2009
影响因子：
3.2
通讯作者：
Williams P
中科院分区：
文献类型：
--
作者：
Williams P
Robert-Asselin 时间滤波器广泛应用于天气和气候的数值模型中。它成功地抑制了与蛙跳时间步进方案相关的虚假计算模式。不幸的是，它对物理模式的抑制也很弱，并严重降低了数值精度。这两个伴随问题的发生是因为滤波器不保留平均状态（在其运行的三个时间片上求平均值）。作者提出了对 Robert-Asselin 滤波器的简单修改，它确实保留了三时间级平均状态。当与蛙跳方案结合使用时，该修改大大减少了对物理模式的影响，并将幅度误差的数值精度提高了两个数量级，达到三阶精度。改进后的过滤器可以很容易地融入现有的大气和海洋大气环流模型中。原则上，它应该提供更忠实的模拟，而几乎不需要额外的计算费用。或者，它可以允许使用更长的时间步长而不损失精度，从而减少给定模拟的计算费用。
The Robert–Asselin time filter is widely used in numerical models of weather and climate. It successfully suppresses the spurious computational mode associated with the leapfrog time-stepping scheme. Unfortunately, it also weakly suppresses the physical mode and severely degrades the numerical accuracy. These two concomitant problems are shown to occur because the filter does not conserve the mean state, averaged over the three time slices on which it operates. The author proposes a simple modification to the Robert–Asselin filter, which does conserve the three-time-level mean state. When used in conjunction with the leapfrog scheme, the modification vastly reduces the impacts on the physical mode and increases the numerical accuracy for amplitude errors by two orders, yielding third-order accuracy. The modified filter could easily be incorporated into existing general circulation models of the atmosphere and ocean. In principle, it should deliver more faithful simulations at almost no additional computational expense. Alternatively, it may permit the use of longer time steps with no loss of accuracy, reducing the computational expense of a given simulation.