Alternative implementations of the semi‐Lagrangian semi‐implicit schemes in the ECMWF model
Alternative implementations of the semi‐Lagrangian semi‐implicit schemes in the ECMWF model
复制标题
ECMWF 模型中半拉格朗日半隐式方案的替代实现
DOI：
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发表时间：
2001
期刊：
影响因子：
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通讯作者：
M. Cullen
中科院分区：
文献类型：
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作者：
M. Cullen
全球模型未来发展的一个重要问题是最佳性能所需的隐式解的程度，以及这是否会改变谱模型和有限差分模型的相对成本效益。这是通过使用欧洲中期天气预报中心模式中的预报器-校正器集成方案来探索的，其中两个步骤都使用当前的半隐式程序进行集成。这相当于使用现有的半隐式方法作为预条件，对全隐式格式进行第一次迭代。结果表明，只要重新计算重力波项的非线性部分和半拉格朗日轨迹，就可以获得好处。这表明更多的全隐式格式在数值模式中将是有益的。然而，椭圆求解器的成本不会占主导地位，因为在每次迭代中都需要重新计算大量的趋势。
An important issue for the future development of global models is the degree of implicit solution required for optimum performance, and whether this will change the relative cost‐effectiveness of spectral and finite‐difference models. This is explored by using a predictor‐corrector integration scheme in the European Centre for Medium‐Range Weather Forecasts model, where both steps are integrated using the current semi‐implicit procedure. This is equivalent to taking a first iteration towards a fully implicit scheme, using the existing semi‐implicit method as a preconditioner. The results show that benefit can be obtained provided that both the nonlinear part of the gravity‐wave terms and the semi‐Lagrangian trajectory are recalculated. This suggests that more fully implicit schemes will be beneficial in numerical models. However, the cost of elliptic solvers will not dominate as significant recalculation of tendencies will be required at each iteration.