In this study, 10-day forecasts of Atlantic lows are investigated by comparing the forecasts of the standard Climate version of the Lokal Modell using terrain-following coordinates to that of the cut-cell Lokal Modell with z coordinates (LMZ). As indicated by idealized tests of the atmosphere at rest and mountain wave tests, LMZ exhibits a much better approximation of the lower boundary condition due to the use of the cut-cell approximation. An important difference to the terrain-following coordinate is that with cut-cells, a single steep mountain as defined different from 0 at only one point, has a reasonable up–downwind scheme and does not become unstable. We are interested in the large-scale structure of Atlantic lows, which are under the influence of the high orography of Greenland. The steep orography of Greenland has a considerable impact on these lows, even though they are positioned to a large part over water. It is found that at Day 6, both models yield similar forecasts, which is consistent with the fact that Day 6 is in the useful forecast range of both models. At Day 10, the forecasts are quite different, indicating a sensitivity of the 10-day forecast to the discretization in question.

中文翻译：

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使用切割单元的中期预测：敏感性研究

在这项研究中，通过比较使用地形跟随坐标的 Lokal Modell 标准气候版本的预测与使用 z 坐标 (LMZ) 的切割单元 Lokal Modell 的预测来研究大西洋低点的 10 天预测。正如对静止大气的理想化测试和山波测试所表明的那样，由于使用了切割单元近似，LMZ 表现出更好的下边界条件近似。与地形跟随坐标的一个重要区别是，对于切割单元，单个陡峭的山峰定义为仅在一个点与 0 不同，具有合理的上-下风方案并且不会变得不稳定。我们对受格陵兰高地地形影响的大西洋低地的大规模结构感兴趣。格陵兰陡峭的地形对这些低点有相当大的影响，即使它们大部分位于水面上。发现在第 6 天，两个模型产生了相似的预测，这与第 6 天在两个模型的有用预测范围内的事实是一致的。在第 10 天，预测完全不同，表明 10 天预测对所讨论的离散化很敏感。