We present an efficient and flexible alternative method to connect islands and offshore tide gauges with the height system on land. The method uses a regional, high-resolution hydrodynamic model that provides total water levels. From the model, we obtain the differences in mean water level (MWL) between tide gauges at the mainland and at the islands or offshore platforms. Adding them to the MWL relative to the national height system at the mainland’s tide gauges realizes a connection of the island and offshore platforms with the height system on the mainland. Numerical results are presented for the connection of the Dutch Wadden islands with the national height system (Normaal Amsterdams Peil, NAP). Several choices of the period over which the MWLs are computed are tested and validated. The best results were obtained when we computed the MWL only over the summer months of our 19-year simulation period. Based on this strategy, the percentage of connections for which the absolute differences between the observation- and model-derived MWL differences are $$\le 1$$≤1 cm is about 34% (46 out of 135 possible leveling connections). In this case, for each Wadden island we can find several connections that allow the transfer of NAP with (sub-)centimeter accuracy.

中文翻译：

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使用流体动力学模型的岛屿和大陆之间的高度系统连接：将荷兰瓦登岛连接到阿姆斯特丹军械基准 (NAP) 的案例研究

我们提出了一种有效且灵活的替代方法，将岛屿和近海潮汐测量仪与陆地上的高度系统连接起来。该方法使用提供总水位的区域高分辨率水动力模型。从模型中，我们获得了大陆与岛屿或海上平台的潮汐计之间的平均水位 (MWL) 差异。将它们添加到大陆测潮仪相对于国家高度系统的MWL中，实现了岛屿和海上平台与大陆高度系统的连接。给出了荷兰瓦登群岛与国家高度系统 (Normaal Amsterdams Peil, NAP) 连接的数值结果。测试并验证了计算 MWL 期间的多种选择。当我们仅在 19 年模拟期的夏季月份计算 MWL 时，获得了最佳结果。基于此策略，观测值和模型得出的 MWL 差异之间的绝对差异为 $$\le 1$$≤1 cm 的连接百分比约为 34%（135 个可能的水平连接中的 46 个）。在这种情况下，对于每个瓦登岛，我们可以找到几个允许以（亚）厘米精度传输 NAP 的连接。