Abstract. On 29 October 2018 a windsurfer's mast broke about 1 km offshore from Istria during a severe scirocco storm in the northern Adriatic Sea. He drifted in severe marine conditions until he eventually beached alive and well in Sistiana (Italy) 24 h later. We conducted an interview with the survivor to reconstruct his trajectory and to gain insight into his swimming and paddling strategy. Part of survivor's trajectory was verified using high-frequency radar surface current observations as inputs for Lagrangian temporal back-propagation from the beaching site. Back-propagation simulations were found to be largely consistent with the survivor's reconstruction. We then attempted a Lagrangian forward-propagation simulation of his trajectory by performing a leeway simulation using the OpenDrift tracking code using two object types: (i) person in water in unknown state and (ii) person with a surfboard. In both cases a high-resolution (1 km ) setup of the NEMO v3.6 circulation model was employed for the surface current component, and a 4.4 km operational setup of the ALADIN atmospheric model was used for wind forcing. The best performance is obtained using the person-with-a-surfboard object type, giving the highest percentage of particles stranded within 5 km of the beaching site. Accumulation of particles stranded within 5 km of the beaching site saturates 6 h after the actual beaching time for all drifting-particle types. This time lag most likely occurs due to poor NEMO model representation of surface currents, especially in the final hours of the drift. A control run of wind-only forcing shows the poorest performance of all simulations. This indicates the importance of topographically constrained ocean currents in semi-enclosed basins even in seemingly wind-dominated situations for determining the trajectory of a person lost at sea.

中文翻译：

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在 2018 年 10 月 29 日的亚得里亚海 scrocco 风暴中迷失在海上的人的拉格朗日模型

摘要。2018 年 10 月 29 日，一名风帆冲浪者的桅杆在亚得里亚海北部的一场严重的西罗科风暴中从伊斯特拉岛离岸约 1 公里处折断。他在恶劣的海洋条件下漂流，直到 24 小时后他最终在 Sistiana（意大利）安然无恙地搁浅。我们对幸存者进行了采访，以重建他的轨迹并深入了解他的游泳和划桨策略。使用高频雷达表面电流观测作为来自搁浅地点的拉格朗日时间反向传播的输入，验证了幸存者的部分轨迹。发现反向传播模拟与幸存者的重建基本一致。然后，我们通过使用 OpenDrift 跟踪代码使用两种对象类型执行余地模拟，尝试对他的轨迹进行拉格朗日前向传播模拟：(i) 处于未知状态的水中的人和 (ii) 有冲浪板的人。在这两种情况下，NEMO v3.6 环流模型的高分辨率（1 公里）设置用于表面流分量，而 ALADIN 大气模型的 4.4 公里操作设置用于风力强迫。使用冲浪板对象类型可获得最佳性能，在离海滩 5 公里范围内滞留的颗粒百分比最高。所有漂流颗粒类型的实际搁浅时间后 6 小时，搁浅在搁浅地点 5 公里范围内的颗粒的积累达到饱和。这种时间滞后最有可能是由于表面电流的 NEMO 模型表现不佳，特别是在漂移的最后几个小时。仅风强迫的控制运行显示了所有模拟中最差的性能。