In the marginal ice zone, surface waves drive motion of sea ice floes. The motion of floes relative to each other can cause periodic collisions, and drives the formation of pancake sea ice. Additionally, the motion of floes relative to the water results in turbulence generation at the interface between the ice and ocean below. These are important processes for the formation and growth of pancakes, and likely contribute to wave energy loss. Models and laboratory studies have been used to describe these motions, but there have been no in situ observations of relative ice velocities in a natural wave field. Here, we use shipboard stereo video to measure wave motion and relative motion of pancake floes simultaneously. The relative velocities of pancake floes are typically small compared to wave orbital motion (i.e. floes mostly follow the wave orbits). We find that relative velocities are well-captured by existing phase-resolved models, and are only somewhat over-estimated by using bulk wave parameters. Under the conditions observed, estimates of wave energy loss from ice–ocean turbulence are much larger than from pancake collisions. Increased relative pancake floe velocities in steeper wave fields may then result in more wave attenuation by increasing ice–ocean shear.

中文翻译：

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使用船载立体视频的煎饼海冰运动学和动力学

在边缘冰区，表面波驱动海冰浮冰运动。浮体之间的相对运动会引起周期性碰撞，并推动薄饼状海冰的形成。此外，漂浮物相对于水的运动导致在下面的冰和海洋之间的界面处产生湍流。这些是煎饼形成和生长的重要过程，可能会导致波浪能损失。模型和实验室研究已用于描述这些运动，但没有对自然波场中相对冰速的现场观测。在这里，我们使用船载立体视频同时测量煎饼漂浮物的波动和相对运动。与波浪轨道运动相比，薄饼状漂浮物的相对速度通常较小（即，漂浮物大多遵循波浪轨道）。我们发现现有的相位分辨模型很好地捕捉到了相对速度，并且使用体波参数只是略微高估了相对速度。在观察到的条件下，对冰洋湍流造成的波能损失的估计远大于煎饼碰撞造成的。在更陡峭的波场中增加的相对薄饼漂浮速度可能会通过增加冰海切变导致更多的波衰减。