再谈海冰边缘区域中尺度涡旋形成机制——非线性平流

利用三维海洋模式与二维海冰模式耦合，研究海冰边缘区域中尺度涡旋形成最重要的机制之一——非线性平流机制。二维海洋模型模拟结果表明，非线性平流机制在水深比较浅的时候更加重要。不同于把海洋考虑成一个正压流体的二维模型，三维海洋模型中海冰通过海-冰相互作用直接影响海洋表层。我们发现在三维海洋模型实验中，中尺度涡旋和海洋表面抬升都对水深变化敏感。海流速度的垂直结构表面，当海水变浅，各层海流都变得更快。相同风应力作用相同时间之后，表面抬升与海水深度成反比关系。同时我们还发现由于垂直运动，在三维海洋模型实验结果中，海面抬升非常小，只有二维海洋模型实验结果的1%。垂直运动是三维海洋模型和二维海洋模型实验结果不同的根本原因。

Revisiting mesoscale eddy genesis mechanism of nonlinear advection in a marginal ice zone

A three-dimensional (3-D) ocean model is coupled with a two-dimensional (2-D) sea ice model, to revisit a nonlinear advection mechanism, one of the most important mesoscale eddy genesis mechanisms in the marginal ice zone. Two-dimensional ocean model simulations suggest nonlinear advection mechanism is more important when the water gets shallower. Instead of considering the ocean as barotropic fluid in the 2-D ocean model, the 3-D ocean model allows the sea ice to affect the current directly in the surface layer via ocean-ice interaction. It is found that both mesoscale eddy and sea surface elevation are sensitive to changes in a water depth in the 3-D simulations. The vertical profile of a current velocity in 3-D experiments suggests that when the water depth gets shallower, the current move faster in each layer, which makes the sea surface elevation be nearly inverse proportional to the water depth with the same wind forcing during the same time. It is also found that because of the vertical motion, the magnitude of variations in the sea surface elevation in the 3-D simulations is very small, being only 1% of the change in the 2-D simulations. And it seems the vertical motion to be the essential reason for the differences between the 3-D and 2-D experiments.