Rai Shikhar, Farrar J Thomas, Aluie Hussein
Department of Mechanical Engineering, University of Rochester, Rochester, NY, USA.
Department of Physical Oceanography, Woods Hole Oceanographic Institution, Woods Hole, MA, USA.
Nat Commun. 2025 Jan 30;16(1):1172. doi: 10.1038/s41467-025-56310-1.
Ocean weather comprises vortical and straining mesoscale motions, which play fundamentally different roles in the ocean circulation and climate system. Vorticity determines the movement of major ocean currents and gyres. Strain contributes to frontogenesis and the deformation of water masses, driving much of the mixing and vertical transport in the upper ocean. While recent studies have shown that interactions with the atmosphere damp the ocean's mesoscale vortices O(100) km in size, the effect of winds on straining motions remains unexplored. Here, we derive a theory for wind work on the ocean's vorticity and strain. Using satellite and model data, we discover that wind damps strain and vorticity at an equal rate globally, and unveil striking asymmetries based on their polarity. Subtropical winds damp oceanic cyclones and energize anticyclones outside strong current regions, while subpolar winds have the opposite effect. A similar pattern emerges for oceanic strain, where subtropical convergent flow is damped along the west-equatorward east-poleward direction and energized along the east-equatorward west-poleward direction. These findings reveal energy pathways through which the atmosphere shapes ocean weather.
海洋天气包含涡旋和应变中尺度运动，它们在海洋环流和气候系统中发挥着截然不同的作用。涡度决定了主要洋流和环流的运动。应变有助于锋生和水体变形，驱动了上层海洋的大部分混合和垂直输运。虽然最近的研究表明，与大气的相互作用会抑制海洋中尺度涡旋（大小约为100公里），但风对应变运动的影响仍未得到探索。在这里，我们推导了风对海洋涡度和应变做功的理论。利用卫星和模型数据，我们发现风在全球范围内以相同的速率抑制应变和涡度，并揭示了基于它们极性的显著不对称性。亚热带风在强流区域以外抑制海洋气旋并增强反气旋，而亚极地风则有相反的效果。海洋应变也出现类似的模式，亚热带辐合流在沿西向赤道东向极地方向受到抑制，而在沿东向赤道西向极地方向则得到增强。这些发现揭示了大气塑造海洋天气的能量途径。
