Renault Lionel, Arsouze Thomas, Desbiolles Fabien, Small Justin
LEGOS, University of Toulouse, IRD, CNRS, CNES, UPS, Toulouse, France.
Barcelona Supercomputing Center, Barcelona, Spain.
Sci Rep. 2024 Dec 30;14(1):31771. doi: 10.1038/s41598-024-82667-2.
The warm Western Boundary Currents (WBCs) and their zonal extensions are persistent, deep, strong and narrow oceanic currents. They are known to anchor and energize the Extra-Tropical storm tracks by frontal thermal air-sea interactions. However, even in the latest generation of climate models, WBCs are characterized by large biases, and both the present storm-track activity and its recent intensification are poorly estimated. Mesoscale air-sea interactions, and in particular the Current Feedback to the Atmosphere (CFB) have been shown to be important in ocean and in particular WBC dynamics as they modify the energy budget of the ocean. CFB causes eddy-killing by drag friction between currents and the atmosphere. It damps the oceanic eddy activity, and, thus, weakens the eddy-mean flow interaction, stabilizing WBCs. Based on cutting-edge high-resolution coupled global simulations, we show that the stabilization of WBCs by CFB modulates the mean Sea Surface Temperature and its meridional gradients as well and the turbulent heat fluxes between the ocean and the atmosphere. This alters the baroclinicity of the lower atmosphere, which in turn modulates the extra tropical storm-tracks intensity by up to 15%.
温暖的西边界流（WBCs）及其纬向延伸是持续存在、深度较大、强劲且狭窄的洋流。众所周知，它们通过锋面热海气相互作用来固定并增强温带风暴路径。然而，即使在最新一代的气候模型中，WBCs仍存在较大偏差，当前的风暴路径活动及其近期的增强情况都估计得很差。中尺度海气相互作用，特别是海流对大气的反馈（CFB），在海洋尤其是WBC动力学中已被证明很重要，因为它们会改变海洋的能量收支。CFB通过海流与大气之间的拖曳摩擦导致涡旋消散。它抑制了海洋涡旋活动，从而削弱了涡旋与平均流的相互作用，使WBCs趋于稳定。基于前沿的高分辨率全球耦合模拟，我们表明CFB对WBCs的稳定作用也会调节平均海表面温度及其经向梯度，以及海洋与大气之间的湍流通量。这改变了低层大气的斜压性，进而使温带风暴路径强度最多改变15%。
