Submesoscale Instabilities in Mesoscale Eddies
Submesoscale Instabilities in Mesoscale Eddies
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DOI：
10.1175/jpo-d-16-0178.1
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发表时间：
2017-12
影响因子：
3.5
通讯作者：
L. Brannigan;David P. Marshall;A. N. Naveira Garabato;A. Nurser;J. Kaiser
中科院分区：
文献类型：
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作者：
L. Brannigan;David P. Marshall;A. N. Naveira Garabato;A. Nurser;J. Kaiser
亚中尺度过程在锋面观测和模拟中得到了广泛的研究。最近的理想化模拟表明，亚中尺度不稳定性也发生在斜压中尺度气旋和反气旋。反气旋中的不稳定性比气旋中的不稳定性增长得更快，网格分辨率也更粗。这种不稳定性导致反气旋的抑制作用大于气旋。不稳定性也导致反气旋周围的平均方位角喷流从2公里分辨率的变化，但类似的效果只发生在0.25公里分辨率的气旋。被动示踪剂的数值实验表明，亚中尺度不稳定性导致更深的俯冲在反气旋内部比气旋性涡旋，因为露头的等密度线延伸到更深的温跃层的反气旋。一个充满活力的分析表明，垂直剪切生产和垂直浮力通量是重要的反气旋，但主要是垂直浮力通量发生在气旋在这些决议。由于Ekman浮力通量的不对称效应，能量源和能量汇在涡旋周围的方位角上发生变化。滑翔机断面的中尺度反气旋在塔斯曼海显示，低层化和高氧浓度的水被发现在反气旋，在一种方式，可能是一致的模式预测中尺度涡的次中尺度俯冲。
Submesoscale processes have been extensively studied in observations and simulations of fronts. Recent idealized simulations show that submesoscale instabilities also occur in baroclinic mesoscale cyclones and anticyclones. The instabilities in the anticyclone grow faster and at coarser grid resolution than in the cyclone. The instabilities lead to larger restratification in the anticyclone than in the cyclone. The instabilities also lead to changes in the mean azimuthal jet around the anticyclone from 2-km resolution, but a similar effect only occurs in the cyclone at 0.25-km resolution. A numerical passive tracer experiment shows that submesoscale instabilities lead to deeper subduction in the interior of anticyclonic than cyclonic eddies because of outcropping isopycnals extending deeper into the thermocline in anticyclones. An energetic analysis suggests that both vertical shear production and vertical buoyancy fluxes are important in anticyclones but primarily vertical buoyancy fluxes occur in cyclones at these resolutions. The energy sources and sinks vary azimuthally around the eddies caused by the asymmetric effects of the Ekman buoyancy flux. Glider transects of a mesoscale anticyclone in the Tasman Sea show that water with low stratification and high oxygen concentrations is found in an anticyclone, in a manner that may be consistent with the model predictions for submesoscale subduction in mesoscale eddies.