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首页> 外文期刊>Journal of Physical Oceanography >Small-Scale Potential Vorticity in the Upper-Ocean Thermocline
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Small-Scale Potential Vorticity in the Upper-Ocean Thermocline

机译：上海热割机中的小规模潜在涡流

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Twenty Electromagnetic Autonomous Profiling Explorer (EM-APEX) floats in the upper-ocean thermocline of the summer Sargasso Sea observed the temporal and vertical variations of Ertel potential vorticity (PV) at 7-70-m vertical scale, averaged over O(4-8)-km horizontal scale. PV is dominated by its linear components-vertical vorticity and vortex stretching, each with an rms value of similar to 0.15f. In the internal wave frequency band, they are coherent and in phase, as expected for linear internal waves. Packets of strong, 0.2f, vertical vorticity and vortex stretching balance closely with a small net rms PV. The PV spectrum peaks at the highest resolvable vertical wavenumber, similar to 0.1 cpm. The PV frequency spectrum has a red spectral shape, a -1 spectral slope in the internal wave frequency band, and a small peak at the inertial frequency. PV measured at near-inertial frequencies is partially attributed to the non-Lagrangian nature of float measurements. Measurement errors and the vortical mode also contribute to PV in the internal wave frequency band. The vortical mode Burger number, computed using time rates of change of vertical vorticity and vortex stretching, is 0.2-0.4, implying a horizontal kinetic energy to available potential energy ratio of similar to 0.1. The vortical mode energy frequency spectrum is 1-2 decades less than the observed energy spectrum. Vortical mode energy is likely underestimated because its energy at vertical scales 70 m was not measured. The vortical mode to total energy ratio increases with vertical wavenumber, implying its importance at small vertical scales.
机译：夏季Sargasso海上海洋热水下划线的二十个电磁自主分析探险员（EM-Apex）浮动观察了垂直尺度为7-70-m垂直尺度的近距离电位涡度（PV）的时间和垂直变化，平均在O（4- 8）-km水平刻度。 PV由其线性组件 - 垂直涡度和涡旋拉伸来支配，每个涡流均为升温值，同样为0.15f。在内部波频带中，它们是连贯的和相位，正如线性内部波的所预期的那样。强大，> 0.2F，垂直涡度和涡旋延伸平衡与小净RMS光伏紧密相提并论。 PV光谱峰值在最高可分辨的垂直波数，类似于0.1cpm。 PV频谱具有红色谱形状，内部波频带中的-1光谱斜率，惯性频率处的小峰值。在近惯性频率下测量的PV部分归因于浮动测量的非拉格朗日性质。测量误差和志性模式也有助于内部波频带中的PV。使用垂直涡度和涡旋拉伸的变化的时间率计算的涡旋模式汉堡数为0.2-0.4，暗示水平动能，以可用潜在的能量比与0.1相似。涡旋模式能量频谱比观察到的能谱小于1-2数十年。由于其垂直尺度> 70米处的能量，因此可能低估了志性模式能量。总能量比的志性模式随垂直波数而增加，暗示其在小垂直尺度上的重要性。

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