Stimulated Imbalance and the Enhancement of Eddy Kinetic Energy Dissipation by Internal Waves
Stimulated Imbalance and the Enhancement of Eddy Kinetic Energy Dissipation by Internal Waves
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DOI：
10.1175/jpo-d-16-0117.1
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发表时间：
2017-01-01
影响因子：
3.5
通讯作者：
McWilliams, James C.
中科院分区：
文献类型：
--
作者：
Barkan, Roy;Winters, Kraig B.;McWilliams, James C.
通过对理想风驱动槽道流场的亚中尺度数值模拟，研究了高频风驱动的内波对能量通道的影响。检查两个过程：由外部强迫的IW直接提取中尺度能量，然后由IW前向能量级联耗散和刺激不平衡，通过这种机制，外部强迫的IW触发前向中尺度到亚中尺度能量级联耗散。本研究发现，频率和波数谱斜率是浅的解决方案与高频强迫相比，没有解决方案，体积平均内部动能耗散率增加十倍。增强耗散率与增加的高频风功之比为1.3，表明了国际水介导的前向叶栅的重要性。低（中尺度），中（次中尺度），和高频（IW）带之间的能量交换的时间尺度分析表明，相应的增加动能E-k和可用的势能APE转移中尺度到次中尺度（受激不平衡）和中尺度到IW（直接提取）。确定了两种直接提取途径：中尺度到IW Ek转移和中尺度到IW APE转移，然后是IW APE到IW Ek转换。空间尺度分析的涡-IW相互作用的解决方案与高频强迫表明，在反气旋和气旋内的前向Ek和APE传输的等效增加。
The effects of internal waves (IWs), externally forced by high-frequency wind, on energy pathways are studied in submesoscale-resolving numerical simulations of an idealized wind-driven channel flow. Two processes are examined: the direct extraction of mesoscale energy by externally forced IWs followed by an IW forward energy cascade to dissipation and stimulated imbalance, a mechanism through which externally forced IWs trigger a forward mesoscale to submesoscale energy cascade to dissipation. This study finds that the frequency and wavenumber spectral slopes are shallower in solutions with high-frequency forcing compared to solutions without and that the volume-averaged interior kinetic energy dissipation rate increases tenfold. The ratio between the enhanced dissipation rate and the added high-frequency wind work is 1.3, demonstrating the significance of the IW-mediated forward cascades. Temporal-scale analysis of energy exchanges among low-(mesoscale), intermediate-(submesoscale), and high-frequency (IW) bands shows a corresponding increase in kinetic energy E-k and available potential energy APE transfers from mesoscales to submesoscales (stimulated imbalance) and mesoscales to IWs (direct extraction). Two direct extraction routes are identified: a mesoscale to IW Ek transfer and a mesoscale to IW APE transfer followed by an IW APE to IW Ek conversion. Spatial-scale analysis of eddy-IW interaction in solutions with high-frequency forcing shows an equivalent increase in forward Ek and APE transfers inside both anticyclones and cyclones.