Mode 2 waves on the continental shelf: Ephemeral components of the nonlinear internal wavefield
Mode 2 waves on the continental shelf: Ephemeral components of the nonlinear internal wavefield
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DOI：
10.1029/2009jc005605
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发表时间：
2010-07
影响因子：
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通讯作者：
E. Shroyer;J. Moum;J. Nash
中科院分区：
文献类型：
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作者：
E. Shroyer;J. Moum;J. Nash
2006年夏季在美国新泽西州近海获得的系泊记录中零星地出现了沿海岸传播的2型非线性波。在相隔1公里的两个系泊之间跟踪单个模式2数据包；然而，在距离较远（约10公里）的系泊间无法跟踪数据包。无法通过系泊阵列远距离跟踪单个数据包，再加上船上的详细观测，表明这些波的寿命很短。利用声波后向散射、声波多普勒流谱仪和湍流谱仪记录了船载波群的演变。领头的模态2波迅速改变了形式，形成了一个短的、小振幅的模态1波尾部。模态1振荡的波长符合线性理论所期望的共传播尾的波长。混合层中的湍流耗散和短模态1波的辐射导致了超前模态2波的快速能量损失，这与观测到的衰减速率和仅几个小时的短寿命一致。导模2波的能量比实验中观测到的1模非线性内波能量小10 ~ 100倍；然而，波浪局域湍流耗散的大小是相似的。
[1] Shoreward propagating, mode 2 nonlinear waves appear sporadically in mooring records obtained off the coast of New Jersey in the summer of 2006. Individual mode 2 packets were tracked between two moorings separated by 1 km; however, packets could not be tracked between moorings separated by greater distances from one another (∼10 km). The inability to track individual packets large distances through the mooring array combined with detailed observations from a ship suggest that these waves are short lived. The evolution of the ship-tracked wave group was recorded using acoustic backscatter, acoustic Doppler current profilers, and turbulence profiling. The leading mode 2 wave quickly changed form and developed a tail of short, small-amplitude mode 1 waves. The wavelength of the mode 1 oscillations agreed with that expected for a copropagating tail on the basis of linear theory. Turbulent dissipation in the mixed layer and radiation of the short mode 1 waves contributed to rapid energy loss in the leading mode 2 wave, consistent with the observed decay rate and short life span of only a few hours. The energy in the leading mode 2 wave was 10–100 times smaller than the energy of mode 1 nonlinear internal waves observed during the experiment; however, the magnitudes of wave-localized turbulent dissipation were similar.