Vertical Structure of Dissipation in the Nearshore
Vertical Structure of Dissipation in the Nearshore
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DOI：
10.1175/jpo3098.1
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发表时间：
2007-07
影响因子：
3.5
通讯作者：
F. Feddersen;J. Trowbridge;A. Williams
中科院分区：
文献类型：
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作者：
F. Feddersen;J. Trowbridge;A. Williams
本文用三个声学多普勒流速仪组成的三脚架在一个桑迪海洋海滩的近岸区（平均水深3.2米）观测了湍流动能耗散的垂直结构。表面和底部边界层耗散标度概念在该区域重叠。在三角架处没有发生深度限制的波浪破碎，但确实发生了风引起的白浪破碎。耗散在表层附近最大，在中层最小，在床附近有一个次大值。观察到的耗散不遵循surfzone缩放，也不遵循“日志层”的表面或底部边界层缩放。在上面的两个流速计，耗散遵循修改后的深水破波缩放。平均流中的垂直切变可以忽略不计，切变产生的幅度远小于耗散，这意味着湍流的垂直扩散是重要的。近床面二次耗散最大值的增加是由于床面温度的降低。
Abstract The vertical structure of the dissipation of turbulence kinetic energy was observed in the nearshore region (3.2-m mean water depth) with a tripod of three acoustic Doppler current meters off a sandy ocean beach. Surface and bottom boundary layer dissipation scaling concepts overlap in this region. No depth-limited wave breaking occurred at the tripod, but wind-induced whitecapping wave breaking did occur. Dissipation is maximum near the surface and minimum at middepth, with a secondary maximum near the bed. The observed dissipation does not follow a surfzone scaling, nor does it follow a “log layer” surface or bottom boundary layer scaling. At the upper two current meters, dissipation follows a modified deep-water breaking-wave scaling. Vertical shear in the mean currents is negligible and shear production magnitude is much less than dissipation, implying that the vertical diffusion of turbulence is important. The increased near-bed secondary dissipation maximum results from a decrease in the tu...