Turbulence, Acoustic Backscatter, and Pelagic Nekton in Monterey Bay
Turbulence, Acoustic Backscatter, and Pelagic Nekton in Monterey Bay
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蒙特利湾的湍流、声学后向散射和远洋游生物
DOI：
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
J. Horne
中科院分区：
文献类型：
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作者：
M. Gregg;J. Horne
摘要2006年8月，在加利福尼亚州蒙特利湾，Nekton(最有可能是小型鱼类)的聚集物相交于微结构测量线，为检验生物产生的混合提供了机会。一些集合体填满了80米深的水柱，并沿着调查轨道延伸了100-200米。其他一些只有一半大小，有些要小得多。用校准的回声探测仪测量了聚集体的声能背向散射，得到了−80到−60dBRe 1m−1的体积后向散射强度Sv值。在强度较高的聚集体中，湍流耗散率ϵ为10−6-10−5W kg−1。其中，ϵ比团聚体外测量的湍流均匀得多，并随Sυ的变化而变化。在一个12.5小时的潮汐周期中，沿着一条5公里长的勘测线采集的142条剖面中，有三个类似的聚集贡献了平均ϵ的一半。集合体内部的湍流在以下三个方面与外部的湍流有明显的不同：(I)索普尺度，即均方根...
Abstract During August 2006 aggregations of nekton, most likely small fish, intersected microstructure survey lines in Monterey Bay, California, providing an opportunity to examine biologically generated mixing. Some aggregations filled the water column, 80 m deep, and extended 100–200 m along the survey track. Others were half that size, and some were much smaller. Acoustic energy backscattered from the aggregations was measured with a calibrated echosounder and yielded volume backscattering strength Sv values of −80 to −60 dB re 1 m−1. Turbulent dissipation rates ϵ were 10−6–10−5 W kg−1 in the more intense aggregations. Within these, ϵ was much more uniform than turbulence measured outside the aggregations and varied with Sυ. Three similar aggregations contributed half of the average ϵ in 142 profiles taken along a 5-km-long survey line during a 12.5-h tidal cycle. Turbulence within aggregations differed markedly from that outside in the following three ways: (i) Thorpe scales, that is, root-mean-square...