Microstructure Measurements from an Underwater Glider in the Turbulent Faroe Bank Channel Overflow
Microstructure Measurements from an Underwater Glider in the Turbulent Faroe Bank Channel Overflow
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DOI：
10.1175/jtech-d-13-00221.1
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发表时间：
2014-05-01
影响因子：
2.2
通讯作者：
Ullgren, Jenny E.
中科院分区：
文献类型：
--
作者：
Fer, Ilker;Peterson, Algot K.;Ullgren, Jenny E.
海洋微结构的测量是在湍流法罗群岛银行渠道溢流使用湍流仪器连接到水下滑翔机。用翼型剪切探针测量了湍流动能耗散率。在2012年6月为期一周的使命中，对滑翔机俯冲和爬升循环的152个剖面和使用垂直微结构剖面仪（VMP）从船上收集的90个剖面进行了比较。大约一半的配置文件是并置的。对于96%的数据集，测量结果具有高质量，潜水和攀爬之间没有系统差异。噪音水平低于5 x 10（-11）W kg（-1），可与最好的显微组织轮廓仪相媲美。在滑翔机的转弯深度和U/u（t）< 20的情况下，剪切探针数据受到污染且不可靠，其中U是经过传感器的流量，u（t）=（μ/N）（1/2）是湍流速度尺度的估计值，N是浮力频率。平均配置文件的VMP和滑翔机同意优于一个因素2的湍流底层的溢流羽流，下面的分层和剪切羽流环境界面。在对应于界面的上部和上方的由3度-6度和6度-9度C的等温线限定的层中，滑动平均值分别比VMP值大大约3倍和9倍。这种差异归因于不同的采样方案和湍流的不稳定性。滑翔机提供了一个适合海洋微观结构测量的无噪音平台。
Measurements of ocean microstructure are made in the turbulent Faroe Bank Channel overflow using a turbulence instrument attached to an underwater glider. Dissipation rate of turbulent kinetic energy epsilon is measured using airfoil shear probes. A comparison is made between 152 profiles from dive and climb cycles of the glider during a 1-week mission in June 2012 and 90 profiles collected from the ship using a vertical microstructure profiler (VMP). Approximately one-half of the profiles are collocated. For 96% of the dataset, measurements are of high quality with no systematic differences between dives and climbs. The noise level is less than 5 x 10(-11) W kg(-1), comparable to the best microstructure profilers. The shear probe data are contaminated and unreliable at the turning depth of the glider and for U/u(t) < 20, where U is the flow past the sensor, u(t) = (epsilon/N)(1/2) is an estimate of the turbulent velocity scale, and N is the buoyancy frequency. Averaged profiles of epsilon from the VMP and the glider agree to better than a factor of 2 in the turbulent bottom layer of the overflow plume, and beneath the stratified and sheared plume-ambient interface. The glider average values are approximately a factor of 3 and 9 times larger than the VMP values in the layers defined by the isotherms 3 degrees-6 degrees and 6 degrees-9 degrees C, respectively, corresponding to the upper part of the interface and above. The discrepancy is attributed to a different sampling scheme and the intermittency of turbulence. The glider offers a noise-free platform suitable for ocean microstructure measurements.