A note on the depth of side-lobe contamination in acoustic Doppler current profiles.
A note on the depth of side-lobe contamination in acoustic Doppler current profiles.
复制标题
关于声多普勒电流分布中旁瓣污染深度的注释。
DOI：
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发表时间：
2021
影响因子：
2.2
通讯作者：
A. Plueddemann
中科院分区：
文献类型：
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作者：
S. Lentz;A. Kirincich;A. Plueddemann
声学多普勒海流剖面仪（ADCP）不能提供可靠的海面或海底附近的水速度测量，因为来自边界的声学旁瓣反射污染了多普勒速度测量。旁瓣反射中心的视深为zsl = ha（1 − cos（θ）），其中ha是ADCP声头到海面的距离，θ是ADCP波束角。然而，旁瓣污染延伸一个半ADCP箱zsl以下的声返回的范围选通导致相邻ADCP箱之间的重叠。因此，污染区域z < zsl + 3Δz/2比传统建议的更深，依赖于箱大小Δz。直接观察确认的旁瓣反射的中心深度和污染的深度为六个底部安装，向上看ADCP。当海面平滑时，通过考虑弱风应力的周期来隔离旁瓣反射，并且远离ADCP的主波束几乎完全反射，因此从主波束到ADCP的声学返回很少。
Acoustic Doppler current profilers (ADCP) do not provide reliable water velocity measurements near the sea surface or bottom because acoustic side-lobe reflections from the boundary contaminate the Doppler velocity measurements. The apparent depth of the center of the side-lobe reflection is zsl = ha(1 − cos(θ)) where ha is the distance from the ADCP acoustic head to the sea surface and θ is the ADCP beam angle. However, side-lobe contamination extends one and a half ADCP bins below zsl as the range gating of the acoustic return causes overlap between adjacent ADCP bins. Consequently the contaminated region z < zsl + 3Δz/2 is deeper than traditionally suggested, with a dependence on bin size Δz. Direct observations confirming both the center depth of the side-lobe reflection and the depth of contamination are presented for six bottom mounted, upward-looking ADCPs. The side-lobe reflection is isolated by considering periods of weak wind stresses when the sea surface is smooth and there is nearly perfect reflection of the main beams away from the ADCP and hence little acoustic return from the main beams to the ADCP.