Effects of orientation on acoustic scattering from Antarctic krill at 120 kHz
Effects of orientation on acoustic scattering from Antarctic krill at 120 kHz
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DOI：
10.1016/s0967-0645(98)00036-8
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发表时间：
1998-01-01
影响因子：
3
通讯作者：
Traykovski, LVM
中科院分区：
文献类型：
--
作者：
McGehee, DE;O'Driscoll, RL;Traykovski, LVM
在加利福尼亚州圣克鲁斯的Long Marine实验室的一个冷冻绝缘罐中，以120 kHz的频率对14只活的南极磷虾（Euphausia superba）进行了后向散射测量。单个动物悬挂在传感器前面，仅受到松散的约束，有很大的移动自由度，并且表现出或多或少的随机方向。每只动物采集1000个回声。定向数据记录在视频上，声学数据进行分析，并从每个回波确定目标强度。一种方法被开发用于估计的三维方向的磷虾的视频图像的基础上，并施加到其中五个，给他们的目标强度作为方向的函数。基于简化的扭曲波玻恩近似（DWBA）方法的散射模型的基础上开发的五种动物和测量结果进行了比较。测量和建模的散射模式表明，120 kHz的声散射水平是高度依赖于动物的取向。使用这些散射模式与定向数据，从船上的研究E。Superba给出的平均散射水平比峰值水平低约12 dB。这些结果强调了需要更好的原位行为数据，以正确解释声学调查结果。E. superba DWBA散射模型，提出了可扩展的动物长度。该模型具有良好的方向信息，可以显著提高磷虾声学调查的精度和准确性。(C)1998爱思唯尔科技有限公司版权所有。
Backscattering measurements of 14 live individual Antarctic krill (Euphausia superba) were made at a frequency of 120 kHz in a chilled insulated tank at the Long Marine Laboratory in Santa Cruz, CA. Individual animals were suspended in front of the transducers, were only loosely constrained, had substantial freedom to move, and showed more or less random orientation. One thousand echoes were collected per animal. Orientation data were recorded on video, The acoustic data were analyzed and target strengths determined from each echo. A method was developed for estimating the three-dimensional orientation of the krill based on the video images and was applied to five of them, giving their target strengths as functions of orientation. Scattering models based on a simplified distorted-wave Born approximation (DWBA) method were developed for five animals and compared with the measurements.Both measured and modeled scattering patterns showed that 120 kHz acoustic scattering levels are highly dependent on animal orientation. Use of these scattering patterns with orientation data from shipboard studies of E. superba gave mean scattering levels approximately 12 dB lower than peak levels. These results underscore the need for better in situ behavioral data to properly interpret acoustic survey results. A generic E. superba DWBA scattering model is proposed that is scalable by animal length. With good orientation information, this model could significantly improve the precision and accuracy of krill acoustic surveys. (C) 1998 Elsevier Science Ltd. All rights reserved.