Stanton T K, Chu D, Wiebe P H
Department of Applied Ocean Physics and Engineering, Woods Hole Oceanographic Institution, Massachusetts 02543-1053, USA.
J Acoust Soc Am. 1998 Jan;103(1):236-53. doi: 10.1121/1.421110.
Mathematical scattering models are derived and compared with data from zooplankton from several gross anatomical groups--fluidlike, elastic shelled, and gas bearing. The models are based upon the acoustically inferred boundary conditions determined from laboratory backscattering data presented in part I of this series [Stanton et al., J. Acoust. Soc. Am. 103, 225-235 (1998)]. The models use a combination of ray theory, modal-series solution, and distorted wave Born approximation (DWBA). The formulations, which are inherently approximate, are designed to include only the dominant scattering mechanisms as determined from the experiments. The models for the fluidlike animals (euphausiids in this case) ranged from the simplest case involving two rays, which could qualitatively describe the structure of target strength versus frequency for single pings, to the most complex case involving a rough inhomogeneous asymmetrically tapered bent cylinder using the DWBA-based formulation which could predict echo levels over all angles of incidence (including the difficult region of end-on incidence). The model for the elastic shelled body (gastropods in this case) involved development of an analytical model which takes into account irregularities and discontinuities of the shell. The model for gas-bearing animals (siphonophores) is a hybrid model which is composed of the summation of the exact solution to the gas sphere and the approximate DWBA-based formulation for arbitrarily shaped fluidlike bodies. There is also a simplified ray-based model for the siphonophore. The models are applied to data involving single pings, ping-to-ping variability, and echoes averaged over many pings. There is reasonable qualitative agreement between the predictions and single ping data, and reasonable quantitative agreement between the predictions and variability and averages of echo data.
推导了数学散射模型，并将其与来自几个大体解剖学类群（类流体、有弹性外壳和含气）浮游动物的数据进行了比较。这些模型基于从本系列第一部分[斯坦顿等人，《美国声学学会杂志》103, 225 - 235 (1998)]中给出的实验室后向散射数据声学推断出的边界条件。模型使用了射线理论、模态级数解和畸变波玻恩近似（DWBA）的组合。这些本质上是近似的公式，旨在仅包含实验确定的主要散射机制。类流体动物（这里指磷虾）的模型范围从涉及两条射线的最简单情况（可定性描述单个ping的目标强度与频率的结构）到使用基于DWBA的公式的最复杂情况（涉及一个粗糙的非均匀不对称锥形弯曲圆柱体，可预测所有入射角（包括端射这一困难区域）的回波水平）。有弹性外壳体（这里指腹足纲动物）的模型涉及开发一个考虑外壳不规则性和不连续性的解析模型。含气动物（管水母）的模型是一个混合模型，它由气球体的精确解与任意形状类流体物体基于DWBA的近似公式的总和组成。还有一个用于管水母的简化基于射线的模型。这些模型被应用于涉及单个ping、ping间变化性以及多个ping平均后的回波的数据。预测结果与单个ping数据之间存在合理的定性一致性，预测结果与回波数据的变化性及平均值之间存在合理的定量一致性。
