Showing papers by "Andone C. Lavery published in 2002"
TL;DR: An acoustic scattering model has been developed for fluid-like zooplankton that is based on the distorted wave Born approximation and that makes use of high-resolution three-dimensional measurements of the animal's outer boundary shape.
Abstract: Scattering models that correctly incorporate organism size and shape are a critical component for the remote detection and classification of many marine organisms. In this work, an acoustic scattering model has been developed for fluid-like zooplankton that is based on the distorted wave Born approximation (DWBA) and that makes use of high-resolution three-dimensional measurements of the animal’s outer boundary shape. High-resolution computerized tomography (CT) was used to determine the three-dimensional digitizations of animal shape. This study focuses on developing the methodology for incorporating high-resolution CT scans into a scattering model that is generally valid for any body with fluid-like material properties. The model predictions are compared to controlled laboratory measurements of the acoustic backscattering from live individual decapod shrimp. The frequency range used was 50 kHz to 1 MHz and the angular characteristics of the backscattering were investigated with up to a 1° angular resolu...
59 citations
01 Jan 2002
TL;DR: In this article, the authors present selected results from a program designed to address the origin of variability in high-frequency acoustic backscattering in the water column and identify the model parameters with the highest degree of uncertainty.
Abstract: High-frequency acoustic backscattering in the water column is highly variable in both space and time. We present selected results from a program designed to address the origin of this variability. There are many naturally occurring processes in the water column, of both physical and biological origin, that give rise to acoustic backscattering. The naturally occurring spatial and temporal variability of these physical and biological processes contribute significantly to variability in acoustic backscatter. In addition, there is uncertainty associated with identifying and obtaining high-resolution information of the physical and biological parameters that contribute to volume scattering. Uncertainty in predicting volume scattering also arises from possible inaccuracies of the scattering models, as well as variability due to speckle. Emphasis is given here to identifying the model parameters with the highest degree of uncertainty.
9 citations
TL;DR: A condensed review of the scattering models available for each of these zooplankton categories, with most emphasis given to a recent model developed for fluid-like zoopLankton.
Abstract: In many regions, zooplankton populations are highly complex, comprising multiple species and size distributions. A key component to the quantitative interpretation of high-frequency acoustic survey data, in terms of relevant biological parameters, such as biomass, is the availability of accurate scattering models. Zooplankton can be divided into three categories according to general anatomical features and material properties: fluid-like, elastic shelled, and gas-bearing. To predict the scattering of sound from individuals from each of these categories, the models must incorporate the dependence on size, shape, material properties, orientation, and frequency. Over the last decade, increasingly more accurate and sophisticated scattering models have been developed. We present here a condensed review of the scattering models available for each of these zooplankton categories, with most emphasis given to a recent model developed for fluid-like zooplankton.
2 citations