echoSMs
Making acoustic scattering models available to fisheries and plankton scientists via the world wide web.
Background
This project is an international collaboration that is, in part, a component of a U.S. NOAA-Fisheries active acoustic strategic initiative, AA-SI.
Quantitative interpretation of acoustic echograms requires software expertise to develop advanced analytical methods for echo classification using mathematical models that predict acoustic backscatter (e.g., target strength, TS re 1 m² [dB]). These models and predictions can be used to inform echo classification by validating empirical measurements and generating training data for machine learning (ML), artificial intelligence (AI), and other advanced analytical methods, such as inverse methods. Application of these models to fish and plankton requires anatomical and morphological data that are easily accessible and available to the models.
The goal of this project is to make acoustic scattering models available to fisheries and plankton acoustic scientists via the world wide web. By providing the models in an open-access and open-source software language (e.g, Python, R) and providing morphological and anatomical data in open data formats (e.g., HDF5, relational databases), the proper and appropriate use of these models can extend to the entire fisheries and plankton acoustics’ community.
Contributing to echoSMs
We welcome all contributions to echoSMs, be it code, test cases, bug reports, discussion of models, etc. Please use the github facilities for this (i.e., issues, pull requests, and discussions). We are also happy to accept directly code that we can add to echoSMs on your behalf.
An objective of echoSMs is to provide scattering models in a form that is easy to access, use, and compare to other models. To help with that, we specify model parameter units, angle conventions, and required model outputs that code contributions should support. We also suggest coding conventions that should be followed.
Scattering Models
The initial set of acoustic scattering models will be those used in Jech et al. (2015). Acoustic model development will follow 3–4 phases:
- Exact solutions and canonical shapes (see table below),
- Approximate analytical models applied to canonical shapes (see table below),
- Approximate analytical models applied to complex shapes approximating biological targets, such as fish and zooplankton,
- Numerical models applied to canonical shapes and biological targets (this phase will depend on time and funding).
Exact Solutions
The exact solutions, shapes, and supported boundary conditions will be:
| Model | Shape | Description | References |
|---|---|---|---|
| Modal Series solution (MSS) | Sphere | Fluid filled | 1,2 |
| Fixed rigid | 2,3 | ||
| Pressure release | 2 | ||
| Gas filled | 2 | ||
| Weakly scattering | 2 | ||
| Spherical fluid shell with fluid interior | 2 | ||
| Fixed rigid spherical shell | 2 | ||
| Spherical fluid shell with pressure release interior | 2 | ||
| Spherical fluid shell with gas interior | 2 | ||
| Spherical fluid shell with weakly scattering interior | 2 | ||
| Prolate spheroid modal series solution | Prolate spheroid | Rigid fixed | 2,4,5 |
| Pressure release | 2,4,5 | ||
| Gas filled | 2,4,5 | ||
| Infinite cylinder? | 3 | ||
| Infinite plane? |
- Anderson, V. C. 1950. Sound scattering from a fluid sphere. JASA. 22(4): 426-431]
- Jech et al. 2015. Comparisons among ten models of acoustic backscattering used in aquatic ecosystem research. JASA. 138: 3742-3764.
- Faran, J. J. 1951. Sound scattering by solid cylinders and spheres. JASA. 23(4): 405-418.
- Skudrzyk. 1971. The Foundations of Acoustics (Springer, NY), pp. 455-465.
- Furusawa. 1988. Prolate spheroidal models for predicting general trends of fish target strength, J. Acoust. Soc. Jpn. (E) 9, 13–14.
Approximate Analytical Models and Shapes
The approximate analytical models,shapes, and supported boundary conditions will be:
| Model | Shape | Description | References |
|---|---|---|---|
| Modal series-based deformed cylinder model | Finite cylinder | Fixed rigid | 1,2,3 |
| Pressure release | 1,2,3 | ||
| Gas filled | 1,2,3 | ||
| Weakly scattering | 1,2,3 | ||
| Prolate spheroid | Fixed rigid | 1,2,3 | |
| Pressure release | 1,2,3 | ||
| Gas filled | 1,2,3 | ||
| Weakly scattering | 1,2,3 | ||
| Kirchhoff approximation (KA) | Sphere | Fixed rigid | 3,4,5 |
| Prolate spheroid | Fixed rigid | 3,4,5 | |
| Finite cylinder | Fixed rigid | 3,4,5 | |
| Kirchhoff ray mode (KRM) | Sphere | Gas filled | 3,6,7,8 |
| Weakly scattering | 3,6,7,8 | ||
| Spherical shell | gas filled | 3,6,7,8 | |
| Weakly scattering | 3,6,7,8 | ||
| Prolate spheroid | gas filled | 3,6,7,8 | |
| Weakly scattering | 3,6,7,8 | ||
| Finite cylinder | gas filled | 3,6,7,8 | |
| Weakly scattering | 3,6,7,8 | ||
| Distorted wave Born approximation (DWBA) | Sphere | Weakly scattering | 3,9,10,11 |
| Prolate spheroid | Weakly scattering | 3,9,10,11 | |
| Finite cylinder | Weakly scattering | 3,9,10,11 | |
| Phase-tracking distorted wave Born approximation (PT-DWBA) | Sphere | Weakly scattering | 3,12 |
| Spherical shell | Weakly scattering | 3,12 | |
| Prolate spheroid | Weakly scattering | 3,12 | |
| Finite cylinder | Weakly scattering | 3,12 | |
| Stochastic distorted wave Born approximation (SDWBA) | Sphere | Weakly scattering | 13,14,15 |
| Prolate spheroid | Weakly scattering | 13,14,15 | |
| Finite cylinder | Weakly scattering | 13,14,15 |
- Stanton. 1988. Sound scattering by cylinders of finite length. I. Fluid cylinders. JASA. 83, 55–63.
- Stanton. 1989. Sound scattering by cylinders of finite length. III. Deformed cylinders. JASA. 86: 691-705.
- Jech et al. 2015. Comparisons among ten models of acoustic backscattering used in aquatic ecosystem research. JASA. 138: 3742-3764.
- Foote. 1985. Rather-high-frequency sound scattering by swimbladdered fish. JASA. 78: 688-700.
- Foote and Francis. 2002. Comparing Kirchhoff approximation and boundary-element models for computing gadoid target strengths. JASA. 111: 1644-1654.
- Clay and Horne. 1994. Acoustic models of fish: The Atlantic cod (Gadus morhua). JASA. 96: 1661-1668.
- Clay. 1991. Low-resolution acoustic scattering models: Fluid-filled cylinders and fish with swim bladders. JASA. 89: 2168-2179.
- Clay. 1992. Composite ray-mode approximations for backscattered sound from gas-filled cylinders and swimbladders. JASA. 92: 2173-2180.
- Chu et al. 1993. Further analysis of target strength measurements of Antarctic krill at 38 and 120 kHz: Comparison with deformed cylinder model and inference of orientation distribution. JASA. 93: 2985-2988.
- Stanton et al. 1993. Average echoes from randomly oriented random-length finite cylinders: Zooplankton models. JASA. 94: 3463-3472.]
- Stanton et al. 1998. Sound scattering by several zooplankton groups II: Scattering models. JASA. 103: 236-253.
- Jones et al. 2009. Use of the distorted wave Born approximation to predict scattering by inhomogeneous objects: Application to squid. JASA. 125: 73-88.
- Demer and Conti. 2003. Reconciling theoretical versus empirical target strengths of krill: Effects of phase variability on the distorted wave Born approximation. ICES J. Mar. Sci. 60: 429-434.
- Demer and Conti. 2004. Erratum: Reconciling theoretical versus empirical target strengths of krill; effects of phase variability on the distorted-wave, Born approximation. ICES J. Mar. Sci. 61: 157-158.
- TBC