acoustic: Acoustic calculations

In sigurdurthorjonsson/bionechi: Utilities for analysis of acoustic survey results

Acoustic calculations

Description

• le2ts: Convert length to target strength

• ts2sigma: Convert target strength to cross-section

• ts2le: Convert target strength to length

• sigma2ts: convert cross-section to target strength.

• sA2sa: Convert NASC (sA) to area backscattering coefficient (sa or ABC)

• sV2sv: Convert mean volum backscattering strength (MVBS) to volume backscattering coefficent

Usage

le2ts(le, species, dead = 0)

ts2sigma(ts, type = "sp")

ts2le(ts, species, dead = 0)

sigma2ts(sigma)

z_le2ts(le, z, species, dead = 0)

sA2sa(sA)

sV2sv(sV)

Arguments

le	length (cm)
species	MRI species code (31:capelin, 30:herring, etc)
dead	small value added to le related to measurement method
ts	target strength (dB re 1 m^2)
type	type of cross-section, sp spherical, bs backscattering
sigma	cross-section (m^2)
z	depth (m)
sA
Sv

Value

• le2ts:

• ts2sigma:

• ts2le:

• sigma2ts:

• sA2sa:

• sV2sv:

References

MacLennan, D. N., Fernandes, P. G., and Dalen, J. 2002. A consistent approach to definitions and symbols in fisheries acoustics. ICES Journal of Marine Science, 59: 365-369.

Examples

# fish length distribution, rounded to the next cm below:
lengths <- floor(rnorm(100, 15, 2))
# cross-section of capelin
sigmas <- ts2sigma(le2ts(lengths, 31, dead = 0.5))
# nautical area scattering coefficient ('back-scattering area density'):
NASC <- 10000
# area density of fish in millions per nmi^2
NASC/mean(sigmas)/1e6

sigurdurthorjonsson/bionechi documentation built on Jan. 25, 2023, 6:37 p.m.