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Propagate a surface spectrum through the water column.

Source: R/depth_propagation.R
attenuate_spectrum.Rd

Applies per-wavelength Kd across a depth grid using the Beer-Lambert law. Returns a tidy data frame, a numeric matrix, or (for lux_spectrum input) a named list of lux_spectrum objects.

Usage

attenuate_spectrum(E0_lambda, ...)

# S3 method for class 'numeric'
attenuate_spectrum(
  E0_lambda,
  Kd_lambda,
  depths,
  format = c("long", "matrix"),
  lambda = NULL,
  ...
)

# S3 method for class 'lux_spectrum'
attenuate_spectrum(E0_lambda, Kd_lambda, depths, ...)

Arguments

E0_lambda

Surface spectral irradiance. Length-N numeric vector or a lux_spectrum object.

...

Ignored.

Kd_lambda

Finite, non-negative diffuse attenuation coefficients (1/m) at the same wavelength bins as E0_lambda. Length-N numeric vector.

depths

Finite, non-negative depths to evaluate in metres. Length-M numeric vector.

format

"long" (default): tidy data frame with columns depth, lambda, E. "matrix": N x M numeric matrix. Ignored for lux_spectrum input.

lambda

Optional wavelength values (nm) for the lambda column of the long-format output. Defaults to bin indices 1:N.

Value

A data frame, matrix, or named list of lux_spectrum.

Details

This is a wavelength-resolved Beer-Lambert calculation, not a radiative-transfer solution. It assumes a homogeneous \(K_d(\lambda)\) over the modeled path, treats wavelengths independently, and accepts only irradiance when a lux_spectrum is supplied. The generic numeric API cannot verify physical quantity or wavelength alignment; callers must supply aligned irradiance and \(K_d\) vectors. Bundled Jerlov coefficients are supported only from 350–700 nm; see jerlov_Kd.

References

Kirk JTO (1994) Light and Photosynthesis in Aquatic Ecosystems, 2nd edn. Cambridge University Press.

See also

propagate_spectrum, band_irradiance, jerlov_Kd

Examples

E0  <- c(10, 20, 30)
Kd  <- c(0.01, 0.05, 0.20)
lam <- c(450, 550, 650)
attenuate_spectrum(E0, Kd, depths = c(0, 10, 25), lambda = lam)
#>   depth lambda          E
#> 1     0    450 10.0000000
#> 2     0    550 20.0000000
#> 3     0    650 30.0000000
#> 4    10    450  9.0483742
#> 5    10    550 12.1306132
#> 6    10    650  4.0600585
#> 7    25    450  7.7880078
#> 8    25    550  5.7300959
#> 9    25    650  0.2021384