Estimate the diffuse attenuation coefficient from two irradiance readings.

Closed-form Beer-Lambert inversion: Kd = log(E1/E2) / (z2 - z1). Works for scalar or spectral (vector) inputs, or lux_spectrum objects.

Usage

fit_Kd(E1, ...)

# S3 method for class 'numeric'
fit_Kd(E1, z1, E2, z2, ...)

# S3 method for class 'lux_spectrum'
fit_Kd(E1, z1, E2, z2, ...)

Arguments

E1

Irradiance at the shallower depth z1. Numeric vector or lux_spectrum. When E1 is a lux_spectrum, S3 dispatch handles both arguments; passing a numeric E1 with a lux_spectrum E2 is not supported.

...

Ignored.

z1

Depth of E1 in metres. Must be < z2.

E2

Irradiance at the deeper depth z2. Numeric vector or lux_spectrum (only when E1 is also a lux_spectrum).

z2

Depth of E2 in metres. Must be > z1.

Value

Kd in 1/m. Same length as E1/E2.

References

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

See also

propagate_spectrum, attenuate_spectrum, jerlov_Kd

Examples

data(Naples)
fit_Kd(sum(Naples$depth_0m), 0, sum(Naples$depth_10m), 10)
#> [1] 0.1147068