Restructure

src/absorption.jl

+abstract type AbsorptionModel end
+
+struct DefaultAbsorption <: AbsorptionModel end
+
+
+const absorptionlengthinterpolator = LinearInterpolator(
+    [0, 290, 310, 330, 350, 375, 412, 440, 475, 488, 510, 532, 555, 650, 676, 715, 720, 999999],
+    [0.0, 0.0, 11.9, 16.4, 20.6, 29.5, 48.5, 67.5, 59.0, 55.1, 26.1, 19.9, 14.7, 2.8, 2.3, 1.0, 0.0, 0.0],
+    NoBoundaries()
+)
+"""
+    absorptionlength(λ)
+
+Returns the absorption length [m] in deep sea water for a given wavelength [nm].
+Reference missing! The interpolation values are taken from the Jpp framework,
+written by Maarten de Jong.
+
+"""
+absorptionlength(::DefaultAbsorption, λ) = absorptionlengthinterpolator(λ)

src/scattering.jl

+abstract type ScatteringModel end
+
+struct Kopelevich <: ScatteringModel end
+
+"""
+    scatteringlength(λ)
+
+Calculates the scattering length [m] for a given wavelength `λ` [ns] using the
+Kopelevich model for spectral volume scattering functions. The model separates
+the contributions by:
+
+    - pure_sea:   pure sea water;
+    - small_par: 'small' particles (size < 1 micro meter);
+    - large_par: 'large' particles (size > 1 micro meter).
+
+Values are taken from reference C.D. Mobley "Light and Water", ISBN 0-12-502750-8, pag. 119.
+
+"""
+function scatteringlength(::Kopelevich, λ)
+    Vs = 0.0075
+    Vl = 0.0075
+    bw = 0.0017
+    bs = 1.340
+    bl = 0.312
+
+    x = 550.0 / λ
+
+    pure_sea  = bw *      x^4.3
+    small_par = bs * Vs * x^1.7
+    large_par = bl * Vl * x^0.3
+
+    1.0 / (pure_sea + small_par + large_par)
+end