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Model of the mean cosine of underwater radiance and estimation of underwater scalar irradiance
Author(s) -
Bannister T. T.
Publication year - 1992
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.1992.37.4.0773
Subject(s) - radiance , irradiance , monte carlo method , underwater , radiative transfer , refraction , scalar (mathematics) , trigonometric functions , scattering , physics , optics , geology , mathematics , geometry , statistics , oceanography
An empirical model has been found with which to calculate depth profiles of the mean cosine of a component of radiance in homogeneous water under a flat surface. Model inputs are the refraction angle ω ′ and the subsurface downwelling irradiance E i due to the entering radiance component. Other inputs are the absorption and scattering coefficients, a and b, and the angular scattering function (here Petzold’s functions for San Diego Harbor or “Tongue of the ocean” Atlantic waters). The model applies to refraction angles up to 48° and b : a ratios up to 20. Model profiles of the mean cosine match Monte Carlo profiles to ±0.01. From mean cosine profiles, scalar irradiance profiles are calculable; down to the 1% light level, model and Monte Carlo irradiances agree within ±10%. The time to compute an irradiance profile with the model is ∼ 10 −4 that of a Monte Carlo calculation.