Radiative Transfer in Oceans

Radiative Transfer in Oceans, Tworzenie gier, Resources, Water

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//-->O. KopelevichTopic 6: Radiative Transfer in OceansTrue ocean color – its formation, characteristics and calculationIn-water optical processesSeawater optical characteristics andoptically active water componentsCase 1 and Case 2 watersOcean reflectance and water leaving radianceComputation methodsInfluence of sea bottomEffect of transspectral processesBasic radiometric quantitiesRadiant flux: the time rate of flow of radiant energyF = Q / t,[W]Irradiance:the ratio of the radiant flux incident on aninfinitesimal element of surface to the area of that elementE (S) = dF / dS,E =∫E(S) dS /∫dS = F / S, [W⋅m-2](S)(S)___Radiance:Radiant flux per unit solid angle per unitprojected area of a surfaceL = d F / dΩ⋅dS⋅cosθ,2[W⋅m sr ]-2-1A considered surface can be real (for example, sea surface orbottom) or imaginary, constructed in mind inside of watermedium, so the radiance or irradiance at an arbitrary point inwater can be considered.The radiance at a given point in the spherical co-ordinatesystem is a function of the polar angleθand the azimuthangleϕL(θ,ϕ)= [dE(θ,ϕ)/ cosθ] / dΩ;dE(θ,ϕ) = L(θ,ϕ) ⋅cosθdΩ;E =∫L(θ,ϕ)⋅cosθ⋅dΩ(2π)Irradiance, like radiance, is characterized by a value anda direction (which is defined by a normal to the consideredsurface).Along with the “vector irradiance”, we canconsider the “scalar irradiance”.Scalar irradiance is the integral of the radiance distributionover all directions about the considered pointEo=∫L(θ,ϕ)⋅dΩ,(4π)[W⋅m-2]Characteristics of underwater light fieldDownwelling irradiance:2ππ/2Ed=∫dϕ∫L(θ,ϕ)⋅cosθ⋅sinθ⋅dθ;Upwelling irradiance:Eu= -∫dϕ∫L(θ,ϕ)⋅cosθ⋅sinθ⋅dθ;π/22ππDownwelling scalar irradiance:2πEod=∫dϕ∫L(θ,ϕ)⋅sinθ⋅dθ;π/2Upwelling scalar irradiance:Eou=∫dϕ∫L(θ,ϕ)⋅sinθ⋅dθ;π/22ππDiffuse attenuation coefficient:dEd, u, od, ou= - Kd, u, od, ou⋅dEd, u, od, ou⋅dz;K = - dE / E⋅dz = - d lnE / dz;Kd≠Ku≠Kod≠Kou.;Optical depth:ζ= Kd⋅zThe average cosine of angular distribution of light field:µ=∫cosθ⋅L(θ,ϕ)⋅dΩ/∫L(θ,ϕ)⋅dΩ;(4π)(4π)The downwelling average cosine:µd=∫dϕ∫cosθ⋅L(θ,ϕ)⋅dθ/∫dϕ∫L(θ,ϕ)⋅dθ;2ππ/22ππ/2The upwelling average cosine:µu= -∫dϕ∫cosθ⋅L(θ,ϕ)⋅dθ/∫dϕ∫L(θ,ϕ)⋅dθ;π/2π/22ππ2ππµd= Ed/ E0d;µu= Eu/ E0u,µ= (Ed- Eu)/ E;Spectral density of an radiometric quantity:Fλ= dF/dλ,Eλ= dE/dλ;Lλ= dL/dλ,Total downwelling irradiance:E∑=∫E(λ) dλ;3002500[ W nm-1];[W⋅m-2nm-1];[W⋅m-2nm-1sr-1];Photosynthetically available radiation:PAR =∫E(λ) dλ;400700 [ Pobierz całość w formacie PDF ]