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Algorithms to retrieve Inherent Optical Properties

Algorithms to retrieve Inherent Optical Properties



GLOSSARY


Rrs(&lambda), &rhow(&lambda) &asymp bb(&lambda) / [a(&lambda) + bb(&lambda)], where

a(&lambda) = aw(&lambda) + adg(&lambda) + aph(&lambda), and

bb(&lambda) = bbw(&lambda) +bbp(&lambda)

coefficients often defined as product of dimensionless basis vector (spectral shape) and magnitude (M), e.g., adg(&lambda) = Mdg adg*(&lambda)
basis vectors used in the following algorithms are graphically presented below


referenceinversionformbbpadgaph
Maritorena et al. 2002 (GSM)L-MG88bbp(&lambdar) [&lambda/&lambdar]-n
n = 1.0337
adg(&lambdar) exp(-S [&lambda - &lambdar])
S = 0.0206
chl aph*
optimized aph* (SA)
Hoge et al. 1996 (LMI)matrixG88bbp(&lambdar) [&lambda/&lambdar]-n
n = 0.8 Rrs(490)/Rrs(555) + 0.2
adg(&lambdar) exp(-S [&lambda - &lambdar])
S = 0.018
Gaussian @ 443
fwhm (&sigma) = 70 nm
aph(&lambda) = aph(&lambdar) exp(u)
u = [&lambdar2+886(&lambda - &lambdar)-&lambda2] / 2 &sigma2
Boss and Roesler 2006
Wang et al. 2005
matrixG88bbp(&lambdar) [&lambda/&lambdar]-n
0 < n < 2
adg(&lambdar) exp(-S [&lambda - &lambdar])
0.01 < S < 0.02
Ciotti et al. 2002
0 < Sf < 1
Lee et al. 2002 (QAA)algebraicG88bbp(&lambdar) [&lambda/&lambdar]-n
n = 2.2 (1 - 1.2 exp[-0.9 Rrs(443)/Rrs(555)])
adg(&lambdar) exp(-S [&lambda - &lambdar])
S = 0.015
a - adg - aw
Smyth et al. 2006 (PML)spectral slope
algebraic
&pi &real f/Q bb/abbp(&lambdar) [&lambda/&lambdar]-n
n = 0.5
adg(&lambdar) exp(-S [&lambda - &lambdar])
S = 0.014
a - adg - aw
Pinkerton et al. 2006 (NIWA)spectral slope
algebraic
&pi &real f/Q bb/abb~ b(490) n
n = 0.841 X2 - 2.806 X + 2.965
X = (&lambda / 490)
bb~ = 0.01756
NANA
Loisel and Stramski 2000algebraic&pi &real f/Q bb/afcn[&rhow(&lambda), Kd(&lambda), solz, &eta(&lambda)]NANA


GSM


n, S, and aph* predefined; optimized (simulated annealing) to in situ data
solution via Levenberg-Marquardt nonlinear inversion

LMI


n, S, and aph* predefined
only 412, 490, and 555-nm considered
solution via 3 x 3 matrix inversion

Boss and Roesler 2006


n, S, and aph* (through Sf) ranges predefined
412 through 555-nm considered
solution via 3 x 5 matrix inversion
multiple solutions achieved using ranges of n, S, and aph*
median of viable solutions retained and uncertainties reported

QAA


a(555) from Rrs(443,490,555,640)
bbp(555) from a(555) and Rrs(555)
n estimated using Rrs(443,555)
bbp(&lambda) from n and bbp(555)
a(&lambda) from bbp(&lambda) and Rrs(&lambda)
aph(412) / aph(443) [ &zeta ] from Rrs(443,555)
adg(412) / adg(443) [ &xi ] from S
adg(443) from a(412,443), &zeta and &xi (algebraic)
adg(&lambda) from adg(443) and S
aph(&lambda) = a(&lambda) - adg(&lambda) - aw(&lambda)

PML


n, S, and, &epsilon predefined
F (= &pi &real f/Q) defined via a, b, and viewing geometry in HydroLight LUT
F(&lambda) initialized using guess of a(&lambda) and b(&lambda)
bb(510) from &epsilona(490,510), &epsilonbb(490,510), F(490,510), and &rhow(490,510)
bb(&lambda) from bb(510) and n
a(&lambda) from bb(&lambda), F(&lambda), and &rhow(&lambda)
updated F(&lambda) from a(&lambda) and b(&lambda) (= bb(&lambda) / 0.01756)
iterate until F(&lambda) remains stable
adg(412) from &epsilondg(412,443), &epsilonph(412,443), and a(412,443)
adg(&lambda) from adg(412) and S
aph(&lambda) = a(&lambda) - adg(&lambda) - aw(&lambda)

NIWA


a(&lambda) and bb(&lambda) only (natively)
n and bb~ (= 0.01756) predefined
F (= &real f/Q) defined via a, b, and viewing geometry in HydroLight LUT
iterate on F(&lambda) and b(&lambda) until F(&lambda) stabilizes, with initial guess for b(&lambda), bb~, aw(&lambda), and &rhow(&lambda)
"lowest" b(490) defined as greatest of b(443) > b(490) > b(510)
define 15-element array of b(490) from "lowest" value to upper limit 60 ...
for each element: iterate on a(&lambda) and F(&lambda) until a(&lambda) stabilizes, with F(&lambda) initialized as 0.02, n, bb~, and &rhow(&lambda)
for each element: retain all b(490) that yield a(&lambda) that satisfy 1.32 < &epsilona(490,510) < 1.58
final b(490) is geometric mean of highest and lowest retained values
final b(&lambda) and bb(&lambda) from n and bb~
iterate on F(&lambda) and a(&lambda) until a(&lambda) stabilizes, with F(&lambda) initialized as last calculated value, final bb(&lambda), and &rhow(&lambda)

Loisel and Stramski 2000


a(&lambda) and bb(&lambda) only (natively)
developed via radiative transfer simulation using infinitely deep ocean, optically homogeneous water column, and flat sea surface
does not assume spectral shapes for a(&lambda) or bb(&lambda)
&rho(&lambda) from Rrs(&lambda,solz) LUT
Kd(&lambda) from Rrs(443,555,solz) LUT
bb(&lambda) from Kd(&lambda), &eta (= bw/b), and &muw (via solz)
&eta initialized as 0.05, then iterated upon using b(&lambda) = bb(&lambda) / 0.0183
a(&lambda) from Kd(&lambda), &rho(&lambda), and solz
can adjust for Raman scattering


IOP spectral shapes

adg



aph



bbp