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Relationships between Q ‐factor and seawater optical properties in a coastal region
Author(s) -
Zibordi Giuseppe,
Berthon Jean-François
Publication year - 2001
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.2001.46.5.1130
Subject(s) - radiance , upwelling , seawater , irradiance , zenith , range (aeronautics) , environmental science , attenuation , solar zenith angle , empirical orthogonal functions , attenuation coefficient , nadir , atmospheric sciences , oceanography , physics , remote sensing , climatology , geology , optics , materials science , satellite , astronomy , composite material
The Q ‐factor—the ratio between upwelling irradiance and upwelling radiance—describes the bidirectional structure of seawater apparent optical properties as a function of geometry and of marine and atmospheric optical characteristics. A 3‐yr time series of Q n (λ) measurements—the Q‐factor determined by nadir radiance—from the North Adriatic Sea coastal waters, has been analyzed. Scatter plots of Qn(λ) versus sun zenith, θ 0 , for different intervals of the diffuse attenuation coefficient Kd(λ) have shown a consistent exponential trend. In addition, leastsquares regressions of Q n (λ) versus Q n (490) have exhibited determination coefficients R 2 that vary from 0.77 to 0.94 in the spectral range between 412 and 555 nm and R 2 = 0.50 at 665 nm. To account for these findings, an empirical model for Q n (λ) as a function of θ 0 and K d (λ 0 ) at the reference wavelength λ 0 = 490 nm is proposed for North Adriatic coastal waters.