Euphotic depth, irradiance attenuation and remote sensing K490 in bio-optical provinces of the Gulf of California

Algorithms are presented using remote sensing optical depth, 1/K490, to estimate the depth of the euphotic zone and depths where spectral irradiance at 490 nm are 10%, 3%, 1% and 0.3% of incident surface value. The linear empirical models are derived using data from radiometric profiles measured at various locations in the Gulf of California during cruises in 1995, 1997 and 1998. The models apply to three geographically and temporally separate bio-optical provinces of the gulf: The northern basin, the Midriff Islands and the southern basins. Relative uncertainties of the regression models for the 1% light depths for both spectral irradiance (490 nm) and E_PAR range from approximately 5% in the northern basin to 10% in the southern basins.