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 est imate the depth of the euphotic zone and depths where spectral irradiance a t 490 nm are 10%, 3%, 1% and 0.3% of incident surface value. The linear emp irical models are derived using data from radiometric profiles measured at various locations in the Gulf of California during cruises in 1995, 1997 an d 1998. The models apply to three geographically and temporally separate bi o-optical provinces of the gulf: the northern basin, the Midriff Islands an d the southern basins. Relative uncertainties of the regression models for the 1% light depths for both spectral irradiance (490 nm) and E-PAR range f rom approximately 5% in the northern basin to 10% in the southern basins.