Jacobs, K. R.. University of New Hampshire, jacobs@kelvin.sr.unh.edu
, . R.. ,

Most ocean color inversion algorithms incorporate a factor, Q (Eu/Lu), which converts irradiance reflectance, R (Eu/Ed), to remote sensing reflectance, Rrs (Lu/Ed). Q is often considered to remain constant over wide geographical areas as well as over the visible spectrum. Previous work by Morel and Gentili (1991, 1993) has shown, through Monte Carlo simulation, that Q is dependent on the solar zenith angle and on inherent optical properties of the water column, specifically the volume scattering function, VSF, and the single scattering albedo, SSA. During the 1998 Optical Oceanography course at Friday Harbor Laboratory, measurements of Q were made on three consecutive days and at three different locations within the San Juan Islands region. Measurements were taken at approximately the same time of day and thus approximately the same solar zenith-angle. At each location the surface values of Q varied spectrally between 3.5 and 4.7. Between the various locations Q varied by from 3.5 to 4.2 at 443 nm. Variability in Q with depth was also observed. In these waters light at 490, 532, and 555 nm penetrated to the greatest depth. At these wavelengths, Q generally increased with depth and for two samples reached a singular value that became constant with depth, suggesting the presence of an asymptotic light field. Variance in Q between locations was accompanied by a similar variance in the SSA as measured with an AC-9. These data suggest a dependence of Q on the SSA and are consistent with theoretical results using Monte Carlo simulations of the underwater light field.
Day: Thursday, Feb. 4
Time: Poster
Location: Sweeney Center
Code: SS53TH1664S