Chang and Dickey: Partitioning in situ total spectral absorption by use of moored spectral absorption and attenuation meters


High temporal resolution spectral absorption data were acquired utilizing one bottom-mounted (~68 m) and three moored spectral absorption and attenuation meters (ac-9s at 14, 37, and 52 m) on the Middle Atlantic Bight (MAB) continental shelf during the fall 1996 period of the Coastal Mixing and Optics (CMO) experiment. We employed a previously published spectral absorption model with the data to partition total absorption into absorption by water, phytoplankton, detritus, and gelbstoff. The model was validated by comparing its results against coincident in vivo absorption coefficients derived from discrete bottle samples. Correlations between modeled and in vivo spectra range from 0.873 to 0.998. These correlations were optimized to determine the model parameters. These parameters could not be determined solely from the moored ac-9 results. Therefore, a separate set of absorption measurements (from discrete bottle samples) was necessary to determine values for the model parameters. Model results allow us to separate particulate and dissolved components of absorption and to examine the temporal variability and the vertical distributions and concentrations of each component, given total absorption in the water column.