HR: 11:50h
AN: OS22B-07    [Abstracts]
TI: Ocean Color Based Estimates of Global Photochemical Rate Processes
AU: * Nelson, N B
EM: norm@icess.ucsb.edu
AF: Institute for Computational Earth System Science, University of California, Santa Barbara, Santa Barbara, CA 93106-3060 United States
AU: Siegel, D A
EM: davey@icess.ucsb.edu
AF: Institute for Computational Earth System Science, University of California, Santa Barbara, Santa Barbara, CA 93106-3060 United States
AU: Toole, D A
EM: dtoole@whoi.edu
AF: Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA 02543 United States
AB: The development and validation of new ocean color data products beyond chlorophyll allows for the assessment of biogeochemically relevant rate processes other than primary production, such as CO production and DMS photolysis. We present here a proof-of-concept study in which we integrate multiple global remote sensing data streams to estimate the solar irradiance absorbed by chromophoric dissolved organic matter (CDOM) in the euphotic zone. This quantity can be convolved with apparent quantum yield spectra to estimate photochemical reaction rates. In this study we use ocean color reflectance spectra from SeaWiFS and/or MODIS to estimate in-water light absorption and backscattering spectra using the Garver-Siegel-Maritorena ocean color model. These quantities were used to empirically estimate the diffuse attenuation coefficient spectrum (Kd) for surface waters, and thus depth profiles of light penetration. UV Irradiance spectra at the surface were estimated using TOMS data. We also estimated the scalar to vector irradiance ratio using information from radiative transfer modeling in conjunction with absorption and backscattering coefficient spectra. These quantities were combined to estimate the spectrum of light absorption by CDOM, or photochemically active radiation. Finally, we combined the photochemically active radiation spectra with open ocean estimates of apparent quantum yield to produce maps of photochemical production of CO. Global maps of time integrated production rates closely resemble similar maps of CDOM distribution, indicating a proximal control of photochemistry by CDOM.
DE: 4264 Ocean optics (0649)
DE: 4275 Remote sensing and electromagnetic processes (0689, 2487, 3285, 4455, 6934)
DE: 4805 Biogeochemical cycles, processes, and modeling (0412, 0414, 0793, 1615, 4912)
DE: 4852 Photochemistry
SC: Ocean Sciences [OS]
MN: Fall Meeting 2005