HR: 0800h
AN: OS31A-0550    [Abstracts]
TI: Dissolved Organic Carbon and Nitrogen Distributions in the North Atlantic Basin
AU: * Carlson, C A
EM: carlson@lifesci.ucsb.edu
AF: Marine Science Institute, University of California, Santa Barbara, Santa Barbara, CA 93106 United States
AU: Hansell, D A
EM: dhansell@rsmas.miami.edu
AF: University of Miami, RSMAS/MAC, 4600 Rickenbacker Causeway, Miami, FL 33149 United States
AU: Meyers, M K
EM: meyers@lifesci.ucsb.edu
AF: Marine Science Institute, University of California, Santa Barbara, Santa Barbara, CA 93106 United States
AB: The U.S. Repeat Hydrography program was instituted to sustain sampling of ocean transports and inventories of climatically significant parameters on decadal time scales. Each ocean basin will be occupied with at least one meridional section to determine inventories and gradients of carbon and tracers. In 2003 DOM was included as a level one measurement for this set of cruises. Paucity of high spatial resolution DOM data has resulted in a limited understanding of the stocks, distributions and processes that control these patterns throughout the World oceans. Here we report DOC and DON data collected from three meridional transects (A16N, A20 and A22 cruises) in the North Atlantic in 2003. The data set displays a first ever high-resolution, basin scale view DOC and DON distribution in the North Atlantic. The findings are at once both consistent and inconsistent with our expectations. While the data displayed incredible information on the export of DOC with the formation of North Atlantic Deep Water, we also observe a larger but systematic variability in DOM concentrations. This DOM variability is consistent with other tracers within the interior of the North Atlantic. The use of certified reference material allowed us to confidently assess low-level variability in DOC concentrations. At depths deeper than 2000 m, DOC concentrations ranged from 48 $\mu$M in waters characteristic of NADW to as low as 39 $\mu$M in waters characteristic of AABW. We also observed a low DOC tongue (i.e. 39 to 42 $\mu$m) extending from South America to 30$\deg$N along 51$\deg$ W, consistent with observations of AAIW. These expansive data sets are already changing our understanding DOM distribution and the processes that control DOM transport in the ocean interior. These DOM data will serve as a base line to be compared with future measurements and will be used to assess temporal as well as spatial trends of this important carbon variable.
DE: 4805 Biogeochemical cycles (1615)
DE: 4806 Carbon cycling
DE: 4850 Organic marine chemistry
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting