HR: 1400h
AN: OS53A-04    [Abstracts]
TI: Penetration of Anthropogenic Chlorofluorocarbon Gases to Thermocline and Intermediate Waters in the Northwestern Gulf of Mexico
AU: * Min, D
EM: min@utmsi.utexas.edu
AF: The University of Texas at Austin, Marine Science Institute, 750 Channel View Drive, Port Aransas, TX 78373, United States
AB: Distributions of the dissolved chlorofluorocarbons (CFCs) were measured at several locations in the northwestern Gulf of Mexico during the Omega 06 expedition in August 2006 as time-dependent tracers for decadal-scale ocean circulation and ventilation processes. Vertical profiles of CFC-11 concentrations exhibit a maximum (~2 pmol/kg) associated with the base of salinity maximum layer (S~36.5 at ~26 σ_θ), and monotonically decreasing concentrations with increasing depth below this layer. A deepest hydrographic measurement (~1900 m) near an anticyclonic Loop Current Eddy shows deepest penetration of CFC-11 over 1000 m depth and below which depth the concentration was at blank level. The penetration depth of CFC-11 in this area is deeper than the oxygen minimum depth (400-500 m) and the intermediate salinity minimum depth (700-800 m). Higher concentrations of CFC-11 and dissolved oxygen near the anticyclonic eddy compared to the other areas at the same depth due to a deepening of isopycnals suggest a potential of diffusive ventilation of intermediate waters by eddy disintegration process near the southern and western shelf areas in the Gulf. Unlike CFC-11, CFC-113 and carbon tetrachloride show rapid decrease with depth toward minimum concentration levels in the upper 200 m water column indicating a presence of non- physical removal mechanism for these gases.
DE: 4223 Descriptive and regional oceanography
DE: 4243 Marginal and semi-enclosed seas
DE: 4271 Physical and chemical properties of seawater
DE: 4520 Eddies and mesoscale processes
DE: 4536 Hydrography and tracers
SC: Ocean Sciences [OS]
MN: 2007 Joint Assembly