HR: 14:10h
AN: OS23F-03    [Abstracts]
TI: Decadal Changes in Dissolved CFCs in the Eastern Basin of the North Atlantic
AU: * Bullister, J L
EM: John.L.Bullister@noaa.gov
AF: NOAA-PMEL, 7600 Sand Point Way NE, Seattle, WA 98115 United States
AU: Warner, M J
EM: mwarner@ocean.washington.edu
AF: University of Washington, Box 357940, Seattle, WA 98195 United States
AU: Sonnerup, R E
EM: Rolf.Sonnerup@noaa.gov
AF: JISAO, Box 354235, Seattle, WA 98195 United States
AU: Johnson, G C
EM: Gregory.C.Johnson@noaa.gov
AF: NOAA-PMEL, 7600 Sand Point Way NE, Seattle, WA 98115 United States
AU: Gruber, N
EM: ngruber@igpp.ucla.edu
AF: UCLA-IGPP, 5853 Slichter Hall, Los Angeles, CA 90095 United States
AB: As part of the CLIVAR Global Repeat Hydrography Program, a hydrographic section was occupied in the eastern basin of North Atlantic in 2003, nominally along 20$\deg$W from 67$\deg$N to 5$\deg$S. The 2003 A16N section repeated 20$\deg$W sections occupied in 1988 and 1993. A full suite of physical and chemical measurements were made along this section. Dissolved CFC concentrations generally increased along the section between 1988 and 2003, with the largest increase occurring in Labrador Sea Water (LSW). The leading edge of the CFC transient moved progressively deeper in the water column. CFC concentrations in maxima along the equator at mid-($\sim$1800 m) and abyssal depths showed large relative increases between 1988 and 2003. Between the 2003 section and earlier occupations, significant changes in water mass properties, including temperature, salinity and dissolved oxygen, were observed in subpolar mode waters and LSW. The changes in apparent oxygen utilization (AOU) observed may be due to changes in the strength of ventilation processes in the region during the decade prior to the 2003 occupation compared to the years prior to the earlier samplings, as well as to possible changes in biological production, export and remineralization rates. Regions in the water column with large increases in apparent oxygen utilization (AOU) tended to have relatively large increases in pCFC derived apparent ages, indicating that the AOU changes may be driven in part by a slowdown in the strength of the ventilation processes. Simple numerical model simulations are used to estimate the contribution of steady-state mixing processes to the temporal trends in pCFC derived apparent age fields observed in this region.
DE: 4805 Biogeochemical cycles (1615)
DE: 4808 Chemical tracers
DE: 4825 Geochemistry
DE: 4536 Hydrography
DE: 1635 Oceans (4203)
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting