HR: 0800h
AN: C41A-0181    [Abstracts]
TI: Isotope tracers of freshwater distributions, pathways and timescales within the Arctic Ocean.
AU: * Newton, B
EM: bnewton@ldeo.columbia.edu
AF: Lamont-Doherty Earth Observatory, 61 Rt 9W, Palisades, NY 10964-8000 United States
AU: Schlosser, P
EM: schlosser@ldeo.columbia.edu
AF: Lamont-Doherty Earth Observatory, 61 Rt 9W, Palisades, NY 10964-8000 United States
AU: Smethie, B
EM: bsmeth@ldeo.columbia.edu
AF: Lamont-Doherty Earth Observatory, 61 Rt 9W, Palisades, NY 10964-8000 United States
AU: Spieler, A
EM: spieler@ldeo.columbia.edu
AF: Lamont-Doherty Earth Observatory, 61 Rt 9W, Palisades, NY 10964-8000 United States
AU: Khatiwala, S
EM: spk@ldeo.columbia.edu
AF: Lamont-Doherty Earth Observatory, 61 Rt 9W, Palisades, NY 10964-8000 United States
AU: Ekwurzel, B
EM: ekwurzel@hwr.arizona.edu
AF: University of Arizona, University of Arizona, Tucson, Az 85721-0011 United States
AB: We present oxygen isotope, tritium and helium isotope data from the Arctic Ocean. The tritium and helium data are used to calculate apparent ages of the water samples (the time since a water sample was last exposed to the atmosphere), the oxygen isotope data for estimates of freshwater content. The data were gathered mostly during the 1990s, and are part of a growing database of these isotopes. Coverage in the Arctic Ocean is still uneven and incomplete, and ongoing work is aimed at filling these data gaps and establishment of time series at important locations in the Arctic Ocean. However, there is sufficient information in the existing data sets to establish pathways and age estimates for broad sections of the upper 300 meters of the Arctic Ocean. This includes the relatively fresh Polar Waters, which are a source of buoyancy for the Nordic Seas, as well as the Halocline, which constitutes the main stratification of the Arctic water column. In this contribution we present the data on depth and density surfaces. The tritium/He-3 apparent ages are interpreted as a relatively accurate estimate of the first moment of the distribution of transit times between the surface and the sampling site for those waters whose mean ages are less than about 30 years. The delta O-18 values and the tritium are used to track the fate of terrestrial runoff in the Arctic Ocean. The results include a surprising range of apparent ages along isopycnal surfaces, and an unexpected age maximum in the lower halocline over much of the central Arctic Ocean. The former is evidence of dynamical barriers to isopycnal dispersion; the latter indicates relatively rapid horizontal ventilation of the "Atlantic Layer" below the halocline. Some halocline waters show apparent ages beyond the "scale" of the tritium decay clock, indicating either upwelling regions or quasi-stagnant features in a generally more active layer. The data also offer estimates of transit times along the boundary current connecting the Atlantic inflow to the Eurasian Basin with the Canadian Basin, which are complementary to recent work using heat anomalies and CFCs. This information can be applied to studies of pathways and time scales for the propagation of changes at the Arctic Ocean boundaries (e.g., inflow properties through Bering Strait and the Nordic Seas, coastal runoff, atmospheric conditions) into the stratified layers of the Arctic Ocean water column.
DE: 9315 Arctic region
DE: 4808 Chemical tracers
DE: 4536 Hydrography
DE: 1655 Water cycles (1836)
DE: 1836 Hydrologic budget (1655)
SC: Cryosphere [C]
MN: 2004 AGU Fall Meeting