HR: 17:30h
AN: OS24B-07    [Abstracts]
TI: Westerly Winds over the Southern Ocean Determine the Partition of Carbon Dioxide Between Atmosphere and Ocean
AU: * Russell, J L
EM: jrussell@princeton.edu
AF: Princeton University, PO Box 308, Princeton, NJ 08542 United States
AU: Toggweiler, R
EM: Robbie.Toggweiler@noaa.gov
AF: GFDL / NOAA, PO Box 308, Princeton, NJ 08542 United States
AB: The recently documented trend in the position and strength of the Westerly Winds in the Southern Hemisphere may be having profound impacts on the fate of anthropogenic carbon dioxide in the ocean. Previous transitions in atmospheric CO2 between low-CO2 periods in Earth's climate (glacial) and high-CO2 periods (interglacial) are usually attributed to changes in the biogeochemistry of the ocean. We propose a new mechanism for determining the partition of CO2 between the atmosphere and ocean. This mechanism depends on the position of the mid-latitude westerlies in relation to the Antarctic Circumpolar Current (ACC) in the Southern Hemisphere. In the past, westerlies that were shifted equatorward of the ACC weakened the divergence around Antarctica allowing biologically-cycled CO2 to accumulate in the deep ocean. Poleward-shifted westerlies that were aligned with the ACC enhanced the divergence around Antarctica, flushing organically cycled CO2 out of the deep ocean and into the atmosphere. Today, the shift in the Westerly Winds associated with the trend in the Southern Annular Mode increases the exposure of Southern Ocean deep waters to the anthropogenically enriched high CO2 atmosphere. We will present results from an atmosphere-ocean MOM4 simulation of the recent changes in the ocean's circulation and carbon chemistry associated with changes in the strength and position of the westerlies.
DE: 4805 Biogeochemical cycles (1615)
DE: 4806 Carbon cycling
DE: 4845 Nutrients and nutrient cycling
DE: 4215 Climate and interannual variability (3309)
DE: 4532 General circulation
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting