HR: 17:00h
AN: A14B-04    [Abstracts]
TI: Storage of Heat in the Glacial Deep Ocean and the Importance of Seawater Thermodynamics in Climate Change
AU: * Adkins, J F
EM: jess@gps.caltech.edu
AF: Caltech, MS 100-23 1200 E. California Blvd., Pasadena, CA 91125 United States
AU: Pasquero, C
EM: claudia@gps.caltech.edu
AF: Caltech, MS 100-23 1200 E. California Blvd., Pasadena, CA 91125 United States
AB: A variety of records of both oceanic and atmospheric variability link Dansgaard/Oeschger events and Bond Cycles to changes in the overturning strength of the deep ocean. Various models have shown that the observed temperature changes and circulation switches can be forced with variations in the freshwater budget of the North Atlantic surface ocean. However, recent evidence from sediment pore fluids show that the stratification of LGM deep waters was dominated by salinity, rather than temperature. If the saltiest waters of the glacial deep ocean were produced in the Southern Ocean, than salinification of surface waters in the North Atlantic cannot produce large transients in overturning strength without some other source of buoyancy to erode the deep stratification. Here we present an energy storage mechanism, thermobaricity, and an energy source, geothermal heating, that implicate the deep ocean as the origin of the glacial rapid climate changes and the source of this buoyancy. Salinity stratification of the deep ocean during the glacial can lead to heat storage in the abyss that will decrease the deep to surface density difference and then, due to the non-linearity of the seawater equation of state, could periodically cause catastrophic convective events. This "thermobaric convection" arises from the pressure dependence of the seawater thermal expansion coefficient. Our contention is that the thermodynamics of seawater could play an important a role in glacial ocean/atmosphere reorganizations. We will outline how the pressure dependence of the seawater thermal expansion coefficient can lead to occasional rapid overturning of the deep ocean and present some new model results that examine the feasibility of this idea.
DE: 4267 Paleoceanography
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting