HR: 12:05h
AN: PP12B-08    [Abstracts]
TI: Conditional Instability of the Glacial Deep Ocean
AU: * Adkins, J F
EM: jess@gps.caltech.edu
AF: Caltech; GPS, MS 100-23 1200 E. California Blvd., Pasadena, CA 91125 United States
AU: Pasquero, C
EM: claudia@gps.caltech.edu
AF: Caltech; GPS, MS 100-23 1200 E. California Blvd., Pasadena, CA 91125 United States
AB: Deep-sea sediment pore fluid results indicate that the Last Glacial Maximum (LGM) deep ocean was at or near the freezing point and very salty. In contrast to the modern, these salty waters were formed in the Southern Ocean and they show how salt, not heat, dominated abyssal density gradients at the LGM. To the degree that these data are representative of the glacial period as a whole, the salty waters allow for heat storage in the abyss. Starting from a stably stratified water column, continuous heat flux to the deep (either from geothermal or advective sources) will initially remain statically stable, but will eventually trigger instability and convective mixing. The accumulated heat is then rapidly released in the upper part of the ocean and eventually into the atmosphere. In this scenario, climate variability is associated with phases of heat accumulation at depth followed by periods of rapid heat release from the ocean into the atmosphere. With the aid of different simplified interhemispheric models, conditional instability in the deep ocean is investigated and time dependent solutions are studied. Deep convection is found to occur periodically in one hemisphere, releasing large quantities of heat into the overlying atmosphere, followed by times where the whole ocean heat content increases. In the opposite hemisphere, a much smaller air-sea heat flux oscillation is found, in phase with the global ocean heat content variability. These oscillations have several features in common with the "bi-polar seesaw" observation and might help explain climate variability during the last glacial period.
DE: 4255 Numerical modeling (0545, 0560)
DE: 4901 Abrupt/rapid climate change (1605)
DE: 4928 Global climate models (1626, 3337)
DE: 4938 Interhemispheric phasing
DE: 4962 Thermohaline
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005