HR: 0800h
AN: PP51A-1327    [Abstracts]
TI: Modeling Freshwater Impacts on Ocean Circulation During the Miocene at 20 and 14 Ma
AU: * Haupt, B J
EM: bjhaupt@psu.edu
AF: The Pennsylvania State University, 2217 Earth & Engineering Science Bldg., University Park, PA 16802 United States
AU: Seidov, D
EM: dseidov@psu.edu
AF: The Pennsylvania State University, 2217 Earth & Engineering Science Bldg., University Park, PA 16802 United States
AB: A large modeling effort has been committed to better understand the role of freshwater impacts on the past climates, the thermohaline ocean circulation (THC) patterns, and variations of sea level. The restructuring of the THC may be caused by many factors, including ice sheets melting of the major ice sheets, sea ice melting and forming, and for long-term variability - also by changes in major gateways. The sensitivity of the past THC to freshwater fluxes could depend critically on the land-sea distribution and thus be different from the present-day. However, our understanding of the role of paleogeography in THC dynamics and climate change is not yet complete. There is a consensus that the Cenozoic cooling trend and southern glaciation during the last 25 million years was largely caused by continental drift and bathymetrical changes. In the Southern Hemisphere, the Miocene marks further widening of the ocean passage between Antarctica and Australia, the opening of the Drake Passage, and therefore the emergence of the fully developed Antarctic Circumpolar Current. We focus on two different Miocene time slices (20 and 14 Ma), which are characterized by major transitions from warm to cold polar climate. In a series of numerical experiments, we show that the Miocene THC is noticeably sensitive to both the geographical conditions and to the southern high-latitudinal freshwater pulses that might have been caused by young cryosphere evolution. Our coupled ocean-atmosphere simulation reveals changes in all major ocean circulation parameters - the ocean heat transport, meridional overturning, sea level, etc. The sensitivity to freshwater impacts appears to be a function of land-sea distribution and is different at all three points on the timeline - the two paleo time slices and the present one.
UR: http://www.personal.psu.edu/bjh18
DE: 9604 Cenozoic
DE: 4255 Numerical modeling
DE: 4267 Paleoceanography
DE: 4532 General circulation
DE: 4572 Upper ocean processes
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2004 AGU Fall Meeting