HR: 0800h
AN: PP31A-0904    [Abstracts]
TI: Simulated Global Response to a Substantial Weakening of the Atlantic Thermohaline Circulation
AU: * Zhang, R
EM: Rong.Zhang@noaa.gov
AF: AOS Program Princeton University, Forrestal Campus, Route 1, Princeton, NJ 08542 United States
AU: Delworth, T L
EM: Tom.Delworth@noaa.gov
AF: Geophysical Fluid Dynamics Laboratory, NOAA, Forrestal Campus, Route 1 Princeton University, Princeton, NJ 08542 United States
AB: In this study we use a newly developed fully coupled global ocean-atmosphere general circulation model to investigate the global scale response of the climate system to a sustained addition of fresh water to the model's North Atlantic, such as may have occurred during glacial periods. In response to this forcing, the model's thermohaline circulation weakens substantially, thereby cooling the North Atlantic and warming the South Atlantic. The associated global response involves a southward shift of the intertropical convergence zone (ITCZ) over both the Atlantic and Pacific sectors, an El Nino like condition and weakened Walker circulation in the southern tropical Pacific, a La Nina like condition and strengthened Walker circulation in the northern tropical Pacific, a dipole subsurface temperature response in the western tropical Pacific, and weakened Indian and east Asian summer monsoons. The substantial weakening of the thermohaline circulation leads to a more symmetric annual mean zonally averaged ITCZ and zonally integrated Hadley circulation about the Equator. These responses are consistent with the global-scale synchronization of millennial-scale abrupt climate change as indicated by paleoclimate records.
DE: 3339 Ocean/atmosphere interactions (0312, 4504)
DE: 3344 Paleoclimatology
DE: 3374 Tropical meteorology
DE: 4255 Numerical modeling
DE: 1620 Climate dynamics (3309)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2004 AGU Fall Meeting