HR: 08:30h
AN: PP21A-03    [PDF]
TI: Tracking Past Shifts in the Eastern Pacific ITCZ With Foraminiferal Oxygen Isotopes and Mg Paleothermometry
AU: * Koutavas, A
EM: koutavas@mit.edu
AF: Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 United States
AU: Lynch-Stieglitz, J
EM: jean@ldeo.columbia.edu
AF: Lamont-Doherty Earth Observatory, Rt. 9W, Palisades, NY 10964 United States
AU: deMenocal, P B
EM: peter@ldeo.columbia.edu
AF: Lamont-Doherty Earth Observatory, Rt. 9W, Palisades, NY 10964 United States
AB: A sensitive coupling between sea surface temperature (SST) and wind stress in the eastern tropical Pacific allows robust predictions of shifts in the mean latitude of the Intertropical Convergence Zone (ITCZ) to be made given the prevailing pattern of SST and its cross-equatorial gradient. We use modern oceanographic data to demonstrate this principle on seasonal to interannual timescales, and apply it to proxy data spanning the last 30,000 years. Oxygen isotopic and Mg/Ca compositions of planktonic foraminifera are used to constrain variability in the cross-equatorial front of the eastern Pacific and to infer relative ITCZ movements. The data are consistent with a southward displacement of the Pacific ITCZ during the last glacial maximum relative to the Holocene, and a more northern ITCZ position in the early/middle Holocene relative to the late Holocene. A progressive equatorward approach of the mean ITCZ position over the last ~7,000 years may be related to a strengthening of ENSO over the same interval, and is consistent with orbital forcing. These results provide support for persistent ocean-atmosphere linkages in the eastern Pacific ITCZ-cold tongue-ENSO system beyond interannual timescales and underscore the need to better characterize and integrate the dynamics of this system in the framework of past (and future) global climate variability.
DE: 1620 Climate dynamics (3309)
DE: 4267 Paleoceanography
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2003 Fall Meeting