HR: 0830h
AN: PP11A-0216    [PDF]
TI: Late Pleistocene 100-kyr Problem Viewed from Sea Surface Temperature Records: A Connection to Obliquity Cycles?
AU: * Liu, Z
EM: Zhonghui_Liu@brown.edu
AF: Brown University, Dept. of Geological Sciences, Providence, RI 02912 United States
AU: Herbert, T D
EM: Timothy_Herbert@brown.edu
AF: Brown University, Dept. of Geological Sciences, Providence, RI 02912 United States
AU: Soon, W
EM: wsoon@cfa.harvard.edu
AF: Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS 16, Cambridge, MA 02138 United States
AB: Predominant late Pleistocene (0-0.6 Ma) 100-kyr cycles occurring in paeloclimatic records has been a major challenge to the orbital theory of climate change. By applying wavelet analysis to two Pleistocene sea surface temperature (SST) records, the onset and dominance of 100-kyr cycles were found to coincide with the reduction in amplitude of the 41-kyr cycles in SST records at about 0.6 Ma. Also the late-Pleistocene 100-kyr cycles were evolving toward longer periods to the present, suggesting the nonexistence of direct orbital forcing from eccentricity. The occurrence of strong power at both 41 and 80-kyr bands at the transitional stage (1.2-0.8 Ma) indicates a nonlinear climatic response to the orbital obliquity forcing. The apparent trade-off between 100 and 41-kyr power and the absence of significant precession power lead us to speculate that the 100-kyr period could be regarded as a `pseudo' cycle, which actually could be a blending of two and three obliquity cycles. The spectral evolution of Pleistocene glacial and interglacial changes is thus interpreted as the development of nonlinearity in the climate system in the mid- and late Pleistocene, which acts on the primary obliquity response. This nonlinearity is associated with the climate responses to weak northern hemisphere summer insolation maxima, arising from the combined variations of all three orbital parameters.
DE: 3344 Paleoclimatology
DE: 4267 Paleoceanography
DE: 4863 Sedimentation
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2003 Fall Meeting