HR: 0830h
AN: U21A-17
TI: Dansgaard-Oeschger Events and the 1.5-kyr Cycle
AU: * Medeiros, B P
EM: brianpm@uclink4.berkeley.edu
AF: Department of Physics, University of California, Berkeley, CA 94720
United States
AU: Karner, D B
EM: dkarner@socrates.berkeley.edu
AF: Department of Physics, University of California, Berkeley, CA 94720
United States
AU: Muller, R A
EM: RAMuller@lbl.gov
AF: Department of Physics, University of California, Berkeley, CA 94720
United States
AB: Millennial-scale oscillations occur in many records, and are widely believed to be continuous and
periodic throughout the last 100 kyr. Such behavior, if true, would suggest an astronomical origin. However, we show that
in the Greenland ice records the 1.5 kyr spectral power arises entirely from the limited time interval 24-36 ka, and that it
is generated five adjacent Dansgaard-Oeschger interstadial events. The remaining 18 Dansgaard-Oeschger events do not
contribute to the 1.5 kyr spectral power. Analysis of several ocean records confirms that they too have millennial-scale
oscillations, but we show that outside of the time interval 24-36 ka, their periods are not statistically compatible with the
1.5 kyr cycle of the Greenland records. From the absence of both continuity and consistency in the signals from these
various records, we conclude that, contrary to the widely-held belief, these millennial-scale oscillations are not a direct
response to orbital forcing.
DE: 1827 Glaciology (1863)
DE: 4267 Paleoceanography
SC: U
MN: 1999 AGU Fall Meeting