HR: 09:45h
AN: PP21C-08    [Abstracts]
TI: 100 kyr-Period in Tropical Insolation
AU: Loutre, M
EM: loutre@astr.ucl.ac.be
AF: Universite catholique de Louvain, Institut d'Astronomie et de Geophysique G. Lemaitre, Chemin du Cyclotron, 2, Louvain-la-Neuve, 1348 Belgium
AU: * Berger, A L
EM: berger@astr.ucl.ac.be
AF: Universite catholique de Louvain, Institut d'Astronomie et de Geophysique G. Lemaitre, Chemin du Cyclotron, 2, Louvain-la-Neuve, 1348 Belgium
AU: Melice, J
EM: jmelice@ocean.uct.ac.za
AF: University of Cape Town, Dept. of Oceanography, Rondebosch, Rondebosch, 7701 South Africa
AB: Since the paper by Hays et al. (1976), spectral analyses of climate proxy records provide substantial evidence that a fraction of the climatic variance is driven by insolation changes in the frequency ranges of obliquity and precession variations. However it is the variance components centered near 100 kyr which dominate most Upper Pleistocene Climatic records, although the amount of insolation perturbation at the eccentricity driven 100-kyr period is much too small to cause a climate change of ice-age amplitude. This direct influence of eccentricity on daily irradiation is actually through the variations of the so-called solar constant which amounts up to a few per mil at the maximum (Berger, 1977). Many attempts to find an explanation to this 100-kyr cycle in climatic records have been made over the last decades. Here we show that the double maximum which characterizes the daily irradiation received in tropical latitudes over the course of the year is at the origin of a 100-kyr and a 5.5-kyr periods related respectively to eccentricity and precession.
DE: 3339 Ocean/atmosphere interactions (0312, 4504)
DE: 3344 Paleoclimatology
DE: 4267 Paleoceanography
DE: 1620 Climate dynamics (3309)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2004 AGU Fall Meeting