HR: 08:45h
AN: PP51A-04 INVITED     [PDF]
TI: Statistical properties and spatial distribution of the low-frequency solar signal in paleoclimate reconstructions and a coupled model
AU: * Oh, H
EM: heeseok@stat.ualberta.ca
AF: University of Alberta, 114 St - 89 Ave, Edmonton, AB T6G 2G1 Canada
AU: Ammann, C M
AF: National Center for Atmospheric Research, 1850 Table Mesa Drive, Boulder, CO 80307 United States
AU: Naveau, P
AF: University of Colorado, ECOT 231, Boulder, CO 80309 United States
AU: Tomas, R
AF: University of Colorado, ECOT 231, Boulder, CO 80309 United States
AU: Joos, F
AF: University of Bern, Sidlerstrasse 5, Bern, 3012 Switzerland
AB: New doubt raised on physical mechanisms previously assumed to be responsible for a low-frequency background trend in the solar activity has put many climate studies in a void. Both climate modeling and proxy based fingerprinting efforts are directly affected by this issue because they strongly depend on the reconstructions of the forcing for which they attempt to find characteristic signals in climate. Although large uncertainty has been known for a long time, the possible lack of a solar trend appears in sharp contrast to what was generally regarded as an already rather too small of a forcing given the magnitude of some of the climate variations over the past centuries and millennia. The new findings now put even more weight onto feedback processes that can magnify the signal. We present statistical analyses of proxies representing different solar activity measures from the last millennium. We then isolate the temporal elements of past solar activity that one would still expect to find even under absence of the stong background trend. Using non- decimated descrete wavelet transform, the spatial features of solar modulated climate variations are extracted from proxy records as well as from two experiments with a coupled General Circulation Model which were forced with solar irradiance variability and explosive volcanism. We discuss important aspects of coherency and stationarity for the known solar variations at 11/22-year, 80-88-year and ~200-year cycles and quasi-cycles. Finally, we present a statistical framework which can help identify mechanisms and feedbacks involved in translating a solar modulated perturbation into the Earth's climate system.
DE: 1650 Solar variability
DE: 3344 Paleoclimatology
DE: 7536 Solar activity cycle (2162)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2003 Fall Meeting