Inter-decadal signals during the last millennium (AD 1117-1992) in the varve record of Santa Barbara Basin, California

F. Biondi, C.B. Lange, M.K. Hughes, W.H. Berger
Scripps Institution of Oceanography, GRD, Mailcode 0215, University of California-San Diego, La Jolla, CA 92093-0215, U.S.A.

Abstract:

A newly developed chronology of annual varve thickness (AD 1117-1992) from Santa Barbara Basin has been decomposed into orthogonal components using singular spectrum analysis (SSA) to identify and retrieve inter-decadal oscillations. After removing all variability with periods greater than 150 years, leading SSA eigenfunctions (EOFs) identify four oscillatory pairs with periods of , , , and years respectively. Based on 2500 simulated series and on two-sided confidence intervals, EOFs 1-7 are significant at the 99% level and EOFs 8-9 are significant at the 90% level. Oscillatory signals retrieved from the marine varves show an abrupt change in frequency and amplitude near AD 1600. The largest contribution to this environmental shift is given by the interdecadal components, especially the and the -year oscillation, suggesting a connection with global-scale decadal cycles identified in the subtropical Pacific gyre circulation and, possibly, with solar-driven phenomena. The near-AD 1600 change identified in the varve record may be related to multi-annual events reported for the nearby Santa Monica Basin and for forest ecosystems of the American Southwest.

AGU Index Terms: 4267 Paleoceanography; 3344 Paleoclimatology; 1620 Climate dynamics; 4221 Dendrochronology
Keywords/Free Terms: Paleoclimatology, climate dynamics, dendrochronology, Santa Barbara Basin.

Geophysical Res. Ltrs. 96GL03813
Vol. 24 , No. 2 , p. 193