Amplitude of ENSO cycles in the Santa Barbara Basin, off California, during the past 15 000 years

Varve thickness time series from ODP Site 893 in the Santa Barbara Basin (off California) were analysed to determine variation in the strength of El Nino/Southern Oscillation (ENSO) cycles during the past 15 000yr. Mean varve thickness and variance changed over time, with thicker varves before similar to 8000 yr BP indicative of wetter than modern climates. A 100-yr running standardisation was applied to correct for non-stationarity. The contribution of ENSO-scale variability was then estimated as the amplitude of 3-8 year bandpassed data. Results show multidecadal- to centennial-scale modulation of the amplitude. On average, however, the amplitude of ENSO scale variability remained constant throughout the past 15 000 yr. We therefore conclude that, although the expression of ENSO cycles may have changed during the Holocene, there is no indication for a significant change in amplitude of interannual variability. Copyright (C) 2005 John Wiley & Sons, Ltd.