thumbnail

Expression of seasonal and ENSO forcing in climatic variability at lower than ENSO frequencies: evidence from Pleistocene marine varves off California

Palaeogeography, Palaeoclimatology, Palaeoecology

By:
, ,

Links

  • The Publications Warehouse does not have links to digital versions of this publication at this time

Abstract

Upper Pleistocene marine sediments along the upper continental slope off northern and central California contain alternations of varved and bioturbated sediments and associated changes in biota and sediment composition. These alternations can be related to conditions that accompany El Nin??o and anti-El Nin??o (ENSO) circulation. Anti-El Nin??o conditions are characterized by increased upwelling and productivity and by low concentrations of dissolved oxygen in the oxygen minimum zone that resulted in varve preservation. El Nin??o conditions are characterized by little or no upwelling, low productivity, and higher concentrations of dissolved oxygen that resulted in zones of bioturbation. Alternations of varves and zones of bioturbation, that range from decades to millennia, occur through the upper Pleistocene section. The inferred long-term alternations in El Nin??o and anti-El Nin??o conditions appear to be a re-expression of ENSO's primary 3-7 year cycle. Decadal to millennial cycles of productivity associated with El Nin??o and anti-El Nin??o conditions may have served as a "carbon pump" and transferred atmospheric CO2 to the marine reservoir. Changes in sediment composition and organisms associated with El Nin??o or anti-El Nin??o conditions can be related to both seasonal and ENSO phenomena. Expression of these changes at lower-than-ENSO frequencies may be partly explained by adding the effects of seasonal variability to effects produced by a self-oscillating ENSO system. However, deterministic mechanisms, including solar modulation of ENSO, may also contribute to long-term alternations of El Nin??o and anti-El Nin??o conditions. ?? 1990.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Expression of seasonal and ENSO forcing in climatic variability at lower than ENSO frequencies: evidence from Pleistocene marine varves off California
Series title:
Palaeogeography, Palaeoclimatology, Palaeoecology
Volume
78
Issue:
3-4
Year Published:
1990
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
287
Last page:
300
Number of Pages:
14