El Niño variability in simple ocean data assimilation (SODA), 1871–2008
Article first published online: 17 FEB 2011
Copyright 2011 by the American Geophysical Union.
Journal of Geophysical Research: Oceans (1978–2012)
Volume 116, Issue C2, February 2011
How to Cite
2011), El Niño variability in simple ocean data assimilation (SODA), 1871–2008, J. Geophys. Res., 116, C02024, doi:10.1029/2010JC006695., and (
- Issue published online: 17 FEB 2011
- Article first published online: 17 FEB 2011
- Manuscript Accepted: 3 DEC 2010
- Manuscript Revised: 15 NOV 2010
- Manuscript Received: 30 SEP 2010
- El Niño;
- ocean reanalysis;
- decadal variability
 A new ocean reanalysis that covers the period from 1871 to 2008 is used to explore the time-evolving characteristics of El Niño. The new reanalysis assimilates all available hydrographic and sea surface temperature data into a model of the global ocean forced with surface boundary conditions from an atmospheric reanalysis that also covers the period from 1871 through 2008. Using traditional measures of El Niño, our reanalysis shows that the timing of El Niño events is in agreement with sea surface temperature reconstructions, but El Niño in the reanalysis is stronger, particularly from 1871 to 1920. A new index based on the first moment of the temperature anomaly is introduced. The new index is used to characterize the strength and location of El Niño events and has the advantage that it is independent of the location of El Niño. Using the new index, El Niño in the reanalysis shows prominent decadal variability of strength but relatively little long-term trend. El Niño events were strong in the last part of the 19th century and first part of the 20th century and again in the latter part of the 20th century, with weak El Niño events in the middle of the 20th century. The location of El Niño also varies considerably, ranging from the western to the eastern Pacific near the coast of South America. However, the null hypothesis that the location of El Niño can be represented as a random distribution about a central longitude of about 140°W cannot be rejected.