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El Nino/Southern Oscillation Research

— last modified Jul 08, 2009 03:10 PM

This page describes ongoing research on the El Niño-Southern Oscillation, more commonly known as the El Niño and La Niña phenomena. El Niño and La Niña are coupled atmosphere-ocean interactions centered in the tropical Pacific that impact on global weather patterns.

Ed Harrison and Sim Larkin have been working to detail the lifecycles of El Niño and La Niña events since the mid-1990s. This work has resulted in the first description of the statistically significant weather impacts of El Niño and La Niña events, the first description of the robust lifecycles of El Niño, La Niña, and their asymmetries, and discussion of the importance of the exact definition of El Niño and La Niña to their usefulness.

Research:                          
Data Access and Maps:




Global Lifecycles of El Niño and La Niña Events

Our work has shown that El Niño and La Niña events have robust lifecycles of sea surface temperature, sea level pressure, and surface wind patterns that occur in all or nearly all events.

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Papers in this series are:

U.S. Seasonal Weather Impacts

Our work was the first to document the statistically significant seasonal weather associations with El Niño and La Niña.

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Papers in this series are:

  • First description of the statistically significant El Niño / U.S. seasonal weather associations
    Harrison and Larkin, 1998; GRL
  • First description of the statistically significant La Niña / U.S. seasonal weather associations
    Harrison and Larkin, 2002; book chapter in "La Niña"
  • Implications of new El Niño definition on U.S. / El Niño seasonal weather associations
    Larkin and Harrison, 2005a; GRL

Global Seasonal Weather Impacts

Our work has shown the statistically significant coarse scale global seasonal weather impacts and their connection with the definition of El Niño.

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Papers in this series are:

  • Implications of El Niño definition on global El Niño impacts
    Larkin and Harrison, 2005b; GRL
  • Comparison of the 1997-98 El Niño with previous events
    Larkin and Harrison, 2008; J. Climate (in review)

El Niño Definition

Our work showed that the 2003 El Niño definition adopted by NOAA and the WMO Region IV had negative impacts on seasonal weather associations with El Niño, thereby reducing the statistical significance of El Nino for seasonal forecasting. Since this work NOAA has altered the way it uses El Niño impacts in seasonal forecasting.

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Papers in this series are:

Complete ENSO Paper List

  • Harrison D.E., Larkin N.K. 1996. The COADS sea level pressure signal: a near-global El Niño composite and time series view, 1946-1993. J. Climate, 9 (12), 3025-3055. View
  • Harrison D.E., Larkin N.K. 1998. Seasonal U.S. temperature and precipitation anomalies associated with El Niño: Historical results and comparison with 1997-98. Geophys. Res. Lett., 25 (21), 3959-3962. View
  • Harrison, D.E., and N.K. Larkin. 1998. El Niño-Southern Oscillation sea surface temperature and wind anomalies. Rev. of Geophys, 36 (3), 353-399.  View
  • Larkin N.K. 2000. Ph.D. Thesis: ENSO warm (El Niño) and cold (La Niña) events: global historical patterns, symmetries, asymmetries, and their implications. University of Washington School of Oceanography, Seattle, Washington. 317pp.
  • Larkin N.K., Harrison D.E. 2001. Tropical Pacific ENSO cold events, 1946-1995: SST, SLP and surface wind composite anomaly patterns. J. Climate, 14, 3904-3931.  View
  • Harrison D.E., Larkin N.K. 2001. Comments on Smith et al. (1999) Comparison of 1997-98 U.S. temperature and precipitation anomalies to historical ENSO warm phases.  J. Climate, 14, 1894-1895. 
  • Harrison D.E., Larkin N.K. 2002. Cold events: anti-El Niño? In: Cold Events, ed. M. Glantz, United Nations Univ. Press., Tokyo, Japan, pp. 237-241.
  • Larkin N.K., Harrison D.E. 2002. ENSO Warm (El Niño) and Cold (La Niña) event life cycles: ocean surface anomaly patterns, their symmetries, asymmetries, and implications. J. Climate, 15, 1118-1140.   View
  • Larkin N.K., Harrison D.E. 2005. On the definition of El Niño and associated seasonal average U.S. weather anomalies.  Geophys. Res. Lett., 32, L13705, doi:10.1029/2005GL022738.  View
  • Larkin N. K., Harrison D.E. 2005. Global seasonal temperature and precipitation anomalies during El Niño autumn and winter.  Geophys. Res. Lett., 32, L16705, doi:10.1029/2005GL022860.  View
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