National Oceanic and
Atmospheric Administration
United States Department of Commerce


FY 2013

El Niño impacts on seasonal U.S. atmospheric circulation, temperature and precipitation anomalies: The OLR-event perspective

Chiodi, A.M., and D.E. Harrison

J. Climate, 26(3), 822–837, doi: 10.1175/JCLI-D-12-00097.1 (2013)

We show that, since 1979 when outgoing longwave radiation (OLR) observations became reliably available, most of the useful U.S. seasonal weather impact of El Niño events is associated with the few events identified by the behavior of outgoing longwave radiation (OLR) over the eastern equatorial Pacific (“OLR-El Niño events”). These events produce composite seasonal regional weather anomalies that are 95% statistically significant and robust (associated with almost all events). We show also that there are very few statistically significant seasonal weather anomalies, even at the 80% level, associated with the non-OLR El Niño events. A major enhancement of statistical seasonal forecasting skill over the contiguous U.S. appears possible by incorporating these results. It is essential to respect that not all events commonly labeled as El Niño events lead to statistically useful U.S. seasonal forecast skill.

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