It is well know that the large-scale climate system is strongly forced by the El Niño/Southern Oscillation (ENSO). Here we attempt to identify atmospheric/oceanic anomaly patterns that represent statistically significant precursors to the onset of ENSO events. By examining the linearly coupled atmospheric and oceanic signals related to interannual variability in observed sea-surface temperatures (SST), upper-air wind fields, and sea-level pressure patterns, a hemispheric-scale ocean/atmosphere teleconnection mode is isolated that precedes equatorial SST anomalies in the tropical Pacific by approximately 12-15 months, overcoming the “spring predictability barrier” associated with ENSO forecasting. The interannual component of this teleconnection mode is related to variability in the upper- and lower-level wind fields over the subtropical/mid-latitude Pacific as well as over North America and the Atlantic basin, suggesting possible extra-tropical forcing of the equatorial Pacific not captured by traditional paradigms of ENSO. Similar results are also seen in coupled ocean-atmosphere Climate System Model data. This talk will investigate the ocean/atmosphere structure associated with this mode of variability, as well as its possible relation to the development of ENSO events. Significant discussion of these results and pertinent areas of future research will also be provided within the broader context of the ENSO system.

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