17A.2 Strong Relations between ENSO and the Arctic Oscillation in the North American Multi-Model Ensemble

Thursday, 11 January 2018: 3:45 PM
406 (Hilton) (Austin, Texas)
Michelle L'Heureux, NOAA, College Park, MD; and M. K. Tippett, A. Kumar, A. H. Butler, L. M. Ciasto, Q. Ding, K. J. Harnos, and N. Johnson

Arctic Oscillation (AO) variability impacts climate anomalies over the mid-to-high latitudes of the Northern Hemisphere. Recently, state-of-the-art climate prediction models have proved capable of skillfully predicting the AO during the winter, revealing a previously unrealized source of climate predictability. Hindcasts from the North American Multi-Model Ensemble (NMME) show that the seasonal 200-hPa AO index is skillfully predicted up to seven months in advance and that this skill, especially at longer leads, is coincident with previously unknown and strong relations (r > 0.9) with the El Niño-Southern Oscillation (ENSO). The NMME is a seasonal prediction system that comprises eight models and up to 100 members with forecasts out to 12 months. Observed ENSO-AO correlations are within the spread of the NMME member correlations, but the majority of member correlations are stronger than observed, pointing toward too high predictability in the model, or over-confidence.
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