Underpredicted ENSO Teleconnections in Seasonal Forecasts

• Published in: Geophysical Research Letters
• Main Authors: N. C. Williams, A. A. Scaife, J. A. Screen
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2023
• Subjects: seasonal forecasts; teleconnections; ENSO; Geophysics. Cosmic physics; QC801-809; North Atlantic
• Online Access: https://doi.org/10.1029/2022GL101689; https://doaj.org/article/44e29f4b72a74715afa9689a7eb2c0fb

Abstract The El Niño‐Southern Oscillation (ENSO) influences climate variability across the globe. ENSO is highly predictable on seasonal timescales and therefore its teleconnections are a source of extratropical forecast skill. To fully harness this predictability, teleconnections must be represented accurately in seasonal forecasts. We find that a multimodel ensemble from five seasonal forecast systems can successfully capture the spatial structure of the late winter (JFM) El Niño teleconnection to the North Atlantic via North America, but the simulated amplitude is half of that observed. We find that weak amplitude teleconnections exist in all five models throughout the troposphere, and that the La Niña teleconnection is also weak. We find evidence that tropical forcing of the El Niño teleconnection is not underestimated and instead, deficiencies are likely to emerge in the extratropics. We investigate the impact of underestimated teleconnection strength on North Atlantic winter predictability, including its relevance to the signal‐to‐noise paradox.