Tropospheric pathways of the late-winter ENSO teleconnection to Europe

• Published in: Climate Dynamics
• Main Authors: Mezzina, Bianca, García Serrano, Javier, Ambrizzi, Tercio, Matei, Daniela, Manzini, Elisa, Bladé, Ileana
• Format: Article in Journal/Newspaper
• Language: English
• Published: Springer Verlag 2022
• Subjects: Corrent del Niño; Climatologia; Canvi climàtic; El Niño Current; Climatology; Climatic change; Pacific; North Atlantic
• Online Access: http://hdl.handle.net/2445/192697

The late-winter signal associated with the El Niño-Southern Oscillation (ENSO) over the European continent is unsettled. Two main anomalous patterns of sea-level pressure (SLP) can be identified: a "wave-like" pattern with two opposite-signed anomalies over Europe, and a pattern showing a single anomaly ("semi-isolated"). In this work, potential paths of the tropospheric ENSO teleconnection to Europe and their role in favoring a more wave-like or semi-isolated pattern are explored. Outputs from historical runs of two versions of the MPI-ESM coupled model, which simulate these two types of patterns, are examined. A novel ray-tracing approach that accounts for zonal asymmetries in the background flow is used to test potential propagation paths in these simulations and in observations; three source regions are considered: the tropical Pacific, the North America/North Atlantic, and the tropical Atlantic. The semi-isolated pattern is suggested to be related to the well-known Rossby wave train emanating from the tropical Pacific, either via a split over northern North America or via reflection due to inhomogeneities in the background flow. The wave-like pattern, in turn, appears to be related to a secondary wave train emerging from the tropical Atlantic. The competition between these two pathways contributes to determining the actual surface response.