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
• Other Authors: Barcelona Supercomputing Center
• Format: Article in Journal/Newspaper
• Language: English
• Published: Springer 2022
• Subjects: Àrees temàtiques de la UPC::Enginyeria agroalimentària::Ciències de la terra i de la vida::Climatologia i meteorologia; El Niño Current; Teleconnections (Climatology); El Niño-Southern Oscillation (ENSO); Sea-level pressure; Tropospheric ENSO teleconnection; Simulació per ordinador; North Atlantic
• Online Access: http://hdl.handle.net/2117/374577; https://doi.org/10.1007/s00382-022-06508-6

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. B.M. and J.G.-S. were supported by the “Contratos Predoctorales para la Formación de Doctores” (BES-2016-076431) and “Ramón y Cajal” (RYC-2016-21181) programmes, respectively. Tercio Ambrizzi was supported by the National Institute of Science and Technology for Climate Change Phase 2 under CNPq Grant 465501/2014-1, 301397/2019-8; FAPESP Grants 2014/50848-9 and 2017/09659-6. This study also received funding from the Spanish ATLANTE project (PID2019-110234RB-C21). We acknowledge the World Climate research Programme’s Working Group on Coupled Modelling, which is responsible for CMIP. Technical support at BSC (Computational Earth Sciences group) is sincerely acknowledged. ...