EMS Annual Meeting Abstracts
Vol. 18, EMS2021-104, 2021
EMS Annual Meeting 2021
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

El Niño teleconnection to the Euro-Mediterranean late-winter: the role of extratropical Pacific modulation 

Marianna Benassi1, Giovanni Conti1, Silvio Gualdi1,2, Paolo Ruggieri1,3, Stefano Materia1, Javier García-Serrano4,5, Froila M. Palmeiro4, Lauriane Batté6, and Constantin Ardilouze6
Marianna Benassi et al.
  • 1CMCC FOUNDATION, CSP, Lecce, Italy (marianna.benassi@cmcc.it)
  • 2Istituto Nazionale di Geofisica e Vulcanologia (INGV), Bologna, Italy
  • 3Dipartimento di Fisica e Astronomia (DIFA), Alma Mater Studiorum University of Bologna, Bologna, Italy
  • 4Group of Meteorology, Universitat de Barcelona (UB), Barcelona, Spain
  • 5Barcelona Supercomputing Center (BSC), Barcelona, Spain
  • 6CNRM, Université de Toulouse, Météo-France, CNRS, Toulouse, France

El Niño Southern Oscillation (ENSO) represents the major driver of interannual climate variability at global scale. Observational and model-based studies have fostered a long-standing debate on the shape and intensity of the ENSO influence over the Euro-Mediterranean sector. Indeed, the detection of this signal is strongly affected by the large internal variability that characterizes the atmospheric circulation in the North Atlantic-European (NAE) region. This study explores if and how the low-frequency variability of North Pacific sea surface temperature (SST) may impact the El Niño-NAE teleconnection in late winter, which consists of a dipolar pattern between middle and high latitudes. A set of idealized atmosphere-only experiments, prescribing different phases of the anomalous SST linked to the Pacific Decadal Oscillation (PDO) superimposed onto an El Niño-like forcing in the tropical Pacific, has been performed in a multi-model framework, in order to assess the potential modulation of the positive ENSO signal. The modelling results suggest, in agreement with observational estimates, that the PDO negative phase (PDO-) may enhance the amplitude of the El Niño-NAE teleconnection, while the dynamics involved appear to be unaltered. On the other hand, the modulating role of the PDO positive phase (PDO+) is not reliable across models. This finding is consistent with the atmospheric response to the PDO itself, which is robust and statistically significant only for PDO-. Its modulation seems to rely on the enhanced meridional SST gradient and the related turbulent heat-flux released along the Kuroshio-Oyashio extension. PDO- weakens the North Pacific jet, whereby favoring more poleward propagation of wave activity, strengthening the El Niño-forced Rossby wave-train.

These results imply that there might be conditional predictability for the interannual Euro-Mediterranean climate variability depending on the background state.

How to cite: Benassi, M., Conti, G., Gualdi, S., Ruggieri, P., Materia, S., García-Serrano, J., Palmeiro, F. M., Batté, L., and Ardilouze, C.: El Niño teleconnection to the Euro-Mediterranean late-winter: the role of extratropical Pacific modulation , EMS Annual Meeting 2021, online, 6–10 Sep 2021, EMS2021-104, https://doi.org/10.5194/ems2021-104, 2021.

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