EGU2020-17743
https://doi.org/10.5194/egusphere-egu2020-17743
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

ENSO and TWC: a multi-model evaluation

Valentina Pivotti1, Annalisa Cherchi2, Alessio Bellucci3, and Bruce Anderson4
Valentina Pivotti et al.
  • 1Boston University, Arts and Sciences, Earth and Environment, United States of America (pivotti@bu.edu)
  • 2National Institute of Geophysics and Volcanology, INGV, Bologna, Italy (annalisa.cherchi@ingv.it)
  • 3Centro Euro-Mediterraneo sui Cambiamenti Climatici, CMCC, Bologna, Italy (alessio.bellucci@cmcc.it)
  • 4Boston University, Arts and Sciences, Earth and Environment, United States of America (brucea@bu.edu)

<p>Previous research has extensively established that, during the last decades, the Trade Wind Charging (TWC) mechanism is a fundamental precursor of El Ni&ntilde;o Southern Oscillation (ENSO). Moreover, recent results suggest that its relevance as an ENSO driver varies when a longer time interval is included the analysis. This article investigates whether TWC is isolated as a significant ENSO precursor; and how the internal variance of their coupling behaves, on a CMIP6 multi model ensemble. In particular, we consider the models participating to the CMIP6 HigResMIP, specifically designed to investigate the role that model resolution plays in simulating climate processes. For each model, we have included in the analysis 100-year long integrations of the present climate that are forced with constant radiative forcing representative of the 1950s at standard and enhanced resolutions.</p>
<p>The analysis follows two steps for each experiment. First, through a combination of Empirical Orthogonal Function (EOF) and Canonical Correlation Analysis (CCA) it isolates ENSO and TWC. Then, in order to study their mutual relation, the combination of EOF and CCA is repeated over shifting time intervals.</p>
<p>The analysis indicates TWC as a strong ENSO precursor for at least one model, and the coupling between the modes shows signs of internal variability. Also, the ways in which the models reconstruct the TWC, in its intensity and shape, and its coupling with ENSO appear to be affected by the changes in resolution. These results provide an insight over the different degrees at which HigResMIP model experiments are able to characterize the features of a fundamental process like ENSO. Moreover, they cast a light over the impacts that a change in oceanic or atmospheric resolution can have when simulating a coupled mode.</p>

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Presentation version 1 – uploaded on 30 Apr 2020
  • CC1: Comment on EGU2020-17743, Paul Pukite, 07 May 2020

    Reviewing your continuous wavelet transform, the latest research by Lin&Qian suggests that tidal forcing nd not wind drives ENSO transitions. Inverting Laplace's Tidal Equation on the equator, the tidal forcing is easily observed from the wavelet transform