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Theses

LA DIVERSITÉ D’ENSO ET LE CHANGEMENT CLIMATIQUE

Abstract : El Niño-Southern Oscillation (ENSO) is the dominant mode of variability in the tropical Pacific on inter-annual scale. This phenomenon affects weather events, ecosystems, agriculture and fisheries worldwide via atmospheric and oceanic teleconnections. This natural phenomenon is likely to be strongly impacted by global warming. In this thesis, we first assessed the characterisation of the diversity of El Niño events. They exhibit a wide range of amplitudes and spatial patterns of sea surface temperature (SST) anomalies. We then analysed the change in ENSO diversity statistics (amplitude, seasonality) with global warming. We used simulations from the coupled climate model CESM-LE, which provides multiple realisations (40 members) of the historical and future climate (1920-2100), under the assumption of the RCP8.5 scenario of sustained greenhouse gas emissions. We show that strong El Niño events, which display significant warming in the eastern Pacific, have their peak of SST shifted from winter to early spring (February-March-April, FMA) in the future climate. Finally, the impact of the increase in the mean vertical stratification of the equatorial Pacific on ENSO diversity is assessed in terms of dynamic processes. We propose the hypothesis that the greater persistence of strong El Niño events and the time lag of their warming peaks are due to a larger recharge process and more effective thermocline feedback in the eastern Pacific in a warmer climate as simulated by CESM-LE.
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https://tel.archives-ouvertes.fr/tel-02481637
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Submitted on : Monday, March 9, 2020 - 9:46:47 AM
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Aude Carreric. LA DIVERSITÉ D’ENSO ET LE CHANGEMENT CLIMATIQUE. Océan, Atmosphère. Université Toulouse III - Paul Sabatier, 2019. Français. ⟨tel-02481637⟩

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