Recent weakening in the winter ENSO teleconnection over the North Atlantic-European region

Sara Ivasić,Ivana Herceg-Bulić,Martin P King

doi:10.1007/s00382-021-05783-z

Sara Ivasić, Ivana Herceg-Bulić + Show 1 more

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https://doi.org/10.1007/s00382-021-05783-z

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Journal: Climate dynamics	Publication Date: May 4, 2021
Citations: 8	License type: open-access

Affiliation: University of Zagreb, University of Bergen

Abstract

New observational evidence for variability of the atmospheric response to wintertime El Niño-Southern Oscillation (ENSO) is found. Using different approaches and datasets, a weakening in the recent ENSO teleconnection over the North Atlantic-European (NAE) region is demonstrated. Changes in both pattern and strength of the teleconnection indicate a turning point in the 1970s with a shift from a response resembling the North Atlantic Oscillation (NAO) to an anomaly pattern orthogonal to NAO with very weak or statistically non-significant values; and to nearly non-existent teleconnection in the most recent decades. Results shows the importance of the background sea surface temperature (SST) state and sea-ice climatology having opposite effects in modulating the ENSO-NAE teleconnection. As indicated with targeted simulations, the recent change in the SST climatology in the Atlantic and Arctic has contributed to the weakening of the ENSO effect. The findings of this study can have implications on our understanding of modulations of ENSO teleconnections and ENSO as a source of predictability in the NAE sector.

Highlights

El Niño-Southern Oscillation (ENSO) is a phenomenon driven by the atmosphere–ocean interaction and a strong driver of climate variability all over the world (Lin and Qian 2019)
We have described but a small part of the substantial progress that has been achieved in understanding the ENSO impact on North AtlanticEuropean (NAE) climate, but there are still many unsettled questions related to the strength, pattern, stationarity, and the underpinning physical mechanisms of the ENSO-NAE teleconnection (Bulić and Kucharski 2012; Hardiman et al 2019; Lorenzo et al 2011; Moron and Ward 1998; van Oldenborgh et al 2000)
According to the scientific literature concerning the ENSONAE teleconnection in late winter, it is widely accepted that the ENSO impact on the NAE region projects onto a North Atlantic Oscillation (NAO)-like pattern, with positive ENSO being associated with the negative NAO

Summary

Introduction

El Niño-Southern Oscillation (ENSO) is a phenomenon driven by the atmosphere–ocean interaction and a strong driver of climate variability all over the world (Lin and Qian 2019). While the ENSO impact is quite clear for certain regions, like Australia and Pacific-North America (PNA) (Power et al 1999; Ropelewski and Halpert 1986), its influence on some other regions, such as NAE, is challenging to establish. There is considerable uncertainty on the amplitude and pattern of the atmospheric response to ENSO over NAE due to internal variability of the atmosphere (Deser et al 2017). While the wave-train originating in tropical Pacific is predominantly responsible for the ENSO influence on NAE region in late winter, interactions between tropical Pacific, Indian Ocean and Atlantic basins are important for establishing the early winter ENSO teleconnection to the NAE region (Abid et al 2020b; Ayarzagüena et al 2018). An important contributor to the observed variety of the ENSO teleconnections is the diversity, in strength and pattern, of the ENSO events that can produce diverse responses (Calvo et al 2017; Ineson and Scaife 2009; Iza and Calvo 2015; Larkin 2005; Li and Lau 2012; Toniazzo and Scaife 2006; Zhang et al 2019)

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