Teleconnections and relationship between the El Niño–Southern Oscillation (ENSO) and the Southern Annular Mode (SAM) in reconstructions and models over the past millennium

Dätwyler, Christoph; Grosjean, Martin; Steiger, Nathan J.; Neukom, Raphael (2020). Teleconnections and relationship between the El Niño–Southern Oscillation (ENSO) and the Southern Annular Mode (SAM) in reconstructions and models over the past millennium. Climate of the past, 16(2), pp. 743-756. Copernicus Publications 10.5194/cp-16-743-2020

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The climate of the Southern Hemisphere (SH) is strongly influenced by variations in the El Niño–Southern Oscillation (ENSO) and the Southern Annular Mode (SAM). Because of the limited length of instrumental records in most parts of the SH, very little is known about the relationship between these two key modes of variability over time. Using proxy-based reconstructions and last-millennium climate model simulations, we find that ENSO and SAM indices are mostly negatively correlated over the past millennium. Pseudo-proxy experiments indicate that currently available proxy records are able to reliably capture ENSO–SAM relationships back to at least 1600 CE. Palaeoclimate reconstructions show mostly negative correlations back to about 1400 CE. An ensemble of last-millennium climate model simulations confirms this negative correlation, showing a stable correlation of approximately −0.3. Despite this generally negative relationship we do find intermittent periods of positive ENSO–SAM correlations in individual model simulations and in the palaeoclimate reconstructions. We do not find evidence that these relationship fluctuations are caused by exogenous forcing nor by a consistent climate pattern. However, we do find evidence that strong negative correlations are associated with strong positive (negative) anomalies in the Interdecadal Pacific Oscillation and the Amundsen Sea Low during periods when SAM and ENSO indices are of opposite (equal) sign.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Institute of Geography > Physical Geography > Unit Paleolimnology
10 Strategic Research Centers > Oeschger Centre for Climate Change Research (OCCR)
08 Faculty of Science > Institute of Geography
08 Faculty of Science > Institute of Geography > Physical Geography

Graduate School:

Graduate School of Climate Sciences

UniBE Contributor:

Dätwyler, Christoph; Grosjean, Martin and Neukom, Raphael

Subjects:

500 Science > 550 Earth sciences & geology
900 History > 910 Geography & travel

ISSN:

1814-9324

Publisher:

Copernicus Publications

Language:

English

Submitter:

Giulia Luise Wienhues

Date Deposited:

14 May 2020 11:58

Last Modified:

14 May 2020 11:58

Publisher DOI:

10.5194/cp-16-743-2020

BORIS DOI:

10.7892/boris.143535

URI:

https://boris.unibe.ch/id/eprint/143535

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