Detectability of an AMOC decline in current and projected climate changes
Detectability of an AMOC decline in current and projected climate changes
Determining whether the Atlantic Meridional Overturning Circulation (AMOC)'s transport is in decline is challenging due to the short duration of continuous observations. To estimate how many years are needed to detect a decline, we conduct a simulation study using synthetic data that mimics an AMOC time series. The time series' characteristics are reproduced using the trend, variance, and autocorrelation coefficient of the AMOC strength at 26.5°N from 20 Coupled Model Intercomparison Project Phase 5 (CMIP5) models under the RCP8.5 future scenario, and from RAPID observations (2004–2018). Our results suggest that the 14-year RAPID length has just entered the lower limits of the trend's “detection window” based on synthetic data generated using CMIP5 trends and variability (14–42 years; median (Formula presented.) 24 years), but twice the length is required for detectability based on RAPID variability (29–67 years; median (Formula presented.) 43 years). The annual RAPID trend is currently not statistically significant (−0.11 Sv yr
−1, p > 0.05).
Lobelle, D.
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Beaulieu, C.
13ae2c11-ebfe-48d9-bda9-122cd013c021
Livina, V.
a4cb0954-12cc-41b5-848e-c01b1578f987
Sévellec, F.
01569d6c-65b0-4270-af2a-35b0a77c9140
Frajka‐williams, E.
2b2338d1-4a28-4785-9e13-c46c35a326b3
28 October 2020
Lobelle, D.
0dccc47f-5187-4b10-a6da-f46d10d1fa3e
Beaulieu, C.
13ae2c11-ebfe-48d9-bda9-122cd013c021
Livina, V.
a4cb0954-12cc-41b5-848e-c01b1578f987
Sévellec, F.
01569d6c-65b0-4270-af2a-35b0a77c9140
Frajka‐williams, E.
2b2338d1-4a28-4785-9e13-c46c35a326b3
Lobelle, D., Beaulieu, C., Livina, V., Sévellec, F. and Frajka‐williams, E.
(2020)
Detectability of an AMOC decline in current and projected climate changes.
Geophysical Research Letters, 47 (20), [e2020GL089974].
(doi:10.1029/2020GL089974).
Abstract
Determining whether the Atlantic Meridional Overturning Circulation (AMOC)'s transport is in decline is challenging due to the short duration of continuous observations. To estimate how many years are needed to detect a decline, we conduct a simulation study using synthetic data that mimics an AMOC time series. The time series' characteristics are reproduced using the trend, variance, and autocorrelation coefficient of the AMOC strength at 26.5°N from 20 Coupled Model Intercomparison Project Phase 5 (CMIP5) models under the RCP8.5 future scenario, and from RAPID observations (2004–2018). Our results suggest that the 14-year RAPID length has just entered the lower limits of the trend's “detection window” based on synthetic data generated using CMIP5 trends and variability (14–42 years; median (Formula presented.) 24 years), but twice the length is required for detectability based on RAPID variability (29–67 years; median (Formula presented.) 43 years). The annual RAPID trend is currently not statistically significant (−0.11 Sv yr
−1, p > 0.05).
Text
2020GL089974 (1)
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Accepted/In Press date: 13 October 2020
Published date: 28 October 2020
Additional Information:
Funding Information:
This study was part of PhD research jointly funded by the Department of Ocean and Earth Science, University of Southampton and the National Physical Laboratory. The research at the National Physical Laboratory was funded by the National Metrology Programme of the UK Department of Business, Energy and Industrial Strategy (BEIS). This research was also supported by the UK Natural and Environmental Research Council (SMURPHS, NE/N005767/1) and by the DECLIC project funded through the French CNRS/INSU/LEFE program. We would like to thank and acknowledge the World Climate Research Programme's Working Group on Coupled Modelling, which is responsible for CMIP. We are very grateful to three anonymous reviewers who provided many constructive comments that helped to improve this manuscript.
Funding Information:
The CMIP5 data can be found from the portal Earth System Grid‐Center for Enabling Technologies (ESG‐CET) at this site ( https://esgf‐node.llnl.gov/search/cmip5/ ). Data from the RAPID AMOC monitoring project are funded by the Natural Environment Research Council and are freely available at this site ( https://rapid.ac.uk ).
Publisher Copyright:
© 2020. The Authors.
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Local EPrints ID: 445156
URI: http://eprints.soton.ac.uk/id/eprint/445156
ISSN: 0094-8276
PURE UUID: eceb4f4e-8379-4fc6-8fd1-3b4a6b50130a
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Date deposited: 24 Nov 2020 17:30
Last modified: 05 Jun 2024 19:10
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Author:
D. Lobelle
Author:
V. Livina
Author:
E. Frajka‐williams
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