Reconstructing extreme AMOC events through nudging of the ocean surface: a perfect model approach
While the Atlantic Meridional Overturning Circulation (AMOC) is thought to be a crucial component of the North Atlantic climate, past changes in its strength are challenging to quantify, and only limited information is available. In this study, we use a perfect model approach with the IPSL-CM5A-LR m...
Published in: | Climate Dynamics |
---|---|
Main Authors: | , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Springer
2017
|
Subjects: | |
Online Access: | https://centaur.reading.ac.uk/68579/ https://centaur.reading.ac.uk/68579/8/art%253A10.1007%252Fs00382-017-3521-4.pdf https://centaur.reading.ac.uk/68579/2/AMOC-peak-recontruction-revised_final-accepted.pdf |
id |
ftunivreading:oai:centaur.reading.ac.uk:68579 |
---|---|
record_format |
openpolar |
spelling |
ftunivreading:oai:centaur.reading.ac.uk:68579 2024-09-15T18:14:29+00:00 Reconstructing extreme AMOC events through nudging of the ocean surface: a perfect model approach Ortega, Pablo Guilyardi, Eric Swingedouw, Didier Mignot, Juliette Nguyen, Sebastien 2017-11 text https://centaur.reading.ac.uk/68579/ https://centaur.reading.ac.uk/68579/8/art%253A10.1007%252Fs00382-017-3521-4.pdf https://centaur.reading.ac.uk/68579/2/AMOC-peak-recontruction-revised_final-accepted.pdf en eng Springer https://centaur.reading.ac.uk/68579/8/art%253A10.1007%252Fs00382-017-3521-4.pdf https://centaur.reading.ac.uk/68579/2/AMOC-peak-recontruction-revised_final-accepted.pdf Ortega, P. <https://centaur.reading.ac.uk/view/creators/90006467.html>, Guilyardi, E. <https://centaur.reading.ac.uk/view/creators/90000869.html>, Swingedouw, D., Mignot, J. and Nguyen, S. (2017) Reconstructing extreme AMOC events through nudging of the ocean surface: a perfect model approach. Climate Dynamics, 49 (9-10). pp. 3425-3441. ISSN 0930-7575 doi: https://doi.org/10.1007/s00382-017-3521-4 <https://doi.org/10.1007/s00382-017-3521-4> cc_by_4 Article PeerReviewed 2017 ftunivreading https://doi.org/10.1007/s00382-017-3521-4 2024-06-25T15:00:08Z While the Atlantic Meridional Overturning Circulation (AMOC) is thought to be a crucial component of the North Atlantic climate, past changes in its strength are challenging to quantify, and only limited information is available. In this study, we use a perfect model approach with the IPSL-CM5A-LR model to assess the performance of several surface nudging techniques in reconstructing the variability of the AMOC. Special attention is given to the reproducibility of an extreme positive AMOC peak from a preindustrial control simulation. Nudging includes standard relaxation techniques towards the sea surface temperature and salinity anomalies of this target control simulation, and/or the prescription of the wind-stress fields. Surface nudging approaches using standard fixed restoring terms succeed in reproducing most of the target AMOC variability, including the timing of the extreme event, but systematically underestimate its amplitude. A detailed analysis of the AMOC variability mechanisms reveals that the underestimation of the extreme AMOC maximum comes from a deficit in the formation of the dense water masses in the main convection region, located south of Iceland in the model. This issue is largely corrected after introducing a novel surface nudging approach, which uses a varying restoring coefficient that is proportional to the simulated mixed layer depth, which, in essence, keeps the restoring time scale constant. This new technique substantially improves water mass transformation in the regions of convection, and in particular, the formation of the densest waters, which are key for the representation of the AMOC extreme. It is therefore a promising strategy that may help to better constrain the AMOC variability and other ocean features in the models. As this restoring technique only uses surface data, for which better and longer observations are available, it opens up opportunities for improved reconstructions of the AMOC over the last few decades. Article in Journal/Newspaper Iceland North Atlantic CentAUR: Central Archive at the University of Reading Climate Dynamics 49 9-10 3425 3441 |
institution |
Open Polar |
collection |
CentAUR: Central Archive at the University of Reading |
op_collection_id |
ftunivreading |
language |
English |
description |
While the Atlantic Meridional Overturning Circulation (AMOC) is thought to be a crucial component of the North Atlantic climate, past changes in its strength are challenging to quantify, and only limited information is available. In this study, we use a perfect model approach with the IPSL-CM5A-LR model to assess the performance of several surface nudging techniques in reconstructing the variability of the AMOC. Special attention is given to the reproducibility of an extreme positive AMOC peak from a preindustrial control simulation. Nudging includes standard relaxation techniques towards the sea surface temperature and salinity anomalies of this target control simulation, and/or the prescription of the wind-stress fields. Surface nudging approaches using standard fixed restoring terms succeed in reproducing most of the target AMOC variability, including the timing of the extreme event, but systematically underestimate its amplitude. A detailed analysis of the AMOC variability mechanisms reveals that the underestimation of the extreme AMOC maximum comes from a deficit in the formation of the dense water masses in the main convection region, located south of Iceland in the model. This issue is largely corrected after introducing a novel surface nudging approach, which uses a varying restoring coefficient that is proportional to the simulated mixed layer depth, which, in essence, keeps the restoring time scale constant. This new technique substantially improves water mass transformation in the regions of convection, and in particular, the formation of the densest waters, which are key for the representation of the AMOC extreme. It is therefore a promising strategy that may help to better constrain the AMOC variability and other ocean features in the models. As this restoring technique only uses surface data, for which better and longer observations are available, it opens up opportunities for improved reconstructions of the AMOC over the last few decades. |
format |
Article in Journal/Newspaper |
author |
Ortega, Pablo Guilyardi, Eric Swingedouw, Didier Mignot, Juliette Nguyen, Sebastien |
spellingShingle |
Ortega, Pablo Guilyardi, Eric Swingedouw, Didier Mignot, Juliette Nguyen, Sebastien Reconstructing extreme AMOC events through nudging of the ocean surface: a perfect model approach |
author_facet |
Ortega, Pablo Guilyardi, Eric Swingedouw, Didier Mignot, Juliette Nguyen, Sebastien |
author_sort |
Ortega, Pablo |
title |
Reconstructing extreme AMOC events through nudging of the ocean surface: a perfect model approach |
title_short |
Reconstructing extreme AMOC events through nudging of the ocean surface: a perfect model approach |
title_full |
Reconstructing extreme AMOC events through nudging of the ocean surface: a perfect model approach |
title_fullStr |
Reconstructing extreme AMOC events through nudging of the ocean surface: a perfect model approach |
title_full_unstemmed |
Reconstructing extreme AMOC events through nudging of the ocean surface: a perfect model approach |
title_sort |
reconstructing extreme amoc events through nudging of the ocean surface: a perfect model approach |
publisher |
Springer |
publishDate |
2017 |
url |
https://centaur.reading.ac.uk/68579/ https://centaur.reading.ac.uk/68579/8/art%253A10.1007%252Fs00382-017-3521-4.pdf https://centaur.reading.ac.uk/68579/2/AMOC-peak-recontruction-revised_final-accepted.pdf |
genre |
Iceland North Atlantic |
genre_facet |
Iceland North Atlantic |
op_relation |
https://centaur.reading.ac.uk/68579/8/art%253A10.1007%252Fs00382-017-3521-4.pdf https://centaur.reading.ac.uk/68579/2/AMOC-peak-recontruction-revised_final-accepted.pdf Ortega, P. <https://centaur.reading.ac.uk/view/creators/90006467.html>, Guilyardi, E. <https://centaur.reading.ac.uk/view/creators/90000869.html>, Swingedouw, D., Mignot, J. and Nguyen, S. (2017) Reconstructing extreme AMOC events through nudging of the ocean surface: a perfect model approach. Climate Dynamics, 49 (9-10). pp. 3425-3441. ISSN 0930-7575 doi: https://doi.org/10.1007/s00382-017-3521-4 <https://doi.org/10.1007/s00382-017-3521-4> |
op_rights |
cc_by_4 |
op_doi |
https://doi.org/10.1007/s00382-017-3521-4 |
container_title |
Climate Dynamics |
container_volume |
49 |
container_issue |
9-10 |
container_start_page |
3425 |
op_container_end_page |
3441 |
_version_ |
1810452253817962496 |