The effect of model bias on Atlantic freshwater transport and implications for AMOC bi-stability
Evidence from paleo-proxy records suggests that the Atlantic Meridional Overturning Circulation (AMOC) can be in both an AMOC on state, the AMOC as we observe it today, and an AMOC off state, where the AMOC becomes extremely weak or even collapses. The freshwater transport due to the AMOC ($ M_{ov}...
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| Format: | Article |
| Language: | English |
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Stockholm University Press
2017-01-01
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| Series: | Tellus: Series A, Dynamic Meteorology and Oceanography |
| Subjects: | |
| Online Access: | http://dx.doi.org/10.1080/16000870.2017.1299910 |
| _version_ | 1818139268167499776 |
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| author | J.V. Mecking S.S. Drijfhout L.C. Jackson M.B. Andrews |
| author_facet | J.V. Mecking S.S. Drijfhout L.C. Jackson M.B. Andrews |
| author_sort | J.V. Mecking |
| collection | DOAJ |
| description | Evidence from paleo-proxy records suggests that the Atlantic Meridional Overturning Circulation (AMOC) can be in both an AMOC on state, the AMOC as we observe it today, and an AMOC off state, where the AMOC becomes extremely weak or even collapses. The freshwater transport due to the AMOC ($ M_{ov} $) at 34°S in the Atlantic has often been used as an indicator for bi-stability, with a positive $ M_{ov} $ suggesting a monostable AMOC and a negative $ M_{ov} $ suggesting a bi-stable AMOC. Often studies have shown that the sign of the divergence of the $ M_{ov} $ might be a good indicator of AMOC bi-stability. In this study we investigate how model bias affects the sign of $ M_{ov} $ across all latitudes in the Atlantic basin, through a detailed analysis of the Coupled Model Inter-Comparison Project 5 (CMIP5) model ensemble. $ M_{ov} $, in the CMIP5 models is generally too positive in the southern Atlantic due to a salinity bias, while in the subtropical North Atlantic the values of $ M_{ov} $ are influenced by a combination of velocity and salinity biases. We compare these results to observations, reanalysis products and Hadley Centre Global Environmental Model version 3 global configuration version 2, a current generation coupled model which exhibits a stable AMOC off state, and discuss the differences that can lead to the possibility of a bi-stable AMOC as opposed to a monostable AMOC. |
| first_indexed | 2024-12-11T10:25:23Z |
| format | Article |
| id | doaj.art-2ec5d9ee834d4249a060b7386fb8062a |
| institution | Directory Open Access Journal |
| issn | 1600-0870 |
| language | English |
| last_indexed | 2024-12-11T10:25:23Z |
| publishDate | 2017-01-01 |
| publisher | Stockholm University Press |
| record_format | Article |
| series | Tellus: Series A, Dynamic Meteorology and Oceanography |
| spelling | doaj.art-2ec5d9ee834d4249a060b7386fb8062a2022-12-22T01:11:11ZengStockholm University PressTellus: Series A, Dynamic Meteorology and Oceanography1600-08702017-01-0169110.1080/16000870.2017.12999101299910The effect of model bias on Atlantic freshwater transport and implications for AMOC bi-stabilityJ.V. Mecking0S.S. Drijfhout1L.C. Jackson2M.B. Andrews3University of SouthamptonUniversity of SouthamptonMet Office, Hadley CentreMet Office, Hadley CentreEvidence from paleo-proxy records suggests that the Atlantic Meridional Overturning Circulation (AMOC) can be in both an AMOC on state, the AMOC as we observe it today, and an AMOC off state, where the AMOC becomes extremely weak or even collapses. The freshwater transport due to the AMOC ($ M_{ov} $) at 34°S in the Atlantic has often been used as an indicator for bi-stability, with a positive $ M_{ov} $ suggesting a monostable AMOC and a negative $ M_{ov} $ suggesting a bi-stable AMOC. Often studies have shown that the sign of the divergence of the $ M_{ov} $ might be a good indicator of AMOC bi-stability. In this study we investigate how model bias affects the sign of $ M_{ov} $ across all latitudes in the Atlantic basin, through a detailed analysis of the Coupled Model Inter-Comparison Project 5 (CMIP5) model ensemble. $ M_{ov} $, in the CMIP5 models is generally too positive in the southern Atlantic due to a salinity bias, while in the subtropical North Atlantic the values of $ M_{ov} $ are influenced by a combination of velocity and salinity biases. We compare these results to observations, reanalysis products and Hadley Centre Global Environmental Model version 3 global configuration version 2, a current generation coupled model which exhibits a stable AMOC off state, and discuss the differences that can lead to the possibility of a bi-stable AMOC as opposed to a monostable AMOC.http://dx.doi.org/10.1080/16000870.2017.1299910AMOCAMOC collapseabrupt climate changeCGCMCMIP5 |
| spellingShingle | J.V. Mecking S.S. Drijfhout L.C. Jackson M.B. Andrews The effect of model bias on Atlantic freshwater transport and implications for AMOC bi-stability Tellus: Series A, Dynamic Meteorology and Oceanography AMOC AMOC collapse abrupt climate change CGCM CMIP5 |
| title | The effect of model bias on Atlantic freshwater transport and implications for AMOC bi-stability |
| title_full | The effect of model bias on Atlantic freshwater transport and implications for AMOC bi-stability |
| title_fullStr | The effect of model bias on Atlantic freshwater transport and implications for AMOC bi-stability |
| title_full_unstemmed | The effect of model bias on Atlantic freshwater transport and implications for AMOC bi-stability |
| title_short | The effect of model bias on Atlantic freshwater transport and implications for AMOC bi-stability |
| title_sort | effect of model bias on atlantic freshwater transport and implications for amoc bi stability |
| topic | AMOC AMOC collapse abrupt climate change CGCM CMIP5 |
| url | http://dx.doi.org/10.1080/16000870.2017.1299910 |
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