CMIP5 Model Intercomparison of Freshwater Budget and Circulation in the North Atlantic
ABSTRACT The subpolar North Atlantic is a center of variability of ocean properties, wind stress curl, and air–sea exchanges. Observations and hindcast simulations suggest that from the early 1970s to the mid-1990s the subpolar gyre became fresher while the gyre and meridional circulations intensifi...
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ftunivcapetownir:oai:localhost:11427/34505 2023-05-15T17:28:34+02:00 CMIP5 Model Intercomparison of Freshwater Budget and Circulation in the North Atlantic Deshayes, Julie Curry, Ruth Msadek, Rym 2014 application/pdf http://hdl.handle.net/11427/34505 https://open.uct.ac.za/bitstream/11427/34505/1/DeshayesJulie_CMIP5_Model_Int_2014.pdf eng eng Faculty of Science Department of Oceanography http://hdl.handle.net/11427/34505 https://open.uct.ac.za/bitstream/11427/34505/1/DeshayesJulie_CMIP5_Model_Int_2014.pdf Journal of Climate https://dx.doi.org/10.1175/JCLI-D-12-00700.1 27 9 3298 - 3317 digital simulation General circulation models Multimodel Climate models Decadal variation Interannual variation time scales Century 20th Hindcast Intensification thermohaline circulation ocean circulation salinity water balance fresh water Comparative study Meridional overturning circulation Subpolar gyre Coupled model North Atlantic Atlantic Ocean Journal Article 2014 ftunivcapetownir https://doi.org/10.1175/JCLI-D-12-00700.1 2022-09-13T05:54:42Z ABSTRACT The subpolar North Atlantic is a center of variability of ocean properties, wind stress curl, and air–sea exchanges. Observations and hindcast simulations suggest that from the early 1970s to the mid-1990s the subpolar gyre became fresher while the gyre and meridional circulations intensified. This is opposite to the relationship of freshening causing a weakened circulation, most often reproduced by climate models. The authors hypothesize that both these configurations exist but dominate on different time scales: a fresher subpolar gyre when the circulation is more intense, at interannual frequencies (configuration A), and a saltier subpolar gyre when the circulation is more intense, at longer periods (configuration B). Rather than going into the detail of the mechanisms sustaining each configuration, the authors’ objective is to identify which configuration dominates and to test whether this depends on frequency, in preindustrial control runs of five climate models from phase 5 of the Coupled Model Intercomparison Project (CMIP5). To this end, the authors have developed a novel intercomparison method that enables analysis of freshwater budget and circulation changes in a physical perspective that overcomes model specificities. Lag correlations and a cross-spectral analysis between freshwater content changes and circulation indices validate the authors’ hypothesis, as configuration A is only visible at interannual frequencies while configuration B is mostly visible at decadal and longer periods, suggesting that the driving role of salinity on the circulation depends on frequency. Overall, this analysis underscores the large differences among state-of-the-art climate models in their representations of the North Atlantic freshwater budget. Article in Journal/Newspaper North Atlantic University of Cape Town: OpenUCT Curl ENVELOPE(-63.071,-63.071,-70.797,-70.797) Journal of Climate 27 9 3298 3317 |
institution |
Open Polar |
collection |
University of Cape Town: OpenUCT |
op_collection_id |
ftunivcapetownir |
language |
English |
topic |
digital simulation General circulation models Multimodel Climate models Decadal variation Interannual variation time scales Century 20th Hindcast Intensification thermohaline circulation ocean circulation salinity water balance fresh water Comparative study Meridional overturning circulation Subpolar gyre Coupled model North Atlantic Atlantic Ocean |
spellingShingle |
digital simulation General circulation models Multimodel Climate models Decadal variation Interannual variation time scales Century 20th Hindcast Intensification thermohaline circulation ocean circulation salinity water balance fresh water Comparative study Meridional overturning circulation Subpolar gyre Coupled model North Atlantic Atlantic Ocean Deshayes, Julie Curry, Ruth Msadek, Rym CMIP5 Model Intercomparison of Freshwater Budget and Circulation in the North Atlantic |
topic_facet |
digital simulation General circulation models Multimodel Climate models Decadal variation Interannual variation time scales Century 20th Hindcast Intensification thermohaline circulation ocean circulation salinity water balance fresh water Comparative study Meridional overturning circulation Subpolar gyre Coupled model North Atlantic Atlantic Ocean |
description |
ABSTRACT The subpolar North Atlantic is a center of variability of ocean properties, wind stress curl, and air–sea exchanges. Observations and hindcast simulations suggest that from the early 1970s to the mid-1990s the subpolar gyre became fresher while the gyre and meridional circulations intensified. This is opposite to the relationship of freshening causing a weakened circulation, most often reproduced by climate models. The authors hypothesize that both these configurations exist but dominate on different time scales: a fresher subpolar gyre when the circulation is more intense, at interannual frequencies (configuration A), and a saltier subpolar gyre when the circulation is more intense, at longer periods (configuration B). Rather than going into the detail of the mechanisms sustaining each configuration, the authors’ objective is to identify which configuration dominates and to test whether this depends on frequency, in preindustrial control runs of five climate models from phase 5 of the Coupled Model Intercomparison Project (CMIP5). To this end, the authors have developed a novel intercomparison method that enables analysis of freshwater budget and circulation changes in a physical perspective that overcomes model specificities. Lag correlations and a cross-spectral analysis between freshwater content changes and circulation indices validate the authors’ hypothesis, as configuration A is only visible at interannual frequencies while configuration B is mostly visible at decadal and longer periods, suggesting that the driving role of salinity on the circulation depends on frequency. Overall, this analysis underscores the large differences among state-of-the-art climate models in their representations of the North Atlantic freshwater budget. |
format |
Article in Journal/Newspaper |
author |
Deshayes, Julie Curry, Ruth Msadek, Rym |
author_facet |
Deshayes, Julie Curry, Ruth Msadek, Rym |
author_sort |
Deshayes, Julie |
title |
CMIP5 Model Intercomparison of Freshwater Budget and Circulation in the North Atlantic |
title_short |
CMIP5 Model Intercomparison of Freshwater Budget and Circulation in the North Atlantic |
title_full |
CMIP5 Model Intercomparison of Freshwater Budget and Circulation in the North Atlantic |
title_fullStr |
CMIP5 Model Intercomparison of Freshwater Budget and Circulation in the North Atlantic |
title_full_unstemmed |
CMIP5 Model Intercomparison of Freshwater Budget and Circulation in the North Atlantic |
title_sort |
cmip5 model intercomparison of freshwater budget and circulation in the north atlantic |
publisher |
Faculty of Science |
publishDate |
2014 |
url |
http://hdl.handle.net/11427/34505 https://open.uct.ac.za/bitstream/11427/34505/1/DeshayesJulie_CMIP5_Model_Int_2014.pdf |
long_lat |
ENVELOPE(-63.071,-63.071,-70.797,-70.797) |
geographic |
Curl |
geographic_facet |
Curl |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
Journal of Climate https://dx.doi.org/10.1175/JCLI-D-12-00700.1 27 9 3298 - 3317 |
op_relation |
http://hdl.handle.net/11427/34505 https://open.uct.ac.za/bitstream/11427/34505/1/DeshayesJulie_CMIP5_Model_Int_2014.pdf |
op_doi |
https://doi.org/10.1175/JCLI-D-12-00700.1 |
container_title |
Journal of Climate |
container_volume |
27 |
container_issue |
9 |
container_start_page |
3298 |
op_container_end_page |
3317 |
_version_ |
1766121320909635584 |