Frequency Domain Multimodel Analysis of the Response of Atlantic Meridional Overturning Circulation to Surface Forcing
The dynamics of the Atlantic meridional overturning circulation (AMOC) vary considerably among different climate models; for example, some models show clear peaks in their power spectra while others do not. To elucidate these model differences, transfer functions are used to estimate the frequency d...
Published in: | Journal of Climate |
---|---|
Main Authors: | , , |
Format: | Article in Journal/Newspaper |
Language: | unknown |
Published: |
American Meteorological Society
2013
|
Subjects: | |
Online Access: | https://doi.org/10.1175/JCLI-D-12-00717.1 |
id |
ftcaltechauth:oai:authors.library.caltech.edu:nv8xw-s5y65 |
---|---|
record_format |
openpolar |
spelling |
ftcaltechauth:oai:authors.library.caltech.edu:nv8xw-s5y65 2024-09-15T18:17:18+00:00 Frequency Domain Multimodel Analysis of the Response of Atlantic Meridional Overturning Circulation to Surface Forcing MacMartin, Douglas G. Tziperman, Eli Zanna, Laure 2013-11 https://doi.org/10.1175/JCLI-D-12-00717.1 unknown American Meteorological Society https://doi.org/10.1175/JCLI-D-12-00717.1 oai:authors.library.caltech.edu:nv8xw-s5y65 eprintid:43924 resolverid:CaltechAUTHORS:20140221-095813127 info:eu-repo/semantics/openAccess Other Journal of Climate, 26(21), 8323-8340, (2013-11) Atlantic Ocean Meridional overturning circulation Ocean dynamics Climate models info:eu-repo/semantics/article 2013 ftcaltechauth https://doi.org/10.1175/JCLI-D-12-00717.1 2024-08-06T15:35:05Z The dynamics of the Atlantic meridional overturning circulation (AMOC) vary considerably among different climate models; for example, some models show clear peaks in their power spectra while others do not. To elucidate these model differences, transfer functions are used to estimate the frequency domain relationship between surface forcing fields, including sea surface temperature, salinity, and wind stress, and the resulting AMOC response. These are estimated from the outputs of the Coupled Model Intercomparison Project phase 5 (CMIP5) and phase 3 (CMIP3) control runs for eight different models, with a specific focus on Geophysical Fluid Dynamics Laboratory Climate Model, version 2.1 (GFDL CM2.1), and the Community Climate System Model, version 4 (CCSM4), which exhibit rather different spectral behavior. The transfer functions show very little agreement among models for any of the pairs of variables considered, suggesting the existence of systematic model errors and that considerable uncertainty in the simulation of AMOC in current climate models remains. However, a robust feature of the frequency domain analysis is that models with spectral peaks in their AMOC correspond to those in which AMOC variability is more strongly excited by high-latitude surface perturbations that have periods corresponding to the frequency of the spectral peaks. This explains why different models exhibit such different AMOC variability. These differences would not be evident without using a method that explicitly computes the frequency dependence rather than a priori assuming a particular functional form. Finally, transfer functions are used to evaluate two proposed physical mechanisms for model differences in AMOC variability: differences in Labrador Sea stratification and excitation by westward-propagating subsurface Rossby waves. © 2013 American Meteorological Society. Manuscript received 30 September 2012, in final form 6 March 2013. This work was supported by Grant DE-SC0004984 from the DOE Climate and Environmental Sciences ... Article in Journal/Newspaper Labrador Sea Caltech Authors (California Institute of Technology) Journal of Climate 26 21 8323 8340 |
institution |
Open Polar |
collection |
Caltech Authors (California Institute of Technology) |
op_collection_id |
ftcaltechauth |
language |
unknown |
topic |
Atlantic Ocean Meridional overturning circulation Ocean dynamics Climate models |
spellingShingle |
Atlantic Ocean Meridional overturning circulation Ocean dynamics Climate models MacMartin, Douglas G. Tziperman, Eli Zanna, Laure Frequency Domain Multimodel Analysis of the Response of Atlantic Meridional Overturning Circulation to Surface Forcing |
topic_facet |
Atlantic Ocean Meridional overturning circulation Ocean dynamics Climate models |
description |
The dynamics of the Atlantic meridional overturning circulation (AMOC) vary considerably among different climate models; for example, some models show clear peaks in their power spectra while others do not. To elucidate these model differences, transfer functions are used to estimate the frequency domain relationship between surface forcing fields, including sea surface temperature, salinity, and wind stress, and the resulting AMOC response. These are estimated from the outputs of the Coupled Model Intercomparison Project phase 5 (CMIP5) and phase 3 (CMIP3) control runs for eight different models, with a specific focus on Geophysical Fluid Dynamics Laboratory Climate Model, version 2.1 (GFDL CM2.1), and the Community Climate System Model, version 4 (CCSM4), which exhibit rather different spectral behavior. The transfer functions show very little agreement among models for any of the pairs of variables considered, suggesting the existence of systematic model errors and that considerable uncertainty in the simulation of AMOC in current climate models remains. However, a robust feature of the frequency domain analysis is that models with spectral peaks in their AMOC correspond to those in which AMOC variability is more strongly excited by high-latitude surface perturbations that have periods corresponding to the frequency of the spectral peaks. This explains why different models exhibit such different AMOC variability. These differences would not be evident without using a method that explicitly computes the frequency dependence rather than a priori assuming a particular functional form. Finally, transfer functions are used to evaluate two proposed physical mechanisms for model differences in AMOC variability: differences in Labrador Sea stratification and excitation by westward-propagating subsurface Rossby waves. © 2013 American Meteorological Society. Manuscript received 30 September 2012, in final form 6 March 2013. This work was supported by Grant DE-SC0004984 from the DOE Climate and Environmental Sciences ... |
format |
Article in Journal/Newspaper |
author |
MacMartin, Douglas G. Tziperman, Eli Zanna, Laure |
author_facet |
MacMartin, Douglas G. Tziperman, Eli Zanna, Laure |
author_sort |
MacMartin, Douglas G. |
title |
Frequency Domain Multimodel Analysis of the Response of Atlantic Meridional Overturning Circulation to Surface Forcing |
title_short |
Frequency Domain Multimodel Analysis of the Response of Atlantic Meridional Overturning Circulation to Surface Forcing |
title_full |
Frequency Domain Multimodel Analysis of the Response of Atlantic Meridional Overturning Circulation to Surface Forcing |
title_fullStr |
Frequency Domain Multimodel Analysis of the Response of Atlantic Meridional Overturning Circulation to Surface Forcing |
title_full_unstemmed |
Frequency Domain Multimodel Analysis of the Response of Atlantic Meridional Overturning Circulation to Surface Forcing |
title_sort |
frequency domain multimodel analysis of the response of atlantic meridional overturning circulation to surface forcing |
publisher |
American Meteorological Society |
publishDate |
2013 |
url |
https://doi.org/10.1175/JCLI-D-12-00717.1 |
genre |
Labrador Sea |
genre_facet |
Labrador Sea |
op_source |
Journal of Climate, 26(21), 8323-8340, (2013-11) |
op_relation |
https://doi.org/10.1175/JCLI-D-12-00717.1 oai:authors.library.caltech.edu:nv8xw-s5y65 eprintid:43924 resolverid:CaltechAUTHORS:20140221-095813127 |
op_rights |
info:eu-repo/semantics/openAccess Other |
op_doi |
https://doi.org/10.1175/JCLI-D-12-00717.1 |
container_title |
Journal of Climate |
container_volume |
26 |
container_issue |
21 |
container_start_page |
8323 |
op_container_end_page |
8340 |
_version_ |
1810455314966773760 |