scholarly journals Observed interannual variability of the Atlantic meridional overturning circulation at 26.5°N

2012 ◽  
Vol 39 (19) ◽  
pp. n/a-n/a ◽  
Author(s):  
G. McCarthy ◽  
E. Frajka-Williams ◽  
W. E. Johns ◽  
M. O. Baringer ◽  
C. S. Meinen ◽  
...  
Keyword(s):  
Interannual Variability ◽  
Atlantic Meridional Overturning Circulation ◽  
Meridional Overturning Circulation ◽  
Overturning Circulation ◽  
Meridional Overturning

scholarly journals Atmosphere drives recent interannual variability of the Atlantic meridional overturning circulation at 26.5°N

2013 ◽  
Vol 40 (19) ◽  
pp. 5164-5170 ◽  
Author(s):  
C. D. Roberts ◽  
J. Waters ◽  
K. A. Peterson ◽  
M. D. Palmer ◽  
G. D. McCarthy ◽  
...  
Keyword(s):  
Interannual Variability ◽  
Atlantic Meridional Overturning Circulation ◽  
Meridional Overturning Circulation ◽  
Overturning Circulation ◽  
Meridional Overturning

scholarly journals Recent Wind-Driven Variability in Atlantic Water Mass Distribution and Meridional Overturning Circulation

2017 ◽  
Vol 47 (3) ◽  
pp. 633-647 ◽  
Author(s):  
Dafydd Gwyn Evans ◽  
John Toole ◽  
Gael Forget ◽  
Jan D. Zika ◽  
Alberto C. Naveira Garabato ◽  
...  
Keyword(s):  
Interannual Variability ◽  
Mass Distribution ◽  
Water Mass ◽  
Heat Content ◽  
Atlantic Meridional Overturning Circulation ◽  
Meridional Overturning Circulation ◽  
Subtropical Gyre ◽  
Thermocline Depth ◽  
Overturning Circulation ◽  
Meridional Overturning

AbstractInterannual variability in the volumetric water mass distribution within the North Atlantic Subtropical Gyre is described in relation to variability in the Atlantic meridional overturning circulation. The relative roles of diabatic and adiabatic processes in the volume and heat budgets of the subtropical gyre are investigated by projecting data into temperature coordinates as volumes of water using an Argo-based climatology and an ocean state estimate (ECCO version 4). This highlights that variations in the subtropical gyre volume budget are predominantly set by transport divergence in the gyre. A strong correlation between the volume anomaly due to transport divergence and the variability of both thermocline depth and Ekman pumping over the gyre suggests that wind-driven heave drives transport anomalies at the gyre boundaries. This wind-driven heaving contributes significantly to variations in the heat content of the gyre, as do anomalies in the air–sea fluxes. The analysis presented suggests that wind forcing plays an important role in driving interannual variability in the Atlantic meridional overturning circulation and that this variability can be unraveled from spatially distributed hydrographic observations using the framework presented here.

scholarly journals High frequency variability of the Atlantic meridional overturning circulation

Ocean Science ◽  
2011 ◽  
Vol 7 (4) ◽  
pp. 471-486 ◽  
Author(s):  
B. Balan Sarojini ◽  
J. M. Gregory ◽  
R. Tailleux ◽  
G. R. Bigg ◽  
A. T. Blaker ◽  
...  
Keyword(s):  
Interannual Variability ◽  
Annual Cycle ◽  
Climate Models ◽  
Atlantic Meridional Overturning Circulation ◽  
Meridional Overturning Circulation ◽  
Western Boundary ◽  
Overturning Circulation ◽  
Wide Range ◽  
Meridional Overturning ◽  
Observational Estimate

Abstract. We compare the variability of the Atlantic meridional overturning circulation (AMOC) as simulated by the coupled climate models of the RAPID project, which cover a wide range of resolution and complexity, and observed by the RAPID/MOCHA array at about 26° N. We analyse variability on a range of timescales, from five-daily to interannual. In models of all resolutions there is substantial variability on timescales of a few days; in most AOGCMs the amplitude of the variability is of somewhat larger magnitude than that observed by the RAPID array, while the time-mean is within about 10 % of the observational estimate. The amplitude of the simulated annual cycle is similar to observations, but the shape of the annual cycle shows a spread among the models. A dynamical decomposition shows that in the models, as in observations, the AMOC is predominantly geostrophic (driven by pressure and sea-level gradients), with both geostrophic and Ekman contributions to variability, the latter being exaggerated and the former underrepresented in models. Other ageostrophic terms, neglected in the observational estimate, are small but not negligible. The time-mean of the western boundary current near the latitude of the RAPID/MOCHA array has a much wider model spread than the AMOC does, indicating large differences among models in the simulation of the wind-driven gyre circulation, and its variability is unrealistically small in the models. In many RAPID models and in models of the Coupled Model Intercomparison Project Phase 3 (CMIP3), interannual variability of the maximum of the AMOC wherever it lies, which is a commonly used model index, is similar to interannual variability in the AMOC at 26° N. Annual volume and heat transport timeseries at the same latitude are well-correlated within 15–45° N, indicating the climatic importance of the AMOC. In the RAPID and CMIP3 models, we show that the AMOC is correlated over considerable distances in latitude, but not the whole extent of the North Atlantic; consequently interannual variability of the AMOC at 50° N, where it is particularly relevant to European climate, is not well-correlated with that of the AMOC at 26° N, where it is monitored by the RAPID/MOCHA array.

scholarly journals High frequency variability of the Atlantic meridional overturning circulation

2011 ◽  
Vol 8 (1) ◽  
pp. 219-246 ◽  
Author(s):  
B. Balan Sarojini ◽  
J. M. Gregory ◽  
R. Tailleux ◽  
G. R. Bigg ◽  
A. T. Blaker ◽  
...  
Keyword(s):  
Interannual Variability ◽  
Climate Models ◽  
Coupled Model ◽  
Atlantic Meridional Overturning Circulation ◽  
Meridional Overturning Circulation ◽  
Overturning Circulation ◽  
The North ◽  
Wide Range ◽  
Meridional Overturning ◽  
Observational Estimate

Abstract. We compare the variability of the Atlantic meridional overturning circulation (AMOC) as simulated by the coupled climate models of the RAPID project, which cover a wide range of resolution and complexity, and observed by the RAPID/MOCHA array at about 26° N. We analyse variability on a range of timescales. In models of all resolutions there is substantial variability on timescales of a few days; in most AOGCMs the amplitude of the variability is of somewhat larger magnitude than that observed by the RAPID array, while the amplitude of the simulated annual cycle is similar to observations. A dynamical decomposition shows that in the models, as in observations, the AMOC is predominantly geostrophic (driven by pressure and sea-level gradients), with both geostrophic and Ekman contributions to variability, the latter being exaggerated and the former underrepresented in models. Other ageostrophic terms, neglected in the observational estimate, are small but not negligible. In many RAPID models and in models of the Coupled Model Intercomparison Project Phase 3 (CMIP3), interannual variability of the maximum of the AMOC wherever it lies, which is a commonly used model index, is similar to interannual variability in the AMOC at 26° N. Annual volume and heat transport timeseries at the same latitude are well-correlated within 15–45° N, indicating the climatic importance of the AMOC. In the RAPID and CMIP3 models, we show that the AMOC is correlated over considerable distances in latitude, but not the whole extent of the North Atlantic; consequently interannual variability of the AMOC at 50° N is not well-correlated with the AMOC at 26° N.

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