Numerical simulations of the Atlantic Ocean during the period 1950 to 1989, using a sigma coordinate, free surface numerical model, show long-term variabilities in the upper ocean subtropical gyre similar to those obtained from observations. The simulations show how westward propagating planetary waves, originated in the eastern North Atlantic, affect interdecadal variabilities of ocean propert...

The responses of North Pacific intermediate and deep water ventilation and ocean biogeochemical properties to northern North Atlantic glacial freshwater perturbations are evaluated with a coupled atmosphere–ocean general circulation model MIROC and an earth system model of intermediate complexity LOVECLIM. When the Atlantic meridional overturning circulation (AMOC) is weakened as a result of th...

In the 1960s North Atlantic sea surface temperatures (SST) cooled rapidly. The magnitude of the cooling was largest in the North Atlantic subpolar gyre (SPG), and was coincident with a rapid freshening of the SPG. Here we analyze hindcasts of the 1960s North Atlantic cooling made with the UK Met Office’s decadal prediction system (DePreSys), which is initialised using observations. It is shown ...

[1] Recent paleoproxy records suggest that the mean latitude of the Atlantic Intertropical Convergence Zone (ITCZ) varied synchronously with North Atlantic climate over a range of timescales throughout the Holocene and Last Glacial Maximum. We show that the present-day ‘‘meridional mode’’ of atmosphere-ocean variability in the tropical Atlantic is a potentially useful model for understanding th...

Simulations performed with Ocean–Atmosphere General Circulation Models (OAGCM) under the Climate Model Intercomparison Project, phase 5 (CMIP5) (Taylor et al. 2012), provide climate predictions for the upcoming 100 years (the so-called radiative concentration pathways emission scenarios). However, CMIP simulations suffer from severe limitations in predicting climate at a shorttime horizon (< 10...

[1] We examine the first decade of adjustment of the North Atlantic climate following an abrupt freshening of the high North Atlantic and resulting slowdown of the Atlantic meridional overturning circulation (AMOC) in a coupled model, with reference to previously proposed teleconnection mechanisms. After an initial ocean-driven cooling at the subtropical-subpolar gyre boundary, subsequent equat...

The global response to a shutdown of the Atlantic meridional overturning circulation (AMOC) is investigated by conducting a water-hosing experiment with a coupled ocean–atmosphere general circulation model. In the model, the addition of freshwater in the subpolar North Atlantic shuts off the AMOC. The intense cooling in the extratropical North Atlantic induces a widespread response over the glo...

The relative flux of North Atlantic Deep Water (NADW) out of the Atlantic can be monitored in the Southern Ocean, where high 813C NADW mixes rapidly with low 813C recirculated Pacific water before forming Antarctic Bottom Water (AABW). By using 813C measured in benthic foraminifera as a water mass tracer, it is shown that the Southern Ocean was dominated by Pacific water, with little NADW contr...

Sudden changes of the Atlantic meridional overturning circulation (AMOC) are believed to have caused large, abrupt climate changes over many parts of the globe during the last glacial and deglacial period. This study investigates the mechanisms by which a large freshwater input to the subarctic North Atlantic and an attendant rapid weakening of the AMOC influence North Pacific climate by analyz...