scholarly journals Projected changes in the seasonal cycle of the Atlantic meridional heat transport in MPI-ESM

2016 ◽  
Author(s):  
Matthias Fischer ◽  
Daniela I. V. Domeisen ◽  
Wolfgang A. Müller ◽  
Johanna Baehr
Keyword(s):  
Heat Transport ◽  
North Atlantic ◽  
Seasonal Cycle ◽  
Coupled Model ◽  
Change Scenario ◽  
Max Planck ◽  
Meridional Heat Transport ◽  
The North ◽  
The North Atlantic ◽  
Projected Changes

Abstract. We investigate the effect of a projected reduction in the Atlantic Ocean meridional heat transport (OHT) on changes in its seasonal cycle. We analyze a climate projection experiment with the Max-Planck Institute Earth System Model (MPI-ESM) performed for the Coupled Model Intercomparison Project phase 5 (CMIP5). In the RCP8.5 climate change scenario, the OHT declines in MPI-ESM in the North Atlantic by 30–50 % by the end of the 23rd century. The decline in the OHT is accompanied by a change in the seasonal cycle of the total OHT and its components. We decompose the OHT into overturning and gyre component. For the total OHT seasonal cycle, we find a northward shift of 5 degrees and latitude dependent temporal shifts of 1 to 6 months that are mainly associated with changes in the meridional velocity field. We find that the shift in the OHT seasonal cycle predominantly results from changes in the wind-driven surface circulation which projects onto the overturning component of the OHT in the tropical and subtropical North Atlantic. This leads to latitude dependent shifts of 1 to 6 months in the overturning component. In the subpolar North Atlantic, we find that the reduction of the North Atlantic Deep Water formation in RCP8.5 and changes in the gyre heat transport result in a strongly weakened seasonal cycle with a weakened seasonal amplitude by the end of the 23rd century and thus changes the OHT seasonal cycle in the SPG.

scholarly journals Changes in the seasonal cycle of the Atlantic meridional heat transport in a RCP 8.5 climate projection in MPI-ESM

2017 ◽  
Vol 8 (1) ◽  
pp. 129-146 ◽  
Author(s):  
Matthias Fischer ◽  
Daniela I. V. Domeisen ◽  
Wolfgang A. Müller ◽  
Johanna Baehr
Keyword(s):  
Heat Transport ◽  
North Atlantic ◽  
Seasonal Cycle ◽  
Climate Projection ◽  
Change Scenario ◽  
Meridional Heat Transport ◽  
Historical Simulation ◽  
The North ◽  
Rcp 8.5 ◽  
The North Atlantic

Abstract. We investigate changes in the seasonal cycle of the Atlantic Ocean meridional heat transport (OHT) in a climate projection experiment with the Max Planck Institute Earth System Model (MPI-ESM) performed for the Coupled Model Intercomparison Project Phase 5 (CMIP5). Specifically, we compare a Representative Concentration Pathway (RCP) RCP 8.5 climate change scenario, covering the simulation period from 2005 to 2300, to a historical simulation, covering the simulation period from 1850 to 2005. In RCP 8.5, the OHT declines by 30–50 % in comparison to the historical simulation in the North Atlantic by the end of the 23rd century. The decline in the OHT is accompanied by a change in the seasonal cycle of the total OHT and its components. We decompose the OHT into overturning and gyre component. For the OHT seasonal cycle, we find a northward shift of 5° and latitude-dependent shifts between 1 and 6 months that are mainly associated with changes in the meridional velocity field. We find that the changes in the OHT seasonal cycle predominantly result from changes in the wind-driven surface circulation, which projects onto the overturning component of the OHT in the tropical and subtropical North Atlantic. This leads in turn to latitude-dependent shifts between 1 and 6 months in the overturning component. In comparison to the historical simulation, in the subpolar North Atlantic, in RCP 8.5 we find a reduction of the North Atlantic Deep Water formation and changes in the gyre heat transport result in a strongly weakened seasonal cycle with a weakened amplitude by the end of the 23rd century.

Micropaleontological Evidence for Increased Meridional Heat Transport in the North Atlantic Ocean During the Pliocene

Science ◽  
1992 ◽  
Vol 258 (5085) ◽  
pp. 1133-1135 ◽  
Author(s):  
H. J. Dowsett ◽  
T. M. Cronin ◽  
R. Z. Poore ◽  
R. S. Thompson ◽  
R. C. Whatley ◽  
...  
Keyword(s):  
Atlantic Ocean ◽  
Heat Transport ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Meridional Heat Transport ◽  
The North ◽  
The North Atlantic

scholarly journals Meridional Heat Transport Variability at 26.5°N in the North Atlantic

1997 ◽  
Vol 27 (1) ◽  
pp. 153-174 ◽  
Author(s):  
Eve R. Fillenbaum ◽  
Thomas N. Lee ◽  
William E. Johns ◽  
Rainer J. Zantopp
Keyword(s):  
Heat Transport ◽  
North Atlantic ◽  
Meridional Heat Transport ◽  
The North ◽  
The North Atlantic

scholarly journals Climate feedbacks induced by the North Atlantic freshwater forcing in a coupled model of intermediate complexity

2010 ◽  
Vol 25 (1) ◽  
pp. 103-113 ◽  
Author(s):  
Flávio Barbosa Justino ◽  
Jeferson Prietsch Machado
Keyword(s):  
Heat Transport ◽  
North Atlantic ◽  
Thermohaline Circulation ◽  
Coupled Model ◽  
The North ◽  
Poleward Heat Transport ◽  
Freshwater Forcing ◽  
Oceanic Response ◽  
The North Atlantic ◽  
The Tropics

Based on coupled model simulations (ECBilt-Clio), we investigate the atmospheric and oceanic response to sustained freshwater input into the North Atlantic under the glacial maximum background state. The results demonstrate that a weakening of the thermohaline circulation triggered by weaker density flux leads to rapid changes in global sea-ice volume and reduced poleward heat transport in the Northern Hemisphere (NH). In the Southern Hemisphere (SH), however, the oceanic heat transport increases substantially. This in turn leads to strong cooling over the North Atlantic whereas the SH extratropical region warms up. The suppression of the NADW also drastically changes the atmospheric circulation. The associated northward wind anomalies over the North Atlantic increase the warm air advection from the tropics and induce the transport of tropical saltier water to mid-latitudes. This negative atmospheric-oceanic feedback should play an important role to resume the NADW, after the freshwater forcing ends up.

scholarly journals Global contributions of mesoscale dynamics to meridional heat transport

2021 ◽  
Author(s):  
Andrew Delman ◽  
Tong Lee
Keyword(s):  
Heat Transport ◽  
North Atlantic ◽  
Large Scale ◽  
Planetary Wave ◽  
Mesoscale Eddy ◽  
Instability Wave ◽  
Meridional Heat Transport ◽  
The North ◽  
Flux Variability ◽  
The North Atlantic

Abstract. Mesoscale ocean processes are prevalent in many parts of the global oceans, and may contribute substantially to the meridional movement of heat. Yet earlier global surveys of meridional heat transport (MHT) have not formally distinguished between mesoscale and large-scale contributions, or have defined eddy contributions based on temporal rather than spatial characteristics. This work uses spatial filtering methods to separate large-scale (gyre and planetary wave) contributions from mesoscale (eddy, recirculation, and tropical instability wave) contributions to MHT by extending beyond a previous effort for the North Atlantic Ocean. Overall, mesoscale temperature fluxes produce a net poleward MHT at mid-latitudes and equatorward MHT in the tropics, thereby resulting in a net divergence of heat from the subtropics. Mesoscale temperature fluxes are often concentrated near the energetic currents at western boundaries, and the temperature difference between the boundary current and its recirculation determines the direction of the mesoscale temperature flux. The mesoscale contribution to MHT yields substantially different results from temporally-based eddy contributions to MHT, with the latter contributed substantially by gyre and planetary wave motions at low latitudes. Mesoscale temperature fluxes contribute the most to interannual and decadal variability of MHT in the Southern Ocean, the tropical Indo-Pacific, and the North Atlantic. Surface eddy kinetic energy (EKE) is not a good proxy for mesoscale temperature flux variability in regions with the highest time-mean EKE, though it does explain much of the temperature flux variability in regions of modest time-mean EKE. This approach to quantifying mesoscale fluxes can be used to improve parameterizations of mesoscale effects in coarse-resolution models, and assess regional impacts of mesoscale eddies and recirculations on tracer fluxes.

scholarly journals Initializing Decadal Climate Predictions with the GECCO Oceanic Synthesis: Effects on the North Atlantic

2009 ◽  
Vol 22 (14) ◽  
pp. 3926-3938 ◽  
Author(s):  
Holger Pohlmann ◽  
Johann H. Jungclaus ◽  
Armin Köhl ◽  
Detlef Stammer ◽  
Jochem Marotzke
Keyword(s):  
North Atlantic ◽  
Climate Model ◽  
Initial Conditions ◽  
Coupled Model ◽  
Meridional Overturning Circulation ◽  
Coupling Scheme ◽  
Max Planck ◽  
The North ◽  
The North Atlantic ◽  
Decadal Climate

Abstract This study aims at improving the forecast skill of climate predictions through the use of ocean synthesis data for initial conditions of a coupled climate model. For this purpose, the coupled model of the Max Planck Institute (MPI) for Meteorology, which consists of the atmosphere model ECHAM5 and the MPI Ocean Model (MPI-OM), is initialized with oceanic synthesis fields available from the German contribution to Estimating the Circulation and Climate of the Ocean (GECCO) project. The use of an anomaly coupling scheme during the initialization avoids the main problems with drift in the climate predictions. Thus, the coupled model is continuously forced to follow the density anomalies of the GECCO synthesis over the period 1952–2001. Hindcast experiments are initialized from this experiment at constant intervals. The results show predictive skill through the initialization up to the decadal time scale, particularly over the North Atlantic. Viewed over the time scales analyzed here (annual, 5-yr, and 10-yr mean), greater skill for the North Atlantic sea surface temperature (SST) is obtained in the hindcast experiments than in either a damped persistence or trend forecast. The Atlantic meridional overturning circulation hindcast closely follows that of the GECCO oceanic synthesis. Hindcasts of global-mean temperature do not obtain greater skill than either damped persistence or a trend forecast, owing to the SST errors in the GECCO synthesis, outside the North Atlantic. An ensemble of forecast experiments is subsequently performed over the period 2002–11. North Atlantic SST from the forecast experiment agrees well with observations until the year 2007, and it is higher than if simulated without the oceanic initialization (averaged over the forecast period). The results confirm that both the initial and the boundary conditions must be accounted for in decadal climate predictions.

Potential Predictability of the North Atlantic Heat Transport Based on an Oceanic State Estimate

2012 ◽  
Vol 25 (24) ◽  
pp. 8475-8486 ◽  
Author(s):  
Bente Tiedje ◽  
Armin Köhl ◽  
Johanna Baehr
Keyword(s):  
Heat Transport ◽  
North Atlantic ◽  
Initial Conditions ◽  
Meridional Overturning Circulation ◽  
Lead Times ◽  
Meridional Heat Transport ◽  
Potential Predictability ◽  
Latitude Dependence ◽  
The North ◽  
The North Atlantic

Abstract This paper investigates the potential predictability of the meridional heat transport (MHT) in the North Atlantic on interannual time scales using hindcast ensembles based on an oceanic data assimilation product. The work analyzes the prognostic potential predictability (PPP), using the ocean synthesis of the German partner of the consortium for Estimating the Circulation and Climate of the Ocean (GECCO) as initial conditions and as boundary conditions. The PPP of the MHT varies with latitude: local maxima are apparent within the subpolar and the subtropical gyres, and a minimum is apparent at the boundary between the gyres. This PPP minimum can also be seen in the PPP structure of the Atlantic meridional overturning circulation (AMOC), although it is considerably less pronounced. The decomposition of the MHT shows that within the subpolar gyre, the gyre component of the MHT influences the PPP structure of the MHT. Within the subtropical gyre, the overturning component of the MHT characterizes the PPP structure of the MHT. At the boundary between the subpolar and the subtropical gyres, the dynamics of the Ekman heat transport limit the predictable lead times of the MHT. At most latitudes, variations in the velocity field control the PPP structure of the MHT. The PPP structure of the AMOC can also be classified into gyre and gyre-boundary regimes, but the predictable lead times within the gyres are only similar to those of the overturning component of the MHT. Overall, the analysis provides a reference point for the latitude dependence of the MHT’s PPP structure and relates it to the latitude dependence of the AMOC’s PPP structure.

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