The Role of Temperature Feedback in Stabilizing the Thermohaline Circulation

Rahmstorf, Stefan; Willebrand, Jürgen

doi:10.1175/1520-0485(1995)025<0787:trotfi>2.0.co;2

Cited by 192 publications

(142 citation statements)

References 0 publications

Supporting

Mentioning

134

Contrasting

Order By: Relevance

“…In particular, large-scale SST anomalies are allowed to exist over a longer time period, while small-scale SST anomalies will be damped out quickly. The need for such a scale-dependent restoration was first pointed out by Rahmstorf and Willebrand (1995). The present formulation can be considered as an empirical approach that captures the scale-dependent feedback of SST on heat flux in the ECHO-G integration.…”

Section: The Empirical Model Of Daily Air-sea Fluxes: Emadmentioning

confidence: 92%

Effects of fluctuating daily surface fluxes on the time-mean oceanic circulation

Sarojini

Storch

2009

Clim Dyn

View full text Add to dashboard Cite

The effect of fluctuating daily surface fluxes on the time-mean oceanic circulation is studied using an empirical flux model. The model produces fluctuating fluxes resulting from atmospheric variability and includes oceanic feedbacks on the fluxes. Numerical experiments were carried out by driving an ocean general circulation model with three different versions of the empirical model. It is found that fluctuating daily fluxes lead to an increase in the meridional overturning circulation (MOC) of the Atlantic of about 1 Sv and a decrease in the Antarctic circumpolar current (ACC) of about 32 Sv. The changes are approximately 7% of the MOC and 16% of the ACC obtained without fluctuating daily fluxes. The fluctuating fluxes change the intensity and the depth of vertical mixing. This, in turn, changes the density field and thus the circulation. Fluctuating buoyancy fluxes change the vertical mixing in a non-linear way: they tend to increase the convective mixing in mostly stable regions and to decrease the convective mixing in mostly unstable regions. The ACC changes are related to the enhanced mixing in the subtropical and the mid-latitude Southern Ocean and reduced mixing in the high-latitude Southern Ocean. The enhanced mixing is related to an increase in the frequency and the depth of convective events. As these events bring more dense water downward, the mixing changes lead to a reduction in meridional gradient of the depth-integrated density in the Southern Ocean and hence the strength of the ACC. The MOC changes are related to more subtle density changes. It is found that the vertical mixing in a latitudinal strip in the northern North Atlantic is more strongly enhanced due to fluctuating fluxes than the mixing in a latitudinal strip in the South Atlantic. This leads to an increase in the density difference between the two strips, which can be responsible for the increase in the Atlantic MOC.

show abstract

Section: The Empirical Model Of Daily Air-sea Fluxes: Emadmentioning

confidence: 92%

Effects of fluctuating daily surface fluxes on the time-mean oceanic circulation

Sarojini

Storch

2009

Clim Dyn

View full text Add to dashboard Cite

show abstract

“…The AMOC weakening is reinforced by a feedback on the surface heat flux whereby, as the AMOC declines, the SST in the North Atlantic tends to cool, so the heat flux from the atmosphere to the ocean increases (Rahmstorf and Willebrand, 1995;Marotzke, 1996). This effectively doubles the heat flux perturbation in that region (although it is a small effect in the global mean).…”

Section: Summary and Plansmentioning

confidence: 99%

The Flux-Anomaly-Forced Model Intercomparison Project (FAFMIP) contribution to CMIP6: investigation of sea-level and ocean climate change in response to CO<sub>2</sub> forcing

et al. 2016

View full text Add to dashboard Cite

Abstract. The Flux-Anomaly-Forced Model Intercomparison Project (FAFMIP) aims to investigate the spread in simulations of sea-level and ocean climate change in response to CO 2 forcing by atmosphere-ocean general circulation models (AOGCMs). It is particularly motivated by the uncertainties in projections of ocean heat uptake, global-mean sealevel rise due to thermal expansion and the geographical patterns of sea-level change due to ocean density and circulation change. FAFMIP has three tier-1 experiments, in which prescribed surface flux perturbations of momentum, heat and freshwater respectively are applied to the ocean in separate AOGCM simulations. All other conditions are as in the pre-industrial control. The prescribed fields are typical of pattern and magnitude of changes in these fluxes projected by AOGCMs for doubled CO 2 concentration. Five groups have tested the experimental design with existing AOGCMs. Their results show diversity in the pattern and magnitude of changes, with some common qualitative features. Heat and water flux perturbation cause the dipole in sea-level change in the North Atlantic, while momentum and heat flux perturbation cause the gradient across the Antarctic Circumpolar Current. The Atlantic meridional overturning circulation (AMOC) declines in response to the heat flux perturbation, and there is a strong positive feedback on this effect due to the consequent cooling of sea-surface temperature in the North Atlantic, which enhances the local heat input to the ocean. The momentum and water flux perturbations do not substantially affect the AMOC. Heat is taken up largely as a passive tracer in the Southern Ocean, which is the region of greatest heat input, while the weakening of the AMOC causes redistribution of heat towards lower latitudes. Future analysis of these and other phenomena with the wider range of CMIP6 FAFMIP AOGCMs will benefit from new diagnostics of temperature and salinity tendencies, which will enable investigation of the model spread in behaviour in terms of physical processes as formulated in the models.

show abstract

“…Once the model has crossed the bifurcation point of the NAMOC even a reduction of additional freshwater supply does not necessarily lead to a substantial recovery of the NAMOC (e.g. Stommel 1961; Manabe and Stouffer 1988;Mikolajewicz and Maier-Reimer 1994;Rahmstorf and Willebrand 1995). Whether such a bifurcation point of the NAMOC exists under present conditions is subject of debate.…”

Section: Introductionmentioning

confidence: 99%

Long-term ice sheet–climate interactions under anthropogenic greenhouse forcing simulated with a complex Earth System Model

et al. 2008

View full text Add to dashboard Cite

Several multi-century and multi-millennia simulations have been performed with a complex Earth System Model (ESM) for different anthropogenic climate change scenarios in order to study the long-term evolution of sea level and the impact of ice sheet changes on the climate system. The core of the ESM is a coupled coarseresolution Atmosphere-Ocean General Circulation Model (AOGCM). Ocean biogeochemistry, land vegetation and ice sheets are included as components of the ESM. The Greenland Ice Sheet (GrIS) decays in all simulations, while the Antarctic ice sheet contributes negatively to sea level rise, due to enhanced storage of water caused by larger snowfall rates. Freshwater flux increases from Greenland are one order of magnitude smaller than total freshwater flux increases into the North Atlantic basin (the sum of the contribution from changes in precipitation, evaporation, run-off and Greenland meltwater) and do not play an important role in changes in the strength of the North Atlantic Meridional Overturning Circulation (NAMOC). The regional climate change associated with weakening/ collapse of the NAMOC drastically reduces the decay rate of the GrIS. The dynamical changes due to GrIS topography modification driven by mass balance changes act first as a negative feedback for the decay of the ice sheet, but accelerate the decay at a later stage. The increase of surface temperature due to reduced topographic heights causes a strong acceleration of the decay of the ice sheet in the long term. Other feedbacks between ice sheet and atmosphere are not important for the mass balance of the GrIS until it is reduced to 3/4 of the original size. From then, the reduction in the albedo of Greenland strongly accelerates the decay of the ice sheet.

show abstract

The Role of Temperature Feedback in Stabilizing the Thermohaline Circulation

Cited by 192 publications

References 0 publications

Effects of fluctuating daily surface fluxes on the time-mean oceanic circulation

Effects of fluctuating daily surface fluxes on the time-mean oceanic circulation

The Flux-Anomaly-Forced Model Intercomparison Project (FAFMIP) contribution to CMIP6: investigation of sea-level and ocean climate change in response to CO<sub>2</sub> forcing

Long-term ice sheet–climate interactions under anthropogenic greenhouse forcing simulated with a complex Earth System Model

Contact Info

Product

Resources

About

The Role of Temperature Feedback in Stabilizing the Thermohaline Circulation

Cited by 192 publications

References 0 publications

Effects of fluctuating daily surface fluxes on the time-mean oceanic circulation

Effects of fluctuating daily surface fluxes on the time-mean oceanic circulation

The Flux-Anomaly-Forced Model Intercomparison Project (FAFMIP) contribution to CMIP6: investigation of sea-level and ocean climate change in response to CO&lt;sub&gt;2&lt;/sub&gt; forcing

Long-term ice sheet–climate interactions under anthropogenic greenhouse forcing simulated with a complex Earth System Model

Contact Info

Product

Resources

About

The Flux-Anomaly-Forced Model Intercomparison Project (FAFMIP) contribution to CMIP6: investigation of sea-level and ocean climate change in response to CO<sub>2</sub> forcing