Sensitivity of the Ocean’s Climate to Diapycnal Diffusivity in an EMIC. Part II: Global Warming Scenario

2005 ◽  
Vol 18 (13) ◽  
pp. 2482-2496 ◽  
Author(s):  
Fabio Dalan ◽  
Peter H. Stone ◽  
Andrei P. Sokolov
Keyword(s):  
Global Warming ◽  
Thermohaline Circulation ◽  
Deep Ocean ◽  
Diffusive Flux ◽  
Ocean Heat Uptake ◽  
Advective Flux ◽  
Warming Scenario ◽  
Heat Uptake ◽  
Global Warming Scenario ◽  
Diapycnal Diffusivity

Abstract The sensitivity of the ocean’s climate to the diapycnal diffusivity in the ocean is studied for a global warming scenario in which CO2 increases by 1% yr−1 for 75 yr. The thermohaline circulation slows down for about 100 yr and recovers afterward, for any value of the diapycnal diffusivity. The rates of slowdown and of recovery, as well as the percentage recovery of the circulation at the end of 1000-yr integrations, are variable, but a direct relation with the diapycnal diffusivity cannot be found. At year 70 (when CO2 has doubled) an increase of the diapycnal diffusivity from 0.1 to 1.0 cm2 s−1 leads to a decrease in surface air temperature of about 0.4 K and an increase in sea level rise of about 4 cm. The steric height gradient is divided into thermal component and haline component. It appears that, in the first 60 yr of simulated global warming, temperature variations dominate the salinity ones in weakly diffusive models, whereas the opposite occurs in strongly diffusive models. The analysis of the vertical heat balance reveals that deep-ocean heat uptake is due to reduced upward isopycnal diffusive flux and parameterized-eddy advective flux. Surface warming, induced by enhanced CO2 in the atmosphere, leads to a reduction of the isopycnal slope, which translates into a reduction of the above fluxes. The amount of reduction is directly related to the magnitude of the isopycnal diffusive flux and parameterized-eddy advective flux at equilibrium. These latter fluxes depend on the thickness of the thermocline at equilibrium and hence on the diapycnal diffusion. Thus, the increase of deep-ocean heat uptake with diapycnal diffusivity is an indirect effect that the latter parameter has on the isopycnal diffusion and parameterized-eddy advection.

scholarly journals The Deep-Ocean Heat Uptake in Transient Climate Change

2003 ◽  
Vol 16 (9) ◽  
pp. 1352-1363 ◽  
Author(s):  
Boyin Huang ◽  
Peter H. Stone ◽  
Andrei P. Sokolov ◽  
Igor V. Kamenkovich
Keyword(s):  
Heat Flux ◽  
Global Warming ◽  
Surface Heat Flux ◽  
Coupled Model ◽  
Deep Ocean ◽  
Surface Heat ◽  
Ocean Heat Uptake ◽  
Warming Scenario ◽  
Heat Uptake ◽  
Global Warming Scenario

Abstract The deep-ocean heat uptake (DOHU) in transient climate changes is studied using an ocean general circulation model (OGCM) and its adjoint. The model configuration consists of idealized Pacific and Atlantic basins. The model is forced with the anomalies of surface heat and freshwater fluxes from a global warming scenario with a coupled model using the same ocean configuration. In the global warming scenario, CO2 concentration increases 1% yr−1. The heat uptake calculated from the coupled model and from the adjoint are virtually identical, showing that the heat uptake by the OGCM is a linear process. After 70 yr the ocean heat uptake is almost evenly distributed within the layers above 200 m, between 200 and 700 m, and below 700 m (about 20 × 1022 J in each). The effect of anomalous surface freshwater flux on the DOHU is negligible. Analysis of the Coupled Model Intercomparison Project (CMIP-2) data for the same global warming scenario shows that qualitatively similar results apply to coupled atmosphere–ocean GCMs. The penetration of surface heat flux to the deep ocean in the OGCM occurs mainly in the North Atlantic and the Southern Ocean, since both the sensitivity of DOHU to the surface heat flux and the magnitude of anomalous surface heat flux are large in these two regions. The DOHU relies on the reduction of convection and Gent–McWilliams–Redi mixing in the North Atlantic, and the reduction of Gent–McWilliams–Redi mixing in the Southern Ocean.

Changes in Dust Activity in Spring over East Asia under a Global Warming Scenario

2021 ◽  
Author(s):  
Qi Zong ◽  
Rui Mao ◽  
Dao-Yi Gong ◽  
Chenglai Wu ◽  
Bing Pu ◽  
...  
Keyword(s):  
Global Warming ◽  
East Asia ◽  
Warming Scenario ◽  
Global Warming Scenario

scholarly journals Global heat balance and heat uptake in potential temperature coordinates

2021 ◽  
Author(s):  
Antoine Hochet ◽  
Rémi Tailleux ◽  
Till Kuhlbrodt ◽  
David Ferreira
Keyword(s):  
Global Warming ◽  
Water Mass ◽  
Potential Temperature ◽  
Effective Diffusion ◽  
Mitigation Strategies ◽  
Ocean Heat Uptake ◽  
Cold Temperatures ◽  
Advection Diffusion Equation ◽  
Advection Diffusion ◽  
Heat Uptake

AbstractThe representation of ocean heat uptake in Simple Climate Models used for policy advice on climate change mitigation strategies is often based on variants of the one-dimensional Vertical Advection/Diffusion equation (VAD) for some averaged form of potential temperature. In such models, the effective advection and turbulent diffusion are usually tuned to emulate the behaviour of a given target climate model. However, because the statistical nature of such a “behavioural” calibration usually obscures the exact dependence of the effective diffusion and advection on the actual physical processes responsible for ocean heat uptake, it is difficult to understand its limitations and how to go about improving VADs. This paper proposes a physical calibration of the VAD that aims to provide explicit traceability of effective diffusion and advection to the processes responsible for ocean heat uptake. This construction relies on the coarse-graining of the full three-dimensional advection diffusion for potential temperature using potential temperature coordinates. The main advantage of this formulation is that the temporal evolution of the reference temperature profile is entirely due to the competition between effective diffusivity that is always positive definite, and the water mass transformation taking place at the surface, as in classical water mass analyses literature. These quantities are evaluated in numerical simulations of present day climate and global warming experiments. In this framework, the heat uptake in the global warming experiment is attributed to the increase of surface heat flux at low latitudes, its decrease at high latitudes and to the redistribution of heat toward cold temperatures made by diffusive flux.

scholarly journals Projection of Extreme Waves under a Global Warming Scenario

2010 ◽  
Vol 66 (1) ◽  
pp. 1231-1235 ◽  
Author(s):  
Nobuhito MORI ◽  
Tomoya SHIMURA ◽  
Tomohiro YASUDA ◽  
Hajime MASE
Keyword(s):  
Global Warming ◽  
Extreme Waves ◽  
Warming Scenario ◽  
Global Warming Scenario

scholarly journals Global Heat Balance and Heat Uptake in Potential Temperature Coordinates

2021 ◽  
Author(s):  
Antoine Hochet ◽  
Remi Tailleux ◽  
Till Kuhlbrodt ◽  
David Ferreira
Keyword(s):  
Global Warming ◽  
Water Mass ◽  
Potential Temperature ◽  
Effective Diffusion ◽  
Mitigation Strategies ◽  
Ocean Heat Uptake ◽  
Cold Temperatures ◽  
Advection Diffusion Equation ◽  
Advection Diffusion ◽  
Heat Uptake

Abstract The representation of ocean heat uptake in Simple Climate Models used for policy advice on climate change mitigation strategies is often based on variants of the one-dimensional Vertical Advection/Diffusion equation (VAD) for some averaged form of potential temperature. In such models, the effective advection and turbulent diffusion are usually tuned to emulate the behaviour of a given target climate model. However, because the statistical nature of such a \behavioural" calibration usually obscures the exact dependence of the effective diffusion and advection on the actual physical processes responsible for ocean heat uptake, it is difficult to understand its limitations and how to go about improving VAD. This paper proposes a physical calibration of the VAD that aims to provide explicit traceability of effective diffusion and advection to the processes responsible for ocean heat uptake. This construction relies on the coarse-graining of the full three-dimensional advection diffusion for potential temperature using potential temperature coordinates. The main advantage of this formulation is that the temporal evolution of the reference temperature profile is entirely due to the competition between effective diffusivity that is always positive definite, and the water mass transformation taking place at the surface, as in classical water mass analyses literature. These quantities are evaluated in numerical simulations of present day climate and global warming experiments. In this framework, the heat uptake in the global warming experiment is attributed to the increase of surface heat flux at low latitudes, its decrease at high latitudes and to the redistribution of heat toward cold temperatures made by diffusive flux.

Optimized Flood Control in the Columbia River Basin for a Global Warming Scenario

2006 ◽  
Author(s):  
Se-Yeun Lee ◽  
Alan F. Hamlet ◽  
Carolyn J. Fitzgerald ◽  
Stephen J. Burges ◽  
Dennis P. Lettenmaier
Keyword(s):  
Global Warming ◽  
River Basin ◽  
Flood Control ◽  
Columbia River ◽  
Columbia River Basin ◽  
Warming Scenario ◽  
Global Warming Scenario

Daily Time-Step Refinement of Optimized Flood Control Rule Curves for a Global Warming Scenario

2011 ◽  
Vol 137 (4) ◽  
pp. 309-317 ◽  
Author(s):  
Se-Yeun Lee ◽  
Carolyn J. Fitzgerald ◽  
Alan F. Hamlet ◽  
Stephen J. Burges
Keyword(s):  
Global Warming ◽  
Flood Control ◽  
Time Step ◽  
Control Rule ◽  
Warming Scenario ◽  
Rule Curves ◽  
Daily Time Step ◽  
Global Warming Scenario ◽  
Daily Time
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