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Author: Sarah Marcil Publisher: ISBN: Category : Languages : en Pages :
Book Description
"Understanding how the ocean takes up heat is crucial to improve prediction of the future global surface temperature increase. While many previous studies have evaluated the spatial distribution of heat content change across the global ocean, a complete explanation of the mechanisms responsible for this distribution remains largely unknown, and hence, we lack a measureable indicator of model performance that could help constrain future prediction. We examine a large ensemble of climate models to understand what creates the large inter-model variability in heat content change under global warming. Based on earlier studies on ocean vertical heat transfer, we hypothesize that open water deep convection is an important mechanism for the transfer of heat from the deep ocean to the atmosphere. Therefore, the cessation of convection, as predicted in future climate change scenario, would contribute to the increase of deep ocean heat content. We compare the convective volume and ocean heat content anomalies in 34 climate models of the IPCC Assessment Report 5. Most of models show signs of open water deep convection in the North Atlantic and in the Southern Ocean, and the variability in convective volume is linked to ocean heat content anomalies in individual models. In order to identify the most realistic climate models in term of these parameters, we compare the model convection against observations. While convection in some models is a robust predictor of deep ocean heat uptake, the models suggest a diversity of processes plays a role in the transfer of heat to the deep ocean." --
Author: Sarah Marcil Publisher: ISBN: Category : Languages : en Pages :
Book Description
"Understanding how the ocean takes up heat is crucial to improve prediction of the future global surface temperature increase. While many previous studies have evaluated the spatial distribution of heat content change across the global ocean, a complete explanation of the mechanisms responsible for this distribution remains largely unknown, and hence, we lack a measureable indicator of model performance that could help constrain future prediction. We examine a large ensemble of climate models to understand what creates the large inter-model variability in heat content change under global warming. Based on earlier studies on ocean vertical heat transfer, we hypothesize that open water deep convection is an important mechanism for the transfer of heat from the deep ocean to the atmosphere. Therefore, the cessation of convection, as predicted in future climate change scenario, would contribute to the increase of deep ocean heat content. We compare the convective volume and ocean heat content anomalies in 34 climate models of the IPCC Assessment Report 5. Most of models show signs of open water deep convection in the North Atlantic and in the Southern Ocean, and the variability in convective volume is linked to ocean heat content anomalies in individual models. In order to identify the most realistic climate models in term of these parameters, we compare the model convection against observations. While convection in some models is a robust predictor of deep ocean heat uptake, the models suggest a diversity of processes plays a role in the transfer of heat to the deep ocean." --
Author: Simon Chu Publisher: Elsevier ISBN: 0080870953 Category : Science Languages : en Pages : 395
Book Description
This book contains articles presenting current knowledge about the formation and renewal of deep waters in the ocean. These articles were presented at an international workshop at the Naval Postgraduate School in Monterey in March 1990. It is the first book entirely devoted to the topic of deep water formation in which articles have been both selected and reviewed, and it is also the first time authors have addressed both surface and deep mixed layers. Highlighted are: past and recent observations (description and analysis), concepts and models, and modern techniques for future research. Thanks to spectacular advances realised in computing sciences over the last twenty years this volume includes a number of sophisticated numerical models. Observational as well as theoretical studies are presented and a clear distinction is established between open-ocean deep convection and shelf processes, both leading to deep- and bottom-water formation. The main subject addressed is the physical mechanism by which the deep water in the ocean can be renewed. Ventilation occurs at the surface in areas called the gills, where water is mixed and oxygenated before sinking and spreading in the abyss of the deep ocean. This phenomenon is a very active area for both experimentalists and theoreticians because of its strong implications for the understanding of the world ocean circulation and Earth climate. This major theme sheds light on specific and complex processes happening in very restricted areas still controlling three quarters of the total volume of the ocean. All articles include illustrations and a bibliography. This book will be of particular interest to physical oceanographers, earth scientists, environmentalists and climatologists.
Author: P. C. Chu Publisher: Elsevier Science Limited ISBN: 9780444887641 Category : Science Languages : en Pages : 382
Book Description
This book contains articles presenting current knowledge about the formation and renewal of deep waters in the ocean. These articles were presented at an international workshop at the Naval Postgraduate School in Monterey in March 1990. It is the first book entirely devoted to the topic of deep water formation in which articles have been both selected and reviewed, and it is also the first time authors have addressed both surface and deep mixed layers. Highlighted are: past and recent observations (description and analysis), concepts and models, and modern techniques for future research. Thanks to spectacular advances realised in computing sciences over the last twenty years this volume includes a number of sophisticated numerical models. Observational as well as theoretical studies are presented and a clear distinction is established between open-ocean deep convection and shelf processes, both leading to deep- and bottom-water formation. The main subject addressed is the physical mechanism by which the deep water in the ocean can be renewed. Ventilation occurs at the surface in areas called the gills , where water is mixed and oxygenated before sinking and spreading in the abyss of the deep ocean. This phenomenon is a very active area for both experimentalists and theoreticians because of its strong implications for the understanding of the world ocean circulation and Earth climate. This major theme sheds light on specific and complex processes happening in very restricted areas still controlling three quarters of the total volume of the ocean. All articles include illustrations and a bibliography. This book will be of particular interest to physical oceanographers, earth scientists, environmentalists and climatologists.
Author: Boyin Huang Publisher: ISBN: Category : Languages : en Pages : 33
Book Description
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 scenario CO2 concentration increases 1% per year. 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 years 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 x 1022 J in each). The effect of anomalous surface fresh water flux on the DOHU is negligible. Analysis of 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 our 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.
Author: Boyin Huang Publisher: ISBN: Category : Languages : en Pages : 43
Book Description
Sensitivities of the net heat flux into the deep-ocean (Qnet) and of the deep-ocean heat content (DOC) below 700 m are studied using an ocean general circulation model and its adjoint. Both are found to have very similar sensitivities. The sensitivity to the surface freshwater flux (E-P-R) is positive in the Atlantic, but negative in the Pacific and Southern Ocean. A positive sensitivity to the downward net surface heat flux is found only in the North Atlantic north of 40ʻN and the Southern Ocean. The diapycnal diffusivity of temperature affects Qnet and DOC positively in a large area of the tropics and subtropics in both the Pacific and Atlantic Ocean. The isopycnal diffusivity contributes to Qnet and DOC mainly in the Southern Ocean. Detailed analysis indicates that the surface freshwater flux affects Qnet and DOC by changing vertical velocity, temperature stratification, and overturning circulation. The downward net surface heat flux appears to increase Qnet and DOC by strengthening vertical advection and isopycnal mixing. The contribution of isopycnal diffusivity to Qnet and DOC is largely associated with the vertical heat flux due to isopycnal mixing. Similarly, the diapycnal diffusivity of temperature modulates Qnet and DOC through the downward heat flux due to diapycnal diffusion. The uncertainties of Qnet and DOC are estimated based on the sensitivities and error bars of observed surface forcing and oceanic diffusivities. For DOC, they are about 0.7°K (1°K = 3 x 1024 J) for the isopycnal diffusivity, 0.4°K for the diapycnal diffusivity of temperature, 0.3°K for the surface freshwater flux, and 0.1°K for the net surface heat flux and zonal wind stress. Our results suggest that the heat uptake by ocean GCMs in climate experiments is sensitive to the isopycnal diffusivity as well to the diapycnal thermal diffusivity.
Author: Publisher: ISBN: Category : Languages : en Pages : 7
Book Description
Deep convection has an important role in the large-scale thermohaline circulation, which in turn plays a central part in determining global climate. Manabe and Stouffer's climate simulations have shown that the thermal and dynamic structure of the oceans have pronounced changes in model climates with increased CO2. In their simulations, the addition of low-salinity surface water at high latitudes prevents the ventilation of the deep ocean, thus reducing or in some cases nearly extinguishing the thermohaline circulation. Siegenthaler and Sarmiento remarked that whereas the ocean is the largest of the rapidly exchanging global carbon reservoirs and a major sink for anthropogenic carbon, this uptake capacity become available only when the whole ocean is chemically equilibrated with the new atmospheric CO2 concentration. The dynamics of the oceanic uptake of CO2 is therefore strongly determined by the rate of downward transport of CO2-laden water from surface to depth. The importance of deep convection in moderating the uptake of CO2 by the ocean and its role in the meridional circulation, which affects climate by transporting heat from the tropics to the polar regions, motivates this research. The experiments described here were designed to study the sensitivity of the onset time and strength of deep convection to changes in the heat flux, latent heat flux, and perturbations of the surface mixed-layer temperature and salinity.
Author: Intergovernmental Panel on Climate Change (IPCC) Publisher: Cambridge University Press ISBN: 9781009157971 Category : Science Languages : en Pages : 755
Book Description
The Intergovernmental Panel on Climate Change (IPCC) is the leading international body for assessing the science related to climate change. It provides policymakers with regular assessments of the scientific basis of human-induced climate change, its impacts and future risks, and options for adaptation and mitigation. This IPCC Special Report on the Ocean and Cryosphere in a Changing Climate is the most comprehensive and up-to-date assessment of the observed and projected changes to the ocean and cryosphere and their associated impacts and risks, with a focus on resilience, risk management response options, and adaptation measures, considering both their potential and limitations. It brings together knowledge on physical and biogeochemical changes, the interplay with ecosystem changes, and the implications for human communities. It serves policymakers, decision makers, stakeholders, and all interested parties with unbiased, up-to-date, policy-relevant information. This title is also available as Open Access on Cambridge Core.
Author: Robert R. Dickson Publisher: Springer Science & Business Media ISBN: 1402067747 Category : Science Languages : en Pages : 728
Book Description
We are only now beginning to understand the climatic impact of the remarkable events that are now occurring in subarctic waters. Researchers, however, have yet to agree upon a predictive model that links change in our northern seas to climate. This volume brings together the body of evidence needed to develop climate models that quantify the ocean exchanges through subarctic seas, measure their variability, and gauge their impact on climate.
Author: Boyin Huang Publisher: ISBN: Category : Languages : en Pages : 18
Book Description
(Cont.) The uncertainties of Qnet and DOC are estimated based on the sensitivities and error bars of observed surface forcing and oceanic diffusivities. For DOC, they are about 0.7°K (1°K = 3 x 1024J) for the isopycnal diffusivity, 0.4°K for the diapycnal diffusivity of temperature, 0.3°K for the surface freshwater flux, and 0.1°K for the net surface heat flux and zonal wind stress. Our results suggest that the heat uptake by ocean GCMs in climate experiments is sensitive to the isopycnal diffusivity as well to the diapycnal thermal diffusivity.
Author: Sarah Marcil
Author: Sarah Marcil
Author: Simon Chu
Author: P. C. Chu
Author: Boyin Huang
Author: Boyin Huang
Author: John Marshall
Author: 
Author: Intergovernmental Panel on Climate Change (IPCC)
Author: Robert R. Dickson
Author: Boyin Huang