The Experts below are selected from a list of 5553 Experts worldwide ranked by ideXlab platform

Stephen R. Rintoul - One of the best experts on this subject based on the ideXlab platform.

  • Zonally asymmetric response of the Southern Ocean mixed-layer depth to the Southern Annular Mode
    Nature Geoscience, 2010
    Co-Authors: Jean-baptiste Sallée, K. G. Speer, Stephen R. Rintoul
    Abstract:

    Interactions between the atmosphere and Ocean are mediated by the mixed layer at the Ocean surface. The depth of this layer is determined by wind forcing and heating from the atmosphere. Variations in mixed-layer depth affect the rate of exchange between the atmosphere and deeper Ocean, the capacity of the Ocean to store heat and carbon and the availability of light and nutrients to support the growth of phytoplankton. However, the response of the Southern Ocean mixed layer to changes in the atmosphere is not well known. Here we analyse temperature and salinity data from Argo profiling floats to show that the Southern Annular Mode (SAM), the dominant mode of atmospheric variability in the Southern Hemisphere, leads to large-scale anomalies in mixed-layer depth that are zonally asymmetric. From a simple heat budget of the mixed layer we conclude that meridional winds associated with departures of the SAM from zonal symmetry cause anomalies in heat flux that can, in turn, explain the observed changes of mixed-layer depth and sea surface temperature. Our results suggest that changes in the SAM, including recent and projected trends attributed to human activity, drive variations in Southern Ocean mixed-layer depth, with consequences for air–sea exchange, Ocean Sequestration of heat and carbon, and biological productivity. Interactions between the atmosphere and Ocean are mediated by the mixed layer at the Ocean surface. Analyses of Ocean temperature and salinity data from Argo floats show that changes in the Southern Annular Mode, including recent and projected trends attributed to human activity, drive variations in mixed-layer depth in the Southern Ocean.

  • Zonally asymmetric response of the Southern Ocean mixed-layer depth to the Southern Annular Mode
    Nature Geoscience, 2010
    Co-Authors: Jean-baptiste Sallée, Kevin Speer, Stephen R. Rintoul
    Abstract:

    Interactions between the atmosphere and Ocean are mediated by the mixed layer at the Ocean surface. The depth of this layer is determined by wind forcing and heating from the atmosphere. Variations in mixed-layer depth affect the rate of exchange between the atmosphere and deeper Ocean, the capacity of the Ocean to store heat and carbon and the availability of light and nutrients to support the growth of phytoplankton. However, the response of the Southern Ocean mixed layer to changes in the atmosphere is not well known. Here we analyse temperature and salinity data from Argo profiling floats to show that the Southern Annular Mode (SAM), the dominant mode of atmospheric variability in the Southern Hemisphere, leads to large-scale anomalies in mixed-layer depth that are zonally asymmetric. From a simple heat budget of the mixed layer we conclude that meridional winds associated with departures of the SAM from zonal symmetry cause anomalies in heat flux that can, in turn, explain the observed changes of mixed-layer depth and sea surface temperature. Our results suggest that changes in the SAM, including recent and projected trends attributed to human activity, drive variations in Southern Ocean mixed-layer depth, with consequences for air‐sea exchange, Ocean Sequestration of heat and carbon, and biological productivity.

Jean-baptiste Sallée - One of the best experts on this subject based on the ideXlab platform.

  • Zonally asymmetric response of the Southern Ocean mixed-layer depth to the Southern Annular Mode
    Nature Geoscience, 2010
    Co-Authors: Jean-baptiste Sallée, K. G. Speer, Stephen R. Rintoul
    Abstract:

    Interactions between the atmosphere and Ocean are mediated by the mixed layer at the Ocean surface. The depth of this layer is determined by wind forcing and heating from the atmosphere. Variations in mixed-layer depth affect the rate of exchange between the atmosphere and deeper Ocean, the capacity of the Ocean to store heat and carbon and the availability of light and nutrients to support the growth of phytoplankton. However, the response of the Southern Ocean mixed layer to changes in the atmosphere is not well known. Here we analyse temperature and salinity data from Argo profiling floats to show that the Southern Annular Mode (SAM), the dominant mode of atmospheric variability in the Southern Hemisphere, leads to large-scale anomalies in mixed-layer depth that are zonally asymmetric. From a simple heat budget of the mixed layer we conclude that meridional winds associated with departures of the SAM from zonal symmetry cause anomalies in heat flux that can, in turn, explain the observed changes of mixed-layer depth and sea surface temperature. Our results suggest that changes in the SAM, including recent and projected trends attributed to human activity, drive variations in Southern Ocean mixed-layer depth, with consequences for air–sea exchange, Ocean Sequestration of heat and carbon, and biological productivity. Interactions between the atmosphere and Ocean are mediated by the mixed layer at the Ocean surface. Analyses of Ocean temperature and salinity data from Argo floats show that changes in the Southern Annular Mode, including recent and projected trends attributed to human activity, drive variations in mixed-layer depth in the Southern Ocean.

  • Zonally asymmetric response of the Southern Ocean mixed-layer depth to the Southern Annular Mode
    Nature Geoscience, 2010
    Co-Authors: Jean-baptiste Sallée, Kevin Speer, Stephen R. Rintoul
    Abstract:

    Interactions between the atmosphere and Ocean are mediated by the mixed layer at the Ocean surface. The depth of this layer is determined by wind forcing and heating from the atmosphere. Variations in mixed-layer depth affect the rate of exchange between the atmosphere and deeper Ocean, the capacity of the Ocean to store heat and carbon and the availability of light and nutrients to support the growth of phytoplankton. However, the response of the Southern Ocean mixed layer to changes in the atmosphere is not well known. Here we analyse temperature and salinity data from Argo profiling floats to show that the Southern Annular Mode (SAM), the dominant mode of atmospheric variability in the Southern Hemisphere, leads to large-scale anomalies in mixed-layer depth that are zonally asymmetric. From a simple heat budget of the mixed layer we conclude that meridional winds associated with departures of the SAM from zonal symmetry cause anomalies in heat flux that can, in turn, explain the observed changes of mixed-layer depth and sea surface temperature. Our results suggest that changes in the SAM, including recent and projected trends attributed to human activity, drive variations in Southern Ocean mixed-layer depth, with consequences for air‐sea exchange, Ocean Sequestration of heat and carbon, and biological productivity.

Makoto Akai - One of the best experts on this subject based on the ideXlab platform.

  • A Lagrangian Two-Phase Model for Assessing the Near-Field Impacts of CO2 Ocean Sequestration
    Volume 4: Terry Jones Pipeline Technology; Ocean Space Utilization; CFD and VIV Symposium, 2006
    Co-Authors: Baixin Chen, Masahiro Nishio, Yongchen Song, Makoto Akai
    Abstract:

    A new version of a two-phase numerical model is developed to simulate CO2 droplet dissolution and the plume dynamics of CO2 enriched seawater produced by direct release of liquid CO2 into deep Ocean from a towed pipe. This Lagrangian framework model consists of three sub-models. They are the CO2 droplet moving and dissolving sub-model, the turbulent dispersion of CO2 enriched seawater sub-model, and the biological impact sub-model. We performed simulations of direct injection of liquid CO2 from a release platform towed by a moving-ship into mid-depth seawater to examine the roles of injection parameters, including release platform type and initial CO2 droplet size. Results from the simulations show that a horizontal release platform can create a plume with less physical and biological impacts than a plume created by a vertical release platform. With an injection rate of 100kg/s, simulations predict that injection of small droplets (5mm in diameter) would produce up to 1.5 times the pH reduction of larger droplets (15 mm in diameter). This large pH reduction may significantly affect ambient zooplankton.Copyright © 2006 by ASME

  • Ecosystem model “DONGRI” study on the efficiency and the leakage of CO2 Sequestration
    Greenhouse Gas Control Technologies 7, 2005
    Co-Authors: Akio Sohma, Tadahide Kakio, Yasuyuki Sekiguchi, Makoto Akai
    Abstract:

    Publisher Summary This chapter evaluates the effectiveness of CO 2 Sequestration including Ocean-air CO 2 communication and the effects of injected depth/area and biochemical processes on the effectiveness of CO 2 Sequestration. The chapter estimates the effectiveness of Ocean Sequestration and perfect Sequestration by using the ecosystem model "DONGRI" that can describe the CO 2 storage from the global scale including the physical and biochemical effects. The formulation of the efficiency of the Sequestration (ES) and the leakage of the Sequestration (LS) are defined, which are useful for assessing not only the Ocean Sequestration, but other media's Sequestrations. The ES and LS include the effects of interaction among Ocean reservoir to other reservoirs through Ocean-air communication. The motivation of these two definitions comes from considering the availability of the relative estimations among any Sequestration on the same base, while including the effect of changes in Oceanic CO 2 absorption due to Sequestrations. The chapter estimates ES of perfect Sequestration to understand the effect of Ocean-air communication on all methods of Sequestration and the effects of CO 2 injected depth/area dependence on ES and LS of Ocean Sequestration are estimated.

  • Density change of underground water due to CO2 dissolution
    Greenhouse Gas Control Technologies 7, 2005
    Co-Authors: Yongchen Song, Masahiro Nishio, Baixin Chen, Makoto Akai
    Abstract:

    Publisher Summary As an alternative technology to mitigate the carbon dioxide (CO2) concentration from the atmosphere, geological Sequestration had been widely accepted as a practical option because of the potential capacity and the relative safety in comparison with another option—Ocean Sequestration. To investigate the sciences and technologies concerned with it, Research Institute of Innovative Technology for the Earth (RITE) initiated a research and development project for CO2 geological Sequestration. The field experiment had been conducted at Nagaoka, Japan. For this technology, one of the geophysical dynamics additionally induced to the original geosystem is the dissolution of injected CO2 into the reservoir water, which is a way for storage. The density of dissolved water is changed leading to a gravity flow. This flow can make contribution to the evolution of CO2 enriched water in the terms of buoyancy.

  • A Eulerian-Eulerian Physical-Biological Impact Model of Zooplankton Injury Due to CO_2 Ocean Sequestration
    Journal of Oceanography, 2004
    Co-Authors: Baixin Chen, Masahiro Nishio, Yongchen Song, Makoto Akai
    Abstract:

    To study the biological impacts of CO_2 Ocean Sequestration on floating marine organisms, a full Eulerian-Eulerian scheme model has been developed in a large-eddy simulation (LES) version using one-way coupling of the equations of seawater flow to the transport equations of the bio-scalar variables. Special attention was paid to deriving the transport equation, involving non-conservative scalars to describe the degree of injury to floating organisms due to the change in the pH environment resulting from CO_2 dissolution. The source terms of the transport equations of bio-scalar variables are based on experimental data on zooplankton activities affected by lower pH seawater, allowing construction of empirical sub-models of three kinds of floating marine organisms: Gaidius variabilis, Paraeuchaeta Birostrata, and Multi-organisms. An example is given to show the applicability of the model to the assessment of the biological impact of CO_2 Sequestration in the Ocean. Given an initial CO_2 droplet diameter of 8.0 mm and an injection rate of 1.0 kg/sec, the model simulation predicts that the zooplanktons lose approximately 90% of their activity when the lowest pH inside the plume decreases from 7.57 to 5.61. These injured zooplanktons then recovered gradually to their normal state within two hours due to dilution of the plume.

  • A Eulerian-Eulerian physical-biological impact model of zooplankton injury due to CO2 Ocean Sequestration
    Journal of Oceanography, 2004
    Co-Authors: Baixin Chen, Masahiro Nishio, Yongchen Song, Makoto Akai
    Abstract:

    To study the biological impacts of CO2 Ocean Sequestration on floating marine organisms, a full Eulerian-Eulerian scheme model has been developed in a large-eddy simulation (LES) version using one-way coupling of the equations of seawater flow to the transport equations of the bio-scalar variables. Special attention was paid to deriving the transport equation, involving non-conservative scalars to describe the degree of injury to floating organisms due to the change in the pH environment resulting from CO2 dissolution. The source terms of the transport equations of bio-scalar variables are based on experimental data on zooplankton activities affected by lower pH seawater, allowing construction of empirical sub-models of three kinds of floating marine organisms: Gaidius variabilis, Paraeuchaeta Birostrata, and Multi-organisms. An example is given to show the applicability of the model to the assessment of the biological impact of CO2 Sequestration in the Ocean. Given an initial CO2 droplet diameter of 8.0 mm and an injection rate of 1.0 kg/sec, the model simulation predicts that the zooplanktons lose approximately 90% of their activity when the lowest pH inside the plume decreases from 7.57 to 5.61. These injured zooplanktons then recovered gradually to their normal state within two hours due to dilution of the plume.

Baixin Chen - One of the best experts on this subject based on the ideXlab platform.

  • Numerical Simulation on Mesoscale Diffusion of CO 2 Sequestrated in the Deep Ocean in Practical Scenario
    OCEANS 2008 - MTS IEEE Kobe Techno-Ocean, 2008
    Co-Authors: Se-min Jeong, Takumi Sato, Baixin Chen
    Abstract:

    Among possible carbon capture and storage (CCS) methods to mitigate the global warming, the direct injection of carbon dioxide (CO2) into the deep Ocean by the moving ship method, is considered to be a feasible way and expected to minimize its environmental impacts on marine organisms in the vicinity of the injection points. In this study, a simple but effective numerical model for the given practical scenario of very large system was developed with adopting moving and nesting grid technique and low- wavenumber forcing technique. The calculated results show that the maximum change of PC02 (DeltaPCO2) is lower than a given criteria, +5,000 muatm, in the both small- and mesoscale domains. This indicates that the scenario of 30 ships with different length of injection pipes injecting total CO2 of 50 million t/yr and moving in the 110 times 330 km operation area is efficient and effective. The developed techniques demonstrated its efficiencies and applicability to give an outline for the optimization of the CO2 Ocean Sequestration system, by which biological impacts should be minimized and insignificant.

  • A Lagrangian Two-Phase Model for Assessing the Near-Field Impacts of CO2 Ocean Sequestration
    Volume 4: Terry Jones Pipeline Technology; Ocean Space Utilization; CFD and VIV Symposium, 2006
    Co-Authors: Baixin Chen, Masahiro Nishio, Yongchen Song, Makoto Akai
    Abstract:

    A new version of a two-phase numerical model is developed to simulate CO2 droplet dissolution and the plume dynamics of CO2 enriched seawater produced by direct release of liquid CO2 into deep Ocean from a towed pipe. This Lagrangian framework model consists of three sub-models. They are the CO2 droplet moving and dissolving sub-model, the turbulent dispersion of CO2 enriched seawater sub-model, and the biological impact sub-model. We performed simulations of direct injection of liquid CO2 from a release platform towed by a moving-ship into mid-depth seawater to examine the roles of injection parameters, including release platform type and initial CO2 droplet size. Results from the simulations show that a horizontal release platform can create a plume with less physical and biological impacts than a plume created by a vertical release platform. With an injection rate of 100kg/s, simulations predict that injection of small droplets (5mm in diameter) would produce up to 1.5 times the pH reduction of larger droplets (15 mm in diameter). This large pH reduction may significantly affect ambient zooplankton.Copyright © 2006 by ASME

  • Density change of underground water due to CO2 dissolution
    Greenhouse Gas Control Technologies 7, 2005
    Co-Authors: Yongchen Song, Masahiro Nishio, Baixin Chen, Makoto Akai
    Abstract:

    Publisher Summary As an alternative technology to mitigate the carbon dioxide (CO2) concentration from the atmosphere, geological Sequestration had been widely accepted as a practical option because of the potential capacity and the relative safety in comparison with another option—Ocean Sequestration. To investigate the sciences and technologies concerned with it, Research Institute of Innovative Technology for the Earth (RITE) initiated a research and development project for CO2 geological Sequestration. The field experiment had been conducted at Nagaoka, Japan. For this technology, one of the geophysical dynamics additionally induced to the original geosystem is the dissolution of injected CO2 into the reservoir water, which is a way for storage. The density of dissolved water is changed leading to a gravity flow. This flow can make contribution to the evolution of CO2 enriched water in the terms of buoyancy.

  • A Eulerian-Eulerian Physical-Biological Impact Model of Zooplankton Injury Due to CO_2 Ocean Sequestration
    Journal of Oceanography, 2004
    Co-Authors: Baixin Chen, Masahiro Nishio, Yongchen Song, Makoto Akai
    Abstract:

    To study the biological impacts of CO_2 Ocean Sequestration on floating marine organisms, a full Eulerian-Eulerian scheme model has been developed in a large-eddy simulation (LES) version using one-way coupling of the equations of seawater flow to the transport equations of the bio-scalar variables. Special attention was paid to deriving the transport equation, involving non-conservative scalars to describe the degree of injury to floating organisms due to the change in the pH environment resulting from CO_2 dissolution. The source terms of the transport equations of bio-scalar variables are based on experimental data on zooplankton activities affected by lower pH seawater, allowing construction of empirical sub-models of three kinds of floating marine organisms: Gaidius variabilis, Paraeuchaeta Birostrata, and Multi-organisms. An example is given to show the applicability of the model to the assessment of the biological impact of CO_2 Sequestration in the Ocean. Given an initial CO_2 droplet diameter of 8.0 mm and an injection rate of 1.0 kg/sec, the model simulation predicts that the zooplanktons lose approximately 90% of their activity when the lowest pH inside the plume decreases from 7.57 to 5.61. These injured zooplanktons then recovered gradually to their normal state within two hours due to dilution of the plume.

  • A Eulerian-Eulerian physical-biological impact model of zooplankton injury due to CO2 Ocean Sequestration
    Journal of Oceanography, 2004
    Co-Authors: Baixin Chen, Masahiro Nishio, Yongchen Song, Makoto Akai
    Abstract:

    To study the biological impacts of CO2 Ocean Sequestration on floating marine organisms, a full Eulerian-Eulerian scheme model has been developed in a large-eddy simulation (LES) version using one-way coupling of the equations of seawater flow to the transport equations of the bio-scalar variables. Special attention was paid to deriving the transport equation, involving non-conservative scalars to describe the degree of injury to floating organisms due to the change in the pH environment resulting from CO2 dissolution. The source terms of the transport equations of bio-scalar variables are based on experimental data on zooplankton activities affected by lower pH seawater, allowing construction of empirical sub-models of three kinds of floating marine organisms: Gaidius variabilis, Paraeuchaeta Birostrata, and Multi-organisms. An example is given to show the applicability of the model to the assessment of the biological impact of CO2 Sequestration in the Ocean. Given an initial CO2 droplet diameter of 8.0 mm and an injection rate of 1.0 kg/sec, the model simulation predicts that the zooplanktons lose approximately 90% of their activity when the lowest pH inside the plume decreases from 7.57 to 5.61. These injured zooplanktons then recovered gradually to their normal state within two hours due to dilution of the plume.

Toru Sato - One of the best experts on this subject based on the ideXlab platform.

  • Model study on even diffusion of CO2 released from 30 ships in mesoscale deep Ocean
    Energy Procedia, 2011
    Co-Authors: Aurelie Carroget, Toru Sato, Taiki Iida, Shinichiro Hirabayashi, Se-min Jeong
    Abstract:

    Abstract Among possible carbon capture and storage methods to mitigate the global warming, the direct injection of CO 2 into the deep Ocean by the moving ship method, is considered to be a feasible way and expected to minimize its environmental impacts on ma rine organisms in the vicinity of the injection points. In this study, a simple but effective numerical model for the given practical scenario of very large system was developed with adopting moving and nesting grid technique and low-wavenumber forcing technique. The calculated results show that the maximum change of additional p CO 2 is lower than a non-observed effect concentration, +5,000 μatm, in the both small and mesoscale domains. This indicates that the scenario of 30 ships with different length of injection pipes injecting total CO 2 of 50 million t/yr and moving in the 111 km × 333 km operation area is efficient and effective. The developed techniques demonstrated its efficiencies and applicability to give an outline for the optimization of the CO 2 Ocean Sequestration system, by which biological impacts should be minimized and insignificant.

  • Public acceptance of the Oceanic carbon Sequestration
    Marine Policy, 2009
    Co-Authors: Norihiro Kamishiro, Toru Sato
    Abstract:

    Abstract CO2 Ocean Sequestration may be an effective option for mitigating global warming. There are risks associated with this process, particularly the local impact on deep-sea environments. Public acceptance is required for the implementation of this technology, even though the impacts have been proven to be trivial. In this study, a questionnaire survey was conducted to find the correlation between public acceptance of CO2 Sequestration and influential factors by covariance structure analysis. In addition, risk communication via the Internet was carried out. These analyses revealed that careful investigation of the target Oceanic site and field experiments are important in gaining public acceptance of CO2 Sequestration.

  • Numerical simulation of diffusion of Co2 released by thirty ships in mesoscale deep Ocean
    Volume 4: Ocean Engineering; Ocean Renewable Energy; Ocean Space Utilization Parts A and B, 2009
    Co-Authors: Toru Sato, Taiki Iida, Se-min Jeong, Shinichiro Hirabayashi
    Abstract:

    Among possible carbon capture and storage methods to mitigate the global warming, the direct injection of CO2 into the deep Ocean by the moving ship method, is considered to be a feasible way and expected to minimize its environmental impacts on marine organisms in the vicinity of the injection points. In this study, a simple but effective numerical model for the given practical scenario of very large system was developed with adopting moving and nesting grid technique and low-wavenumber forcing technique. The calculated results show that the maximum change of additional PCO2 is lower than a non-observed effect concentration, +5,000 μatm, in the both small and mesoscale domains. This indicates that the scenario of 30 ships with different length of injection pipes injecting total CO2 of 50 million t/yr and moving in the 110 × 330 km operation area is efficient and effective. The developed techniques demonstrated its efficiencies and applicability to give an outline for the optimization of the CO2 Ocean Sequestration system, by which biological impacts should be minimized and insignificant.Copyright © 2009 by ASME

  • Modelling of Biological Impact In Direct Injection of Carbon Dioxide in the Ocean
    Greenhouse Gas Control Technologies - 6th International Conference, 2003
    Co-Authors: Toru Sato
    Abstract:

    Publisher Summary The CO2 Ocean Sequestration by direct injection can be categorized into three methods: shallow dissolution, middle-depth dissolution, and deep storing. This chapter focuses on middle-depth dissolution. One of uncertainties in this method is its impact on marine organisms around injection points before CO2 is diluted widely in the Ocean. Because field experiments cost enormously, computational simulations are expected to show detailed information on the dilution process near injection points from a fluid-dynamical point of view. This chapter presents the computational simulations by using an acute biological impact model of CO2-rich water on marine organisms and the two-phase computational fluid dynamics (CFD) method, which predicts the behavior of CO2 injected in the forms of droplets (liquid CO2, LCO2) and solute (DCO2) in the deep Ocean. It is important to predict biological impacts caused by the Ocean Sequestration of CO2. The model was incorporated in the two-phase flow solver and predicts that the business case of CO2 Ocean Sequestration proposed in this study does not cause remarkable fatal effects on zooplankton. There is criticism that marine ecosystems should be taken into account instead only of the mortality of selected zooplankton.

  • Numerical prediction of the dilution process and its biological impacts in CO_2 Ocean Sequestration
    Journal of Marine Science and Technology, 2002
    Co-Authors: Toru Sato, Kei Sato
    Abstract:

     In order to investigate the biological impacts of the Ocean Sequestration of CO_2 (carbon dioxide), the dilution processes of CO_2 were investigated near injection points in the deep Ocean. From a combined fluid-dynamics, chemical, and biological approach, a two-phase computational fluid dynamics (CFD) method with mass transfer was developed to predict droplet plume flow, the dissolution of CO_2 from droplets into seawater, and the advection–diffusion of dissolved CO_2 (DCO_2) in the deep Ocean. Changes in pH due to the concentration of DCO_2 were also calculated. In addition, the isomortality concept of Auerbach et al. was incorporated to predict the lethal damage to marine organisms caused by DCO_2. The simulation results suggested that the biological impacts of CO_2 Sequestration were insignificant in terms of mortality in both small-scale field experiments and the real-life cases we propose.