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Author: Adele Kim Morrison
Publisher:
ISBN:
Category : Climatic changes
Languages : en
Pages : 158
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Book Description
The Southern Ocean circulation plays a central role in the dynamics of past and future global climate change. However, due to a scarcity of observations and the difficulty of accurately modelling the Southern Ocean, we lack a comprehensive understanding of how the circulation responds to change. The energetic eddy field directly impacts the response of the circulation, but the small scale of the eddies has generally been below the resolution of numerical ocean models. This thesis makes use of two high resolution idealised ocean models to investigate the role of eddies in modifying the response of the Southern Ocean circulation to changing wind stress and surface buoyancy forcing. The simulations demonstrate that the eddy field is significant in the dynamical response, but that the impact on different aspects of the circulation is complex and subtle. The Antarctic Circumpolar Current (ACC) transport increases only weakly in response to enhanced Southern Ocean wind stress, due to the enhanced eddy field, which efficiently eliminates momentum input. In contrast, the eddy field only partially compensates wind- driven increases in the upper overturning circulation, resulting in a moderate overturning increase in response to enhanced westerly winds. Southern Ocean heat uptake is also shown to be dependent on changes in the eddy field. Mid-depth warming occurs primarily due to a decrease in the upward eddy heat flux, associated with reduced isopycnal temperature gradients in a warmer climate. However, increased wind stress may reduce the mid-depth heat uptake; a transient cooling trend arises from the wind-driven enhancement of the vertical eddy heat flux. The uncoupled idealised models also permit an in-depth analysis of the response of the Southern Ocean overturning to changes in surface buoyancy forcing. A suite of buoyancy forcing perturbations show that mid-latitude heat and freshwater fluxes may be as significant as wind stress in altering the strength of the upper overturning circulation. Analysis of the transient model response to a range of surface buoyancy forcing perturbations also indicates that recent observations are consistent with a slowdown of the lower overturning cell. In summary, this thesis has refined our understanding of how the large scale Southern Ocean circulation responds to atmospheric change and the role of the eddy field in modifying that response. This work provides a basis to interpret the more complicated response of coupled and coarse resolution models.
Author: Adele Kim Morrison
Publisher:
ISBN:
Category : Climatic changes
Languages : en
Pages : 158
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Book Description
The Southern Ocean circulation plays a central role in the dynamics of past and future global climate change. However, due to a scarcity of observations and the difficulty of accurately modelling the Southern Ocean, we lack a comprehensive understanding of how the circulation responds to change. The energetic eddy field directly impacts the response of the circulation, but the small scale of the eddies has generally been below the resolution of numerical ocean models. This thesis makes use of two high resolution idealised ocean models to investigate the role of eddies in modifying the response of the Southern Ocean circulation to changing wind stress and surface buoyancy forcing. The simulations demonstrate that the eddy field is significant in the dynamical response, but that the impact on different aspects of the circulation is complex and subtle. The Antarctic Circumpolar Current (ACC) transport increases only weakly in response to enhanced Southern Ocean wind stress, due to the enhanced eddy field, which efficiently eliminates momentum input. In contrast, the eddy field only partially compensates wind- driven increases in the upper overturning circulation, resulting in a moderate overturning increase in response to enhanced westerly winds. Southern Ocean heat uptake is also shown to be dependent on changes in the eddy field. Mid-depth warming occurs primarily due to a decrease in the upward eddy heat flux, associated with reduced isopycnal temperature gradients in a warmer climate. However, increased wind stress may reduce the mid-depth heat uptake; a transient cooling trend arises from the wind-driven enhancement of the vertical eddy heat flux. The uncoupled idealised models also permit an in-depth analysis of the response of the Southern Ocean overturning to changes in surface buoyancy forcing. A suite of buoyancy forcing perturbations show that mid-latitude heat and freshwater fluxes may be as significant as wind stress in altering the strength of the upper overturning circulation. Analysis of the transient model response to a range of surface buoyancy forcing perturbations also indicates that recent observations are consistent with a slowdown of the lower overturning cell. In summary, this thesis has refined our understanding of how the large scale Southern Ocean circulation responds to atmospheric change and the role of the eddy field in modifying that response. This work provides a basis to interpret the more complicated response of coupled and coarse resolution models.
Author: Stephen R. Rintoul
Publisher: Elsevier Inc. Chapters
ISBN: 0128058676
Category : Science
Languages : en
Pages : 58
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Book Description
The Southern Ocean circulation connects the ocean basins as well as the upper and deep layers of the ocean. As a result, the region has a profound influence on the global ocean circulation and climate. The Antarctic Circumpolar Current and the overturning circulation are dynamically linked through interactions between the mean flow, eddies, topography, air–sea forcing, and mixing and stirring by small- and mesoscale processes. A new dynamical paradigm is emerging that emphasizes the fully three-dimensional nature of the circulation, including the localization of meridional and vertical exchange of momentum, vorticity, and tracers by interactions between the flow and topography. Changes observed in the Southern Ocean in recent decades have implications for global climate and provide insight into the response of the Southern Ocean circulation to changes in forcing.
Author: National Academies of Sciences, Engineering, and Medicine
Publisher: National Academies Press
ISBN: 0309456002
Category : Science
Languages : en
Pages : 83
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Book Description
The sea ice surrounding Antarctica has increased in extent and concentration from the late 1970s, when satellite-based measurements began, until 2015. Although this increasing trend is modest, it is surprising given the overall warming of the global climate and the region. Indeed, climate models, which incorporate our best understanding of the processes affecting the region, generally simulate a decrease in sea ice. Moreover, sea ice in the Arctic has exhibited pronounced declines over the same period, consistent with global climate model simulations. For these reasons, the behavior of Antarctic sea ice has presented a conundrum for global climate change science. The National Academies of Sciences, Engineering, and Medicine held a workshop in January 2016, to bring together scientists with different sets of expertise and perspectives to further explore potential mechanisms driving the evolution of recent Antarctic sea ice variability and to discuss ways to advance understanding of Antarctic sea ice and its relationship to the broader ocean-climate system. This publication summarizes the presentations and discussions from the workshop.
Author: Fabio Florindo
Publisher: Elsevier
ISBN: 0080931618
Category : Science
Languages : en
Pages : 606
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Book Description
Antarctic Climate Evolution is the first book dedicated to furthering knowledge on the evolution of the world’s largest ice sheet over its ~34 million year history. This volume provides the latest information on subjects ranging from terrestrial and marine geology to sedimentology and glacier geophysics. An overview of Antarctic climate change, analyzing historical, present-day and future developments Contributions from leading experts and scholars from around the world Informs and updates climate change scientists and experts in related areas of study
Author: National Research Council
Publisher: National Academies Press
ISBN: 0309133041
Category : Science
Languages : en
Pages : 252
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Book Description
The climate record for the past 100,000 years clearly indicates that the climate system has undergone periodic-and often extreme-shifts, sometimes in as little as a decade or less. The causes of abrupt climate changes have not been clearly established, but the triggering of events is likely to be the result of multiple natural processes. Abrupt climate changes of the magnitude seen in the past would have far-reaching implications for human society and ecosystems, including major impacts on energy consumption and water supply demands. Could such a change happen again? Are human activities exacerbating the likelihood of abrupt climate change? What are the potential societal consequences of such a change? Abrupt Climate Change: Inevitable Surprises looks at the current scientific evidence and theoretical understanding to describe what is currently known about abrupt climate change, including patterns and magnitudes, mechanisms, and probability of occurrence. It identifies critical knowledge gaps concerning the potential for future abrupt changes, including those aspects of change most important to society and economies, and outlines a research strategy to close those gaps. Based on the best and most current research available, this book surveys the history of climate change and makes a series of specific recommendations for the future.
Author: Intergovernmental Panel on Climate Change (IPCC)
Publisher: Cambridge University Press
ISBN: 9781009157971
Category : Science
Languages : en
Pages : 755
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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: Thomas F. Stocker
Publisher: Elsevier Inc. Chapters
ISBN: 0128058501
Category : Science
Languages : en
Pages : 67
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Book Description
A broad perspective of the ocean as a key component of the Earth System and of its role in the past, present, and future climate change is provided. The ocean is a huge reservoir of heat, mass, carbon, and many other quantities, and their estimated exchange fluxes suggest characteristic timescales of adjustment ranging from decades to many thousands of years. Surface patterns and meridional fluxes of these quantities highlight the important role of the wind-driven circulation and the deep ocean flow systems through all ocean basins. Ocean-dominated phenomena of natural variability, in particular associated with the tropical oceans, are explained. The relevance of the ocean circulation for abrupt climate change, as recorded from a variety of paleoclimate records, is discussed. This includes the bipolar seesaw concept which explains many features of interhemispheric response during the sequence of rapid warmings in the past ice age. Finally, the ocean’s role during the anthropocene, the time epoch which is dominated by the human-caused increase in greenhouse gases to levels unprecedented in the past 800,000 years, is explored. Both the warming and the increase in atmospheric transport of water polewards create conditions for the ocean that may induce large and irreversible changes in the Atlantic meridional overturning circulation.
Author: Antony Joseph
Publisher: Newnes
ISBN: 0123914280
Category : Science
Languages : en
Pages : 447
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Book Description
Measuring Ocean Currents: Tools, Technologies, and Data covers all major aspects of ocean current measurements in view of the implications of ocean currents on changing climate, increasing pollution levels, and offshore engineering activities. Although more than 70% of the Earth is covered by ocean, there is limited information on the countless fine- to large-scale water motions taking place within them. This book fills that information gap as the first work that summarizes the state-of-the-art methods and instruments used for surface, subsurface, and abyssal ocean current measurements. Readers of this book will find a wealth of information on Lagrangian measurements, horizontal mapping, imaging, Eulerian measurements, and vertical profiling techniques. In addition, the book describes modern technologies for remote measurement of ocean currents and their signatures, including HF Doppler radar systems, satellite-borne sensors, ocean acoustic tomography, and more. Crucial aspects of ocean currents are described in detail as well, including dispersion of effluents discharged into the sea and transport of beneficial materials—as well as environmentally hazardous materials—from one region to another. The book highlights several important practical applications, showing how measurements relate to climate change and pollution levels, how they affect coastal and offshore engineering activities, and how they can aid in tsunami detection. Coverage of measurement, mapping and profiling techniques Descriptions of technologies for remote measurement of ocean currents and their signatures Reviews crucial aspects of ocean currents, including special emphasis on the planet-spanning thermohaline circulation, known as the ocean's "conveyor belt," and its crucial role in climate change
Author: Michael Meredith
Publisher: Elsevier
ISBN: 0128215135
Category : Science
Languages : en
Pages : 386
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Book Description
Ocean Mixing: Drivers, Mechanisms and Impacts presents a broad panorama of one of the most rapidly-developing areas of marine science. It highlights the state-of-the-art concerning knowledge of the causes of ocean mixing, and a perspective on the implications for ocean circulation, climate, biogeochemistry and the marine ecosystem. This edited volume places a particular emphasis on elucidating the key future questions relating to ocean mixing, and emerging ideas and activities to address them, including innovative technology developments and advances in methodology. Ocean Mixing is a key reference for those entering the field, and for those seeking a comprehensive overview of how the key current issues are being addressed and what the priorities for future research are. Each chapter is written by established leaders in ocean mixing research; the volume is thus suitable for those seeking specific detailed information on sub-topics, as well as those seeking a broad synopsis of current understanding. It provides useful ammunition for those pursuing funding for specific future research campaigns, by being an authoritative source concerning key scientific goals in the short, medium and long term. Additionally, the chapters contain bespoke and informative graphics that can be used in teaching and science communication to convey the complex concepts and phenomena in easily accessible ways. Presents a coherent overview of the state-of-the-art research concerning ocean mixing Provides an in-depth discussion of how ocean mixing impacts all scales of the planetary system Includes elucidation of the grand challenges in ocean mixing, and how they might be addressed
Author: Jennifer A. Graham
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Observations suggest that properties of Antarctic Intermediate Water (AAIW) are changing. The impact of these variations is explored using a series of idealised perturbation experiments. Two sets of ensembles have been used. The first varied initial atmospheric states; the second varied initial states in the ocean and atmosphere. The ensemble simulations were integrated over 120 and 100 years, respectively, altering AAIW from 10-200S in the Atlantic, Pacific and Indian oceans separately in a coupled climate model, HadCM3. Potential temperature was changed by ±1 DC, along with corresponding changes in salinity, maintaining constant potential density. There is a surface response to changes in AAIW in each of the three major ocean basins. When the water mass surfaces in the equatorial regions, there is no significant change in sea surface temperature (SST). However, there is a SST response when the anomalies surface at higher latitudes (>300). Anomalous sea-to-air heat fluxes leave density anomalies in the ocean. Resulting changes in ocean circulation cause responses to opposite perturbations to be nonlinear. In the Southern Ocean, changes in the meridional density gradient lead to changes in Antarctic Circumpolar Current transport. The North Atlantic is particularly sensitive, with density anomalies causing changes in the meridional overturning circulation of up to 1 Sv. Surfacing anomalies and changes in meridional ocean heat transport cause basin-wide changes in the surface ocean and overlying atmosphere on multi-decadal timescales. Cooling in the North Atlantic Current may be self-sustaining as it leads to high pressure anomalies in the overlying atmosphere, and increased wind stress over the sub-polar gyre. The spatial pattern of SST anomalies in the North Pacific resembles the Pacific Decadal Oscillation. Heat and salt distribution in the Indian Ocean is influenced by the Indonesian Through-Flow (ITF). Long-term trends in the ITF are caused by bottom pressure anomalies in the Pacific.
