Impact of Ocean Heat Transport on the Natural and Forced Variability of Arctic Sea-ice in the GFDL CM2-O Model Suite PDF Download
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Author: Marine Decuypère
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
"A recent study links an increase in the horizontal resolution of ocean models to improved representations of Arctic sea-ice and Ocean Heat Transport (OHT, Docquier et al., 2019). Here, the impact of horizontal resolution on meridional OHT, sea-ice natural variability and response to climate change is investigated over a broader range of spatial resolutions, using the GFDL CM2-O climate model suite (1°, 1/4°, and 1/10°) in both preindustrial control and climate change simulations. Results show a direct link between OHT and sea-ice extent (SIE) in the Arctic. This link, however, is not monotonic with spatial resolution contrary to findings by Docquier et al. (2019). While OHT increases and SIE decreases from the Low to the Medium resolution models, the reverse is true from the Medium to the High resolution models. Differences in OHT and SIE between the three models mostly arise from the preindustrial state. As the spatial resolution increases, the Irminger Current - recirculating waters around the southern tip of Greenland - is favored at the expense of the North Atlantic Drift - bringing water in the Arctic through Fram Strait and the Barents Sea Opening (BSO). This rerouting of water to the Western side of Greenland results in less heat delivered to the Arctic in the High resolution model than in its Medium counterpart. As a result, the Medium resolution model is in best agreement with observed SIE and OHT in the BSO and Fram Strait - the Bering Strait OHT is smaller than observed in all models. Concurrent with the change in the partitioning in volume is a gradual change in deep convection centers from the Greenland-Irminger-Norwegian (GIN) Seas in the Low resolution model to the Labrador Sea in the High resolution model. Results strongly suggest a role for the deep convection in the North Atlantic on the OHT into the Arctic"--
Author: Marine Decuypère
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
"A recent study links an increase in the horizontal resolution of ocean models to improved representations of Arctic sea-ice and Ocean Heat Transport (OHT, Docquier et al., 2019). Here, the impact of horizontal resolution on meridional OHT, sea-ice natural variability and response to climate change is investigated over a broader range of spatial resolutions, using the GFDL CM2-O climate model suite (1°, 1/4°, and 1/10°) in both preindustrial control and climate change simulations. Results show a direct link between OHT and sea-ice extent (SIE) in the Arctic. This link, however, is not monotonic with spatial resolution contrary to findings by Docquier et al. (2019). While OHT increases and SIE decreases from the Low to the Medium resolution models, the reverse is true from the Medium to the High resolution models. Differences in OHT and SIE between the three models mostly arise from the preindustrial state. As the spatial resolution increases, the Irminger Current - recirculating waters around the southern tip of Greenland - is favored at the expense of the North Atlantic Drift - bringing water in the Arctic through Fram Strait and the Barents Sea Opening (BSO). This rerouting of water to the Western side of Greenland results in less heat delivered to the Arctic in the High resolution model than in its Medium counterpart. As a result, the Medium resolution model is in best agreement with observed SIE and OHT in the BSO and Fram Strait - the Bering Strait OHT is smaller than observed in all models. Concurrent with the change in the partitioning in volume is a gradual change in deep convection centers from the Greenland-Irminger-Norwegian (GIN) Seas in the Low resolution model to the Labrador Sea in the High resolution model. Results strongly suggest a role for the deep convection in the North Atlantic on the OHT into the Arctic"--
Author: Stephen Griffies
Publisher: Princeton University Press
ISBN: 0691187126
Category : Science
Languages : en
Pages : 553
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Book Description
This book sets forth the physical, mathematical, and numerical foundations of computer models used to understand and predict the global ocean climate system. Aimed at students and researchers of ocean and climate science who seek to understand the physical content of ocean model equations and numerical methods for their solution, it is largely general in formulation and employs modern mathematical techniques. It also highlights certain areas of cutting-edge research. Stephen Griffies presents material that spans a broad spectrum of issues critical for modern ocean climate models. Topics are organized into parts consisting of related chapters, with each part largely self-contained. Early chapters focus on the basic equations arising from classical mechanics and thermodynamics used to rationalize ocean fluid dynamics. These equations are then cast into a form appropriate for numerical models of finite grid resolution. Basic discretization methods are described for commonly used classes of ocean climate models. The book proceeds to focus on the parameterization of phenomena occurring at scales unresolved by the ocean model, which represents a large part of modern oceanographic research. The final part provides a tutorial on the tensor methods that are used throughout the book, in a general and elegant fashion, to formulate the equations.
Author: Priska Schäfer
Publisher: Springer Science & Business Media
ISBN: 9783540672319
Category : Science
Languages : en
Pages : 520
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Book Description
The northern North Atlantic is one of the regions most sensitive to past and present global changes. This book integrates the results of an interdisciplinary project studying the properties of the Greenland-Iceland-Norwegian Seas and the processes of pelagic and benthic particle formation, particle transport, and deposition in the deep-sea sediments. Ice-related and biogeochemical processes have been investigated to decipher the spatial and temporal variability of the production and fate of organic carbon in this region. Isotopic stratigraphy, microfossil assemblages and paleotemperatures are combined to reconstruct paleoceanographic conditions and to model past climatic changes in the Late Quaternary. The Greenland-Iceland-Norwegian Seas can now be considered one of the best studied subbasins of the world`s oceans.
Author: Laura Elizabeth Fleming
Publisher:
ISBN:
Category : Arctic regions
Languages : en
Pages : 56
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Book Description
The Arctic surface air temperature has warmed nearly twice as much as the global mean since the mid-20th century. Arctic sea ice has also been declining rapidly in recent decades. There is still discussion about how much of this Arctic amplification is caused by local factors, such as changes in surface albedo, versus remote factors, such as changes in heat transport from the midlatitudes. This thesis focuses mainly on the role of poleward heat transport on Arctic amplification. Most of the previous studies on this topic have defined ocean heat transport as the zonally averaged ocean heat transport at 65∘N or 70∘N, which ignores the physical pathways of heat into the Arctic and may include recirculation of heat in the North Atlantic. In this thesis, we define the ocean heat transport as the heat transport across five sections surrounding the Arctic, to create a closed domain in the Arctic. Previous studies on Arctic amplification have used either a single model run or have compared results from a multi-model ensemble. While the multi-model ensemble approach may potentially average out biases in individual models, the ensemble spread confounds the model differences and the internal climate variability. In this thesis, we investigate the Arctic amplification in the Community Earth System Model version 1 (CESM1) Large Ensemble. The CESM1 Large Ensemble includes 40 members that use the same model and external forcing, but different initializations. This simulates different climate trajectories that can occur in a given atmosphere-ocean-land-cryosphere system. We find that CESM1 Large Ensemble projects a large increase towards the end of the 21st century in ocean heat transport into the Arctic, and that the increase in ocean heat transport is significantly correlated with Arctic amplification. The main contributor to the increase in ocean heat transport is the increase across the Barents Sea Opening. The increase in Barents Sea Opening ocean heat transport is highly correlated with the decrease in sea ice in the Barents-Kara Sea region. We propose that this is because the increase in ocean heat transport melts the ice at the sea ice margin, which results in increased surface heat flux from the ocean and further local feedback through decreased surface albedo and increased cloud coverage. We also find that while the changes in atmosphere heat transport into the Arctic circle at 66.5∘N are on the same order as the changes in ocean heat transport, they are not correlated with Arctic amplification.
Author: National Academies of Sciences, Engineering, and Medicine
Publisher: National Academies Press
ISBN: 0309492432
Category : Science
Languages : en
Pages : 29
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Book Description
We live on a dynamic Earth shaped by both natural processes and the impacts of humans on their environment. It is in our collective interest to observe and understand our planet, and to predict future behavior to the extent possible, in order to effectively manage resources, successfully respond to threats from natural and human-induced environmental change, and capitalize on the opportunities â€" social, economic, security, and more â€" that such knowledge can bring. By continuously monitoring and exploring Earth, developing a deep understanding of its evolving behavior, and characterizing the processes that shape and reshape the environment in which we live, we not only advance knowledge and basic discovery about our planet, but we further develop the foundation upon which benefits to society are built. Thriving on Our Changing Planet: A Decadal Strategy for Earth Observation from Space (National Academies Press, 2018) provides detailed guidance on how relevant federal agencies can ensure that the United States receives the maximum benefit from its investments in Earth observations from space, while operating within realistic cost constraints. This short booklet, designed to be accessible to the general public, provides a summary of the key ideas and recommendations from the full decadal survey report.
Author: Simon Chu
Publisher: Elsevier
ISBN: 0080870953
Category : Science
Languages : en
Pages : 395
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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: Louis Renaud-Desjardins
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
"This thesis furthers the understanding of thermal interactions between the ocean and the sea ice using the Community Climate System Model (CCSM). It focuses on the results from the six simulations under the Special Report on Emissions Scenarios (SRES) A1B from the CCSM version 3 (CCSM3) and the five simulations under the Representative Concentration Pathways (RCP) 6.0 scenario from the CCSM version 4 (CCSM4). Rapid losses of September sea ice extent were simulated through all the A1B simulations from the CCSM3. A rapid loss event is recorded when the derivative of the five-year running mean of September sea ice extent is inferior to -0.5 million km$^2$ per year. These events are preceded by pulses of warm water toward the Arctic Ocean one to two years beforehand. The presented analysis includes all the physical processes affecting sea ice in connection with the years of rapid September sea ice extent loss. Every melt process increases until the years of rapid sea ice extent loss. At the same time, the sea ice formation processes stagnate and the sea ice transport through the gates of the Arctic Ocean decreases. Therefore, we conclude that the rapid losses of September sea ice extent are caused by increased melt -- especially bottom melt. In the A1B simulations, the sea ice receives from the ocean 20 W/m$^2$ of heat in 1900 up to 120~W/m$^2$ in 2100. This is significantly more than the conventional 2 W/m$^2$ found in the literature. This important increase in heat transfer is caused by a combination of multiplicative of a significant increase in sea surface temperature and currents all over the Arctic Ocean. The heat sources causing the significant increase in sea surface temperature can be uncovered through a temperature-heat ocean budget. The temperature-heat ocean budget proved impossible to close satisfactorily. This was the case for both versions 3 and 4. In particular, for version 4 which has extended output variables, we found an error for the vertically integrated budget exceeding 50~W/m$^2$. Nevertheless, the study of advective heat transport through the gateways of the Arctic Ocean can provide insight on the warming of the Arctic Ocean and its impact on sea ice melt. The heat transport through the gateways of the Arctic Ocean is studied for both the CCSM versions 3 and 4. Both models forecast very different Arctic conditions. The CCSM3 advective heat transport is dominated by the heat fluxes through the Barents Sea Opening. Its total advective heat transfer to the Arctic Ocean is positive, warming the Arctic Ocean, from 35 W/m$^2$ in 1900 up to 13~W/m$^2$ in 2100. The CCSM4 advective heat transport is not dominated by the advective heat flux from one of its gateways. Indeed, in this case, the heat transport gets important contributions from all the gateways. Its total advective heat transfer starts from 19 W/m$^2$ in 1900 up to 60~W/m$^2$ in 2100. The CCSM3 advective heat transfer is more than twice as important than the one simulated by the CCSM4"--
Author: Charles R. Goldman
Publisher: John Wiley & Sons
ISBN: 1118470613
Category : Science
Languages : en
Pages : 481
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Book Description
Effects of global warming on the physical, chemical, ecological structure and function and biodiversity of freshwater ecosystems are not well understood and there are many opinions on how to adapt aquatic environments to global warming in order to minimize the negative effects of climate change. Climatic Change and Global Warming of Inland Waters presents a synthesis of the latest research on a whole range of inland water habitats – lakes, running water, wetlands – and offers novel and timely suggestions for future research, monitoring and adaptation strategies. A global approach, offered in this book, encompasses systems from the arctic to the Antarctic, including warm-water systems in the tropics and subtropics and presents a unique and useful source for all those looking for contemporary case studies and presentation of the latest research findings and discussion of mitigation and adaptation throughout the world. Edited by three of the leading limnologists in the field this book represents the latest developments with a focus not only on the impact of climate change on freshwater ecosystems but also offers a framework and suggestions for future management strategies and how these can be implemented in the future. Limnologists, Climate change biologists, fresh water ecologists, palaeoclimatologists and students taking relevant courses within the earth and environmental sciences will find this book invaluable. The book will also be of interest to planners, catchment managers and engineers looking for solutions to broader environmental problems but who need to consider freshwater ecology.
Author: National Research Council
Publisher: National Academies Press
ISBN: 0309301912
Category : Science
Languages : en
Pages : 98
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Book Description
The Arctic has been undergoing significant changes in recent years. Average temperatures are rising twice as fast as they are elsewhere in the world. The extent and thickness of sea ice is rapidly declining. Such changes may have an impact on atmospheric conditions outside the region. Several hypotheses for how Arctic warming may be influencing mid-latitude weather patterns have been proposed recently. For example, Arctic warming could lead to a weakened jet stream resulting in more persistent weather patterns in the mid-latitudes. Or Arctic sea ice loss could lead to an increase of snow on high-latitude land, which in turn impacts the jet stream resulting in cold Eurasian and North American winters. These and other potential connections between a warming Arctic and mid-latitude weather are the subject of active research. Linkages Between Arctic Warming and Mid-Latitude Weather Patterns is the summary of a workshop convened in September 2013 by the National Research Council to review our current understanding and to discuss research needed to better understand proposed linkages. A diverse array of experts examined linkages between a warming Arctic and mid-latitude weather patterns. The workshop included presentations from leading researchers representing a range of views on this topic. The workshop was organized to allow participants to take a global perspective and consider the influence of the Arctic in the context of forcing from other components of the climate system, such as changes in the tropics, ocean circulation, and mid-latitude sea surface temperature. This report discusses our current understanding of the mechanisms that link declines in Arctic sea ice cover, loss of high-latitude snow cover, changes in Arctic-region energy fluxes, atmospheric circulation patterns, and the occurrence of extreme weather events; possible implications of more severe loss of summer Arctic sea ice upon weather patterns at lower latitudes; major gaps in our understanding, and observational and/or modeling efforts that are needed to fill those gaps; and current opportunities and limitations for using Arctic sea ice predictions to assess the risk of temperature/precipitation anomalies and extreme weather events over northern continents.
Author: Gabriel Auclair
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
"Many climate models predict future rapid sea ice declines in the Arctic. These events are linked with anomalous northward Ocean Heat Transport (OHT). Using the Community Earth System Model Large Ensemble (CESM-LE), we find that the partitioning of the poleward OHT between the different gates of the Arctic (Barents Sea Opening (BSO), Fram Strait or Bering Strait) is key to this link with the rapid declines. In total, 64 of the 79 rapid declines in CESM-LE are linked with anomalous OHT. The interaction between OHT and sea ice happens mainly over continental shelves. The Bering Strait OHT is linked to more rapid declines than the BSO OHT, presumably because of the broader Eurasian shelf. No clear link is found between rapid declines and the OHT through the Fram Strait, which is a deep gate to the Arctic Ocean, except when the rapid decline is also linked to the BSO or Bering Strait OHTs. When the September Sea Ice Extent (SIE) before the rapid decline is located only over deep basins in the central Arctic, we observe a decrease in basal melt during the decline. We hypothesize that this is due to an enhanced stratification that reduces heat transfer between the ocean and the ice. The ice-atmosphere heat flux anomalies are more strongly correlated with the sea ice concentration anomalies over the deep basins in the 21st century than the ice-ocean heat flux anomalies. Our results suggest that OHTs are causing rapid sea ice declines mostly when the SIE is large enough to cover the continental shelves and that the atmosphere is the main driver when the initial SIE is located only over the deep basins." --
