On the Development of Antarctic Katabatic Winds and Their Impact on Ocean and Ice Processes in the Coastal Southern Ocean with Implications for Primary Productivity PDF Download

Author: Scott Lawrence Goodrick
Publisher:
ISBN:
Category : Antarctica
Languages : en
Pages : 212

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Author:
Publisher:
ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 836

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Author: Per Gloersen
Publisher:
ISBN:
Category : Microwave remote sensing
Languages : en
Pages : 324

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Author: Julia Eileen Hazel
Publisher:
ISBN:
Category :
Languages : en
Pages : 168

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The circulation at the margins of Antarctica closes the meridional overturning circulation, ventilating the abyssal ocean with 0$_{2}$ and modulating deep CO$_{2}$ storage on millennial timescales. This circulation also mediates the melt rates of Antarctica's floating ice shelves, and thereby exerts a strong influence on future global sea level rise. The near-Antarctic circulation has been hypothesized to respond sensitively to changes in the easterly winds that encircle the Antarctic coastline. In particular, the easterlies may be expected to weaken in response to the ongoing strengthening and poleward shifting of the mid-latitude westerlies, associated with a trend toward the positive index of the Southern Annular Mode (SAM). However, multi-decadal changes in the easterlies have not been systematically quantified, and previous studies have yielded limited insight into the oceanic response to such changes. In this work we first quantify multi-decadal changes in wind forcing of the near-Antarctic ocean using a suite of reanalysis products that compare favorably with local meteorological measurements. Contrary to expectations, we find that the circumpolar-averaged easterly wind stress has not weakened over the past 3-4 decades, and if anything has slightly strengthened. However, there has been a substantial increase in the seasonality of the easterlies: our results suggest that in austral summer the intensification of the SAM has weakened the easterly winds, while during austral winter an intensification of Antarctica's katabatic winds has strengthened the easterlies. These trends have wide-ranging implications for oceanic transport of heat to Antarctica's floating glaciers, formation of dense waters on the continental shelf, and sea ice production and export. To explore the impacts of Antarctica' changing winds, we develop a comprehensive model of the southern Weddell Sea, including the Filchner-Ronne Ice Shelf (FRIS), Antarctica's largest floating glacier. We investigate the wind-driven sensitivity of the circulation, dense water production, and glacial melt to idealized climate changes. We find that the circulation is relatively insensitive to changes in the zonal winds and atmospheric temperature, but strongly sensitive to changes in the meridional winds. Varying the strength of the meridional winds by a few tens of percent is sufficient to switch the FRIS cavity circulation between bi-stable ``warm'' and ``cold' states, accompanied by an order of magnitude change in the glacier's melt rate. These findings imply that Antarctica's major ice shelves may experience rapid changes in melt if certain climatic thresholds are exceeded, and that such changes would strongly inhibit a return to present-day melt rates. Alternatively, existing cold, dense water masses within the cavities might buffer against future intrusions of warm water and acceleration of Antarctic mass loss.

Author: Stanley S. Jacobs
Publisher: American Geophysical Union
ISBN:
Category : Science
Languages : en
Pages : 400

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In this latest oceanology volume of the Antarctic Research Series, polar scientists describe and model air-sea and ice-ocean interactions, the formation and chemistry of deep and bottom waters, regional circulations, tidal heights and currents, ocean bathymetry, interannual variability and the Antarctic Slope Front.

Author: Jan Zalasiewicz
Publisher: Cambridge University Press
ISBN: 110847523X
Category : Medical
Languages : en
Pages : 385

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Reviews the evidence underpinning the Anthropocene as a geological epoch written by the Anthropocene Working Group investigating it. The book discusses ongoing changes to the Earth system within the context of deep geological time, allowing a comparison between the global transition taking place today with major transitions in Earth history.

Author: Woo Geunn Cheon
Publisher:
ISBN:
Category :
Languages : en
Pages :

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This dissertation discusses a linkage between the Southern Ocean (SO) winds and the global ocean circulation in the framework of a coarse-resolution global ocean general circulation model coupled to a sea-ice model. In addition to reexamination of the conventional linkage that begins with northward Ekman transport and extends to the North Atlantic (NA) overturning, the author investigates a new linkage that begins with the Southern Hemisphere (SH) sea-ice 0́3 ocean interaction perturbed by the anomalous SO winds and extends to the SH overturning, the response of the NA overturning, and the long-term baroclinic adjustment of the Antarctic Circumpolar Current (ACC). How the above two linkages will interact with each other in a warming world is also investigated. An interactive momentum flux forcing, allowing for the strength of momentum flux between atmosphere and sea ice to vary in response to the simulated sea-ice conditions, enhances wind-driven ice divergence to increase the fraction of leads and polynyas, which increases dense water formation, and thus intensifies convection. Within three experimental frameworks, this increased dense water consistently increases the Antarctic Bottom Water formation, which directly intensifies the SH overturning and indirectly weakens the NA overturning. As a result of the hemispheric change in overturning circulations, the meridional density gradient across the ACC appears to increase, ultimately increasing the baroclinic part of the ACC via an enhanced thermal wind shear. Subsequently, impacts of the poleward shifted and intensified SH subpolar westerly winds (SWWs) on the global ocean circulation are investigated in phases. When the SWWs are only shifted poleward, the effect of the anomalous winds is transmitted to the northern NA, decreasing both the NA overturning and the North Atlantic Deep Water (NADW) outflow. However, when the SWWs are shifted poleward and intensified, this effect is cut off by the intensified Deacon cell overturning, and is not transmitted to the northern NA, and instead increases the NADW outflow substantially. To sum up, with respect to the SO winds perturbed by the global warming, the SH overturning cell and the NADW outflow increase, leading to an increase in the volume transport of the ACC.

Author: American Geophysical Union. Meeting
Publisher:
ISBN:
Category : Geophysics
Languages : en
Pages : 476

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Author:
Publisher:
ISBN:
Category : Desert ecology
Languages : en
Pages : 396

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Author: Peter Wadhams
Publisher: CRC Press
ISBN: 9789056992965
Category : Science
Languages : en
Pages : 376

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Book Description
ICe in the Ocean examines sea ice and icebergs and their role in the global climate system. It is comprehensive textbook suitablefor students, pure and applied researchers, and anyone interested in the polar oceans; the distribution of sea ice; the mechanisms of growth, development and decay; the thermodynamics and dynamics of sea ice; sea ice deformation and ridge-building; the role of marginal ice zones; the characteristics of icebergs; and the part played by sea ice in the climate system and in the transport of pollutants. An extensive reference list and recommendations for further reading and numerous illustrations, and add to the usefulness of the text.