Dynamic Changes at Tidewater Glacier Termini in Central West Greenland PDF Download
Are you looking for read ebook online? Search for your book and save it on your Kindle device, PC, phones or tablets. Download Dynamic Changes at Tidewater Glacier Termini in Central West Greenland PDF full book. Access full book title Dynamic Changes at Tidewater Glacier Termini in Central West Greenland by Mason Joseph Fried. Download full books in PDF and EPUB format.
Author: Mason Joseph Fried
Publisher:
ISBN:
Category :
Languages : en
Pages : 270
Get Book Here
Book Description
The Greenland Ice Sheet rapidly lost mass over the last two decades, in part due to increases in ice loss from termini of large tidewater glaciers. Terminus melting and calving can drive glacier retreat and the pattern of ice sheet mass loss through reductions in resistive stresses near the glacier front and, in turn, increases in ice flow to the ocean. Despite their importance to ice sheet mass balance, factors controlling terminus positions are poorly constrained in ice sheet models, which fundamentally obscures sea level rise predictions. In this dissertation, I use a suite of novel observations and techniques to quantify controls on frontal ablation and terminus positions at tidewater glaciers in central west Greenland. Until recently, frontal ablation processes were obscured due to limited observations of submarine termini. Here, I use observations from multibeam echo sonar to show the morphological complexity of the submarine terminus face and identify previously unrecognized melting and calving processes. The terminus features numerous secondary subglacial plume outlets outside of the main subglacial channel system that drive and disperse large submarine melt rates across the glacier front. Submarine melting drives steep, localized terminus undercutting that can trigger calving by connecting to finely-spaced surface crevasses. In turn, large calving events cause the terminus face to become anomalously overcut. Incorporating observed outlet geometries in a numerical plume model, I estimate small subglacial discharge fluxes feeding secondary plume outlets that are reminiscent of a distributed subglacial network. Regional remote-sensing observations reveal that, for most glaciers in central west Greenland, seasonal terminus positions are more sensitive to glacial runoff than ice mélange or ocean thermal forcing. Shallow, serac-failing tidewater glaciers are most sensitive, where subglacial plumes melt the terminus and locally enhance retreat. Glaciers with large ice fluxes and deep termini retreat sporadically through full ice-thickness calving events less dependent on runoff. Together, these results provide process-oriented constraints on the shape of the submarine terminus face, the geometry of subglacial discharge and submarine melting, the influence of environmental forcing mechanisms and the impact that these variables have on terminus positions and dynamics in a warming climate.
Author: Mason Joseph Fried
Publisher:
ISBN:
Category :
Languages : en
Pages : 270
Get Book Here
Book Description
The Greenland Ice Sheet rapidly lost mass over the last two decades, in part due to increases in ice loss from termini of large tidewater glaciers. Terminus melting and calving can drive glacier retreat and the pattern of ice sheet mass loss through reductions in resistive stresses near the glacier front and, in turn, increases in ice flow to the ocean. Despite their importance to ice sheet mass balance, factors controlling terminus positions are poorly constrained in ice sheet models, which fundamentally obscures sea level rise predictions. In this dissertation, I use a suite of novel observations and techniques to quantify controls on frontal ablation and terminus positions at tidewater glaciers in central west Greenland. Until recently, frontal ablation processes were obscured due to limited observations of submarine termini. Here, I use observations from multibeam echo sonar to show the morphological complexity of the submarine terminus face and identify previously unrecognized melting and calving processes. The terminus features numerous secondary subglacial plume outlets outside of the main subglacial channel system that drive and disperse large submarine melt rates across the glacier front. Submarine melting drives steep, localized terminus undercutting that can trigger calving by connecting to finely-spaced surface crevasses. In turn, large calving events cause the terminus face to become anomalously overcut. Incorporating observed outlet geometries in a numerical plume model, I estimate small subglacial discharge fluxes feeding secondary plume outlets that are reminiscent of a distributed subglacial network. Regional remote-sensing observations reveal that, for most glaciers in central west Greenland, seasonal terminus positions are more sensitive to glacial runoff than ice mélange or ocean thermal forcing. Shallow, serac-failing tidewater glaciers are most sensitive, where subglacial plumes melt the terminus and locally enhance retreat. Glaciers with large ice fluxes and deep termini retreat sporadically through full ice-thickness calving events less dependent on runoff. Together, these results provide process-oriented constraints on the shape of the submarine terminus face, the geometry of subglacial discharge and submarine melting, the influence of environmental forcing mechanisms and the impact that these variables have on terminus positions and dynamics in a warming climate.
Author:
Publisher: Academic Press
ISBN: 0123964733
Category : Nature
Languages : en
Pages : 787
Get Book Here
Book Description
Snow and Ice-Related Hazards, Risks, and Disasters provides you with the latest scientific developments in glacier surges and melting, ice shelf collapses, paleo-climate reconstruction, sea level rise, climate change implications, causality, impacts, preparedness, and mitigation. It takes a geo-scientific approach to the topic while also covering current thinking about directly related social scientific issues that can adversely affect ecosystems and global economies. Puts the contributions from expert oceanographers, geologists, geophysicists, environmental scientists, and climatologists selected by a world-renowned editorial board in your hands Presents the latest research on causality, glacial surges, ice-shelf collapses, sea level rise, climate change implications, and more Numerous tables, maps, diagrams, illustrations and photographs of hazardous processes will be included Features new insights into the implications of climate change on increased melting, collapsing, flooding, methane emissions, and sea level rise
Author: Taryn Elizabeth Black
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
Get Book Here
Book Description
Glacier retreat and mass loss are contributing to global sea-level rise and environmental change. One method to improve our understanding of how glaciers affect local and global environments is to measure historical and ongoing glacier retreat. In this dissertation, I use satellite images to measure glacier terminus change in Greenland and Alaska. In both regions, I quantify glacier retreat and advance on time scales ranging from seasons to decades.In northwest and central-west Greenland, I investigate multi-decadal outlet glacier retreat and its potential driving mechanisms from 1972 through 2021. Over this time period, glaciers in this region of Greenland represented nearly half of Greenland's total contribution to sea-level rise. I show that regional glacier retreat accelerated from 1996, and that this retreat is most sensitive to runoff and ocean temperatures. Because runoff and ocean temperatures can influence terminus positions through several mechanisms, it is likely that multiple mechanisms are contributing to the observed retreat in this region. I also examine multi-decadal glacier retreat, as well as seasonal terminus variations, for maritime glaciers in Kenai Fjords National Park, Alaska, from 1984 through 2021. I show that most glaciers retreated substantially, and those that did not were predominantly tidewater. Seasonally, tidewater, lake-terminating, and land-terminating glaciers all tended to retreat during the summer; in the winter, tidewater glaciers tended to advance, while lake-terminating glaciers continued to retreat, and land-terminating glaciers were more variable. Glacier change in Kenai Fjords National Park is driving changes in landcover and viewscapes, which affects local ecosystems and ecotourism. Finally, I characterize seasonal terminus variations around the full margin of Greenland at monthly and six-day temporal resolution. I show that nearly 75% of outlet glaciers exhibit terminus position seasonality, with seasonal retreat typically beginning in mid-May and continuing through early October. The onset and duration of the retreat period appears to be related to the timing of the onset of melt, while the magnitude of terminus position seasonality correlates with glacier velocity. Glacier dynamics are influenced by conditions at the terminus, and terminus position seasonality can affect projections of future ice-sheet mass balance.
Author: Ireneo Peter Martini
Publisher: Geological Society of London
ISBN: 9781862393271
Category : Drift
Languages : en
Pages : 304
Get Book Here
Book Description
Understanding the sediments deposited by glaciers or other cold-climate processes assumes enhanced significance in the context of current global warming and the predicted melt and retreat of glaciers and ice sheets. This volume analyses glacial, proglacial and periglacial settings. Papers include topics such as sedimentation at termini of tidewater glaciers, poorly understood high-mountain features, and slope and aeolian deposits that have been sourced in glacial and periglacial regions and subsequently transported and deposited by azonal processes. Difficulties encountered in inferring Pleistocene and pre-Pleistocene cold-climate conditions when the sedimentary record lacks specific diagnostic indicators are discussed. The main objective of this volume is to establish the validity and limitations of the evidence that is used to achieve reliable palaeogeographic and palaeoclimatic reconstructions. On the much longer geological timescale, an understanding of ice-marginal and periglacial environments may better prepare us for the unavoidable reversal towards cooler and perhaps even glacial times in the future.
Author: Carlos R. Mechoso
Publisher: Cambridge University Press
ISBN: 1108492703
Category : Science
Languages : en
Pages : 359
Get Book Here
Book Description
A comprehensive review of interactions between the climates of different ocean basins and their key contributions to global climate variability and change. Providing essential theory and discussing outstanding examples as well as impacts on monsoons, it a useful resource for graduate students and researchers in the atmospheric and ocean sciences.
Author: Sophie Ann Goliber
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
Get Book Here
Book Description
Since the 1980s, the Greenland ice sheet has been losing ice mass at an increased rate. Our current understanding of the complex physical processes that control dynamic mass loss is incomplete and, therefore, leads to a wide range of possible future contributions to sea level. Ice dynamics, or changes due to changes in ice flux, is dominated by the behavior of fast-moving outlet glaciers in Greenland. These glaciers are changing through melting of the terminus face and/or calving of icebergs; the combination of these processes and ice motion determines the position of a glacier terminus. In understanding how and why outlet glacier termini change over time compared to external forcing and internal glacier dynamics, we are able to move toward a better understanding of marine-terminating glaciers. In this dissertation, I use terminus traces to observe how and why marine-terminating glaciers change in order to better understand the mechanisms behind these complex heterogeneous changes in Greenland. I develop the largest database of manually-traced marine-terminating glacier terminus data for use in scientific and machine learning applications. These data have been collected, cleaned, assigned with appropriate metadata, including image scenes, and compiled so that they can be easily accessed by scientists. Then I use the location of the termini to identify features in the bed topography that inhibit the retreat of glaciers following the onset of ocean warming and widespread glacier retreat in the late 1990s. I find that the slope and lateral dimensions of bed features exhibit the strongest correlation to retreat and that the shape of the bed features allows different styles of terminus retreat, which may be indicative of how different ablation mechanisms are distributed across termini. Finally, I produce a time series of terminus morphological properties for four glaciers in western Greenland to identify the characteristics that are indicative of calving processes with the goal of categorizing glaciers by calving style. I find that a concave shape and low sinuosity are present at glaciers that calve via buoyant flexure, while the opposite is true at glaciers that are dominated by melt-induced calving via serac failure. I also find that glaciers do not persistently fit into single calving styles and may change over time. By studying how the terminus changes over time compared to external forcing and internal glacier dynamics, we are able to move toward a better understanding of marine-terminating glaciers
Author: Wilfried Haeberli
Publisher: Elsevier
ISBN: 0128171308
Category : Nature
Languages : en
Pages : 786
Get Book Here
Book Description
Snow and Ice-Related Hazards, Risks, and Disasters, Second Edition, provides you with the latest scientific developments in sea level rise, permafrost degradation, rock/ice avalanches, glacier surges, glacial lake outburst floods, ice shelf collapses, climate change implications, causality, impacts, preparedness and mitigation. The book takes a geo-scientific approach to the topic while also covering current thinking about directly related social scientific issues that can affect ecosystems and global economies. Special emphasis is placed on the rapidly progressing effects from global warming on the cryosphere, perspectives for the future and latest scientific advances, and technological developments. Presents the latest research on causality, glacial surges, ice-shelf collapses, sea level rise, climate change implications, and more Contains numerous tables, maps, diagrams, illustrations and photographs of hazardous processes Features new insights on the implications of climate change, including increased melting, collapsing, flooding, methane emissions, and sea level rise
Author: Tong Lee
Publisher: Frontiers Media SA
ISBN: 2889631206
Category : Science
Languages : en
Pages : 867
Get Book Here
Book Description
This eBook is a collection of articles from a Frontiers Research Topic. Frontiers Research Topics are very popular trademarks of the Frontiers Journals Series: they are collections of at least ten articles, all centered on a particular subject. With their unique mix of varied contributions from Original Research to Review Articles, Frontiers Research Topics unify the most influential researchers, the latest key findings and historical advances in a hot research area! Find out more on how to host your own Frontiers Research Topic or contribute to one as an author by contacting the Frontiers Editorial Office: frontiersin.org/about/contact.
Author: James M. Lea
Publisher:
ISBN:
Category : Geological modeling
Languages : en
Pages : 0
Get Book Here
Book Description
Significant uncertainty surrounds the influence of atmospheric and oceanic forcing on the fluctuations of tidewater glacier outlets of the Greenland ice sheet (GrIS), with the majority of studies focussing on dynamics over the last two decades. Although numerical model based projections exist anticipating the future dynamics of major GrIS outlets, these have been made using temporally limited model calibration periods (5 years) compared to the centennial timescales that they seek to predict over. The ability of these numerical models to simulate the centennial timescale dynamics of GrIS tidewater glaciers has therefore not been explicitly tested. This thesis seeks to calibrate a well-established one-dimensional tidewater glacier numerical model against post-Little Ice Age maximum (LIAmax) observations of a major tidewater glacier outlet of GrIS. The study site chosen is Kangiata Nunaata Sermia (KNS); the largest tidewater outlet in SW Greenland south of Jakobshavn Isbræ. This glacier is known to have undergone retreat of20 km since its LIAmax, though the timing of this retreat and response to climate forcing is currently poorly constrained. Utilising a range of source material, it is demonstrated that KNS is likely to have achieved its LIAmax by 1761, experiencing either one, or two multi-kilometre retreats by 1859, and retreats of a similar scale between 1921-1968, and 1997-2012. Terminus fluctuations of KNS were in phase with climate anomalies, where data were available for comparison (1871-2012). To allow accurate comparison to numerical model output, the accuracy of different methods of quantifying glacier terminus change was also evaluated. Two new methods were devised so observations could be matched with greater accuracy than existing methods allowed. Glacier sensitivity to climate forcing was evaluated using the numerical model.
Author: Kristin Meredith Schild
Publisher:
ISBN:
Category : Earthquakes
Languages : en
Pages : 0
Get Book Here
Book Description
