Download or read book Experimental Insights Into Subglacial Mechanics written by Dougal Douglas Omar Hansen and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ice mass flux for many of the world's most active glaciers and ice streams arises from glacier ice slipping over a lubricated substrate of bedrock or sediment. The physics controlling this "basal slip" fundamentally control glacier dynamics and drive the rapid denudation of alpine landscapes. Many tenets in the field of glaciology related to these processes currently lack a solid empirical basis, yet are repeatedly applied in theory or models of glacier dynamics and landscape evolution. Until these assumptions are thoroughly vetted, our understanding of glacier processes will be limited by this uncertainty. Here, I employ a range of novel experimental techniques to test long-standing hypotheses regarding the mechanics of hard and soft glacier beds. Specifically, I focus on questions related to subglacial rock friction/abrasion, which increases drag at the ice-bed interface and drives erosion, and till deformation, a first-order control on glacier dynamics, landform generation, and erosion. In chapter one, I constrain the influence of two fundamental controls on subglacial sediment transport during till deformation-effective stress and slip speed. Using digital image correlation to quantify flux rates from a photographic time series of the till bed, I demonstrate that sediment flux scales nearly linearly with slip speed when ice and till are coupled, but flux varies non-monotonically with effective stress, contradicting prior assumptions. In chapter two, I test physical controls on subglacial friction for hard-bedded glaciers under drained hydrologic conditions. Using a modified direct shear apparatus with an insulating sample chamber, I slid limestone slabs beneath slabs of debris-laden ice and assessed the relative influence of basal melt rate, effective stress and ice temperature on frictional resistance during slip. I show that basal drag scales linearly with both melt rate and normal stress in these experiments, confirming they influence the contact force in the presence of efficient drainage. Lastly in chapter three, I examine physical expression of rock-on-rock friction at glacier beds-subglacial abrasion-and use these observations to test the validity of the basal-power abrasion law. Using a novel cryogenic ring shear device in concert with the direct shear, I produce the most realistic simulations of abrasion to date, estimate abrasion rates from high-resolution 3D models of the eroded surface, and then quantify the energy dissipated through this process during slip. For planar rock beds, I show that i) average rock-frictional shear force at the bed increases linearly with abraded volume (per unit area), ii) abrasion rates increase linearly with basal power, and iii) percentage of slip energy expended through abrasion is one-two orders of magnitude lower than prior estimates
Download or read book Investigations Into the Regional and Local Timescale Variations of Subglacial Drainage Networks written by and published by . This book was released on 2013 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt: Subglacial water plays an important role in the regulation of an ice sheet's mass balance. It may be the dominant control on the velocities of ice streams and outlet glaciers on scales of months to millennia. Recent satellite observations of ice surface elevation changes have given researchers new insights into how subglacial water is stored and transported. Localized uplift and settling of the ice surface implies that lakes exist beneath the ice sheet that are being filled and drained on relatively short time scales. %At the base of an ice sheet water can be transported through a variety of drainage networks or stored in subglacial lakes. Here, a numerical investigation of the mechanisms of transport and storage of subglacial water and the associated time scales is presented. Experiments are carried out using a finite element model of coupled ice and water flow. The first experiment seeks to understand the relationship between the depth of a basal depression and the area over which the feature affects basal water flow. It is found that as the perturbation to a topographic depression's depth is increased, water is rerouted in response to the perturbation. Additionally it is found that the relationship between perturbation depth and the extent upstream to which its effects reach is nonlinear. The second experiment examines how the aspect ratio of bed features (prolate, oblate, or equidimensional) influences basal water flow. It is found that the systems that develop and their interactions are mediated by both the topography and the feedbacks taken into account by the coupling of the systems in the model. Features oriented parallel to ice and water flow are associated with distributed fan systems that develop branches which migrate laterally across the domain and interact with one another on monthly and yearly timescales. Laterally oriented features develop laterally extensive ponds. As the ratio of longitudinal to lateral dimension of the topography is increased, a combination of these two water distributions is seen.
Download or read book Linking subaqueous subglacial and subaerial volcanism How water influences eruption dynamics and creation of volcanic products written by Tobias Dürig and published by Frontiers Media SA. This book was released on 2023-10-25 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Experimental Studies in Physico chemical Mechanics of Ice written by Solomon Markovich Aleĭnikov and published by . This book was released on 1984 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Principles of Glacier Mechanics written by Roger LeB. Hooke and published by Cambridge University Press. This book was released on 2019-12-05 with total page 537 pages. Available in PDF, EPUB and Kindle. Book excerpt: The principles of glacier physics are developed from basic laws in this up-to-date third edition for advanced students and researchers.
Download or read book Experimental fracture and mechanics of Antarctic ice written by M.A. RIST and published by . This book was released on 1995 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Principles of Glacier Mechanics written by Roger LeB. Hooke and published by Cambridge University Press. This book was released on 2005-02-24 with total page 452 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book, first published in 2005, provides students and practising glaciologists with the tools they need to understand modern glaciology. Relatively simple concepts are introduced first, followed by mathematically more sophisticated chapters. A knowledge of basic calculus is assumed, but important concepts of physical processes are developed from elementary principles. Emphasis is placed on connections between modern research in glaciology and the origin of features of glacial landscapes. Student exercises are included. This new edition builds on the successful first edition: it has been completely updated, and important new sections and whole chapters have been added. Principles of Glacier Mechanics is designed to be used as a primary textbook in upper division and graduate courses in glaciology, and can be used as either a primary or supplementary text in courses in glacial geology. Practising glacial geologists and glaciologists will also find it useful as a reference book.
Download or read book Fundamental Glaciology written by Kolumban Hutter and published by . This book was released on 2020-05 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Themes in Geomorphology written by Alistair Pitty and published by Routledge. This book was released on 2020-05-13 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book, first published in 1985, conveys the flavours of geomorphology and the bases of its ideas. It portrays the positive features of pluralism in geomorphology, and focuses on processes operative and their associated landforms; the distinctive geological settings of karst, volcanicity and tectonic activity; and technological advances.
Download or read book Dynamics of Crustal Magma Transfer Storage and Differentiation written by Catherine Annen and published by Geological Society of London. This book was released on 2008 with total page 300 pages. Available in PDF, EPUB and Kindle. Book excerpt: Magmas are subject to a series of processes that lead to their differentiation during transfer through and storage within the Earth's crust. The depths and mechanisms of differentiation, the crustal contribution to magma generation through wall-rock assimilation, the rates and timescales of magma generation, transfer and storage, and how these link to the thermal state of the crust are subject to vivid debate and controversy. This volume presents a collection of research articles that provide a balanced overview of the diverse approaches available to elucidate these topics, and includes both theoretical models and case studies. By integrating petrological, geochemical and geophysical approaches, it provides new insights to the subject of magmatic processes operating within the Earth's crust, and reveals important links between subsurface processes and volcanism.
Download or read book Selected Water Resources Abstracts written by and published by . This book was released on 1976 with total page 976 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dawn Dusk Asymmetries in Planetary Plasma Environments written by Stein Haaland and published by John Wiley & Sons. This book was released on 2017-10-04 with total page 380 pages. Available in PDF, EPUB and Kindle. Book excerpt: DawnDusk Asymmetries in Planetary Plasma Environments Dawn-dusk asymmetries are ubiquitous features of the plasma environment of many of the planets in our solar system. They occur when a particular process or feature is more pronounced at one side of a planet than the other. For example, recent observations indicate that Earth's magnetopause is thicker at dawn than at dusk. Likewise, auroral breakups at Earth are more likely to occur in the pre-midnight than post-midnight sectors. Increasing availability of remotely sensed and in situ measurements of planetary ionospheres, magnetospheres and their interfaces to the solar wind have revealed significant and persistent dawn-dusk asymmetries. As yet there is no consensus regarding the source of many of these asymmetries, nor the physical mechanisms by which they are produced and maintained. Volume highlights include: A comprehensive and updated overview of current knowledge about dawn-dusk asymmetries in the plasma environments of planets in our solar system and the mechanisms behind them Valuable contributions from internationally recognized experts, covering both observations, simulations and theories discussing all important aspects of dawn-dusk asymmetries Space weather effects are caused by processes in space, mainly the magnetotail, and can be highly localized on ground. Knowing where the source, i.e., where dawn-dusk location is will allow for a better prediction of where the effects on ground will be most pronounced Covering both observational and theoretical aspects of dawn dusk asymmetries, Dawn-Dusk Asymmetries in Planetary Plasma Environments will be a valuable resource for academic researchers in space physics, planetary science, astrophysics, physics, geophysics and earth science.
Download or read book Hydrodynamics of Time Periodic Groundwater Flow written by Joe S. Depner and published by John Wiley & Sons. This book was released on 2016-12-19 with total page 322 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hydrodynamics of Time-Periodic Groundwater Flow introduces the emerging topic of periodic fluctuations in groundwater. While classical hydrology has often focused on steady flow conditions, many systems display periodic behavior due to tidal, seasonal, annual, and human influences. Describing and quantifying subsurface hydraulic responses to these influences may be challenging to those who are unfamiliar with periodically forced groundwater systems. The goal of this volume is to present a clear and accessible mathematical introduction to the basic and advanced theory of time-periodic groundwater flow, which is essential for developing a comprehensive knowledge of groundwater hydraulics and groundwater hydrology. Volume highlights include: Overview of time-periodic forcing of groundwater systems Definition of the Boundary Value Problem for harmonic systems in space and time Examples of 1-, 2-, and 3-dimensional flow in various media Attenuation, delay, and gradients, stationary points and flow stagnation Wave propagation and energy transport Hydrodynamics of Time-Periodic Groundwater Flow presents numerous examples and exercises to reinforce the essential elements of the theoretical development, and thus is eminently well suited for self-directed study by undergraduate and graduate students. This volume will be a valuable resource for professionals in Earth and environmental sciences who develop groundwater models., including in the fields of groundwater hydrology, soil physics, hydrogeology, geoscience, geophysics, and geochemistry. Time-periodic phenomena are also encountered in fields other than groundwater flow, such as electronics, heat transport, and chemical diffusion. Thus, students and professionals in the field of chemistry, electronic engineering, and physics will also find this book useful. Read an interview with the editors to find out more: https://eos.org/editors-vox/a-foundation-for-modeling-time-periodic-groundwater-flow
Download or read book Volcanism in Antarctica 200 Million Years of Subduction Rifting and Continental Break up written by J.L. Smellie and published by Geological Society of London. This book was released on 2021-06-09 with total page 802 pages. Available in PDF, EPUB and Kindle. Book excerpt: This memoir is the first to review all of Antarctica’s volcanism between 200 million years ago and the Present. The region is still volcanically active. The volume is an amalgamation of in-depth syntheses, which are presented within distinctly different tectonic settings. Each is described in terms of (1) the volcanology and eruptive palaeoenvironments; (2) petrology and origin of magma; and (3) active volcanism, including tephrochronology. Important volcanic episodes include: astonishingly voluminous mafic and felsic volcanic deposits associated with the Jurassic break-up of Gondwana; the construction and progressive demise of a major Jurassic to Present continental arc, including back-arc alkaline basalts and volcanism in a young ensialic marginal basin; Miocene to Pleistocene mafic volcanism associated with post-subduction slab-window formation; numerous Neogene alkaline volcanoes, including the massive Erebus volcano and its persistent phonolitic lava lake, that are widely distributed within and adjacent to one of the world’s major zones of lithospheric extension (the West Antarctic Rift System); and very young ultrapotassic volcanism erupted subglacially and forming a world-wide type example (Gaussberg).
Download or read book Glacier Science and Environmental Change written by Peter G. Knight and published by John Wiley & Sons. This book was released on 2008-04-15 with total page 544 pages. Available in PDF, EPUB and Kindle. Book excerpt: Glacier Science and Environmental Change is an authoritative and comprehensive reference work on contemporary issues in glaciology. It explores the interface between glacier science and environmental change, in the past, present, and future. Written by the world’s foremost authorities in the subject and researchers at the scientific frontier where conventional wisdom of approach comes face to face with unsolved problems, this book provides: state-of-the-art reviews of the key topics in glaciology and related disciplines in environmental change cutting-edge case studies of the latest research an interdisciplinary synthesis of the issues that draw together the research efforts of glaciologists and scientists from other areas such as geologists, hydrologists, and climatologists color-plate section (with selected extra figures provided in color at www.blackwellpublishing.com/knight). The topics in this book have been carefully chosen to reflect current priorities in research, the interdisciplinary nature of the subject, and the developing relationship between glaciology and studies of environmental change. Glacier Science and Environmental Change is essential reading for advanced undergraduates, postgraduate research students, and professional researchers in glaciology, geology, geography, geophysics, climatology, and related disciplines.
Download or read book Ionospheric Space Weather written by Timothy Fuller-Rowell and published by John Wiley & Sons. This book was released on 2016-12-05 with total page 311 pages. Available in PDF, EPUB and Kindle. Book excerpt: This monograph is the outcome of an American Geophysical Union Chapman Conference on longitude and hemispheric dependence of ionospheric space weather, including the impact of waves propagating from the lower atmosphere. The Chapman Conference was held in Africa as a means of focusing attention on an extensive geographic region where observations are critically needed to address some of the fundamental questions of the physical processes driving the ionosphere locally and globally. The compilation of papers from the conference describes the physics of this system and the mechanisms that control ionospheric space weather in a combination of tutorial-like and focused articles that will be of value to the upper atmosphere scientific community in general and to ongoing global magnetosphere-ionosphere-thermosphere (MIT) modeling efforts in particular. A number of articles from each science theme describe details of the physics behind each phenomenon that help to solve the complexity of the MIT system. Because this volume is an outcome of the research presented at this first space science Chapman Conference held in Africa, it has further provided an opportunity for African scientists to communicate their research results with the international community. In addition, the meeting and this conference volume will greatly enhance the space science education and research interest in the African continent and around the world. Ionospheric Space Weather includes articles from six science themes that were discussed at the Chapman Conference in 2012. These include: Hemispherical dependence of magnetospheric energy injection and the thermosphere-ionosphere response Longitude and hemispheric dependence of storm-enhanced densities (SED) Response of the thermosphere and ionosphere to variability in solar radiation Longitude spatial structure in total electron content and electrodynamics Temporal response to lower-atmosphere disturbances Ionospheric irregularities and scintillation Ionospheric Space Weather: Longitude Dependence and Lower Atmosphere Forcing will be useful to both active researchers and advanced graduate students in the field of physics, geophysics, and engineering, especially those who are keen to acquire a global understanding of ionospheric phenomena, including observational information from all longitude sectors across the globe.
Download or read book Papers from the International Symposium on the Verification of Cryospheric Models written by Konrad Steffen and published by . This book was released on 2000 with total page 502 pages. Available in PDF, EPUB and Kindle. Book excerpt:
