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1
Kramer, Michiel Arij. "Meltwater storage and its effect on ice-surface velocity, Matanuska Glacier, Alaska." Diss., Connect to online resource - MSU authorized users, 2006.
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Wuite, Jan. "Spatial and temporal dynamics of three East Antarctic outlet glaciers and their floating ice tongues." Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1162225099.
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Brett, Melissa Carrie. "Glacier Inventories and Change in Glacier National Park." PDXScholar, 2018. https://pdxscholar.library.pdx.edu/open_access_etds/4348.
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Glacier National Park, in northwestern Montana, is a unique and awe-inspiring national treasure that is often used by the media and public-at-large as a window into the effects of climate change. An updated inventory of glaciers and perennial snowfields (G&PS) in the Park, along with an assessment of their change over time, is essential to understanding the role that glaciers are playing in the environment of this Park. Nine inventories between 1966 and 2015 were compiled to assess area changes of G&PS. Over that 49-year period, total area changed by nearly -34 ± 11% between 1966 and 2015. Volume change, determined from changes in surface topography for nine glaciers, totaling 8.61 km² in area, was +0.142 ± 0.02 km³, a specific volume loss of -16.3 ± 2.5m. Extrapolating to all G&PS in the Park in 1966 yields a park-wide loss of -0.660 ± 0.099 km³. G&PS have been receding in the Park due to warming air temperatures rather than changes in precipitation, which has not changed significantly. Since 1900, air temperatures in Glacier National Park have warmed by +1.3 C°, compared to +0.9 C° globally. Spatially, G&PS at lower elevations and on steeper slopes lost relatively more area than other G&PS.
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Stearns, Leigh Asher. "Outlet Glacier Dynamics in East Greenland and East Antarctica." Fogler Library, University of Maine, 2007. http://www.library.umaine.edu/theses/pdf/StearnsLA2007.pdf.
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Thompson, Derrick R. "Glacier variability (1966--2006) in the Wind River Range, Wyoming, U.S.A." Laramie, Wyo. : University of Wyoming, 2009. http://proquest.umi.com/pqdweb?did=1950188861&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.
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Goodsell, Becky. "The structure, dynamics and debris transport of two alpine glaciers : Haut Glacier d'Arolla and Bas Glacier d'Arolla, Valais, Switzerland." Thesis, Aberystwyth University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.422321.
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Caruso, Raven, and University of Lethbridge Faculty of Arts and Science. "Flow obstructions in valley glaciers." Thesis, Lethbridge, Alta. : University of Lethbridge, Faculty of Arts and Science, 2007, 2007. http://hdl.handle.net/10133/654.
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Valley glaciers often occur within complex dendritic systems where tributary glaciers
contribute ice mass and blocking potential to the trunk glacier. Analysis of glacier
inventories and maps in the regions of Svalbard, East Greenland, Yukon Territory and the
Thompson Glacier system indicates that trunk - tributary intersections commonly occur at
angles between 45° and 90°. An analogue material with flow properties similar to creep
in pure ice has been used to simulate flow in a model valley glacier. The model and a
series of blockages were constructed based on dimensions derived from the inventory and
map analysis. The angled blockage indicates lower overall velocity rates and appears to
have a funnelling rather than blocking affect on the analogue material. The perpendicular
obstruction that blocked half the width of the model valley caused a piling up of analogue
material prior to a release into the unobstructed side of the valley.ix, 149 leaves : ill. ; 29 cm.
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O'Leary, Martin Eugene William. "Frontal processes on tidewater glaciers." Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610259.
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Monnier, Sébastien Fouache Eric Kaiser Brigitte. "Les glaciers-rocheux, objets géographiques." Créteil : Université de Paris-Val-de-Marne, 2006. http://doxa.scd.univ-paris12.fr:80/theses/th0245655.pdf.
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Smith, Colby. "An Interhemispheric Comparison of the Recession of Mountain Glaciers in the Last 150 Years." Fogler Library, University of Maine, 2003. http://www.library.umaine.edu/theses/pdf/SmithC2003.pdf.
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Pfeffer, William Ted. "Structure and deformation in a propagating surge front /." Thesis, Connect to this title online; UW restricted, 1988. http://hdl.handle.net/1773/6810.
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Kern, Jennifer M. "Modelling hydrologic system change in a paraglacial catchment in the Northern Rocky Mountains." Thesis, Virginia Tech, 2021. http://hdl.handle.net/10919/103778.
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The Northern Rocky Mountains, home to the highest concentration of glaciers in the American West, are undergoing increased rates of climate warming, resulting in previously unseen ecological and hydrological outcomes. Globally, many glacier basins have experienced glacial recession to the threshold point of surpassing peak basin runoff, resulting in substantial decreases in local hydrological yield. Such findings call for models that do not alone examine glacial runoff but a complete examination of changes in the water budget. Alpine catchments are increasingly vulnerable to evapotranspirative losses due to climatic warming, and the rates of vegetation succession are often unable to keep up with the rate of warming. Basin scale analyses of glacial recession on streamflow are then confounded by ecohydrologic dynamics created by primary succession and the associated increase in evapotranspiration. In this study, I present a conceptual framework for modelling basin runoff in landscapes responding to paraglacial adjustment. The study goal was achieved by calibrating and running the Hydrologiska Byråns Vattenbalansavdelning (HBV) model in Swiftcurrent basin and investigating change across the basin water balance through baseflow analysis. The research findings indicate catchment scale changes in the timing and magnitude of the flow regime in the deglaciating Swiftcurrent basin, by employing HBV and empirical baseflow analysis. While most components of the water balance appear consistent across the study period, late summer baseflow values suggest the basin hydrology is undergoing changes, possibly a result of melt occurring earlier in the season. Ultimately, I advocate for an adaptable and accessible approach to understanding paraglacial basins by constructing an estimation of basin-scale water budgets.Master of Science
Large scale trends in climate change are impacting a variety of ecosystems, especially alpine environments. Glacial recession has been well documented and studied in mountain chains across the globe, including the Rocky Mountains. Recession of these massive bodies of ice, which can be viewed as reservoirs of water in droughts or low flow months, has severe implications for society, the economy, and sensitive mountain environments. Furthermore, the new terrain exposed from beneath the melting glacier is dynamic and will undergo many adjustments geomorphically, in soil development, and ecologically as plants move up the glacier foreland. Ecological systems experiencing warming, deglaciation, and vegetation succession are not well understood and are complex environments due to the multiple inputs, interactions, and feedbacks. As such, this research examines how hydrologic conditions across a forty year period are changing in response to the complex feedbacks between glaciers, newly exposed terrain, and associated runoff. Through modeling and analysis, this study offers a method for understanding the water balance of Swiftcurrent basin in Glacier National Park, which can be used in other catchments experiencing similar changes.
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Roux, Pierre-François. "Méthodes sismologiques pour l'étude de la fracturation dans les glaciers alpins : glaciers d'Argentières et du Gorner." Chambéry, 2008. https://tel.archives-ouvertes.fr/tel-00275319.
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Le mouvement des glaciers alpins est fortement conditionné par un grand nombre de processus complexes, alliant a la fois l'hydrologie, la mécanique, la thermodynamique, et dont la taille caractéristique peut varier de l'échelle microscopique à l'échelle macroscopique. Les mécanismes de fracturation peuvent être associés à des causes aussi nombreuses que diverses : frottement basal, ouverture de crevasses, variations de la température (fracturation thermique), variations de hauteur d'eau (fracturation hydraulique). Dans tous les cas, il a été démontré par le passé que la fracturation était génératrice de sismicité, enregistrable a l'aide de sismomètres. Cette sismicité permet par conséquent l'auscultation des conditions mécaniques d 'un glacier, et en particulier son champ de contrainte. Nous nous proposons, dans ce travail, d'appliquer des méthodes sismologiques inédites pour l'étude et la caractérisation de la fracturation dans les glaciers alpins, au travers de deux exemples (Ie glacier d'Argentière, dans Ie massif du Mont-Blanc, et le glacier du Gorner, dans Ie massif du Mont Rose, en Suisse). La 1ocalisation des sources a été effectuée par Ie biais de techniques d'antennes. Dans ce cadre, nous avons développé line méthode de recherche sur grille, bien adaptée à ces objets de taille limitée. Cette dernière permet Ie calcul de la densité de probabilité complète de la position de l'hypocentre. Elle nous a permis de mettre en évidence une activité sismique en essaim sur Ie glacier d'Argentière, et dont il a été possible de calculer une magnitude locale. Nous avons également montré que les séismes profonds ayant lieu au glacier du Gorner sont localisés à proximité immédiate de l'interface glace - roche. Parallèlement, d'autres techniques (corrélation de bruit, beam-forming) nous ont permis de préciser l'information obtenue par la méthode de recherche exhaustiveAlpine glaciers' motion results from a number of complex mechanisms involving hydrology, mechanics and thermodynamics on microscopic to kilometre-sized scales. Fracturing can be linked with a wide variety of causes : basal friction, opening of crevasses, variations in temperature (thermo-fracturing), changes in water pressure (hydro-fracturing). Previous studies showed that fracturing generated seismic waves that could be recorded using seismometers. Passive seismic studies therefore allow for probing the in situ mechanical properties of a glacier. In this work, we intend to apply new seismological methods the study and characterize fracturing processes in alpine glaciers. To this effect, we focused on two specific sites (Glacier d' Argentière, Mont-Blanc, France, and Gornergletscher, Valais, Switzerland). Source location was performed using array techniques. Within this framework, we developed a grid-search method that is well suited for such sites. This method yields the whole hypocenter probability density function. It allowed us to bring to light a clustered seismic activity on glacier d'Argentière. In this specific case, events' local magnitude could be determined. We also showed that deep events recorded on the Gornergletscher were located nearby the ice - rock interface. In the same way, other techniques (noise correlation, beamforming) allowed us to enhance the information already obtained via the exhaustive grid-search method
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SCOTTI, RICCARDO. "Spatial and temporal variability of glaciers and rock glaciers in the central italian alps (Lombardy region)." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2013. http://hdl.handle.net/10281/41861.
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This study aims to investigate the cryosphere of the Lombardy region (Central Italian Alps) by compiling and analysing glacier, rock glacier, and protalus rampart inventories. To this purpose, I have employed remote sensing techniques and in-situ measurements for delineating the contemporary and historical extent of glaciers and contemporary extent of rock glaciers and protalus ramparts. In order to better identify and highlight the response of the regional cryosphere to climate change, the LIA maximum extent has been reconstructed for nine selected glaciers and their fluctuations since then have been discussed and analyzed in relation to temperature and precipitation recorded at ground weather stations.
The main objectives of this doctoral dissertation are to: compile glacier, rock glacier and protalus rampart regional inventory for the Central Italian Alps (Lombardy region) exploitable for investigations about permafrost distribution; elucidate the linkages between the occurrence of periglacial landforms (rock glaciers and protalus ramparts) and local litho-topographic attributes; examine the variability of periglacial activity in relation to terrain elevation and mean annual precipitation; gain new insights about the impact of the Pleistocene-Holocene climatic transition on the periglacial domain within the study area; examine the linkages between glaciers location, glaciers attributes (e.g., size, aspect, ELA0) and mean annual precipitation; analyze the relations between glaciers location, size, aspect, ELA0 and areal variations since 1991; analyze post-LIA (1860) glacier fluctuations for nine selected glaciers from different sub-regions of the central Italian Alps; investigate glacier sensitivity to climate change (i.e., precipitation and temperature).
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Balise, Michael John. "The relation between surface and basal velocity variations in glacier, with application to the mini-surges of variegated glacier /." Thesis, Connect to this title online; UW restricted, 1988. http://hdl.handle.net/1773/6846.
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Aschwanden, Andreas. "Mechanics and thermodynamics of polythermal glaciers /." Zürich : ETH, 2008. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17874.
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Fyffe, Catriona Louise. "The hydrology of debris-covered glaciers." Thesis, University of Dundee, 2012. https://discovery.dundee.ac.uk/en/studentTheses/1ff21418-34ba-4e0a-97ed-69510f3b882c.
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Studies of glacier-hydrology have focused on clean Alpine glaciers, and recently ice sheet outlet glaciers, but there are few studies on debris-covered glaciers. It is known debris affects ablation rates, and that debris-covered glaciers evolve differently to their debris-free counterparts, but how the debris influences the hydrology is poorly understood. This thesis aims to understand the influence of the debris on the hydrological system and water balance of Miage Glacier, Western Italian Alps. The supraglacial hydrology was studied by modelling ablation using a distributed energy balance melt model, and measuring supraglacial stream discharges; the structure and evolution of the englacial and subglacial network was investigated using dye tracing and water chemistry monitoring; and the proglacial runoff was examined through detailed hydrograph analysis. Glacier velocity measurements were used to investigate the debris’ influence on the glacier dynamics. High ablation rates occurred on clean ice and beneath thin debris on the upper glacier, resulting in large supraglacial streams which led into an efficient drainage system. Glacier velocities had a greater magnitude and variability close to the upper glacier moulins. Thick debris on the lower glacier reduced ablation, and consequently the discharge of supraglacial streams and efficiency of the hydrological network. Despite locally inefficient subglacial drainage, glacier velocities on the lower glacier remained subdued, partly because the debris attenuated water inputs. This attenuation reduced the occurrence of high amplitude diurnal cycles in the proglacial runoff and confined them to particularly warm weather. Lag times from peak air temperature to peak runoff were long relative to comparable debris-free glaciers. Evaporation of rainfall from debris-surfaces was high, and dependant on the debris permeability, suggesting this is an important water balance component. Under climate warming, it is predicted the ablation of Miage Glacier will increase, but this may be negated given an increase in debris cover.
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Schäfer, Martina. "Modélisation de l'écoulement des glaciers tempérés." Grenoble 1, 2007. http://www.theses.fr/2007GRE10245.
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Des aspects variés de la modélisation de l'écoulement glaciaire sont abordés. Le modèle de Le Meur et Vincent (2003) est utilisé à plusieurs reprises. Plusieurs améliorations sont effectuées (conservation de la masse, traitement des épaisseurs négatives, traitement de la glace située en amont de la rimaye). Sur le glacier de St. Sorlin (France) une comparaison entre le champ de bilan issu des mesures et celui issu d'un modèle est effectuée. Le comportement du glacier sous un scénario climatique futur est prédit. Une intercomparaison entre différents types de modèles est effectuée avec pour objectif la détermination du type de modèle le plus approprié en fonction du type de glacier. Les modèles testés sont le modèle SIA de Le Meur et Vincent (2003), le modèle SIA et le modèle d'ordre supérieur de Pattyn (2003) et un modèle Full Stokes (Elmer). Des géométries synthétiques sont utilisées ainsi qu'un cas réel. Les tests synthétiques montrent les limites de l'applicabilité de la SIA. Par contre, une comparaison rapide montre le gain considérable en temps CPU. D'un autre côté, l'augmentation du coût en terme de temps CPU ne s'avère pas très importante lors du passage d'un modèle d'ordre supérieur à un modèle Full Stokes. Les simulations effectuées sur le glacier de St. Sorlin donnent un aperçu des limites de la validité de la SIA sur ce glacier. Même si elle reproduit globalement l'évolution observée du glacier, elle ne reproduit pas correctement le champ de vitesse ni certaines structures de la géométrie. Les simulations sont comparées avec les observations pour la position du front et les vitesses de surface. Un dernier chapitre est consacré au glacier Cotopaxi (Andes)In this work, various aspects of glacier flow modelling are addressed. The model developed by Le Meur and Vincent (2003) is used at different occasions. It is upgraded by switching to a semi-implicit scheme, mass conservation is improved and other shortcomings are resolved (ice-thickness that may become negative and an unrealistic ice settlement above the bergschrund). A comparison between two different approaches for mass balance fields is performed on the St. Sorlin glacier (France) : mass balance from measurements and mass balance from a model. The future behaviour of the glacier under a climatic scenario is also predicted. An intercomparison is done with the goal to determine the type of model that is the most appropriate for a given type of glacier geometry. The models used are : the SIA model from Le Meur and Vincent (2003), the SIA model and the higher-order model from Pattyn (2003) and a Full Stokes model (Elmer). Different synthetic geometries are used as well as a real case. The synthetic tests show on the one hand the limits of the applicability of the SIA. On the other hand a rough comparison of CPU times shows the gain in CPU time. Conversely, the increase in CPU time turns out to be reduced when switching from a higher-order model to a Full Stokes model. The simulations on the St. Sorlin glacier give an insight into the validity of the SIA on this glacier. Even if the large-scale evolution is correctly reproduced, neither the velocity field nor some small structures in the surface geometry can be properly reproduced. Simulations are compared to observations for snout position and surface velocities. A last chapter deals with the Cotopaxi glacier (Andes)
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Drocourt, Yoann. "Using remote sensing, in-situ measurements and data visualisation to investigate tidewater glaciers behaviour in Greenland." Thesis, Swansea University, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.678404.
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The aims of this thesis was to participate in the improvement of the current knowledge of tidewater glaciers' behaviour in Greenland. This was achieved by a multi-scale and multi-disciplinary approach.
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Cheesbrough, Kyle S. "Glacial recession in Wyoming's Wind River Range." Laramie, Wyo. : University of Wyoming, 2007. http://proquest.umi.com/pqdweb?did=1445046281&sid=2&Fmt=2&clientId=18949&RQT=309&VName=PQD.
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Évin, Michèle. "Dynamique, répartition et âge des glaciers rocheux des Alpes du Sud." Lille 3 : ANRT, 1989. http://catalogue.bnf.fr/ark:/12148/cb37604953d.
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Lefauconnier, Bernard. "Fluctuations glaciaires dans le Kongsford (Baie du roi), 79 N. Spitsbergen, Svalbard analyses et conséquences /." Lille 3 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb376071997.
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Bamber, Jonathan L. "Radio echo sounding studies of Svalbard glaciers." Thesis, University of Cambridge, 1987. https://www.repository.cam.ac.uk/handle/1810/268048.
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The objective of this study was to investigate the radio echo sounding properties of Svalbard glaciers and to use these data to obtain information about the glaciological environment. Particular emphasis was placed on obtaining an understanding of the dielectric properties of the ice and reflecting boundaries present. These were then used to elucidate the physical processes causing them. First, a theoretical model, describing the dielectric properties of a wet bed, was developed. The ice/bed interface was then investigated using, as the primary data source, radar reflection coefficients. From these data inferences about the presence of water and/or debris, roughness of the interface and geographical trends were made. A number of geological divides were detected. Second, the dielectric properties of Svalbard ice were considered using i) radio echo sounding data on the bulk in situ radar absorption and ii) measurements made on the dielectric properties of a sample of Spitsbergen ice. Data were collected between 20 Hz and 100 kHz in the temperature range -2.5 to -44.0C . From these and other data deductions about the thermal regime of the ice masses were made and a geographical trend, linked to the reflection coefficients, observed. The theory of dielectric absorption in ice was discussed with an emphasis on the high frequency, radio echo sounding characteristics. Third, the properties of an extraordinary internal reflecting horizon ( observed on 60% of the glaciers sounded in 1983) were investigated. A model was developed to describe the scattering properties of inhomogeneities ( of arbitrary size) within ice. Using this, and data on the re:flec~ing properties of the horizons, they were attributed to the presence of a finite quantity of water. The implications of this finding were considered. Finally, the surface and, where available, bedrock profiles of 40 glaciers and six ice caps, in Spitsbergen, were presented.
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Breton, Daniel James. "Radionuclide Fluxes in Glaciers and Seasonal Snowpack." Fogler Library, University of Maine, 2004. http://www.library.umaine.edu/theses/pdf/BretonDJ2004.pdf.
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Haresign, Eleanor C. "Glacio-limnological interactions at lake-calving glaciers." Thesis, University of St Andrews, 2004. http://hdl.handle.net/10023/2793.
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Iceberg calving is an efficient ablation process which introduces mechanical instability to glacier systems and can cause non-linear climatic response. This thesis uses glaciological and limnological data to examine the relative contributions of calving and melting to mass loss at glacier termini, and the interplay between glaciological and limnological processes. Calving dynamics are investigated at two lake-terminating glaciers; Glaciar Leon in Chile and Fjallsjokull in Iceland. Glaciar Leon, a temperate, grounded outlet of the North Patagonian Icefield, terminates at an active but stable calving margin in Lago Leones. The calving rate of 880 m a-1 in a mean water depth of 65 m is high for lake-calving glaciers. Detailed survey of the physical limnology of Lago Leones, important for considering heat transfer to the subaqueous ice face, revealed thermocline development towards the terminus between spring and summer. Melting at the waterline along the glacier terminus facilitates calving by undercutting the subaerial calving cliff, and accounts for around a quarter of mass loss at the terminus. Waterline melting is also an important rate-controlling process for calving at Fjallsjokull. Precise quantification of melt rates (subaerial, waterline and subaqueous) at the termini of calving glaciers is difficult and hazardous, but this study has demonstrated the value of two techniques: (1) detailed survey of melt notch growth, and (2) use of a radiocontrolled boat to record water temperatures at the ice-water interface. Continuous automated monitoring showed that lake-level fluctuations are integral to calving behaviour, influencing calving event timing and size over diurnal and hourly timescales. Fjallsjokull is sensitive to climatic forcing whereas Glaciar Leon, which exhibits larger seasonal than annual fluctuations, is less sensitive. Additional controls on calving at both sites are (1) buoyancy, (2) longitudinal stretching, and (3) the force balance at the ice-water interface. Calving operates along a continuum defined by the relative importance of interacting calving mechanisms, to which the climatic response of calving glaciers is sensitive.
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Reznichenko, Natalya. "Rock Avalanches on Glaciers: Processes and Implications." Thesis, University of Canterbury. Geological Sciences, 2012. http://hdl.handle.net/10092/6524.
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This thesis examines the role of rock avalanches in tectonically active terrains including the effects of the deposits on glacier behaviour and their contribution to moraine formation. The chronologies of mountain glacier fluctuations, based on moraine ages, are widely used to infer regional climate change and are often correlated globally. In actively uplifting mountain ranges rock avalanches that travel onto the ablation zone of a glacier can reduce ice-surface melting by insulating the ice. This can cause buried ice to thicken due to slower ablation and can significantly alter the overall glacier mass balance. This glacier response to supraglacial rock avalanche deposits can confound apparent climatic signals extracted from moraine chronologies. This thesis investigates the processes through which rock avalanche deposits may affect glaciers and develops a new technique to identify the presence of rock avalanche debris in glacial moraines.
From laboratory experiments on the effects of debris on ice ablation it is demonstrated that the rate of underlying ice ablation is controlled by diurnal cyclicity and is amplified at high altitude and in lower latitudes. The relatively low permeability of rock avalanche sediment in comparison with non-rock avalanche supraglacial debris cover contributes to the suppression of ablation, at least partly because it greatly reduces the advection of heat from rain water to the underlying ice.
The laboratory findings are supplemented by field investigations of two recent rock avalanche deposits on glaciers in the Southern Alps of New Zealand. This work demonstrates that the rock avalanche deposits are very thick (10 m at Aoraki/Mt. Cook and 7m at Mt. Beatrice) and almost stopped the ablation of the overlying ice. This resulted in the formation of an ice-platform more than 30 m high. This led to a reduction of the existing negative mass balance of the affected Tasman and Hooker Glaciers. There was little noticeable alteration of the overall glacial regime due to the small scale of the debris covered area (4 and 1% of the ablation zones for the Tasman and Hooker Glaciers, respectively) but there is a significant contribution to supraglacial debris, which is passively transported toward the terminus. A conceptual model of the response of mountain valley glaciers to emplacement of extensive rock avalanche debris on the ablation zone has been proposed for the effect of this type of debris on terminal moraine formation based on enhanced ‘dumping’ of supraglacial sediments.
A new technique has been developed to distinguish rock-avalanche-derived sediment from sediment of glacial origin, based on the sedimentary characteristics of the finest fraction. Examination of rock avalanche sediment under the Scanning Electron Microscope showed that finer particles tend to form strong clumps, which comprise many smaller (down to nanometre-scale) clasts, named here ‘agglomerates’. These agglomerates are present in the fine fraction of all examined rock avalanche deposits and absent in known non-rock-avalanche-derived glacial sediments. The agglomerates are characteristics of sediment produced under the high-stress conditions of rock avalanche emplacement and contrast with lower-stress process sub- and en-glacial environments. It is demonstrated that these agglomerates are present in some moraines in the Southern Alps of New Zealand that have been attributed to climate fluctuation. Consequently, this technique has the potential to resolve long-standing arguments about the role of rock avalanches in moraine formation, and to enhance the use of moraines in palaeoclimatological studies.
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Maclean, Alison F. "The formation of valley-wall rock glaciers." Thesis, University of St Andrews, 1991. http://hdl.handle.net/10023/2797.
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In recent years, the study of rock glaciers has increased remarkably. Substantive progress has been made, particularly in understanding the formation of rock glaciers that have developed adjacent to existing or former valley or cirque glaciers, However, our understanding of valley-wall rock glaciers that are located at the base of talus slopes remains scant. Published work exhibits little consensus on the formation of valley-wall rock glaciers and several hypotheses remain under vigorous debate. The major objective of the research reported in this thesis has been to test the generality and feasibility of seven major models of valley-wall rock glacier formation using both empirical and theoretical evidence. The primary conclusion is that only one of these models, the segregation ice model, emerges as a general model of valley-wall rock glacier genesis. The model assumes that a thin layer or several thin layers of segregated ice are overlain by interstitially frozen sediments and an unfrozen mantle of coarse debris. A wide range of empirical and theoretical findings are shown to be consistent with the implications of the segregation ice model. Detailed observations on the morphology, sedimentology and distribution of active, inactive and relict valley-wall rock glaciers studied in Switzerland, northern Norway and Scotland provided a range of findings that support this model. Theoretical evidence was obtained by modelling a number of different density models that reflect different distribution of internal ice by applying a simple laminar flow equation to field measurements. Although only the segregation ice model appears to be valid at a general level, the possibility cannot be excluded of alternative modes of valley-wall rock glacier formation under particular circumstances. Snow avalanching, deformation of snowbank or matrix ice, and basal sliding under conditions of high hydrostatic pressure all constitute possible contributing mechanisms of formation and movement in particular cases.
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Hamilton, Samantha J. "Age determination of rock glaciers using lichenometry." Thesis, Queen's University Belfast, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.318766.
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Goldsack, Anne Elizabeth. "Oceanographic controls on glaciers in southeast Greenland." Thesis, Swansea University, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.678487.
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Hamilton, Gordon Stuart. "Investigations of surge-type glaciers in Svalbard." Thesis, University of Cambridge, 1992. https://www.repository.cam.ac.uk/handle/1810/280140.
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The factors affecting the distribution of surge-type glaciers and the causes of the surge mechanism are not fully understood. Statistical analyses of glaciers in Svalbard have been used to identify characteristics which are related to surging. Field experiments were undertaken on Bjuvbreen, a small surge-type glacier in central Spitsbergen, to determine the dynamics and hydrology of the glacier during its quiescent phase. The probability that a glacier in the Svalbard sample population was surge-type was 36·4%. The probability varied spatially within the sample area. Glaciers resting on sedimentary tocks had a greater probability of being surge-type compared to those overlying igneous or metamorphic rocks. The probability of surging was also increased in glaciers with a two-layered thermal structure as indicated by radio echo sounding. Geometrical characteristics such as slope, orientation, curvature and the presence of tributaries were not related to surge-type behaviour, although long glaciers had a greater chance of being surge-type. Certain aspects of Kamb's and Fowler's theories of surging were not supported by the statistical analysis. Despite the associations between surging and certain characteristics, no single factor fully explained the observed geographical distribution of surge-type glaciers in Svalbard. Bjuvbreen is a small surge-type in its quiescent phase. Changes in the geometry of the glacier are occurring relatively slowly. This slow rate of change is a function the low accumulation rates on Svalbard glaciers. On the basis of a simple model, the next surge of Bjuvbreen is predicted to occur between .2022- 2055, indicating a comparatively long quiescent period of -90-130 years. Bjuvbreen is comprised of two dynamically distinct zones which are separated by a large bulge. The lower portion of the glacier is inactive and stagnating, in contrast to the active ice up.:.glacier from the bulge. The observed velocity of the active region was compared with various hydrological characteristics of the glacier. The inferred behaviour of water within the glacier seems to have some, although limited, influence on the ice motion. A spatially restricted drainage system is the probable reason for this limited influence of hydrology on glacier velocity.
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Pedicino, Jon Richard 1969. "Climate change on Mars: Modeling possible glaciers." Diss., The University of Arizona, 1996. http://hdl.handle.net/10150/290694.
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The purpose of this dissertation is to explore the physical possibility of ancient glacial occurrences on the surface of Mars. Furthermore, I will elucidate the nature and extent of hypothetical ice sheets by modeling the ancient glacier inferred for the Hellas region. Individually, many of the proposed glacial features can indeed be interpreted as aeolian, fluvial, or another type of feature. It is, however, the spatial and temporal association of these features, and the incongruity presented by various alternative explanations, that makes the glacial theory more complete and universal than other hypotheses. The proposed glacial system has an extent on the order of two million square kilometers. My results include profiles of the Hellas glacier. In addition, calculations of erosion rates seem to imply an approximate time scale of erosion of between 110,000 and 1,440,000 years. Taking into consideration the plausible range of geothermal flux values (32 to 72 mW/m² I have also calculated the time frames to fill the Hellas pro-glacial lake, as well as lose it to the atmosphere via evaporation and/or sublimation. The majority of these values seem to point to a glacial epoch that took place over a period of 100,000 to 500,000 years. It is suggested that, similar to the Earth, Mars has two stable climate regimes whose shift is triggered at least in part by orbital forcing parameters. The warmer climate corresponds to more of a glacial climate on the Earth, while the cooler climate resembles the cold, dry environment that exists on Mars today. There is also evidence that, geologically, these features are relatively pristine, and therefore probably relatively young. This is in comparison to a Mars generally inferred to have been warmer and wetter earlier in its history. A second climatological scenario does not even call for a drastically different climate than today, with a localized hot spot or impact providing the short-lived heat and volatiles to create a glacier. Indeed, this glacier may have been cold based for a time, or warm based due to the thickness of the overlying ice combined with the geothermal gradient.
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David, Höglin. "Regional and Local Factors Influencing the Mass Balance of the Scandinavian Glaciers." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-311152.
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According to climatic models there will be an increase in the amount of greenhouse gases which results in a warming of the earth where the change will be most prominent in the high latitudes. Glaciers mass balance is a good climate change indicator as the response is fast when climate is changing. Glacier mass balance, area of glaciers, elevation line altitude data for 13 glaciers in Scandinavia as well as North Atlantic oscillation (NAO), Arctic oscillation (AO) and sunspot data where gathered and a principle component analysis (PCA) where made. PCA is a multivariate statistical technique with the goal to extract important information and reduce the dimension of data. Three distinct groupings where found within the data set and was identified as extreme years of North Atlantic Oscillation and Arctic Oscillation and one glacier which had the largest area of the 13 glaciers. The PCA explained that all the variables in the data set is correlated with North Atlantic and Arctic Oscillation to about 40 % and we can conclude that there is a regional and local forcing within our data where the regional (NAO and AO) is of more importance for the variance and for the mass balance.Enligt klimatmodeller kommer en ökning av växthusgaser i atmosfären leda till en ökning av temperaturen på jorden, den ökningen kommer främst att ske på höga latituder. Glaciärer är bra indikation på förändrat klimat på grund av deras korta responstid när klimatet ändrar sig. För tillfället finns det ca 1900 glaciärer utspridda i de Skandinaviska bergen. Eftersom Skandinavien är så avlångt är det en skillnad i meterologiska och klimatiska förhållanden, både i en nord-syd riktning men även i en öst-väst riktning med kontinentala glaciärer i öst och mer marina i väst. Klimat och glaciärdata för 13 olika glaciärer i Skandinavien, 5 från Sverige och 8 ifrån Norge har samlats in och en statistisk analys, principle component analysis (PCA) har gjorts för att se vad som påverkar massbalansen för glaciärerna. De klimat parametrar som har undersökts är Nordatlantsika oscillationen (NAO), Arktiska oscillationen (AO) och solfläckar tillsammans med massbalans, equilibrium line altitude (ELA) och area för glaciärerna. Tre grupperingar har hittats som kan kopplas till olika klimatvariabler och PCA visar extremår för NAO och AO samt en glaciär som har den största arean. PCA analysen visade att alla variabler korrelerade till NAO och AO med omkring 40 % och vi kan dra slutsatsen att det finns en drivande regional och lokal kraft inom vårat dataset där NAO och AO är viktigast för massbalansen.
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Marcer, Marco. "Déstabilisation des glaciers rocheux dans les Alpes Françaises : une évaluation à l'échelle régionale et locale." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAU048/document.
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Le permafrost de montagne est menacé par le réchauffement atmosphérique, une évolution qui s’accompagne de l’augmentation des phénomènes tels que les chutes de pierres, la formation de thermokarsts et l’accélération des glaciers rocheux. La déstabilisation des glaciers rocheux, qui compromet l’intégrité structurelle de ces formes, semble liée au réchauffement atmosphérique, et a suscité un intérêt grandissant au cours des dernières années. Ce phénomène, qui peut être provoqué par le réchauffement du pergélisol ou des contraintes mécaniques externes, est caractérisé par une accélération anormale des glaciers rocheux affectés, et par l’apparition des signes géomorphologiques telles que des fissures et des crevasses à sa surface. Bien que ce processus peut être transitoire, il peut déterminer une phase de crise amenant le glacier rocheux à un effondrement.Cet étude se préfixe de fournir une première évaluation des phénomènes de déstabilisation de glacier rocheux à l’échelle des Alpes françaises. Dans un premier temps, l’empreinte spatiale du pergélisol a été évaluée afin de produire une carte de répartition du pergélisol régionale, un outil nécessaire pour estimer l’état du permafrost dans les glaciers rocheux. La deuxième étape a consisté à identifier les formes déstabilisées grâce à une observation ponctuelle des images aériennes afin d’identifier les caractéristiques typiquement observables sur les glaciers rocheux déstabilisés. Il est alors possible de comprendre les conditions topoclimatiques typiques dans lesquelles se produit ce phénomène et de repérer les formes susceptibles de subir ce processus. Enfin, les efforts ont été concentrés sur le glacier rocheux du Lou, déstabilisé, qui, du fait d’un détachement de couche active, a conduit à une lave torrentielle en Août 2015. L’analyse a visé à mieux définir les circonstances de cet événement, en mettant l’accent sur les facteurs de préconditionnement, de préparation et de déclenchement et sur leur interaction avec le processus de déstabilisation.Les résultats ont fourni des informations riches sur la zone périglaciaire de la région. La modélisation de la répartition du pergélisol a mis en évidence les étendues de la zone périglaciaire dans la région qu’on peut trouver sur les pentes de débris au-dessus de 2300 - 2500 m.a.s.l. en fonction de l’exposition solaire et des caractéristiques régionales des précipitations. L’observation des photographies aériennes a permis d’observer 46 formes en cours de déstabilisation, soit 12% des glaciers rocheux actifs des Alpes françaises. Il apparaît que la déstabilisation est plus susceptible de se produire dans certaines conditions topoclimatiques locales spécifiques, en particulier dans des pentes exposées au nord, raides et convexes situées aux marges inférieures de la zone de pergélisol. Un grand nombre de glaciers rocheux ne présentant actuellement aucune déstabilisation sont donc susceptibles d’être affectés par une déstabilisation future. L’analyse du glacier rocheux du Lou a révélé que la déstabilisation est liée à une avancée rapide du front vers un ravin torrentiel. Ce processus semble avoir accru la prédisposition des matériaux détritiques du front à être mobilisés par du ruissellement, des précipitations relativement modérées ayant suffi à déclencher l’événement.Malgré les incertitudes liées aux méthodes impliquées, les résultats suggèrent que les conditions favorables à la déstabilisation sont fréquentes, et que cette dernière peut augmenter le niveau de risque si le site est connecté à des infrastructures humaines. Des efforts supplémentaires doivent donc être entrepris, afin d’améliorer la compréhension de ces processus, notamment par la surveillance des sites ainsi que par une évaluation locale complète des cascades de processus liés à ce phénomèneAs occurring to several geosystems on our planet, mountain permafrost is threatened by climate change as prolonged warming may compromise the geotechnical properties of the frozen ground. As result, increasing occurrence of rockfall activity, thermokarst formation and rock glacier acceleration was observed in the past decades. Rock glacier destabilization, a process that compromises the structural integrity of these landforms, seems to be linked to atmospheric warming, gaining interest in the past years. The destabilization, which may be triggered by warming permafrost or mechanical stress, is characterized by an anomalous acceleration of the landform and the occurrence of specific features such as cracks and crevasses on its surface. Although the occurrence of these processes is mostly transitory, determining a textit{crisis} phase of the landform, in exceptional cases it may lead the rock glacier to structural collapse.This PhD thesis provided an assessment on the occurrence and related processes of rock glacier destabilization in the French Alps. At first, the spatial occurrence of debris permafrost was assessed in order to provide the permafrost distribution map of the French Alps, a tool that was necessary to evaluate permafrost conditions at rock glaciers sites. The second step consisted in an identification of destabilized rock glaciers in the region, which was done by multiple orthoimages interpretation aimed to identify features typically observable on destabilized rock glacier. Once identified the destabilized rock glaciers it was possible to analyse the typical topographical settings in which destabilization occurs and to to spot those landforms that are susceptible to experience this phenomenon. After these efforts at the regional scale, the focus was shifted towards local scale investigations at the Lou rock glacier, a partially destabilized landform that, due to frontal failure, in August 2015 triggered a debris flow that caused significant damages to buildings. The analysis aimed to better define the circumstances of this event, focusing on preconditioning, preparatory and triggering factors and their interaction with the destabilization process.The results provided interesting insights on the issue of destabilizing rock glaciers in the region. Permafrost distribution modeling demonstrated the large extents of the periglacial zone in the region as it can be found in debris slopes above 2300 - 2900 m.a.s.l. depending upon solar exposure and regional precipitation characteristics. Rock glacier destabilization was observed on 46 landforms, i.e. the 12% of the active rock glaciers. Destabilization was found to be more likely to occur in specific local topo-climatic conditions, consisting of north facing, steep and convex slopes at the lower margins of the permafrost zone. A large number of rock glaciers currently not showing destabilization was found to be located in these conditions and suggested to be susceptible to future destabilization. As demonstrated by the Lou rock glacier analysis, destabilization was found to be a relevant phenomena in the context of permafrost hazards. At this site, rock glacier destabilization was linked to a rapid frontal advance towards a torrential gully. This process seemed to have increased the site predisposition to frontal failure as a mild rainstorm was sufficient to trigger the event.Despite methodological uncertainties, results indicated that destabilization occurrence is widespread and it may rise the hazard level of a site connected to human infrastructures. Therefore, it is suggested that, where it has been modelled and where stakes may be at risk downslope, rock glacier destabilization deserves to be more carefully investigated. In this sense further efforts should focus towards a better understanding of the destabilization process by site monitoring as well as towards a comprehensive hazard assessment linked to this phenomenon
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Muñoz-Cobo, Belart Joaquín. "Bilan de masse des glaciers islandais depuis 1945 : reconstruction et relation avec la variabilité climatique." Thesis, Toulouse 3, 2018. http://www.theses.fr/2018TOU30236.
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Le bilan de masse des glaciers est fortement lié au climat. Aux hautes latitudes, l'accumulation de neige pendant l'hiver et la fonte de glace pendant l'été sont les principales composantes du bilan de masse. En Islande, le bilan de masse des trois plus larges calottes glaciaires (~600-~8000 km²) a été suivi régulièrement depuis 25 ans notamment grâce à des mesures in situ. Mais les bilans de masse des autres glaciers et calottes glaciaires islandaises ont été très peu étudiés. Aujourd'hui, les données de télédétection, notamment via la comparaison des modèles numériques du terrain (MNT), permettent de mesurer le bilan de masse par la méthode géodésique. Pour ces glaciers et calottes de plus petites tailles (de 1 km² et à quelques centaines de km²), les photographies aériennes, l'imagerie satellitaire stéréoscopique sub-métriques, et le lidar aérien sont parfaitement adaptées. Cette thèse se focalise donc sur l'estimation des bilans de masse des " petits " glaciers et calottes islandaises depuis le pas de temps saisonnier jusqu'à pluri-décennal et leur relation avec les variations spatiales et temporelles du climat. Le bilan de masse hivernal de la calotte du Drangajökull (NO-Islande) a été mesuré par des images satellitaires stéréoscopiques sub-métriques (données Pléiades et WorldView-2) acquises au début, milieu et à la fin de l'hiver 2014-2015. Les changements de volume ont été convertis en bilan de masse grâce à des mesures in situ de densité de neige, et validés avec des mesures in situ de profondeur de neige. Ce travail permet d'envisager désormais un suivi du bilan de masse saisonnier sans un laborieux travail de terrain. Une importante archive de photographies aériennes est disponible en Islande depuis 1945. Ces données offrent une revisite de 5 à 20 ans pour la majorité des glaciers. De plus, depuis 2000, cette archive est complétée par les données des capteurs satellitaires stéréoscopiques et de lidar aérien acquis entre 2008 et 2013. Cet ensemble de données est exploité pour créer une série temporelle de 70 ans de bilan de masse en Islande. La calotte d'Eyjafjallajökull (~70 km²) sert de zone test pour la création et l'automatisation d'une chaîne de traitement, basée sur des logiciels libres. [....]The mass balance of a glacier is strongly connected to climate. At high latitudes, mass balance is typically controlled by snow accumulation during the winter and the glacier ablation during the summer. In Iceland, direct mass balance observations have been mostly focused on the three largest ice caps (~600 to ~8000 km2), measured in situ for the last 25 years. There are, however, glaciers and ice caps distributed over all quarters of the country that lack mass balance observations. Remote sensing data with the capability to retrieve the glacier surface geometry through Digital Elevation Models (DEMs) are valuable tools to measure mass balance using the geodetic method. For a typical Icelandic glacier (with an area between 1 km2 and hundreds of km2), this can be optimally achieved from optical stereoscopic imagery, emplaced in airborne or spaceborne sensors, and from airborne lidar. This thesis focuses on remote sensing techniques to accurately measure geodetic mass balance from seasonal to decadal time spans and the relationship of mass balance to climate. As an example of seasonal mass balance, the winter mass balance of Drangajökull was measured from satellite sub-meter stereo images at the beginning, middle and end of the 2014-2015 winter using data from the Pléiades and WorldView-2 satellites. The results were complemented with in situ snow density measurements and validated with snow thickness measurements. The study concludes that images from the sensors mentioned above may often be used to monitor seasonal mass balance without tedious field logistics. A vast archive of aerial photographs exists for Iceland extending back to 1945. Since then, most glaciers were surveyed every 5 to 20 years. In addition, a wealth of modern satellite stereo images is available since the early 2000s as well as airborne lidar data in 2008-2013. This creates a unique dataset to construct a 70-year time series of geodetic mass balances.[...]
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Brun, Fanny. "Influence de la couverture détritique sur le bilan de masse des glaciers des Hautes Montagnes d’Asie : une approche multi-échelle." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAU024/document.
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Les Hautes Montagnes d’Asie (HMA) abritent la plus grande superficie de glaciers en dehors des régions polaires. Environ 15 % des ~100 000 km² de glaciers des HMA sont couverts de débris d’épaisseur variable. L’influence de cette couverture détritique sur la réponse des glaciers au changement climatique reste méconnue. Au-delà d’une épaisseur critique (quelques cm), les débris protègent les glaciers de la fonte par effet isolant. Mais ces glaciers présentent des structures qui pourraient sensiblement accentuer leur fonte : en surface ce sont les falaises où la glace est à nue et les lacs supra-glaciaires, alors qu’au cœur des glaciers c’est leur réseau hydrologique intra-glaciaire complexe. L’objectif de cette thèse est d’évaluer l’influence de la couverture détritique sur le bilan de masse des glaciers des HMA. Jusqu’à présent, cette influence a été évaluée à partir de changements de longueurs ou sur des échantillons de glaciers restreints, et aucune étude n’a quantifié l’influence de la couverture détritique sur le bilan de masse des glaciers à grande échelle.Nous avons d’abord traité plus de 50 000 couples stéréoscopiques du capteur ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) pour dériver des modèles numériques de terrain (MNTs) sur la quasi-totalité des glaciers des HMA. Nous avons mesuré ainsi le bilan de masse régional entre 2000 et 2016 avec une résolution jamais atteinte auparavant. La perte totale est de 16.3 ± 3.5 Gt a-1 soit un bilan de masse moyen de -0.18 ± 0.04 m équivalent (éq.) eau a-1, très variable spatialement, avec une perte de masse record pour le Nyainqentanglha (-0.62 ± 0.23 m éq. eau a-1) et un léger gain pour le Kunlun (+0.14 ± 0.08 m éq. eau a-1).Cette variabilité spatiale des bilans de masse reflète au premier ordre la variabilité des climats, différents d’un bout à l’autre des HMA. Pour s’en affranchir, nous avons découpé cette région en 12 sous-régions supposées homogènes climatiquement, où nous avons étudié l’influence de la couverture détritique sur le bilan de masse des glaciers de plus de 2 km² (>6 500 glaciers soit 54 % de la surface englacée totale). Statistiquement, la couverture de débris n’est pas un bon prédicteur du bilan de masse. Dans quatre sous-régions, les glaciers couverts ont des bilans de masse plus négatifs que les glaciers blancs, c’est l’opposé dans le Tien Shan alors que pour les sept sous-régions restantes, les bilans ne sont pas différents statistiquement entre glaciers blancs et couverts. Souvent, la couverture détritique a une influence plus faible que la pente de la langue ou l’altitude moyenne du glacier, car les langues couvertes de débris descendent plus bas en altitude, là où l’ablation est la plus forte.Ce type d’étude statistique est intéressant pour se forger une intuition, mais reste peu informatif en termes de compréhension des processus glaciologiques. Pour mieux contraindre les contributions des processus responsables de la fonte, nous avons travaillé en parallèle à une échelle plus fine en nous intéressant au glacier du Changri Nup (2.7 km²) situé non loin de l’Everest au Népal. A partir de MNTs haute résolution dérivés d’images des satellites Pléiades ou acquises avec un drone, nous avons montré que les falaises de glace, bien qu’elles n’occupent que 7 à 8 % de la surface de la langue de ce glacier, ont contribué à ~23 ± 5 % de l’ablation nette totale au cours de deux années contrastées. Ces falaises sont donc des zones d’ablation préférentielle mais couvrent des surfaces trop faibles pour compenser la réduction d’ablation induite par la couverture détritique environnante. Si l’on observe des taux d’amincissement similaires sur les langues couvertes ou non de débris, c’est que la vitesse d’émergence est plus faible sur les langues couvertes ce qui compense un bilan de masse de surface moins négatif que sur les glaciers blancs. Il est néanmoins nécessaire de mieux comprendre la dynamique des langues couvertes de débrisHigh Mountain Asia (HMA) hosts the largest glacierized area outside the polar regions. Approximately 15 % of the ~100 000 km² of HMA glaciers is covered by a debris layer of various thickness. The influence of this debris on the HMA glacier response to climate change remains debated. In principle, the presence of a thick layer of debris reduces the melt of the ice beneath it, due to the insulating effect. However, other processes such as ablation of bare ice cliff faces, subaqueous melt of supraglacial ponds and internal ablation due to englacial hydrology could substantially contribute to enhance the debris-covered glacier mass losses. The aim of this PhD work is to assess the impact of the debris on glacier mass balance in HMA. Up to now, the influence of the debris cover has been assessed through glacier front position changes or on a restricted sample of glaciers, and no large scale study of the influence of the debris cover on the glacier-wide mass balance is available.As a starting point, we derived glacier mass changes for the period 2000-2016 for the entire HMA, with an unprecedented resolution, using time series of digital elevation models (DEMs) derived from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) optical satellite imagery. We calculated a total mass loss of -16.3 ± 3.5 Gt yr-1 (-0.18 ± 0.04 m w.e. yr-1) with contrasted rates of regionally-averaged mass changes ranging from -0.62 ± 0.23 m w.e. yr-1 for the eastern Nyainqentanglha to +0.14 ± 0.08 m w.e. yr-1 for the western Kunlun Shan.At the scale of HMA, the pattern of glacier mass changes is not related to the presence of debris, but is linked with the climatology. Consequently, we studied the influence of the debris-cover on mass balance within climatically homogeneous regions. Based on the mass balances of individual glaciers larger than 2 km² (more than 6 500 glaciers, which represent 54% of the total glacierized area), we found that debris-covered glaciers have significantly more negative mass balances for four regions out of twelve, a significantly less negative mass balance for one region and non-significantly different mass balances for the remaining seven regions. The debris-cover is generally a less significant predictor of the mass balance than the slope of the glacier tongue or the glacier mean elevation. The influence of the debris is not completely clear and complicated to untangle from the effect of the other morphological parameters, because heavily debris-covered tongues are situated at lower elevations than debris-free tongues, where ablation is higher.However, such a statistical analysis of the influence of the debris-cover on the glacier-wide mass balance variability is not very informative in terms of glaciological processes. In order to better constrain the contribution of the different ablation processes on debris-covered tongues, work at a finer scale is required. For the debris-covered tongue of Changri Nup Glacier, Everest region, Nepal, we quantified the contribution of ice cliffs to the ablation budget. Using a combination of very high resolution DEMs derived from Pléiades images and an unmanned aerial vehicle, we found that ice cliffs contributed to ~23 ± 5 % of the total net ablation of the tongue, over two contrasted years, although they occupy only 7 to 8 % of its area. Ice cliffs are large contributors to the ablation of a debris-covered tongue, but they cannot alone explain the so-called debris cover anomaly, i.e. the fact that debris free and debris covered tongues have similar thinning rates. This anomaly is probably due to smaller emergence velocity over debris-covered tongues than over debris-free tongues, resulting in similar thinning rates, despite less negative surface mass balance rates. We advocate for more measurements of ice thickness of debris-covered tongues in order to better understand their dynamics
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Samyn, Denis. "Structural and geochimical analysis of basal ice from Taylor Glacier, Antarctica: on role and behaviour of the interstistial fluid phase." Doctoral thesis, Universite Libre de Bruxelles, 2005. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210968.
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Lecourt, Grégoire. "Modélisation à bases physiques de l'hydrologie de l'Arve à Chamonix et application à la prévision des crues." Thesis, Toulouse 3, 2018. http://www.theses.fr/2018TOU30134/document.
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Les risques naturels en montagne font l'objet de mesures de prévention, souvent liées à des démarches de prévision. Dans certaines situations, la prévision de la survenue d'évènements liés à ces risques, voire la simple connaissance des processus physiques qui leur est associé, constitue un enjeu scientifique important compte-tenu de la grande complexité et de la forte hétérogénéité de ce milieu. La connaissance des mécanismes de formation des crues rapides sur les petits bassins versants englacés, ainsi que la perspective de leur prévision, est un exemple de ces risques difficilement maitrisables. La diversité des facteurs influençant les débits des rivières, leur complexité individuelle ainsi que celle de la manière dont ils interagissent, la forte variabilité spatio-temporelle des conditions météorologiques de la montagne ainsi que les modifications ayant lieu sur le long terme en raison du changement climatique font que ce phénomène nécessite une étude approfondie mobilisant des compétences pluri-disciplinaires, allant de la mesure de terrain au développement de modèles numériques prenant en compte les divers phénomènes liés à ce risque. Cette thèse s'inscrit dans le cadre d'un projet mis en oeuvre en partenariat avec les collectivités locales oevrant dans la vallée de Chamonix, voué à apporter un appui scientifique à la maitrise de ce risque. Au sein de ce projet, cette thèse porte sur le développement et le déploiement d'un modèle hydrologique prenant en compte la neige et les glaciers. Ce modèle se veut avoir deux objectifs : 1) servir d'outil de recherche permettant par exemple d'exploiter les mesures de terrain réalisées, en les confrontant aux résultats produits par ce modèle, et plus généralement de servir d'outil d'étude et de compréhension du fonctionnement de ce bassin, et 2) servir d'outil d'aide à la prévision des crues, en étant en mesure de fournir une prévision des débits de l'Arve à Chamonix à partir des données de prévision météorologique. L'exploitation des possibilités toujours grandissantes de la modélisation à bases physiques fait également partie des objectifs de cette thèse. En particulier, l'utilisation d'un modèle de neige à bilan d'énergie permettant notamment une représentation détaillée de l'interaction neige-glace a été mise en oeuvre, associée à l'exploitation des nombreuses mesures de terrain pour une évaluation en profondeur des résultats du modèle. Enfin, un déploiement expérimental de ce modèle en prévision a eu lieu à la fin de cette thèseNatural hazards in mountain are subject to prevention measures, which often partly rely on a forecasting component. In some situations, forecasting these hazards and understanding their underlying physical processes is a major scientifical issue, considering the great complexity and the strong heterogeneity of these backgrounds. Knowing underlying mechanisms of flash-floods on little catchments with glacier cover, and the perspective to forecast be able to forecast it, is an example of these risks difficult to master. The diversity of contributions to river discharge, their individual complexity and the one of the way they interact, the strong spatio-temporal variability of meteorological conditions of mountain and long-terms modifications occuring due to climate change make that this phenomenon needs to be deeply studied within a plury- disciplinary work, going from terrain measurement to development of computationnal models taking into account the diversity of physical phenomenons relating to this risk. This thesis belongs to a research project conducted in collaboration with local authorities operating in the Chamonix Valley. The goal is to provide a scientific support to help managing this hazard. The role of this thesis in this research project is to develop, test and deploy an hydrologic model taking snow and ice into account. This model is intended to be used as a research tool among other research tools of this projects (terrain measurements for example) and also to be able to help forecasting floods, when being driven by forecast meteorological data. This thesis benefitted from the continuous development of new possibilities from physically-based simulation. We have used an energy-balance multi layer snowpack model that permits a detailled representation of glacier accumulation and melt, and snow-ice interaction. It was possible to perform a multi-criteria evaluation of the model, thanks to the numerous in-situ field measurements in the Arve valley, especially glaciers mass balance measurements. Finally, this model has been deployed and tested as a pre-operationnal forecast tool
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Patel, Angira. "Identification and comparison of fungi from different depths of ancient glacial ice." Connect to this title online, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=bgsu1141752883.
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Hubbard, Bryn Pugh. "Basal ice facies and their formation in the western Alps." Thesis, University of Cambridge, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239624.
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Butts, Eric Clark. "Models of glacial flow /." The Ohio State University, 1985. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487262825076709.
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Scapin, Nikita. "Inventario dei rock glaciers in Val Formazza, Piemonte." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/19897/.
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In questo lavoro vengono presentati i metodi ed i principali risultati ottenuti dall’inventario dei rock glaciers in Val Formazza, Piemonte. Il lavoro presenta la compilazione di un nuovo inventario dei rock glaciers sulla base di ortofoto e DSM, in ambiente QGIS. L’attività di fotointerpretazione di ortoimmagini aeree e rilievi ombreggiati viene integrata con l’utilizzo dell’applicazione QGIS che permette la mappatura e la determinazione dei principali attributi topografici e geomorfologici dei rock glaciers. Le informazioni contenute nel nuovo inventario integrano e aggiornano la mappatura già esistente dei rock glaciers in Val Formazza, svolta da Arpa Piemonte. I rock glaciers censiti nel vecchio inventario sono 27; con questa nuova mappatura se ne possono contare 115, di cui 23 sono stati classificati come intatti e 92 come relitti. Oltre al grado di attività, per ognuno dei rock glaciers mappati è stata descritta la forma (linguoidi, lobati o multilobo) e sono stati estratti l’area, l’esposizione e la quota minima, che corrisponde alla quota del fronte del rock glacier. I risultati mostrano che la maggior parte della Val Formazza è occupata da rock glaciers relitti. I rock glaciers relitti si trovano a quote inferiori (2000 m) rispetto a quelli intatti (2500 m). In termini di esposizione, non risultano esserci rock glaciers esposti a Nord, ma sono presenti sia a Nord-Ovest che a Nord-Est. Per quanto riguarda la distribuzione dei rock glaciers intatti non è stato trovato nessun rock glacier con classe di esposizione Est. Le quote più basse dei rock glaciers relitti sono esposte ad Est mentre le quote più alte si trovano ad Ovest. I rock glaciers intatti hanno un andamento simile ai relitti con esposizione ad Oriente per quanto riguarda le quote minori e in merito alle quote maggiori i rock glaciers intatti differiscono dai relitti e presentano quote più elevate a Sud e Sud-Ovest e a Nord-Ovest.
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Parmhed, Oskar. "Near surface atmospheric flow over high latitude glaciers." Doctoral thesis, Stockholm University, Department of Meteorology, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-197.
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In this thesis various descriptions of the near surface atmospheric flow over a high latitude glacier is used in an effort to increase our understanding of the basic flow dynamics there.
Through their contribution to sea-level change, mountain glaciers play a significant role in Earth’s climate system. Properties of the near surface atmospheric flow are important for understanding glacier response to climate change.
Here, the near surface atmospheric flow is studied from several perspectives including the effects of both rotation and slope. Rotation is an important aspect of most atmospheric flows and its significance for mesoscale flows have gained recognition over the last years. Similarly, the very stable boundary layer (VSBL) has lately gained interest. Within a VSBL over sloping terrain katabatic flow is known to be usual and persistent. For the present thesis a combination of numerical and simple analytical models as well as observations from the Vatnajökull glacier on Iceland have been used. The models have continuously been compared to available observations. Three different approaches have been used: linear wave modeling, analytic modeling of katabatic flow and of the Ekman layer, and numerical simulations of the katabatic flow using a state of the art mesoscale model. The analytic models for the katabatic flow and the Ekman layer used in this thesis both utilizes the WKB method to allow the eddy diffusivity to vary with height. This considerably improves the results of the models. Among other findings it is concluded that: a large part of the flow can be explained by linear theory, that good results can be obtained for surface energy flux using simple models, and that the very simple analytic models for the katabatic flow and the Ekman layer can perform adequately if the restraint of constant eddy diffusivity is relieved.
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Vincent, Christian. "L'impact des changements climatiques sur les glaciers alpins." Phd thesis, Université de Grenoble, 2010. http://tel.archives-ouvertes.fr/tel-00596523.
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L'objectif de cette thèse est d'analyser les impacts des changements climatiques sur l'évolution des glaciers alpins. L'impact le plus direct concerne les changements des bilans de masse des 25 dernières années. L'analyse des bilans de masse de plusieurs glaciers au cours des 50 dernières années indique un signal commun sur l'ensemble de la chaine alpine. Il en résulte des variations très importantes de la dynamique des glaciers, en terme de variations d'épaisseur, de longueurs et de vitesses d'écoulement. Le réchauffement climatique a également un impact sur le régime thermique des glaciers "froids" de très haute altitude. Enfin, notre étude s'est intéressée à 3 cas de risque d'origine glaciaire qui sont les séracs de Taconnaz, le lac de Rochemelon en 2005 et la poche d'eau du glacier de Tête Rousse.
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Flink, Anne. "Dynamics of surging tidewater glaciers in Tempelfjorden, Spitsbergen." Thesis, Stockholms universitet, Institutionen för naturgeografi och kvartärgeologi (INK), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-88458.
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Terrestrial glacial geomorphology has long been used to evaluate the extent, chronology and dynamics of former glaciers and ice sheets. New marine geophysical methods provide an opportunity to study the glacial submarine morphology of modern continental shelves and fjord systems. This makes it possible to study landform assemblages in the submarine settings that are often better preserved than their terrestrial counterparts. This study focuses mainly on the recent surge history of the tidewater glacier Tunabreen, which calves into Tempelfjorden in Western Spitsbergen. Tunabreen is a small outlet glacier of the Lomonosovfonna ice cap and has experienced severalsurges and terminal retreats during the last century. The multiple surge events havemost likely removed or reworked landform assemblages created by earlier surges,resulting in a complex geomorphological imprint on the bed of Tempelfjorden. Tunabreen has left a specific morphological imprint on the sea floor, consisting of iceflow‐parallel lineations and generally flow‐transverse retreat moraines. Comparisonof retreat moraines mapped from high resolution multibeam bathymetric data andglacier terminal positions, established using remote sensing imagery suggest that themoraines in the inner part of Tempelfjorden are annually formed recessionalmoraines, formed during winter still stands of the glacier margin or during its minorreadvances. Although detailed reconstruction of glacier surge dynamics based solelyon the landform distribution is challenging, it is evident that Tunabreen hasexperienced fast flow during surges and semiannual retreat of the margin after thesurges. The main achievements of this study are a spatial reconstruction of the dynamics ofTunabreen, which has experienced three surges during the last hundred years.Together with the Little Ice Age surge of the adjacent von Postbreen, four recentsurges have been recorded in Tempelfjorden since 1870, which distinguishes thestudy area from earlier studied Svalbard tidewater surge glacier settigs, where theglaciers have been known to surge only once or twice. However a detailedunderstanding of surge triggering mechanisms and their role in controlling thedynamics of the tidewater glaciers in Svalbard is still poor and requires furtherinvestigations. Svalbard, where most of the small outlet glaciers are believed to be ofsurge type, is an excellent natural laboratory for such investigations.
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Roehl, Katrin, and n/a. "Terminus disintegration of debris-covered, lake-calving glaciers." University of Otago. Department of Geography, 2006. http://adt.otago.ac.nz./public/adt-NZDU20070502.112854.
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Numerous supraglacial and proglacial lakes have developed on debris-covered glaciers in conjunction with 20th-century retreat associated with global warming. When a glacier holds a substantial debris cover on its lower reach and/or is calving into a proglacial water body, the behaviour of its terminus can be modified to varying degrees compared to that of land-terminating or debris-free glaciers. The terminus is not just retreating from its frontal position but it is disintegrating through several processes that are linked. An improved understanding of these glacier margins is needed for the prediction and management of hazards associated with these types of lakes for hydroelectric power generation, recreational purposes and areas threatened by potential glacier outburst floods as well as for the interpretation of glacio-geological records and reconstruction of former glacial environments and palaeoclimate.
The principal research question of this study is how processes of ice loss contribute to the terminus disintegration of a debris-covered, lake-calving glacier. This is addressed by an application of a field-based strategy which includes extensive field observations of variables, processes and their controls, and subsequent analysis of the data in the light of previous models and concepts. The study attempts to combine and integrate different aspects of glaciological research that have previously been examined mostly separately. It investigates the prevalent processes at the glacier terminus and their controls over different time periods ranging from days to years at Mueller, Hooker and Tasman Glaciers in Mount Cook National Park, New Zealand. The data form the basis for models of calving and pond development and future retreat scenarios.
This study has demonstrated that this glacial environment is characterised by ice-frontal processes with complex inter-relationships that vary between glaciers and in particular between stages of terminus development. While surface ice melt in the terminus area is substantially reduced by supraglacial debris, sub-debris melt contributes the largest fraction of ice loss. Other important effects of debris are restraining thermal undercutting, reducing subaqueous melt and decreasing buoyancy. Data from supraglacial ponds and proglacial lakes show that limnological factors become increasingly important with increasing pond/lake size. Changes in water currents and temperature lead to changes in significance and rates of ice loss processes, the most important being the change from melting to predominantly calving. This study has confirmed the hypothesis that thermal undercutting is the rate-controlling process for calving. This process is controlled by the cliff geometry, debris supply, subaqueous geometry and water temperatures, currents and level variations. The results from the examination of calving processes suggest that the process of regular, progressive calving through the stages suggested previously may not be widely applicable to slow-moving, lake-calving glaciers. The several forms of subaerial calving identified in this study can present themselves as largely independent events, a combination of events or as a progression. At the central submerged part of the ice face, subaqueous ice melt is likely to be the dominant form of ice loss, leading to horizontal ice loss. Subaqueous calving is prevalent in gently-sloping lateral areas, leading to vertical ice loss. This process is controlled by buoyancy forces which are affected by sedimentation and lake and glacier geometry. The onset of subaqueous calving in the earlier stages of lake development is a crucial process for the transition to faster disintegration and ice loss, accelerating subaqueous melt. Due to the complex inter-relationships attempts to formulate general relationships between calving or retreat rates and other glaciological parameters may not be feasible.
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Mair, Douglas W. F. "Hydrological influences on the dynamics of valley glaciers." Thesis, University of Cambridge, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.413113.
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King, Owen. "Characterising the evolution of Himalayan debris covered glaciers." Thesis, University of Leeds, 2018. http://etheses.whiterose.ac.uk/21574/.
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The majority of the 20,000 glaciers found in the Himalaya are in a state of negative mass balance, and have been for decades. Broad spatial trends in ice mass loss have been identified by large scale geodetic mass balance studies, but regional averaging of mass loss data has masked catchment or glacier scale variability. This thesis has the broad aim of examining the catchment scale variability of ice mass loss, in order to identify factors that might promote, or inhibit, more substantial ice mass loss from the region in the future. Ice mass loss rates from Everest region glaciers were calculated using the geodetic approach, over the period 2000-2015, and compared depending on glacier terminus type. Lake-terminating glaciers were found to have lost 32% more ice mass than land-terminating glaciers, and maximum surface lowering rates of lake-terminating glaciers peaked at more than twice the rate of land-terminating counterparts. Glacier hypsometry was found to be contrasting at the catchment scale, and predicted accumulation area ratio (AARs) change in response to different RCP warming scenarios emphasises the importance of considering glacier area-altitude distribution in future ice loss estimates. A more detailed assessment of the evolving geometry, dynamics and ice loss rates of nine lake-terminating glaciers suggested two phases of glacier-lake interaction may exist. A phase of dynamic lake-terminating glacier retreat was evident where terminus proximal surface lowering rates were high (up to 3 m a-1), ice front retreat rates were steady or accelerating, and surface velocities increased (by up to 10 m a-1, between 1999 and 2015). Alternatively, a phase of retreat typified by surface lowering rates akin to land-terminating glaciers (~1 m a-1), where ice front retreat rates were steady or diminishing, and where surface velocity reduction occurred. The dynamic phase of ice loss observed on lake-terminating glaciers in the Everest region is not of the same magnitude as larger waterter-minating glaciers found in other glacierised regions, probably because of the topographic confinement of host glaciers and the dominance of resistive stresses, but the now populous nature of glacial lakes in the region means the potential for amplified future ice loss exists. The impact of long-term ice loss on the topographic characteristics of debris covered glacier surfaces was also examined. Ice cliff and supraglacial pond expansion was identified as the main driver of topographic change on slow flowing, land-terminating glaciers. A more pitted surface topography of greater relief developed on most glaciers, which has implications for the energy balance at the glacier surface, and for supraglacial hydrology. Overall, the results of this thesis emphasise the need to incorporate a range of glacier dynamics scenarios and melt processes into simulations of future ice loss in the Himalaya.
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Cook, Susan Jennifer. "Environmental controls on calving in grounded tidewater glaciers." Thesis, Swansea University, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.678282.
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Sugden, Lindsay. "Glaciers, climate and the '8.2ka event' in Iceland." Thesis, University of Edinburgh, 2006. http://hdl.handle.net/1842/30802.
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The “8.2ka event” is the largest recorded climatic reversal in the Holocene. The research combines new high resolution empirical evidence with ice sheet modelling to assess the extent and nature of glacial activity at 8.2ka. New geomorphic evidence is presented for the Early Holocene in the Borgarfjörour Eystri region of northeast Iceland. In total, thirteen landform ‘suites’ are identified which are indicative primarily of glacial activity, but also contain evidence for mass-movement events. Landform suites are backed by cliffs or scree slopes, and consist, in the upper parts, of high-relief ridges and terraces interpreted as landslide deposits. The middle and lower parts are made up of longitudinal ridges and hummocky terrain, with clear terminal and lateral moraines defining former glacier margins. Phases of glacial and mass-movement activity which generated these landforms are Holocene in age, dated to between 7600-4000 Cal. Yrs. B.P. It is suggested that glacial advances represent the primary response to the 8.2ka cooling event, while the mass-movement events which occurred later were a result of paraglacial slope instabilities, and thus can be seen as a secondary response. Ice sheet modelling experiments suggest that extreme climatic conditions, involving a temperature drop of as much as 7°C, would have been necessary to initiate glaciers in the locations where Holocene activity has been observed. It is suggested that abundant debris supplies generated from the friable exposures of rhyolitic bedrock, would have inhibited the ablation of glacier ice, so that cooling may not have had to be as much as 7°C to promote and preserve the recorded glacial activity. This study presents evidence for a time-transgressive glacial and geomorphic response to the 8.2ka event in Iceland, providing a site-specific example of regional environmental response to climate change, and promoting understanding of potential response mechanisms to future rapid climate change events.
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Williamson, R. J. "Meltwater temperature in streams draining from Alpine glaciers." Thesis, University of Salford, 2016. http://usir.salford.ac.uk/40062/.
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Thermal conditions in river water are of importance as they influence water quality, chemical processes, ecology, and biological conditions in rivers. In meltwater streams draining from Alpine glaciers, temperatures measured close to glacier termini show strong diurnal variation and paradoxical seasonal variation, being cool when energy availability is greatest. This thesis aims to describe temporal variations of water temperatures in five glacier-fed streams, which drain catchments of varying percentage glacierisation, in the Swiss Alps. Contrasting patterns of ablation season meltwater temperatures, and influences of basin characteristics and river channel morphology on water temperature are assessed. Relationships between solar radiation, air temperature, and water temperature were also investigated. A model was developed in order to estimate the impact of glacier recession on meltwater temperature. Observed temperatures in the Findelenbach during one ablation season were used to calibrate the model, which was subsequently validated on other years. Paucity of data in mountainous regions necessitated a model that required few measured variables to be developed. Distinctive seasonal water temperature regime was identified for larger rivers which drain relatively steep catchments, with substantial basin ice coverage. Such a regime is not replicated in streams draining smaller glaciers with lower gradients. Patterns in diurnal ranges of temperature in rivers draining large glaciers have been identified, temperature ranges reducing during days with high radiation and rising riverflows. Stream surface area was found to be the main catchment characteristic influencing temperature in glacier-fed rivers. Measured stream albedo values suggest that surface reflectivity is unlikely to be a major control on water temperature. Stream temperatures simulated by the model demonstrate high fidelity to those measured in the field. The temperature of glacier-fed streams will increase as climate warms as the distance over which heating can occur will lengthen as glaciers retreat, despite volume of flow being augmented by the deglaciation discharge dividend.