No description available.

No description available.

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.

L'albédo, fraction de rayonnement réfléchi dans le spectre solaire, est une variable clef du bilan énergétique des surfaces enneigées et englacées. Cette grandeur possède une forte variabilité spatio-temporelle ce qui fait de la télédétection un outil adapté pour son étude. L'albédo dépend à la fois des propriétés physiques du milieu considéré et des caractéristiques du rayonnement incident. Les différentes grandeurs liées à l'albédo sont fonction des domaines angulaires et spectraux des radiations considérées. Les mesures de répartition angulaire du rayonnement réfléchi par la neige ont montré que l'hypothèse lambertienne pouvait conduire à des erreurs non négligeables lors de la détermination de l'albédo par télédétection. La connaissance des caractéristiques de la répartition angulaire du rayonnement réfléchi par la neige permet de développer une nouvelle méthode de détermination de l'albédo en zones montagneuses. Cette méthode prend en compte les effets liés à la forte variabilité topographique des terrains de montagne, à l'anisotropie du rayonnement réfléchi par la neige et par la glace ainsi que les variations spectrales de l'albédo en fonction des propriétés physiques de la surface. Elle a été appliquée à deux types de données : des photographies terrestres visibles et proche infrarouges (résolution spatiale 10 m) et des images MODIS (résolution spatiale 250 m). L'incertitude sur la valeur de l'albédo ainsi déterminée est évaluée à ±10% grâce aux mesures de terrain effectuées sur le glacier de Saint Sorlin (massif des Grandes Rousses, France). L'étude des cartes d'albédo issues de dix années (2000-2009) d'images MODIS montre qu'il n'y a pas de décroissance marquée de la valeur de l'albédo en zone d'ablation au contraire de ce qui a été prouvé pour le glacier du Morteratsch (Suisse). De plus, il existe une corrélation très élevée entre la valeur minimale de la moyenne de l'albédo sur le glacier, i.e. l'albédo moyen du glacier le jour où la ligne de neige est proche de la ligne d'équilibre, et la valeur du bilan de masse annuel spécifique. L'assimilation des données d'albédo obtenues grâce aux images MODIS et aux photographies terrestres dans le modèle de neige CROCUS permet une bonne estimation du bilan de masse spatialisé du glacier de Saint Sorlin (rmse=0.5 m w.e. pour les cinq années hydrologiques étudiées). Les forçages météorologiques utilisés pour cette étude sont de moyenne échelle. L'analyse succincte de la contribution des différents flux atmosphériques au bilan d'énergie de surface montre qu'en zone d'ablation comme en zone d'accumulation, le bilan radiatif net courtes longueurs d'ondes constitue la source principale d'énergie et que la variabilité de ce flux explique la majeure partie de la variabilité journalière de la somme des flux atmosphériques. Appliquées à d'autres glaciers, ces méthodes permettraient de savoir si les conclusions établies pour notre seul glacier d'étude sont valables pour d'autres glaciers. Elles rendraient également possibles la reconstruction du bilan de masse spatialisé sur 10 ans d'autres glaciers et potentiellement une meilleure quantification des processus physiques mis en jeu dans le bilan de masse de ces glaciers tempérés / Albedo is defined as the ratio of reflected to incident radiation over the solar spectrum and is a key parameter in the surface energy balance of snow and ice. This parameter is highly variable both temporally and spatially; thus remote sensing is an ideally suited approach for the retrieval of albedo data.The albedo value depends on both physical properties of the target and the characteristics of the incident radiation. Furthermore, the physical parameters linked with the albedo concept vary in consideration with spectral and angular ranges. Measurements of bi-directional reflectance over natural snow have shown that the Lambertian hypothesis may lead to significant error when estimating albedo from remote sensing data.Detailed knowledge of the angular distribution of radiation reflected by snow allows for the development of a new method to retrieve albedo values for mountainous, snow/ice covered areas. This method takes into account multiple reflections on mountainous areas, anisotropy of radiation reflected by snow and ice, and albedo spectral variations with surface physical properties. The method is applied to visible and near-infrared terrestrial photographs (spatial resolution 10 m) and MODIS data (spatial resolution 250 m). The accuracy of the method is evaluated at ±10% on the retrieved albedo value using concurrent field measurements at theSaint Sorlin Glacier (Grandes Rousses, France) during the summers of 2008 and 2009. The method is used to retrieve albedo data for this glacier from 2000 to 2009. Results indicate that the albedo of the ablation area of the Saint Sorlin Glacier has not shown any decreasing trend over this decade, in opposition to results presented for the Morteratsch Glacier (Switzerland). In addition, the minimal value over the summer period of the whole glacier averaged albedo is highly correlated to the specific annual mass-balance.Albedo data from MODIS and terrestrial photographs are then assimilated into the snow model CROCUS. This assimilation allows for an estimation of the spatialized mass-balance of the Saint Sorlin Glacier over the five studied hydrological years. Root mean square error is evaluated to 0.5 m w.e. For this study, we have used mid-scale meteorological data from SAFRAN. A brief analysis of the contribution from the atmospheric fluxes to the surface energy balance shows that, for the time period considered in this study, the shortwave radiation budget is the main process determining the surface energy balance. Furthermore, variability in shortwave radiation budget explains the major part of the daily variability in surface energy balance.The methods developed in this work are readily applicable to other temperate glaciers. They allows spatialized mass-balance reconstruction on a decadal scale and lead to improved quantification of the physical processes controlling mass-balance in temperate glaciers

Die vorliegende Arbeit beschäftigt sich mit der Bestimmung von räumlich und zeitlich hochaufgelösten Bewegungsvektorfeldern von Gletschern aus monokularen Bildsequenzen. Diese stellen eine wertvolle Grundlage für glaziologische Analysen des Bewegungsverhaltens von Gletschern dar. Im Rahmen der Arbeit wurden Bildsequenzmessungen an fünf schnellfließenden Gletschern im Bereich der Diskobucht in Westgrönland durchgeführt. Insbesondere erfolgte die Aufnahme von Bildsequenzen und multi-temporalen Laserscannerdaten am Jakobshavn Isbræ, einem der schnellsten und produktivsten Gletscher Grönlands. Diese Messungen bilden die Datengrundlage der Arbeit. Es werden Messkonzepte zur Aufnahme der entsprechenden Bildsequenzen und multi-temporalen Laserscans bereitgestellt sowie Methoden entwickelt, um die Auswertung dieser Daten nach dem Prinzip der monoskopischen Bildsequenzanalyse zu ermöglichen. Die Bildsequenzen und multi-temporalen Laserscans werden von einem festen Standpunkt aus aufgenommen. Die Ableitung von Bewegungsvektorfeldern erfolgt dann durch eine automatische Zuordnung von Grauwertmustern in den Bildsequenzen bzw. durch die Zuordnung von 3D-Punktmustern in den multi-temporalen Laserscannerdaten. Bestehende Punktzuordnungsmethoden werden einerseits an die besonderen Eigenschaften der Gletscherdaten angepasst, andererseits werden geeignete Methoden zur Lösung von Detailproblemen neu entwickelt. Die Methodik der Bildsequenzanalyse wird dabei vor allem hinsichtlich ihrer Robustheit – beispielsweise gegenüber durch Schattenwurf verursachten Störungen im Bild – optimiert und es werden Bewegungseffekte in den Bildsequenzen korrigiert, die durch die Eigenbewegung der Kamera verursacht werden. Bei der Entwicklung der Methodik zur Analyse multitemporaler Laserscannerdaten werden vor allem Effekte berücksichtigt, die durch das sequenzielle Aufnahmeprinzip eines Scanners auftreten. Auf Basis der entwickelten und implementierten Methodik erfolgt die Auswertung der aufgenommenen Bildsequenzen und multi-temporalen Laserscans. Das Ergebnis der monoskopischen Bildsequenzauswertung ist ein dichtes Raster an Bewegungskurven für jede Bildsequenz. Die einzelnen Translationen der Bewegungskurven können mit einer Genauigkeit von einigen Zentimetern bis zu einem Dezimeter bestimmt werden. Die Auswertung der Laserscannerdaten liefert räumlich hochaufgelöste digitale Geländemodelle der Gletscheroberfläche sowie ein dichtes Raster von 3D-Bewegungsvektoren, deren Genauigkeit im Dezimeterbereich liegt. Anhand von Beispielen wird gezeigt, dass sich die aus monokularen Bildsequenzen abgeleiteten Bewegungsvektorfelder zur Bestimmung frontnaher Geschwindigkeitsfelder mit hoher räumlicher Auflösung, zur Ableitung der Lage und der Migration der Aufsetzlinie aus gezeiteninduzierten Vertikalbewegungen sowie zur Untersuchung des Geschwindigkeitsverhalten von Gletschern bei Kalbungsereignissen eignen. Aus den Laserscannerdaten können hochaufgelöste digitale Geländemodelle zur Dokumentation von Fronthöhen und Gletscherstrukturen abgeleitet werden, zudem eignen sie sich zur Bestimmung von Geschwindigkeitsfeldern, die eine sehr hohe räumliche Auflösung besitzen. / This research aims to determine the motion vector fields of glaciers with high spatial and temporal resolution. These vector fields can be derived from monocular image sequences and are a valuable data source for glaciological analysis of the motion behaviour of glaciers. Image sequence measurements have been conducted at five fast-flowing glaciers in the Disko Bay region in western Greenland. Especially at the Jakobshavn Isbræ – one of the fastest and most productive glaciers in Greenland – numerous image sequences have been recorded, as well as multi-temporal laser scanner data sets. These measurements provide the basic data sets for this thesis. The measurement concepts for the acquisition of image sequences and multi-temporal laser scans are presented, and procedures for the processing of the recorded data are developed, based on the principle of monoscopic image sequence analysis. Both the image sequences and multi-temporal laser scans are acquired statically. Motion vector fields can be derived by applying automatic co-registration methods on grey value patterns in the image sequences and on 3D point patterns in the laser scanner datasets respectively. Thus, standard matching techniques have been adapted to the special characteristics of the glacier data, and suitable methods that solve detail problems have been developed in addition. The method of the image sequence analysis has been optimised with respect to its robustness against errors caused by moving shadows. Furthermore, motion effects caused by small instabilities in the camera setup have been corrected. Regarding the analysis of multi-temporal laser scanner data, effects that occur because of the sequential acquisition principle of a laser scanner must also be considered. Based on the developed method, the image sequences and multi temporal laser scans have been processed. The result of the monoscopic image sequence analysis is a dense raster of trajectories for each image sequence. Each translation component from these trajectories can be determined with an accuracy of some centimeters up to one decimetre. The processing of the laser scanner data provides digital surface models of the glacier with high spatial resolution, and a dense raster of 3D motion vectors with accuracy in the range of decimetres. Specific examples show that motion vector fields derived from monocular image sequences can be used for the determination of high resolution velocity fields of glaciers, for the determination of the position and migration of the grounding line and for the investigation of a glacier’s motion behaviour during calving events. From the multi-temporal laser scanner data, velocity fields with high spatial resolution can be derived as well as digital surface models from single scans that document glacier front heights and glacier structures.

Les glaciers de montagne sont l'un des meilleurs indicateurs des changements climatiques du fait de leur réponse rapide à de faibles variations des paramètres de forçage et de leur large distribution sur la planète. Les chronologies glaciaires représentent de ce fait des enregistrements de référence parmi les reconstitutions paléo-environnementales. Dans le contexte actuel de réchauffement et de retrait glaciaire accéléré, le développement de telles chronologies est nécessaire afin de mettre en perspective ces changements rapides et de grande ampleur avec ceux du Quaternaire récent. Si les fluctuations glaciaires holocènes sont relativement bien contraintes dans les Alpes centrales et orientales, les données sont en revanche extrêmement fragmentaires dans les Alpes occidentales avant la seconde moitié du Petit Age Glaciaire ss (1570-1850 AD). Pour pallier ce manque, nous avons conduit une étude sur plusieurs sites répartis dans trois massifs des Alpes françaises (Mont Blanc, Belledonne, Ecrins), en mettant en œuvre une approche multi-proxies basée sur plusieurs méthodes de datation (dendrochronologie, datation cosmogéniques 10Be, lichénométrie, datations radiocarbone) – dont certaines utilisées pour la première fois à cette échelle spatiale et temporelle. Tandis que les potentialités de chacune de ces méthodes sont discutées, notre étude a permis de proposer une chronologie des variations glaciaires couvrant la période holocène, dont les résultats sont comparés à d'autres enregistrements paléoclimatiques régionaux à haute résolution. Les résultats révèlent un schéma des fluctuations glaciaires holocènes comparable à celui généralement admis dans le reste des Alpes, avec la mise en évidence de récurrences glaciaires importantes au début de l'Holocène, antérieures à 9.3 ka, et la datation du début de la période du Néoglaciaire dès 4.2 ka. Une contrainte précise des différents stades de la seconde moitié de l'Holocène a pu être obtenue sur le site de la Mer de Glace grâce à l'approche dendroglaciologique sur bois subfossiles (Pinus cembra). Ce site apparaît d'ores et déjà comme l'un des plus importants pour l'étude de cette période puisque la chronologie établie couvre les 4000 dernières années et représente le quatrième enregistrement de cette précision à être développé dans les Alpes. Les datations obtenues indiquent en outre un synchronisme marqué des maxima glaciaires à l'échelle régionale, ce qui suggère une similarité des forçages sur la frange occidentale des Alpes. Les différences observées avec les chronologies du reste de la chaine s'expliqueraient principalement par les caractéristiques des glaciers étudiés, en particulier leur temps de réponse différent. / Mountain glaciers are one of the most reliable climatic proxy on Earth through their rapid response to slight changes in forcing and their wide distribution. For these reasons glacial chronologies constitutes reference series against which other paleoenvironmental reconstructions are evaluated. In the current context of global warming and glacier withdrawal worldwide, the building of such records is increasingly needed to assess these rapid and dramatic changes on the longer Late Quaternary timescale. The Holocene glacier fluctuations are now fairly well known in the Central and Eastern Alps, but datas from the Western Alps are extremely sparse, and the chronology of glacier fluctuations before the second half of the Little Ice Age (LIA) ss (1570-1850 AD) is thus poorly constrained. To fill this gap, we carried out a study on several sites distributed in three glaciated range of the French Alps (Mont Blanc, Belledonne, Ecrins). We choose a multi-proxies approach based on the implementation of several dating methods (dendrochronology, Cosmic Ray Exposure dating with 10Be, lichenometry, radiocarbon) – some of which were used for the first time on these spatial- and time-scales. This approach allowed us to propose a glacial chronology spanning the Holocene. Moreover, strength and weakness of the different methods used are discussed, and the results are compared to other high resolution proxies from the Great Alpine Region. Our results shows a picture broadly similar to the Holocene glacier variations model currently accepted in the European Alps : we shows evidence for large Early-Holocene advances prior to 9.3 ka and for the beginning of the Neoglacial period from 4.2 ka onwards. An accurate dating of the Neoglacial stadials was possible at Mer de Glace through the use of a dendroglaciological approach on subfossil woods (Pinus cembra). This site already appears as one of the most interesting in the whole Alps to study the Neoglacial period, as the chronology established there spans the last 4 ka and is the 4th record of this kind builds in the Alps. The datings presented here reveals a marked synchroneity for Neoglacial maxima at the Alpine scale, which could indicate similar forcing on glaciers from the Western fringe. Main discrepancies between the records could be explained by topographic and size characteristics of the studied glaciers, as expressed by their response time.

La région du Pamir - Karakoram - Himalaya (PKH) constitue la plus grande réserve de glace terrestre après les régions polaires. Cependant, l'évolution récente de ces glaciers, indicateurs privilégiés du changement climatique en haute altitude, reste encore mal connue, du fait notamment de difficultés d'accès et de conditions climatiques qui rendent délicate l'acquisition de mesures in situ. L'objectif de cette thèse est de contribuer à l'amélioration des connaissances sur l'évolution globale des glaces du PKH au cours de la dernière décennie, en s'appuyant sur des images satellite et des modèles numériques de terrain (MNTs). Une premièreméthodologie a été développée pour assurer le suivi automatique de la distribution spatiale et de l'évolution temporelle des lacs glaciaires à partir d'images Landsat entre 1990 et 2009 sur sept zones d'études réparties le long du PKH. Ainsi, une certaine disparité des types, tailles et évolutions des lacs entre la partie orientale et occidentale du PKH a été mise en évidence. Sur la période de temps considérée, la superficie des lacs a légèrement diminué à l'ouest (Karakoram et Hindu Kush), a été en très nette augmentation à l'est (Népal et Bouthan) et relativement stable sur la partie centrale (Inde du nord-ouest). Le bilan de masse des glaciers a ensuite été calculé, à partir des variations d'épaisseurs mesurées en comparant deuxMNTs, acquis à deux dates différentes, et issus de lamission SRTM et du satellite SPOT5. Cette méthode implique un certain nombre de corrections et d'ajustements au préalable, afin de garantir des mesures les moins biaisées possible. Ainsi, la différence de résolution spatiale initiale des MNTs peut être à l'origine d'un biais fonction de l'altitude, de même que la pénétration des ondes radar de la mission SRTM dans la neige et la glace est à prendre en compte le cas échéant, pour ne pas sous-estimer les altitudes sur les glaciers. Là encore, on observe des disparités entre les différents bilans de masse régionaux sur la période 1999-2011, avec des pertes de masse modérées sur l'Himalaya central et oriental(-0.30±0.08 m a-1 w.e.), plus accentuées sur l'Himalaya occidental (-0.43±0.09 m a-1 w.e.) et des gains de masse plus à l'ouest, pour les glaciers des massifs du Pamir (+0.14±0.11 m a-1 w.e.) et du Karakoram (+0.10±0.20 m a-1 w.e.). Ces résultats confirment donc l'anomalie des glaciers du Karakoram et suggèrent des comportements similaires au Pamir. Le bilan de masse global des glaciers du PKH est estimé à -0.13±0.06 m a-1 w.e. / The Pamir - Karakoram - Himalaya (PKH) mountain range is considered to be the largest terrestrial ice reservoir outside polar regions. However, the recent evolution of these glaciers, recognized as valuable high-altitude climatic indicators, remains poorly known, mainly because of accessibility issues and harsh meteorologic conditions that hamper field work and in situ observations. The aim of this thesis is therefore to improve the knowledge of glacier changes in PKH and study their evolution over the past decade, based on satellite images and digital elevation models (DEMs). We first developed automatic classification algorithms to monitor the spatial distribution and temporal evolution of glacial lakes between 1990 and 2009 along the PKH, based on Landsat images. We thereby highlight different types, sizes and evolutions of glacial lakes between eastern and western PKH. During the study period the total glacial lake area slightly decreased in the west (Hindu Kush and Karakoram), greatly increased in the east (Nepal, Bhutan) and remained stable in the central part (north-west India). We then computed the mass balance of PKH glaciers from elevation changes measured by comparing two DEMs, acquired ∼10 years appart, by the SRTM mission and the SPOT5 satellite. This method relies on a precise relative adjustment (horizontal and vertical) of the DEMs to remove possible systematic biases within glacier elevation changes. The difference in the original spatial resolution of the DEMs can result in an elevation-dependent bias, as well as the radar penetration into snow and ice can seriously underestimate glacier elevation in the case of a DEM derived from radar data such as SRTM. The spatial pattern of regional glacier mass balances between 1999 and 2011 turns out to be contrasted, with moderatemass losses in eastern and central Himalaya (-0.30±0.08m yr-1 w.e.), stronger in western Himalaya (-0.43±0.09 m yr-1 w.e.) and mass gains further west, for Pamir(+0.14±0.11 m yr-1 w.e.) and Karakoram glaciers (+0.10±0.20 m yr-1 w.e.). The global mass balance of PKH glaciers is estimated at -0.13±0.06 m yr-1 w.e.

Die vorliegende Arbeit beschäftigt sich mit der Bestimmung von räumlich und zeitlich hochaufgelösten Bewegungsvektorfeldern von Gletschern aus monokularen Bildsequenzen. Diese stellen eine wertvolle Grundlage für glaziologische Analysen des Bewegungsverhaltens von Gletschern dar. Im Rahmen der Arbeit wurden Bildsequenzmessungen an fünf schnellfließenden Gletschern im Bereich der Diskobucht in Westgrönland durchgeführt. Insbesondere erfolgte die Aufnahme von Bildsequenzen und multi-temporalen Laserscannerdaten am Jakobshavn Isbræ, einem der schnellsten und produktivsten Gletscher Grönlands. Diese Messungen bilden die Datengrundlage der Arbeit. Es werden Messkonzepte zur Aufnahme der entsprechenden Bildsequenzen und multi-temporalen Laserscans bereitgestellt sowie Methoden entwickelt, um die Auswertung dieser Daten nach dem Prinzip der monoskopischen Bildsequenzanalyse zu ermöglichen. Die Bildsequenzen und multi-temporalen Laserscans werden von einem festen Standpunkt aus aufgenommen. Die Ableitung von Bewegungsvektorfeldern erfolgt dann durch eine automatische Zuordnung von Grauwertmustern in den Bildsequenzen bzw. durch die Zuordnung von 3D-Punktmustern in den multi-temporalen Laserscannerdaten. Bestehende Punktzuordnungsmethoden werden einerseits an die besonderen Eigenschaften der Gletscherdaten angepasst, andererseits werden geeignete Methoden zur Lösung von Detailproblemen neu entwickelt. Die Methodik der Bildsequenzanalyse wird dabei vor allem hinsichtlich ihrer Robustheit – beispielsweise gegenüber durch Schattenwurf verursachten Störungen im Bild – optimiert und es werden Bewegungseffekte in den Bildsequenzen korrigiert, die durch die Eigenbewegung der Kamera verursacht werden. Bei der Entwicklung der Methodik zur Analyse multitemporaler Laserscannerdaten werden vor allem Effekte berücksichtigt, die durch das sequenzielle Aufnahmeprinzip eines Scanners auftreten. Auf Basis der entwickelten und implementierten Methodik erfolgt die Auswertung der aufgenommenen Bildsequenzen und multi-temporalen Laserscans. Das Ergebnis der monoskopischen Bildsequenzauswertung ist ein dichtes Raster an Bewegungskurven für jede Bildsequenz. Die einzelnen Translationen der Bewegungskurven können mit einer Genauigkeit von einigen Zentimetern bis zu einem Dezimeter bestimmt werden. Die Auswertung der Laserscannerdaten liefert räumlich hochaufgelöste digitale Geländemodelle der Gletscheroberfläche sowie ein dichtes Raster von 3D-Bewegungsvektoren, deren Genauigkeit im Dezimeterbereich liegt. Anhand von Beispielen wird gezeigt, dass sich die aus monokularen Bildsequenzen abgeleiteten Bewegungsvektorfelder zur Bestimmung frontnaher Geschwindigkeitsfelder mit hoher räumlicher Auflösung, zur Ableitung der Lage und der Migration der Aufsetzlinie aus gezeiteninduzierten Vertikalbewegungen sowie zur Untersuchung des Geschwindigkeitsverhalten von Gletschern bei Kalbungsereignissen eignen. Aus den Laserscannerdaten können hochaufgelöste digitale Geländemodelle zur Dokumentation von Fronthöhen und Gletscherstrukturen abgeleitet werden, zudem eignen sie sich zur Bestimmung von Geschwindigkeitsfeldern, die eine sehr hohe räumliche Auflösung besitzen. / This research aims to determine the motion vector fields of glaciers with high spatial and temporal resolution. These vector fields can be derived from monocular image sequences and are a valuable data source for glaciological analysis of the motion behaviour of glaciers. Image sequence measurements have been conducted at five fast-flowing glaciers in the Disko Bay region in western Greenland. Especially at the Jakobshavn Isbræ – one of the fastest and most productive glaciers in Greenland – numerous image sequences have been recorded, as well as multi-temporal laser scanner data sets. These measurements provide the basic data sets for this thesis. The measurement concepts for the acquisition of image sequences and multi-temporal laser scans are presented, and procedures for the processing of the recorded data are developed, based on the principle of monoscopic image sequence analysis. Both the image sequences and multi-temporal laser scans are acquired statically. Motion vector fields can be derived by applying automatic co-registration methods on grey value patterns in the image sequences and on 3D point patterns in the laser scanner datasets respectively. Thus, standard matching techniques have been adapted to the special characteristics of the glacier data, and suitable methods that solve detail problems have been developed in addition. The method of the image sequence analysis has been optimised with respect to its robustness against errors caused by moving shadows. Furthermore, motion effects caused by small instabilities in the camera setup have been corrected. Regarding the analysis of multi-temporal laser scanner data, effects that occur because of the sequential acquisition principle of a laser scanner must also be considered. Based on the developed method, the image sequences and multi temporal laser scans have been processed. The result of the monoscopic image sequence analysis is a dense raster of trajectories for each image sequence. Each translation component from these trajectories can be determined with an accuracy of some centimeters up to one decimetre. The processing of the laser scanner data provides digital surface models of the glacier with high spatial resolution, and a dense raster of 3D motion vectors with accuracy in the range of decimetres. Specific examples show that motion vector fields derived from monocular image sequences can be used for the determination of high resolution velocity fields of glaciers, for the determination of the position and migration of the grounding line and for the investigation of a glacier’s motion behaviour during calving events. From the multi-temporal laser scanner data, velocity fields with high spatial resolution can be derived as well as digital surface models from single scans that document glacier front heights and glacier structures.

No description available.

Understanding the movement behavior and foraging strategies of individuals across multiple spatial and temporal scales is essential not only for understanding the biological requirements of individuals but also for linking individual strategies to population level effects. Glacial fjords scattered throughout south-central and southeastern Alaska host some of the largest seasonal aggregations of harbor seals (Phoca vitulina richardii) in the world, and an estimated 15% of the harbor seal population in Alaska is found seasonally at these glacial ice sites. Over the last two decades, the number of harbor seals has declined at two of the primary glacial fjords, in Aialik Bay in south-central Alaska and in Glacier Bay in southeastern Alaska, thus raising concerns regarding the viability of seal populations in glacial fjord environments. From 2004-2009, the foraging ecology, diving behavior, and migration patterns of harbor seals from Glacier Bay National Park, Alaska were examined in relation to prey availability and oceanographic features in Glacier Bay and the surrounding regions of southeastern Alaska. Time-depth recorders, very high frequency transmitters, and satellite-linked transmitters were used to quantify the vertical and horizontal movement patterns of harbor seals in the marine environment. Specifically, (1) I characterized the diving behavior, foraging areas, and foraging strategies of female harbor seals from terrestrial and glacial ice sites relative to prey availability during the breeding season (May-June) in Glacier Bay, (2) I quantified the intra-population variation in at-sea post-breeding season (September-April) distribution and movement patterns of female harbor seals in relation to oceanographic features, (3) I quantified the post-breeding season migration patterns of female harbor seals relative to the boundaries of the marine protected area of Glacier Bay National Park, and (4) I characterized the use of the continental shelf region of the eastern Gulf of Alaska by female harbor seals from Glacier Bay, both as a foraging area and as a migratory corridor in relation to oceanographic features. During the breeding season, there was a substantial degree of intra-population variation in the diving behavior and foraging areas of juvenile and adult female seals from glacial ice and terrestrial sites in Glacier Bay. The presence of multiple diving strategies suggests that differences in the relative density and depth of prey fields in glacial ice and terrestrial habitats in addition to seal age and reproductive status may influence diving and foraging behavior of harbor seals. During the post-breeding season, juvenile and adult female harbor seals ranged extensively beyond the boundaries of the marine protected area of Glacier Bay National Park, throughout the northern inshore waters of southeastern Alaska and the continental shelf region of the eastern Gulf of Alaska between Cross Sound and Prince William Sound, Alaska (up to 900 kilometers away). Seals exhibited a relatively high degree of intra-population variation in their at-sea post-breeding season distribution patterns that may be a function of extrinsic factors such as oceanographic characteristics, which can influence prey availability as well as intrinsic factors including previous experience with foraging areas and seal condition and age. Use of the continental shelf region of the eastern Gulf of Alaska by harbor seals as a foraging area may be due to enhanced biological productivity which may be associated with ephemeral hydrographic and/or static bathymetric features. Despite extensive migrations of seals from Glacier Bay during the post-breeding season, there was a high degree of inter-annual site fidelity of seals to Glacier Bay the following breeding season after seals were captured. / Graduation date: 2012