Bibliografias temáticas / Marine Ice sheet

Literatura científica selecionada sobre o tema "Marine Ice sheet"

Autor: Grafiati

Publicado: 25 de maio de 2024

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Artigos de revistas sobre o assunto "Marine Ice sheet"

Gandy, Niall, Lauren J. Gregoire, Jeremy C. Ely, Christopher D. Clark, David M. Hodgson, Victoria Lee, Tom Bradwell e Ruza F. Ivanovic. "Marine ice sheet instability and ice shelf buttressing of the Minch Ice Stream, northwest Scotland". Cryosphere 12, n.º 11 (23 de novembro de 2018): 3635–51. http://dx.doi.org/10.5194/tc-12-3635-2018.

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Abstract. Uncertainties in future sea level projections are dominated by our limited understanding of the dynamical processes that control instabilities of marine ice sheets. The last deglaciation of the British–Irish Ice Sheet offers a valuable example to examine these processes. The Minch Ice Stream, which drained a large proportion of ice from the northwest sector of the British–Irish Ice Sheet during the last deglaciation, is constrained with abundant empirical data which can be used to inform, validate, and analyse numerical ice sheet simulations. We use BISICLES, a higher-order ice sheet model, to examine the dynamical processes that controlled the retreat of the Minch Ice Stream. We perform simplified experiments of the retreat of this ice stream under an idealised climate forcing to isolate the effect of marine ice sheet processes, simulating retreat from the continental shelf under constant “warm” surface mass balance and sub-ice-shelf melt. The model simulates a slowdown of retreat as the ice stream becomes laterally confined at the mouth of the Minch strait between mainland Scotland and the Isle of Lewis, resulting in a marine setting similar to many large tidewater glaciers in Greenland and Antarctica. At this stage of the simulation, the presence of an ice shelf becomes a more important control on grounded ice volume, providing buttressing to upstream ice. Subsequently, the presence of a reverse slope inside the Minch strait produces an acceleration in retreat, leading to a “collapsed” state, even when the climate returns to the initial “cold” conditions. Our simulations demonstrate the importance of the marine ice sheet instability and ice shelf buttressing during the deglaciation of parts of the British–Irish Ice Sheet. We conclude that geological data could be applied to further constrain these processes in ice sheet models used for projecting the future of contemporary ice sheets.

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Mulder, T. E., S. Baars, F. W. Wubs e H. A. Dijkstra. "Stochastic marine ice sheet variability". Journal of Fluid Mechanics 843 (23 de março de 2018): 748–77. http://dx.doi.org/10.1017/jfm.2018.148.

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It is well known that deterministic two-dimensional marine ice sheets can only be stable if the grounding line is positioned at a sufficiently steep, downward sloping bedrock. When bedrock conditions favour instabilities, multiple stable ice sheet profiles may occur. Here, we employ continuation techniques to examine the sensitivity of a two-dimensional marine ice sheet to stochastic noise representing short time scale variability, either in the accumulation rate or in the sea level height. We find that in unique regimes, the position of the grounding line is most sensitive to noise in the accumulation rate and can explain excursions observed in field measurements. In the multiple equilibrium regime, there is a strong asymmetry in transition probabilities between the different ice sheet states, with a strong preference to switch to the branch with a steeper bedrock slope.

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HASELOFF, MARIANNE, e OLGA V. SERGIENKO. "The effect of buttressing on grounding line dynamics". Journal of Glaciology 64, n.º 245 (7 de maio de 2018): 417–31. http://dx.doi.org/10.1017/jog.2018.30.

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ABSTRACTDetermining the position and stability of the grounding line of a marine ice sheet is a major challenge for ice-sheet models. Here, we investigate the role of lateral shear and ice-shelf buttressing in grounding line dynamics by extending an existing boundary layer theory to laterally confined marine ice sheets. We derive an analytic expression for the ice flux at the grounding line of confined marine ice sheets that depends on both local bed properties and non-local ice-shelf properties. Application of these results to a laterally confined version of the MISMIP 1a experiment shows that the boundary condition at the ice-shelf front (i.e. the calving law) is a major control on the location and stability of the grounding line in the presence of buttressing, allowing for both stable and unstable grounding line positions on downwards sloping beds. These results corroborate the findings of existing numerical studies that the stability of confined marine ice sheets is influenced by ice-shelf properties, in contrast to unconfined configurations where grounding line stability is solely determined by the local slope of the bed. Consequently, the marine ice-sheet instability hypothesis may not apply to buttressed marine ice sheets.

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Schoof, Christian. "Marine ice sheet stability". Journal of Fluid Mechanics 698 (15 de março de 2012): 62–72. http://dx.doi.org/10.1017/jfm.2012.43.

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AbstractWe examine the stability of two-dimensional marine ice sheets in steady state. The dynamics of marine ice sheets is described by a viscous thin-film model with two Stefan-type boundary conditions at the moving boundary or ‘grounding line’ that marks the transition from grounded to floating ice. One of these boundary conditions constrains ice thickness to be at a local critical value for flotation, which depends on depth to bedrock at the grounding line. The other condition sets ice flux as a function of ice thickness at the grounding line. Depending on the shape of the bedrock, multiple equilibria may be possible. Using a linear stability analysis, we confirm a long-standing heuristic argument that asserts that the stability of these equilibria is determined by a simple mass balance consideration. If an advance in the grounding line away from its steady-state position leads to a net mass gain, the steady state is unstable, and stable otherwise. This also confirms that grounding lines can only be stable in positions where bedrock slopes downwards sufficiently steeply.

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Pegler, Samuel S. "Suppression of marine ice sheet instability". Journal of Fluid Mechanics 857 (25 de outubro de 2018): 648–80. http://dx.doi.org/10.1017/jfm.2018.742.

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A long-standing open question in glaciology concerns the propensity for ice sheets that lie predominantly submerged in the ocean (marine ice sheets) to destabilise under buoyancy. This paper addresses the processes by which a buoyancy-driven mechanism for the retreat and ultimate collapse of such ice sheets – the marine ice sheet instability – is suppressed by lateral stresses acting on its floating component (the ice shelf). The key results are to demonstrate the transition between a mode of stable (easily reversible) retreat along a stable steady-state branch created by ice-shelf buttressing to tipped (almost irreversible) retreat across a critical parametric threshold. The conditions for triggering tipped retreat can be controlled by the calving position and other properties of the ice-shelf profile and can be largely independent of basal stress, in contrast to principles established from studies of unbuttressed grounding-line dynamics. The stability and recovery conditions introduced by lateral stresses are analysed by developing a method of constructing grounding-line stability (bifurcation) diagrams, which provide a rapid assessment of the steady-state positions, their natures and the conditions for secondary grounding, giving clear visualisations of global stabilisation conditions. A further result is to reveal the possibility of a third structural component of a marine ice sheet that lies intermediate to the fully grounded and floating components. The region forms an extended grounding area in which the ice sheet lies very close to flotation, and there is no clearly distinguished grounding line. The formation of this region generates an upsurge in buttressing that provides the most feasible mechanism for reversal of a tipped grounding line. The results of this paper provide conceptual insight into the phenomena controlling the stability of the West Antarctic Ice Sheet, the collapse of which has the potential to dominate future contributions to global sea-level rise.

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Pegler, Samuel S. "Marine ice sheet dynamics: the impacts of ice-shelf buttressing". Journal of Fluid Mechanics 857 (25 de outubro de 2018): 605–47. http://dx.doi.org/10.1017/jfm.2018.741.

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Marine ice sheets are continent-scale glacial masses that lie partially submerged in the ocean, as applies to significant regions of Antarctica and Greenland. Such ice sheets have the potential to destabilise under a buoyancy-driven instability mechanism, with considerable implications for future sea level. This paper and its companion present a theoretical analysis of marine ice sheet dynamics under the effect of a potentially dominant control of the buttressing force generated by lateral stresses on the downstream floating component of the ice sheet (the ice shelf). The analysis reveals critical conditions under which ice-shelf buttressing suppresses the buoyancy-driven collapse of an ice sheet and elucidates the implications of lateral stresses on grounding-line control and overall ice-sheet structure. Integrations of a suitably simplified quasi-two-dimensional model are conducted, yielding analytical results that provide a quick assessment of steady-state balances for a given ice-sheet configuration. An analytical balance equation describing the spectrum of marine ice sheet flow regimes spanning zero to strong ice-shelf buttressing is developed. It is determined that the dynamics across this spectrum exhibits markedly different flow regimes and structural characteristics. For sufficient buttressing, the grounding line occurs near to where a lateral-drag controlled section of the ice shelf meets the bedrock, implying an independent control of the grounding line by the ice shelf. The role of basal stresses is relegated to controlling only the thickness of the ice sheet upstream of the grounding line, with no significant control of the grounding line itself. It is further demonstrated that lateral stresses are responsible for inducing additional secondary contacts between the ice shelf and the bedrock downstream of the grounding line, resulting in a rich variety of additional steady states. These inducements generate a further stabilising mechanism that can fully suppress grounding-line retreat and eliminate otherwise irreparable hysteresis effects. The results provide a conceptual framework for numerical and observational interpretation of marine ice sheet dynamics, and clarifies the manner in which ice shelves can control grounding-line positions independently. It is thus indicated that a full resolution of the fine details of the flow of ice shelves and the processes controlling their erosion and disintegration is necessary for the confident forecasting of possible ice-sheet collapse over the course of the next few centuries.

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Meur, E. Le, e Richard C. A. Hindmarsh. "Coupled marine-ice-sheet/Earth dynamics using a dynamically consistent ice-sheet model and a self-gravitating viscous Earth model". Journal of Glaciology 47, n.º 157 (2001): 258–70. http://dx.doi.org/10.3189/172756501781832322.

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AbstractWe use a self-gravitating viscoelastic model of the Earth and a dynamically consistent marine ice-sheet model to study the relationships between marine ice-sheet dynamics, relative sea level, basal topography and bedrock dynamics. Our main conclusion is that sea-level change and lithospheric coupling are likely to have played limited roles in the postglacial retreat of marine ice sheets. The postglacial rise in sea level would only have caused at the most around 100 km of grounding-line retreat for an ice sheet of similar dimensions to the West Antarctic ice sheet, compared with the several hundred km of retreat which has occurred in the Ross Sea. There is no evidence that reverse slopes lead to instability. Incorporating coupling with lithospheric dynamics does not produce markedly different effects. The implication of these studies is that marine ice-sheet retreat is the result of physical mechanisms other than lithospheric coupling and sea-level rise.

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Leguy, Gunter R., William H. Lipscomb e Xylar S. Asay-Davis. "Marine ice sheet experiments with the Community Ice Sheet Model". Cryosphere 15, n.º 7 (14 de julho de 2021): 3229–53. http://dx.doi.org/10.5194/tc-15-3229-2021.

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Abstract. Ice sheet models differ in their numerical treatment of dynamical processes. Simulations of marine-based ice are sensitive to the choice of Stokes flow approximation and basal friction law and to the treatment of stresses and melt rates near the grounding line. We study the effects of these numerical choices on marine ice sheet dynamics in the Community Ice Sheet Model (CISM). In the framework of the Marine Ice Sheet Model Intercomparison Project 3d (MISMIP3d), we show that a depth-integrated, higher-order solver gives results similar to a 3D (Blatter–Pattyn) solver. We confirm that using a grounding line parameterization to approximate stresses in the grounding zone leads to accurate representation of ice sheet flow with a resolution of ∼2 km, as opposed to ∼0.5 km without the parameterization. In the MISMIP+ experimental framework, we compare different treatments of sub-shelf melting near the grounding line. In contrast to recent studies arguing that melting should not be applied in partly grounded cells, it is usually beneficial in CISM simulations to apply some melting in these cells. This suggests that the optimal treatment of melting near the grounding line can depend on ice sheet geometry, forcing, or model numerics. In both experimental frameworks, ice flow is sensitive to the choice of basal friction law. To study this sensitivity, we evaluate friction laws that vary the connectivity between the basal hydrological system and the ocean near the grounding line. CISM yields accurate results in steady-state and perturbation experiments at a resolution of ∼2 km (arguably 4 km) when the connectivity is low or moderate and ∼1 km (arguably 2 km) when the connectivity is strong.

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Tsai, Victor C., Andrew L. Stewart e Andrew F. Thompson. "Marine ice-sheet profiles and stability under Coulomb basal conditions". Journal of Glaciology 61, n.º 226 (2015): 205–15. http://dx.doi.org/10.3189/2015jog14j221.

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AbstractThe behavior of marine-terminating ice sheets, such as the West Antarctic ice sheet, is of interest due to the possibility of rapid grounding-line retreat and consequent catastrophic loss of ice. Critical to modeling this behavior is a choice of basal rheology, where the most popular approach is to relate the ice-sheet velocity to a power-law function of basal stress. Recent experiments, however, suggest that near-grounding line tills exhibit Coulomb friction behavior. Here we address how Coulomb conditions modify ice-sheet profiles and stability criteria. The basal rheology necessarily transitions to Coulomb friction near the grounding line, due to low effective stresses, leading to changes in ice-sheet properties within a narrow boundary layer. Ice-sheet profiles ‘taper off’ towards a flatter upper surface, compared with the power-law case, and basal stresses vanish at the grounding line, consistent with observations. In the Coulomb case, the grounding-line ice flux also depends more strongly on flotation ice thickness, which implies that ice sheets are more sensitive to climate perturbations. Furthermore, with Coulomb friction, the ice sheet grounds stably in shallower water than with a power-law rheology. This implies that smaller perturbations are required to push the grounding line into regions of negative bed slope, where it would become unstable. These results have important implications for ice-sheet stability in a warming climate.

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Zweck, Chris, e Philippe Huybrechts. "Modeling the marine extent of Northern Hemisphere ice sheets during the last glacial cycle". Annals of Glaciology 37 (2003): 173–80. http://dx.doi.org/10.3189/172756403781815870.

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AbstractMechanisms that determine time-dependent changes of the marine ice margin in dynamic ice-sheet models are important but poorly understood. Here we derive an empirical formulation for changes in the marine extent when modelling the Northern Hemisphere ice sheets over the last glacial cycle in a three-dimensional thermomechanically coupled ice-sheet model. We assume that the strongest control on changes in marine extent is ice calving, and that the variable most crucial to calving is water depth. The empirical marine-extent relationship is tuned so that the major marine-retreat history of the Laurentide and Eurasian ice sheets is modelled accurately in time and space. We find that this empirical treatment relating marine extent to water depth is sufficient to reproduce the observations, and discuss the implications for the physics of marine margin changes and the dynamics of the Northern Hemisphere ice sheets since the Last Glacial Maximum.

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Mais fontes

Teses / dissertações sobre o assunto "Marine Ice sheet"

Koester, Alexandria Jo. "Rapid thinning of the Laurentide Ice Sheet in coastal Maine, USA during late Heinrich Stadial 1:". Thesis, Boston College, 2017. http://hdl.handle.net/2345/bc-ir:107308.

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Thesis advisor: Jeremy D. Shakun
Few data are available to infer the thinning rate of the Laurentide Ice Sheet (LIS) through the last deglaciation, despite its importance for constraining past ice sheet response to climate warming. We measured 31 cosmogenic 10Be exposure ages in samples collected on coastal mountainsides in Acadia National Park and from the slightly inland Pineo Ridge moraine complex, a ~100-km-long glaciomarine delta, to constrain the timing and rate of LIS thinning and subsequent retreat in coastal Maine. Samples collected along vertical transects in Acadia National Park have indistinguishable exposure ages over a 300 m range of elevation, suggesting that rapid, century-scale thinning occurred at 15.2 ± 0.7 ka, similar to the timing of abrupt thinning inferred from cosmogenic exposure ages at Mt. Katahdin in central Maine (Davis et al., 2015). This rapid ice sheet surface lowering, which likely occurred during the latter part of the cold Heinrich Stadial 1 event (19-14.6 ka), may have been due to enhanced ice-shelf melt and calving in the Gulf of Maine, perhaps related to regional oceanic warming associated with a weakened Atlantic Meridional Overturning Circulation at this time. The ice margin subsequently stabilized at the Pineo Ridge moraine complex until 14.5 ± 0.7 ka, near the onset of Bølling Interstadial warming. Our 10Be ages are substantially younger than marine radiocarbon constraints on LIS retreat in the coastal lowlands, suggesting that the deglacial marine reservoir effect in this area was ~1,200 14C years, perhaps also related to the sluggish Atlantic Meridional Overturning Circulation during Heinrich Stadial 1
Thesis (MS) — Boston College, 2017
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Earth and Environmental Sciences

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Nicholl, Joseph Anthony Leo. "Changes in ice sheet dynamics across the mid-Pleistocene transition recorded in North Atlantic sediments". Thesis, University of Cambridge, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.648858.

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Simmons, Sarah-Louise. "An investigation into the effect of glacially exported nutrients from the Greenland Ice Sheet on marine primary production". Thesis, University of Bristol, 2016. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.742982.

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Cook, Carys Patricia. "Insights into the behaviour of the Pliocene East Antarctic ice sheet from provenance studies of marine sediments using radiogenic isotopoes". Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/14262.

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Direct evidence for the response of Earth’s largest continental ice mass, the East Antarctic ice sheet (EAIS), to climatic warmth is extremely limited. The primary aim of this thesis is to improve understanding of the behaviour of the EAIS during the warmer-than-present Pliocene Epoch (2.58 to 5.33 million years ago). To this end, I analysed the radiogenic neodymium and strontium isotopic provenance of fine-grained (<63μm) Pliocene detrital marine sediments deposited offshore of the East Antarctic continent, which can provide information on source bedrock characteristics, continental erosional patterns and marine sediment depositional processes. In addition, I also analysed argon isotopic ages of ice-rafted hornblende grains (>150μm), to infer sites of major iceberg production events through time. Within this thesis, I present Pliocene marine sediment data from various cores drilled from the East Antarctic margin, thereby developing a detailed framework for linking provenance variability to ice sheet behaviour. My key findings have been collated into five distinct chapters, providing: i) the first evidence for significant retreat of the EAIS in the low-lying Wilkes Subglacial Basin in response to the earliest Pliocene climatic warmth; ii) insights into the benefits and pitfalls associated with utilising different tools in glaciomarine sediment provenance studies; iii) constraints on the behaviour of the EAIS and West Antarctic ice sheet during the warmth of Pleistocene super-interglacial, Marine Isotope Stage 31; iv) insights into the role of declining sea surface termperatures during the Pliocene on the flux and provenance of distally sourced ice-rafted detritus, along with evidence for potential ice sheet destabilisation events in the Aurora Subglacial Basin during Pliocene interglacials; and v) advances in understanding of the evolution of the EAIS during the Late Pliocene climatic transition, and its role in global Pliocene climate change. Hence, the findings presented within this thesis provide new and significant evidence for the behaviour of the EAIS during the Pliocene, and suggest it has in the past been more sensitive to climatic change than previously realised.

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Sacchetti, Fabio. "Late Quaternary sedimentation associated with the British-Irish Ice Sheet on the NW Irish continental slope: a marine geological and geophysical investigation". Thesis, University of Manchester, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.646396.

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This research demonstrates the impact that glaciations had on the geomorphology and sediment deposition of the NW Irish continental margin, including both sides of the Rockall Trough and the Rockall Bank. A modern hydrographic, geophysical and sedimentological approach is used to analyse and interpret new and historical datasets, including multi beam, sidescan sonar, seismic and core data. New methodologies such as CUBE and Geocoder algorithms for multi beam bathymetry and backscatter data processing, 3D visualisations, ArcGIS Spatial and Hydrological Analysis and digital X-Ray scanning are used to deliver an accurate geomorphological and sedimentological interpretation and to understand the changes that occurred in the sedimentary processes from shelf edge to basin floor since the last glaciation, through deglaciation and in the Holocene. This research demonstrates a number of correlations between glacial geomorphology observed on the continental shelf and the various geomorphological and sedimentary features observed along the NW Irish continental slope and trough. It also provides extensive evidence that the Rockall Bank was scoured by several generations of icebergs and acted as a natural barrier against which icebergs coming from the western Atlantic Ocean grounded. Near seabed geophysical investigation throughout the Irish Rockall Trough is used to classify the area into six sedimentary provinces, each characterised by different depositional processes. This also provides new evidence of previously undetected mass transport deposits and extensive fluid-migration on a wide area of the trough. Finally, the study of sediment cores along two major canyons and across the trough provides a regional perspective on the sedimentary processes that took place since the last glaciation on the north-eastern margin of the Rockall Trough. The study reveals that margin physiography, distance from the ice sheet grounding zone, style of glaciation on the shelf and strength of deep sea circulation are the main controlling factors over the depositional processes.

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Leigh, Sasha Naomi Bharier. "A study of the dynamics of the British Ice Sheet during Marine Isotope Stages 2 and 3, focusing on Heinrich Events 2 and 4 and their relationship to the North Atlantic glaciological and climatological conditions /". St Andrews, 2007. http://hdl.handle.net/10023/525.

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Hibbert, Fiona Danielle. "Dynamics of the British Ice Sheet and prevailing hydrographic conditions for the last 175,000 years : an investigation of marine sediment core MD04-2822 from the Rockall Trough". Thesis, University of St Andrews, 2011. http://hdl.handle.net/10023/3136.

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This study presents a stratigraphic investigation of the marine sediment core MD04-2822 from the Rockall Trough (56° 50.54' N, 11° 22.96' W; 2344 m water depth). This core is currently the only available high resolution record for the calibration of Late Quaternary sedimentary sequences of the British (Hebridean) margin. It therefore offers an unprecedented archive of changing sedimentological and climatological conditions for the last 175,000 years. The high resolution, multi-proxy records have enabled surface and deep water conditions within the Rockall Trough to be reconstructed. In addition, the fluctuating nature of ice-rafted debris (IRD) inputs to the MD04-2822 site allows a first order attempt of BIS dynamics for the entirety of the last glacial period (i.e. from the demise of the last interglacial to the decay of the Devensian/Weichselian ice sheet) as well as the majority of the penultimate (Saalian/MIS 6) glaciation. Sediment core MD04-2822 is ideally located to capture the dynamics of the British Ice Sheet (BIS) via a continuous record of IRD and fine-grained terrigenous inputs. Fundamental to this is the construction of a robust chronology. This was achieved via: the correlation of the benthic δ¹⁸O record to a global δ¹⁸O stack (SPECMAP); the correlation of the surface proxies (% N. pachyderma (sinistral) and XRF Ca) to the Greenland δ¹⁸O and Antarctic methane ice core records; and radiocarbon dating. This chronology was validated using both radiocarbon dating and tephra horizons. An evaluation of the event stratigraphy approach used in the construction of the MD04-2822 chronology is presented. The marine record provides a valuable archive of past ice sheet dynamics as much terrestrial evidence is removed or obscured by subsequent ice sheet oscillations MD04-2822 provides the first evidence for the expansion of the BIS onto the Hebridean Margin during MIS6 (thereby confirming previous long-range seismic correlations). The continuous sedimentation at MD04-2822 enabled the first insights into the early dynamics of the last BIS. Increases in IRD and fine grained terrigenous material delivered to the MD04-2822 at ca. 72 kyr represent the first significant delivery of material from the BIS across the continental shelf to the core site. The BIS would therefore have attained a marine calving margin by this time. A multi-proxy investigation of provenance was undertaken, however unequivocal provenance determinations remain problematic. The location of the core suggest the proximal BIS as the most likely source of terrigenous inputs. The expanded nature of the MD04-2822 sediments during the penultimate deglacial (Termination II) provides the first details of BIS dynamics for this period: the interplay of large inputs of freshwater from the decay of the Saalian (MIS 6) ice sheets (including the BIS) upon the surface and deep water circulation of the North Atlantic is investigated. In addition, sub-orbital climatic variability is documented at this location throughout the last interglacial (MIS 5e) and appears to be an intrinsic feature of both the N.E. Atlantic surface and deep water circulation of the last 175 kyr.

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Hill, Heather W. "Abrupt climate change during the last glacial period : a Gulf of Mexico perspective". [Tampa, Fla] : University of South Florida, 2006. http://purl.fcla.edu/usf/dc/et/SFE0001539.

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Van, Aalderen Victor. "Modéliser l'évolution du climat global et de la calotte eurasienne pendant la dernière déglaciation". Electronic Thesis or Diss., université Paris-Saclay, 2023. http://www.theses.fr/2023UPASJ029.

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La calotte marine de l'Antarctique de l'Ouest présente la particularité d'être en grande partie en contact avec l'océan. Les dernières observations révèlent une accélération de sa perte de masse sur les dernières décennies, essentiellement provoquée par l'augmentation de la fonte sous les plateformes de glace flottante. En revanche, son évolution future reste très incertaine, du fait de notre mauvaise compréhension des processus physiques mis en jeu entre la calotte et l'océan.La dernière déglaciation (-21 000 - -11 000 ans), constitue l'un des changements climatiques majeurs les plus récents de notre histoire. Cette période est marquée par une augmentation des températures atmosphériques globales et la disparition des calottes nord-américaine et eurasienne. L'étude de la calotte marine de Barents-Kara (BKIS), qui couvrait les mers de Barents et de Kara au Dernier Maximum Glaciaire (DMG, -21 000 ans) et faisait partie intégrante de la calotte eurasienne, revêt un intérêt particulier en raison de ses caractéristiques communes avec l'Antarctique de l'Ouest actuel. Identifier les mécanismes responsables de son recul permet de fournir des informations pour mieux comprendre le comportement de l'Antarctique de l'Ouest dans des contextes climatiques actuel et futur.L'impact du climat sur l'évolution d'une calotte marine dépend de deux processus principaux : le bilan de masse de surface, influencé par les températures atmosphériques et précipitations, ainsi que la fonte sous la glace flottante, liée aux températures océaniques et la salinité. Pour identifier les mécanismes ayant initié la fonte de BKIS, j'ai utilisé le modèle de glace GRISLI2.0 afin d'analyser la réponse de cette calotte à des perturbations du climat au DMG. Cette étude a mis en évidence le rôle déterminant des températures atmosphériques dans le déclenchement de la fonte de la calotte via la fonte de surface, tandis que les températures océaniques n'ont eu qu'un impact limité malgré une grande partie de la calotte BKIS en contact avec l'océan. J'ai aussi identifié que la fonte totale BKIS pouvait être attribuée à une instabilité mécanique à la ligne d'échouage, provoquée par une diminution de l'épaisseur de glace dû à une augmentation de la fonte de surface. Afin de mieux comprendre l'impact des calottes sur le climat global, j'ai également réalisé la première simulation transitoire de la dernière déglaciation avec le modèle IPSL-CM5A2 en modifiant à certaines périodes clés la géométrie des calottes de glace donnée par la reconstruction GLAC-1D. Les simulations montrent une tendance du réchauffement en accord avec les reconstructions, notamment lors du MWP1A caractérisé par une augmentation abrupte des températures atmosphériques. A partir d'expériences de sensibilité, j'ai mis en évidence que les changements de géométrie des calottes glaciaires ont participé à l'augmentation des températures atmosphérique via les rétroactions température-altitude et l'effet d'albédo. Par ailleurs, j'ai aussi montré que la dynamique océanique a été notablement perturbée par les flux d'eau douce issus de la fonte des calottes. Ce phénomène a conduit à une atténuation de l'intensité de la circulation méridienne de retournement de l'Atlantique et à une réduction de sa profondeur de plongée, entraînant un ralentissement du réchauffement, principalement dans l'Atlantique Nord. De plus, les expériences IPSL-CM5A2 simulent toutes un arrêt de la circulation des eaux de fond antarctiques au début du MWP1A, entraînant un refroidissement significatif d'une centaine d'années dans la mer d'Amundsen, suivi d'une réactivation de cette même circulation. Ces travaux contribuent ainsi à une meilleure compréhension des mécanismes complexes régissant la dynamique des calottes glaciaires et de leur interaction avec le climat, tout en offrant des éléments de réponse pour anticiper les conséquences des changements climatiques actuels et futurs, notamment en ce qui concerne l'Antarctique de l'Ouest
The marine West Antarctic ice sheet is characterized by being largely in contact with the ocean. The latest observations reveal an acceleration in its mass loss over the last few decades, mainly due to increased melting under floating ice shelves. However, its future evolution remains highly uncertain, due to our poor understanding of the physical processes at play between the ice sheet and the ocean.The last deglaciation (21 ka-11 ka) is one of the most recent major climatic changes in our history. This period is marked by an increase in global atmospheric temperatures and the melting of the North American and Eurasian ice sheets. The study of the Barents-Kara Ice Sheet (BKIS), which covered the Barents and Kara Seas during the Last Glacial Maximum (LGM, 21 ka) and was an integral part of the Eurasian Ice Sheet, is of particular interest because of its common features with present-day West Antarctica. Identifying the mechanisms responsible for its retreat allows to provide information to better understand the West Antarctic behavior within under present and future climatic conditions.The impact of climate on the evolution of a marine ice sheet depends on two main processes: The surface mass balance, depending on atmospheric temperatures and precipitation, and melting under floating ice, related to oceanic temperatures and salinity. In order to identify the mechanisms triggering the BKIS retreat, I used the GRISLI2.0 ice-sheet model to analyse the ice-sheet response to climate perturbations at the LGM. This study highlighted the key role of atmospheric temperatures in triggering the melting of the ice sheet via surface melting, while ocean temperatures had only a limited impact despite a large part of BKIS being in contact with the ocean. I also identified that the total retreat of BKIS could be attributed to a mechanical instability at the grounding line, caused by a decrease in ice thickness resulting from an increase in surface melting.In order to better understand the impact of ice sheets on the global climate, I have also carried out the first transient simulation of the last deglaciation with the IPSL-CM5A2 model, modifying the geometry of the ice sheets provided by the GLAC-1D reconstruction at some key periods. The simulations show a warming trend in line with the reconstructions, particularly during MWP1A, which was characterised by an abrupt rise in atmospheric temperatures. Using sensitivity experiments, I have shown that changes in the ice sheet geometry have contributed to the increase in atmospheric temperatures via temperature-altitude feedbacks and the albedo effect. Moreover, I have shown that ocean dynamics have been significantly altered by freshwater fluxes from the melting ice sheets. This has led to a weakening of the strength of the Atlantic Meridional Overturning Circulation and a reduction of its deepening, resulting in a warming slowdown, mainly located in the North Atlantic Ocean. In addition, the IPSL-CM5A2 experiments all simulate a shutdown of the Antarctic bottom water circulation at the onset of MWP1A, leading to a significant cooling of about 100 years in the Amundsen Sea, followed by a restart of this circulation.This work is contributing to a better understanding of the complex mechanisms governing the dynamics of the ice sheets and their interaction with the climate, while also providing a basis for anticipating the consequences of current and future climate change, particularly in West Antarctica

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Nowicki, Sophie Marie Jeanne. "Modelling the transition zone of marine ice sheets". Thesis, University College London (University of London), 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.499076.

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Livros sobre o assunto "Marine Ice sheet"

Bindschadler, R. A. SeaRISE: A multidisciplinary research initiative to predict rapid changes in global sea level caused by collapse of marine ice sheets. Washington, D.C: National Aeronautics and Space Administration, Office of Management, Scientific and Technical Information Division, 1990.

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Office, General Accounting. Coast Guard: Federal costs resulting from the Exxon Valdez oil spill : fact sheet for congressional requesters. Washington, D.C: GAO, 1990.

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Kassens, Heidemarie. Sistema mori͡a Laptevykh i prilegai͡ushchikh moreĭ Arktiki: Sovremennoe sostoi͡anie i istorii͡a razvitii͡a. Moskva: Moskovskiĭ gos. universitet, 2009.

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Bindschadler, R. A. SeaRISE: a multidisciplinary research initiative to predict rapid changes in global sea level caused by collapse of marine ice sheets: Proceedings of a workshop cosponsored by the National Science Foundation, Washington, D.C., and the National Aeronautics and Space Administration, Washington, D.C., and held in College Park, Maryland, January 23-25, 1990. Greenbelt, Md: Goddard Space Flight Center, 1990.

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Omstedt, Anders. The Development of Climate Science of the Baltic Sea Region. Oxford University Press, 2017. http://dx.doi.org/10.1093/acrefore/9780190228620.013.654.

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Dramatic climate changes have occurred in the Baltic Sea region caused by changes in orbital movement in the earth–sun system and the melting of the Fennoscandian Ice Sheet. Added to these longer-term changes, changes have occurred at all timescales, caused mainly by variations in large-scale atmospheric pressure systems due to competition between the meandering midlatitude low-pressure systems and high-pressure systems. Here we follow the development of climate science of the Baltic Sea from when observations began in the 18th century to the early 21st century. The question of why the water level is sinking around the Baltic Sea coasts could not be answered until the ideas of postglacial uplift and the thermal history of the earth were better understood in the 19th century and periodic behavior in climate related time series attracted scientific interest. Herring and sardine fishing successes and failures have led to investigations of fishery and climate change and to the realization that fisheries themselves have strongly negative effects on the marine environment, calling for international assessment efforts. Scientists later introduced the concept of regime shifts when interpreting their data, attributing these to various causes. The increasing amount of anoxic deep water in the Baltic Sea and eutrophication have prompted debate about what is natural and what is anthropogenic, and the scientific outcome of these debates now forms the basis of international management efforts to reduce nutrient leakage from land. The observed increase in atmospheric CO2 and its effects on global warming have focused the climate debate on trends and generated a series of international and regional assessments and research programs that have greatly improved our understanding of climate and environmental changes, bolstering the efforts of earth system science, in which both climate and environmental factors are analyzed together.Major achievements of past centuries have included developing and organizing regular observation and monitoring programs. The free availability of data sets has supported the development of more accurate forcing functions for Baltic Sea models and made it possible to better understand and model the Baltic Sea–North Sea system, including the development of coupled land–sea–atmosphere models. Most indirect and direct observations of the climate find great variability and stochastic behavior, so conclusions based on short time series are problematic, leading to qualifications about periodicity, trends, and regime shifts. Starting in the 1980s, systematic research into climate change has considerably improved our understanding of regional warming and multiple threats to the Baltic Sea. Several aspects of regional climate and environmental changes and how they interact are, however, unknown and merit future research.

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Capítulos de livros sobre o assunto "Marine Ice sheet"

Kumar, Rajesh. "Marine Ice Sheet". In Encyclopedia of Earth Sciences Series, 725. Dordrecht: Springer Netherlands, 2011. http://dx.doi.org/10.1007/978-90-481-2642-2_340.

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Mulder, T. E., H. A. Dijkstra e F. W. Wubs. "Numerical Bifurcation Analysis of Marine Ice Sheet Models". In Computational Methods in Applied Sciences, 503–27. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-91494-7_14.

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Pattyn, Frank, Ann Huyghe, Sang De Brabander e Bert De Smedt. "Role of Transition Zones in Marine Ice Sheet Dynamics". In Collected Reprint Series, 1–10. Washington, DC: American Geophysical Union, 2014. http://dx.doi.org/10.1002/9781118782033.ch20.

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Scherer, Reed P. "Quaternary interglacials and the West Antarctic Ice Sheet". In Earth's Climate and Orbital Eccentricity: The Marine Isotope Stage 11 Question, 103–12. Washington, D. C.: American Geophysical Union, 2003. http://dx.doi.org/10.1029/137gm08.

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Pollard, David, e Robert M. Deconto. "A Coupled Ice-Sheet/Ice-Shelf/Sediment Model Applied to a Marine-Margin Flowline: Forced and Unforced Variations". In Glacial Sedimentary Processes and Products, 37–52. Oxford, UK: Blackwell Publishing Ltd., 2009. http://dx.doi.org/10.1002/9781444304435.ch4.

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Singh, Ashutosh K., Devesh K. Sinha, Vikram Pratap Singh, Kirtiranjan Mallick, Ankush Shrivastava e Tushar Kaushik. "Cenozoic Evolution of Antarctic Ice Sheet, Circum Antarctic Circulation and Antarctic Climate: Evidence from Marine Sedimentary Records". In Earth and Environmental Sciences Library, 47–71. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-87078-2_4.

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Hindmarsh, Richard C. A. "Qualitative Dynamics of Marine Ice Sheets". In Ice in the Climate System, 67–99. Berlin, Heidelberg: Springer Berlin Heidelberg, 1993. http://dx.doi.org/10.1007/978-3-642-85016-5_5.

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Johnston, Arch C. "The Effect of Large Ice Sheets on Earthquake Genesis". In Earthquakes at North-Atlantic Passive Margins: Neotectonics and Postglacial Rebound, 581–99. Dordrecht: Springer Netherlands, 1989. http://dx.doi.org/10.1007/978-94-009-2311-9_34.

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Holmes, R., J. Bulat, I. Hamilton e D. Long. "Morphology of an Ice-Sheet Limit and Constructional Glacially-Fed Slope Front, Faroe-Shetland Channel". In European Margin Sediment Dynamics, 149–52. Berlin, Heidelberg: Springer Berlin Heidelberg, 2003. http://dx.doi.org/10.1007/978-3-642-55846-7_24.

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Grgić, Marijan, e Tomislav Bašić. "Radar Satellite Altimetry in Geodesy - Theory, Applications and Recent Developments". In Geodetic Sciences - Theory, Applications and Recent Developments [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.97349.

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Radar satellite altimetry has revolutionized our understanding of the Earth’s sea-level shape and its change over time, monitoring of the natural and human-induced water cycle, marine gravity computations, seafloor relief (bathymetry) reconstruction, tectonics, water mass balance change monitoring, etc., thus providing significant impact in geodesy. Today satellite radar altimetry is critical for unifying the vertical height systems, regional and global geoid modeling, monitoring of the sea level rise impact, monitoring of the ice sheet melting, and others. This chapter gives an overview of the technology itself and the recent developments including the SAR (Synthetic Aperture Radar) altimetry, coastal altimetry retracking methods, and new satellite missions (e.g. Sentinel-6). Besides, the chapter presents recent applied studies utilizing the altimeter data for ice sheet monitoring, vertical land motion estimating, bathymetric computations, and marine geoid modeling.

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Trabalhos de conferências sobre o assunto "Marine Ice sheet"

Dowdeswell, Julian A. "THE GEOMORPHIC SIGNATURE OF PAST ICE-SHEET GROUNDING LINES IN THE MARINE RECORD". In GSA Annual Meeting in Seattle, Washington, USA - 2017. Geological Society of America, 2017. http://dx.doi.org/10.1130/abs/2017am-306091.

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Shakun, Jeremy D., Lee B. Corbett, Paul R. Bierman e Susan H. Zimmerman. "PLIOCENE GREENLAND ICE SHEET GROWTH RECORDED BY IN SITU 10BE DECREASE IN MULTIPLE MARINE SEDIMENT CORES". In GSA Annual Meeting in Seattle, Washington, USA - 2017. Geological Society of America, 2017. http://dx.doi.org/10.1130/abs/2017am-305299.

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Hemming, Sidney. "MARINE SEDIMENT PROVENANCE EVIDENCE FOR THE EXTENT OF THE LAURENTIDE ICE SHEET DURING THE LAST GLACIAL CYCLE". In GSA Connects 2022 meeting in Denver, Colorado. Geological Society of America, 2022. http://dx.doi.org/10.1130/abs/2022am-379913.

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Dalton, April S., Tamara Pico, Evan J. Gowan, John J. Clague, Steven Forman, Isabelle McMartin, Perrti Sarala e Karin F. Helmens. "REVIEWING GEOLOGICAL AND NUMERICAL EVIDENCE ON THE EXTENT OF THE LAURENTIDE ICE SHEET DURING MARINE ISOTOPE STAGE 3". In GSA Connects 2022 meeting in Denver, Colorado. Geological Society of America, 2022. http://dx.doi.org/10.1130/abs/2022am-380966.

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Christ, Andrew J., e David R. Marchant. "A TERRESTRIAL PERSPECTIVE OF THE LGM IN MCMURDO SOUND, ANTARCTICA: IMPLICATIONS FOR MARINE ICE SHEET DYNAMICS, ICE FLOW, AND DEGLACIATION OF THE ROSS SEA EMBAYMENT". In GSA Annual Meeting in Seattle, Washington, USA - 2017. Geological Society of America, 2017. http://dx.doi.org/10.1130/abs/2017am-305311.

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Parker, Shane T., e Jonathan P. Warnock. "THE EFFECT OF A WESTERN ANTARCTIC ICE SHEET COLLAPSE ON NUTRIENT RECYCLING RATES DURING MARINE ISOTOPE STAGE 31: INITIAL FINDINGS". In 53rd Annual GSA Northeastern Section Meeting - 2018. Geological Society of America, 2018. http://dx.doi.org/10.1130/abs/2018ne-311175.

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Venturelli, Ryan, Brad Rosenheim, Christina Davis, Alex Michaud, Brenna Boehman, Brent Christner, Valier Galy et al. "Millennial scale marine incursion into an isolated environment fuels a contemporary subglacial microbial community beneath the West Antarctic Ice Sheet". In Goldschmidt2023. France: European Association of Geochemistry, 2023. http://dx.doi.org/10.7185/gold2023.13607.

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Larson, Phillip, Howard D. Mooers, Angela J. Berthold e Kristi M. Kotrapu. "SEDIMENT TRANSPORT CYCLES OF THE LAURENTIDE ICE SHEET I: SOFT TO HARD BED TRANSITION DURING WISCONSIN MARINE ISOTOPE STAGE 5D-2". In 54th Annual GSA North-Central Section Meeting - 2020. Geological Society of America, 2020. http://dx.doi.org/10.1130/abs/2020nc-348205.

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BANIK, ARNOB, M. H. KHAN e K. T. TAN. "IMPACT PERFORMANCE COMPARISON OF FIBER REINFORCED COMPOSITE SANDWICH STRUCTURES IN ARCTIC CONDITION". In Proceedings for the American Society for Composites-Thirty Seventh Technical Conference. Destech Publications, Inc., 2022. http://dx.doi.org/10.12783/asc37/36380.

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About 40% of sea ice-covered areas have been reduced over the last three decades due to the effect of global warming. The Northern Sea route has been considered as a more effective, quicker, and economical sea route for marine vessels. But it is not safe to operate in such a cold and harsh environment due to the potential risk of collision with ice chunks, resulting in damages in the marine structures. It is therefore important to understand the behavior of marine composites at low temperatures, with the overarching goal that leads to improved design for marine structures and materials that can operate safely and effectively in the Arctic environment. This study investigates the low-velocity impact performance and damage mechanisms of woven carbon fiber reinforced polymer (CFRP), glass fiber reinforced polymer (GFRP), and carbon-glass fiber hybrid face sheets sandwich panel at both room temperature (23 °C) and low temperature (-70 °C) to mimic the Arctic environment. A series of low-velocity impact tests (3.46 m/s and 4.92 m/s) is performed at 15 J and 30 J energy using a drop tower testing machine. A relative comparison of the impact response due to different face sheet materials is presented in terms of force, displacement, and energy. Force-time and force-displacement plots show that GFRP sandwich composites have the highest damage initiation force and peak force values across different temperatures and impact energies. Furthermore, the lowest energy absorption for GFRP composites is found responsible for the least impact-induced damage. X-ray microcomputed tomography reveals severe fiber breakage on the compression side of CFRP sandwich panel and back face spitting at both temperatures for 30 J impacts. By replacing carbon fibers with glass fibers, the damage mechanism switches from fiber breakage to delamination as the dominant failure mode. The findings from this work will aid in a better understanding of the impact failure modes of composite sandwich structures at extremely low-temperature conditions.

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Degnan, John J., e Steven C. Cohen. "Spaceborne picosecond lidars for geoscience and other remote sensing applications". In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1986. http://dx.doi.org/10.1364/oam.1986.thk2.

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The Geoscience Laser Ranging System (GLRS), a spaceborne picosecond laser ranging and altimetry system, has been proposed as an instrument on the Earth Observing System (EOS), an unmanned remote sensing platform to be launched by NASA in the 1990s. In the ranging mode, the GLRS instrument measures the times-of-flight between the spacecraft and an array of ground-based retroreflectors. The total data set of individual range measurements can be processed to yield the 3-D relative coordinates of each target with centimeter accuracies. By revisiting the target sites at periodic intervals on subsequent orbits, relative motions can be observed. Applications include the measurement of tectonic plate or ice sheet velocities, crustal deformation, ground subsidence caused by oil or water withdrawal, large scale engineering projects (highways, pipelines, etc.), and survey densification. In the altimetry mode, GLRS measures time-of-flight to an underlying diffuse scattering surface. The altimetry capabilities of GLRS are greatly enhanced by its unique ability to provide centimeter accuracy updates to its own orbital ephemeris while retroranging. Potential applications include measurement of terrain profiles, biomass (tree canopy heights), ice-sheet thickness, marine geoid, atmospheric surface pressure over oceans, and oceanographic features (wave height, surface roughness, etc.). The presentation reviews the design, applications, simulations, hardware status, and instrument heritage of the GLRS system.

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Relatórios de organizações sobre o assunto "Marine Ice sheet"

Kerr, D. E. Reconnaissance surficial geology, Brichta Lake, Nunavut, NTS 76-P. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/329670.

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Preliminary surficial geology studies, based on air photo interpretation and limited legacy field data in the Brichta Lake map area, provide an understanding of the distribution and nature of surficial materials, and regional glacial history. The terrain is characterized by extensive glacial and meltwater scouring that has affected bedrock outcrops, and eroded hummocky and streamlined till, till blankets, and till veneers in the southwest regions. Streamlined bedrock and till landforms indicate ice flow towards the northwest and north-northwest during the last glaciation. Subglacial meltwater corridors and broader erosional zones, trending north-northwest, consisting of eskers, washed till veneer, ridged till, and scoured bedrock, result from late-phase ablation of the ice sheet during deglaciation. Glaciomarine and postglacial marine sediments extend discontinuously inland from the Queen Maud Gulf to 200 m a.s.l. elevation, notably up Tingmeak and Ellice rivers and their tributaries. In some eastern parts of the map area below 160 m a.s.l. elevation, thick marine deposits form plains that blanket broad shallow valleys.

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Paulen, R. C., J. M. Rice e M. Ross. Surficial geology, Lac aux Goélands, Quebec, NTS 23-P southeast. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/328291.

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The Lac aux Goélands area is of moderate relief characterized by till blankets in the lowlands and till veneers with large expanses of bedrock outcrops in the western and eastern margins. Bedrock was variably eroded by the Laurentide Ice Sheet, east of the Ancestral Labrador ice divide. Phases of ice flow imparted multiple sets of glacially streamlined landforms and erosional paleo-flow indicators on the landscape. However, the dominant eastward-trending, elongated streamlined landforms were formed by ice streaming during deglaciation. Multiple sets of discordant meltwater channels were formed from both an early phase of deglaciation, which fed into an eastward-trending esker network, and a subsequent late-phase ablation of the ice sheet, with north-south trending channels parallel to the retreating ice margin. Glaciolacustrine strandlines and littoral sediments within the upper George River basin mark the former northeastern extent of inundation of the earliest phase of glacial Lake Naskaupi.

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Tremblay, T., e M. Lamothe. New contributions to the ice-flow chronology in the Boothia-Lancaster Ice Stream catchment area. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/331062.

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Within the Boothia-Lancaster Ice Stream (BLIS) catchment area, ice flow patterns were reconstructed based on the synthesis of striation directions and cross-cutting relationships, transport patterns of erratic boulders, glacial landforms, cold-based glacial landsystems, and ice-retreat chronology. New ArcticDEM data, high-definition satellite imagery and multibeam echosounder bathymetric datasets provided increased details on ice flow indicators. Convergent high-velocity ice flows through the BLIS main axis were major, persistent features in the northeastern Laurentide Ice Sheet through the last glaciation, and this study highlights intensity fluctuations and ice flow pattern variations that occurred during that time. Highly contrasting glacial geomorphology, notably in the abundance of moraines, reflects marked differences in ice-margin retreat rates and patterns during deglaciation between the western and eastern sides of the BLIS.

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Tremblay, T., e M. Lamothe. New contributions to the ice-flow chronology in the Boothia-Lancaster ice-stream catchment area, Nunavut. Natural Resources Canada/CMSS/Information Management, 2023. http://dx.doi.org/10.4095/331424.

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Within the Boothia-Lancaster ice stream (BLIS) catchment area, ice-flow patterns were reconstructed based on the synthesis of striation directions and crosscutting relationships, transport patterns of erratic boulders, glacial landforms, cold-based glacial landsystems, and ice-retreat chronology. New ArcticDEM data, high-definition satellite imagery, and multibeam echosounder bathymetric data sets provided increased details on ice-flow indicators. Convergent high-velocity ice flows through the BLIS main axis were major, persistent features in the northeastern Laurentide Ice Sheet through the last glaciation, and this study highlights intensity fluctuations and ice-flow pattern variations that occurred during that time. Highly contrasting glacial geomorphology, notably in the abundance of moraines, reflects marked differences in ice-margin retreat rates and patterns during deglaciation between the western and eastern sides of the BLIS.

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Smith, I. R. Surficial geology, La Biche River northwest, Yukon-Northwest Territories, NTS 95-C/11, 12, 13, and 14. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/330591.

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This map is situated in the Hyland Plateau, west of the Mackenzie Mountains, southeast Yukon. The area was inundated by the Cordilleran Ice Sheet during the Late Wisconsinan glaciation. Ice advanced east to northeast across the rolling bedrock terrain, producing dense networks of sometimes cross-cutting bedrock flutings and drumlinoid ridges. During deglaciation, ice flow became increasingly topographically constrained, shifting to more northward flow along major valleys. Meltwater flowing north initially crossed the divide into the Nahanni River basin. Later, as ice retreated south and eastwards, ice-contact deltas and kame terraces formed along the retreating margins. The area is largely covered by till veneer, with bedrock exposed along most ridge crests and glacially-incised valley walls. Shale units within the Besa River and Mattson formations appear prone to failure, and large rotational landslides are common.

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Kerr, D. E. Reconnaissance surficial geology, Nose Lake, Nunavut-Northwest Territories, NTS 76-F. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/329666.

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The oldest regional ice flow in the Nose Lake map area is southwestward. Subsequent northwestward flow is inferred from streamlined bedrock in central and eastern regions. The final and youngest flow was southwestward in these same regions, recorded by an abundance of streamlined landforms in till blanket and bedrock. The western edge of this late active ice lobe is defined by recessional moraines, part of the Twin Jugs moraine, also marking the eastern limit of a broad band of hummocky till from downwasting ice. During deglaciation, short-lived proglacial lakes, identified by raised beaches and deltas, developed within parts of the river valleys of the Mara (420 to 410 m elevation), Hackett (445 to 395 m), and Storak (440 to 415 m). Lakes also formed west of Nose Lake (490 to 430 m elevation) and in the Contwoyto-Pellatt-Ghurka lake basins (470 to 450 m). Orientation of many eskers, associated subglacial meltwater corridors, and sheet drainage is variable, but can be perpendicular to local ice flow.

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Bartolino, Valerio, Birgit Koehler e Lena Bergström, eds. Climate effects on fish in Sweden : Species-Climate Information Sheets for 32 key taxa in marine and coastal waters. Department of Aquatic Resources, Swedish University of Agricultural Sciences, 2023. http://dx.doi.org/10.54612/a.4lmlt1tq5j.

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The purpose of this publication is to summarize the state of knowledge on the effects of environmental variability and climate change for individual species and stocks based on literature review, giving species-climate information for 32 key taxa in Swedish marine and coastal waters. The report is written in English. The extent and scale of recent changes in climate due to global warming is unprecedented and causes increasing effects on ecosystems. In oceans, ongoing warming leads to, for example, increased water temperatures, decreased ice cover and effects on hydrology and water circulation patterns that can in turn influence salinity. The environmental alterations affect species distribution, biology, and hence also the delivery of marine ecosystem services and human well-being. The results of this review on the effects of environmental variability and climate change on marine taxa are presented as species-climate information sheets designed in a user-friendly format aimed to enhance accessibility for professionals spanning different fields and roles, including e.g. scientific experts, NGOs affiliates and managers. The species-climate information sheets presented here cover 32 key taxa selected among the economically and ecologically most important coastal and marine fish and crustacean species in Swedish waters. The species-wise evaluations show that climate change leads to a wide range of effects on fish, reflecting variations in their biology and physiological tolerances. The review also highlights important data and knowledge gaps for each species and life stage. Despite the high variability and prevailing uncertainties, some general patterns appeared. On a general level, most fish species in Swedish marine and coastal waters are not expected to benefit from climate change, and many risks are identified to their potential for recruitment, growth and development. Boreal, marine and cold-adapted species would be disadvantaged at Swedish latitudes. However, fish of freshwater origin adapted to warmer temperature regimes could benefit to some extent in the Baltic Sea under a warming climate. Freshwater fish could also be benefitted under further decreasing salinity in the surface water in the Baltic Sea. The resulting effects on species will not only depend on the physiological responses, but also on how the feeding conditions for fish, prey availability, the quality of essential fish habitats and many other factors will develop. A wide range of ecological factors decisive for the development of fish communities are also affected by climate change but have not been explored here, where we focused on the direct effects of warming. The sensitivity and resilience of the fish species to climate change will also depend on their present and future health and biological status. Populations exposed to prolonged and intense fishing exploitation, or affected by environmental deterioration will most likely have a lower capacity to cope with climate change effects over time. For both the Baltic Sea and the North Sea, it is important to ensure continued work to update and improve the species-climate information sheets as results from new research become available. It can also be expected that new important and relevant biological information and improved climate scenarios will emerge continuously. Continued work is therefore important to update and refine the species-climate information sheets, help filling in currently identified knowledge gaps, and extend to other species not included here. Moreover, there is need to integrate this type of species-level information into analyses of the effects of climate change at the level of communities and ecosystems to support timely mitigation and adaptation responses to the challenges of the climate change.

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Surficial geology, Dendale Lake, Yukon-Northwest Territories, NTS 95-C/15. Natural Resources Canada/CMSS/Information Management, 2023. http://dx.doi.org/10.4095/331886.

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This map area is situated within the Hyland Plateau and comprises the headwaters of the La Biche River. It is framed by the La Biche Range on the east, the Tlogotsho Range on the north, and an unnamed ridge along its western boundary. The map area was inundated by the Cordilleran Ice Sheet during the Late Wisconsinan glaciation, and ice advanced east to northeast across the region. Coalescence with the Laurentide Ice Sheet is considered to have occurred just east and north of this area. During deglaciation, ice retreated generally south and westwards. Prominent northward-aggrading ice-contact and proglacial deltas formed between retreating Cordilleran and Laurentide ice margins, within early stages of glacial Lake Nahanni. Well-developed cirque basins point to a prolonged glacial history that predates the Late Wisconsinan glaciation. Small lobate moraines extending into valley bottoms below these cirques suggests that during regional Late Wisconsinan deglaciation, upland ice persisted through a phase of late glacial-early Holocene alpine cirque glaciation.

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