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Academic literature on the topic 'Ice shelf channel'

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Published: 10 December 2022
Last updated: 28 January 2023

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Journal articles on the topic "Ice shelf channel"

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Drews, R. "Evolution of ice-shelf channels in Antarctic ice shelves." Cryosphere 9, no. 3 (June 4, 2015): 1169–81. http://dx.doi.org/10.5194/tc-9-1169-2015.

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Abstract. Ice shelves buttress the continental ice flux and mediate ice–ocean interactions. They are often traversed by channels in which basal melting is enhanced, impacting ice-shelf stability. Here, channel evolution is investigated using a transient, three-dimensional full Stokes model and geophysical data collected on the Roi Baudouin Ice Shelf (RBIS), Antarctica. The modeling confirms basal melting as a feasible mechanism for channel creation, although channels may also advect without melting for many tens of kilometers. Channels can be out of hydrostatic equilibrium depending on their width and the upstream melt history. Inverting surface elevation for ice thickness using hydrostatic equilibrium in those areas is erroneous, and corresponding observational evidence is presented at RBIS by comparing the hydrostatically inverted ice thickness with radar measurements. The model shows that channelized melting imprints the flow field characteristically, which can result in enhanced horizontal shearing across channels. This is exemplified for a channel at RBIS using observed surface velocities and opens up the possibility to classify channelized melting from space, an important step towards incorporating these effects in ice–ocean models.
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Drews, R. "Evolution of ice-shelf channels in Antarctic ice shelves." Cryosphere Discussions 9, no. 2 (March 13, 2015): 1603–31. http://dx.doi.org/10.5194/tcd-9-1603-2015.

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Abstract. Ice shelves buttress the continental ice flux and mediate ice–ocean interactions. They are often traversed by channels in which basal melting is enhanced, impacting ice-shelf stability. Here, channel evolution is investigated using a transient, three-dimensional full Stokes model and geophysical data collected on Roi Baudouin Ice Shelf (RBIS), Antarctica. The modeling confirms basal melting as a feasible mechanism for channel creation, although channels may also advect without melting for many tens of kilometers. Channels can be out of hydrostatic equilibrium depending on their width and the upstream melt history. Inverting surface elevation for ice thickness in those areas is erroneous and corresponding observational evidence is presented at RBIS by comparing the hydrostatically inverted ice thickness with radar measurements. The model shows that channelized melting imprints the flowfield characteristically, which can result in enhanced horizontal shearing across channels. This is exemplified for a channel at RBIS using observed surface velocities and opens up the possibility to classify channelized melting from space, an important step towards incorporating these effects in ice–ocean models.
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Wang, Zemin, Xiangyu Song, Baojun Zhang, Tingting Liu, and Hong Geng. "Basal Channel Extraction and Variation Analysis of Nioghalvfjerdsfjorden Ice Shelf in Greenland." Remote Sensing 12, no. 9 (May 6, 2020): 1474. http://dx.doi.org/10.3390/rs12091474.

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The ice shelf controls the ice flow and affects the rates of sea level rise. Its stability is affected by the basal channel to some extent. However, despite its importance, high spatiotemporal variation in the length of the basal channels and influencing factors remain poorly characterized. Here, we present evidence from satellite and airborne remote-sensing for the basal channel beneath the floating Nioghalvfjerdsfjorden (79 North Glacier) ice shelf in Northeast Greenland. We observe the surface depression of the ice shelf using IceBridge, which is an ongoing NASA mission to monitor changes in polar ice. We find that the basal channel corresponds with the depression. Temporal and spatial changes of the basal channels from 2000 to 2018 are obtained annually. The results show that the main influencing factor affecting the basal channel is the sea surface temperature (SST), and the major area of the channel length change is found in the midstream area of the ice shelf.
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Gladish, Carl V., David M. Holland, Paul R. Holland, and Stephen F. Price. "Ice-shelf basal channels in a coupled ice/ocean model." Journal of Glaciology 58, no. 212 (2012): 1227–44. http://dx.doi.org/10.3189/2012jog12j003.

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AbstractA numerical model for an interacting ice shelf and ocean is presented in which the ice- shelf base exhibits a channelized morphology similar to that observed beneath Petermann Gletscher’s (Greenland) floating ice shelf. Channels are initiated by irregularities in the ice along the grounding line and then enlarged by ocean melting. To a first approximation, spatially variable basal melting seaward of the grounding line acts as a steel-rule die or a stencil, imparting a channelized form to the ice base as it passes by. Ocean circulation in the region of high melt is inertial in the along-channel direction and geostrophically balanced in the transverse direction. Melt rates depend on the wavelength of imposed variations in ice thickness where it enters the shelf, with shorter wavelengths reducing overall melting. Petermann Gletscher’s narrow basal channels may therefore act to preserve the ice shelf against excessive melting. Overall melting in the model increases for a warming of the subsurface water. The same sensitivity holds for very slight cooling, but for cooling of a few tenths of a degree a reorganization of the spatial pattern of melting leads, surprisingly, to catastrophic thinning of the ice shelf 12 km from the grounding line. Subglacial discharge of fresh water along the grounding line increases overall melting. The eventual steady state depends on when discharge is initiated in the transient history of the ice, showing that multiple steady states of the coupled system exist in general.
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Humbert, Angelika, Julia Christmann, Hugh F. J. Corr, Veit Helm, Lea-Sophie Höyns, Coen Hofstede, Ralf Müller, et al. "On the evolution of an ice shelf melt channel at the base of Filchner Ice Shelf, from observations and viscoelastic modeling." Cryosphere 16, no. 10 (October 10, 2022): 4107–39. http://dx.doi.org/10.5194/tc-16-4107-2022.

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Abstract. Ice shelves play a key role in the stability of the Antarctic Ice Sheet due to their buttressing effect. A loss of buttressing as a result of increased basal melting or ice shelf disintegration will lead to increased ice discharge. Some ice shelves exhibit channels at the base that are not yet fully understood. In this study, we present in situ melt rates of a channel which is up to 330 m high and located in the southern Filchner Ice Shelf. Maximum observed melt rates are 2 m yr−1. Melt rates inside the channel decrease in the direction of ice flow and turn to freezing ∼55 km downstream of the grounding line. While closer to the grounding line melt rates are higher within the channel than outside, this relationship reverses further downstream. Comparing the modeled evolution of this channel under present-day climate conditions over 250 years with its present geometry reveals a mismatch. Melt rates twice as large as the present-day values are required to fit the observed geometry. In contrast, forcing the model with present-day melt rates results in a closure of the channel, which contradicts observations. The ice shelf experiences strong tidal variability in vertical strain rates at the measured site, and discrete pulses of increased melting occurred throughout the measurement period. The type of melt channel in this study diminishes in height with distance from the grounding line and is hence not a destabilizing factor for ice shelves.
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Hofstede, Coen, Sebastian Beyer, Hugh Corr, Olaf Eisen, Tore Hattermann, Veit Helm, Niklas Neckel, et al. "Evidence for a grounding line fan at the onset of a basal channel under the ice shelf of Support Force Glacier, Antarctica, revealed by reflection seismics." Cryosphere 15, no. 3 (March 25, 2021): 1517–35. http://dx.doi.org/10.5194/tc-15-1517-2021.

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Abstract. Curvilinear channels on the surface of an ice shelf indicate the presence of large channels at the base. Modelling studies have shown that where these surface expressions intersect the grounding line, they coincide with the likely outflow of subglacial water. An understanding of the initiation and the ice–ocean evolution of the basal channels is required to understand the present behaviour and future dynamics of ice sheets and ice shelves. Here, we present focused active seismic and radar surveys of a basal channel, ∼950 m wide and ∼200 m high, and its upstream continuation beneath Support Force Glacier, which feeds into the Filchner Ice Shelf, West Antarctica. Immediately seaward from the grounding line, below the basal channel, the seismic profiles show an ∼6.75 km long, 3.2 km wide and 200 m thick sedimentary sequence with chaotic to weakly stratified reflections we interpret as a grounding line fan deposited by a subglacial drainage channel directly upstream of the basal channel. Further downstream the seabed has a different character; it consists of harder, stratified consolidated sediments, deposited under different glaciological circumstances, or possibly bedrock. In contrast to the standard perception of a rapid change in ice shelf thickness just downstream of the grounding line, we find a flat topography of the ice shelf base with an almost constant ice thickness gradient along-flow, indicating only little basal melting, but an initial widening of the basal channel, which we ascribe to melting along its flanks. Our findings provide a detailed view of a more complex interaction between the ocean and subglacial hydrology to form basal channels in ice shelves.
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Dallaston, M. C., I. J. Hewitt, and A. J. Wells. "Channelization of plumes beneath ice shelves." Journal of Fluid Mechanics 785 (November 11, 2015): 109–34. http://dx.doi.org/10.1017/jfm.2015.609.

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We study a simplified model of ice–ocean interaction beneath a floating ice shelf, and investigate the possibility for channels to form in the ice shelf base due to spatial variations in conditions at the grounding line. The model combines an extensional thin-film description of viscous ice flow in the shelf, with melting at its base driven by a turbulent ocean plume. Small transverse perturbations to the one-dimensional steady state are considered, driven either by ice thickness or subglacial discharge variations across the grounding line. Either forcing leads to the growth of channels downstream, with melting driven by locally enhanced ocean velocities, and thus heat transfer. Narrow channels are smoothed out due to turbulent mixing in the ocean plume, leading to a preferred wavelength for channel growth. In the absence of perturbations at the grounding line, linear stability analysis suggests that the one-dimensional state is stable to initial perturbations, chiefly due to the background ice advection.
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Mathews, William H. "Ice Sheets and Ice Streams: Thoughts on the Cordilleran Ice Sheet Symposium." Géographie physique et Quaternaire 45, no. 3 (December 13, 2007): 263–67. http://dx.doi.org/10.7202/032873ar.

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ABSTRACT This paper comments on preconceptions about what is meant by the terms "Cordilleran Ice Sheet" and "ice stream". Contemporary Antarctic ice streams are described. The Laurentian Channel and throughs crossing the continental ice shelf between Vancouver and Queens Charlotte Islands are suggested as candidates for the tracks of past ice streams.
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Drews, Reinhard, Joel Brown, Kenichi Matsuoka, Emmanuel Witrant, Morgane Philippe, Bryn Hubbard, and Frank Pattyn. "Constraining variable density of ice shelves using wide-angle radar measurements." Cryosphere 10, no. 2 (April 15, 2016): 811–23. http://dx.doi.org/10.5194/tc-10-811-2016.

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Abstract. The thickness of ice shelves, a basic parameter for mass balance estimates, is typically inferred using hydrostatic equilibrium, for which knowledge of the depth-averaged density is essential. The densification from snow to ice depends on a number of local factors (e.g., temperature and surface mass balance) causing spatial and temporal variations in density–depth profiles. However, direct measurements of firn density are sparse, requiring substantial logistical effort. Here, we infer density from radio-wave propagation speed using ground-based wide-angle radar data sets (10 MHz) collected at five sites on Roi Baudouin Ice Shelf (RBIS), Dronning Maud Land, Antarctica. We reconstruct depth to internal reflectors, local ice thickness, and firn-air content using a novel algorithm that includes traveltime inversion and ray tracing with a prescribed shape of the depth–density relationship. For the particular case of an ice-shelf channel, where ice thickness and surface slope change substantially over a few kilometers, the radar data suggest that firn inside the channel is about 5 % denser than outside the channel. Although this density difference is at the detection limit of the radar, it is consistent with a similar density anomaly reconstructed from optical televiewing, which reveals that the firn inside the channel is 4.7 % denser than that outside the channel. Hydrostatic ice thickness calculations used for determining basal melt rates should account for the denser firn in ice-shelf channels. The radar method presented here is robust and can easily be adapted to different radar frequencies and data-acquisition geometries.
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Münchow, Andreas, Laurie Padman, and Helen A. Fricker. "Interannual changes of the floating ice shelf of Petermann Gletscher, North Greenland, from 2000 to 2012." Journal of Glaciology 60, no. 221 (2014): 489–99. http://dx.doi.org/10.3189/2014jog13j135.

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AbstractPetermann Gletscher, northwest Greenland, drains 4% of the Greenland ice sheet into Nares Strait. Its floating ice shelf retreated from 81 to 48 km in length during two large calving events in 2010 and 2012. We document changes in the three-dimensional ice-shelf structure from 2000 to 2012, using repeated tracks of airborne laser altimetry and ice radio-echo sounding, ICESat laser altimetry and MODIS visible imagery. The recent ice-shelf velocity, measured by tracking surface features between flights in 2010 and 2011, is ~1.25 km a−1, ~15–30% faster than estimates made before 2010. The steady- state along-flow ice divergence represents 6.3 Gta−1 mass loss through basal melting (~5Gta−1) and surface melting and sublimation (~1.0Gta−1). Airborne laser altimeter data reveal thinning, both along a thin central channel and on the thicker ambient ice shelf. From 2007 to 2010 the ice shelf thinned by ~5 m a−1, which represents a non-steady mass loss of ~4.1 Gta−1. We suggest that thinning in the basal channels structurally weakened the ice shelf and may have played a role in the recent calving events.
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Dissertations / Theses on the topic "Ice shelf channel"

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Mortimer, Colleen Adel. "Quantification of Changes for the Milne Ice Shelf, Nunavut, Canada, 1950 - 2009." Thesis, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/19773.

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This study presents a comprehensive overview of the current state of the Milne Ice Shelf and how it has changed over the last 59 years. The 205 ±1 km2 ice shelf experienced a 28% (82 ±0.8 km2) reduction in area between 1950 – 2009, and a 20% (2.5 ±0.9km3 water equivalent (w.e.)) reduction in volume between 1981 – 2008/2009, suggesting a long-term state of negative mass balance. Comparison of mean annual specific mass balances (up to -0.34 m w.e. yr-1) with surface mass balance measurements for the nearby Ward Hunt Ice Shelf suggest that basal melt is a key contributor to total ice shelf thinning. The development and expansion of new and existing surface cracks, as well as ice-marginal and epishelf lake development, indicate significant ice shelf weakening. Over the next few decades it is likely that the Milne Ice Shelf will continue to deteriorate.
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White, Adrienne. "Dynamics and Historical Changes of the Petersen Ice Shelf and Epishelf Lake, Nunavut, Canada, since 1959." Thèse, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/23574.

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This study presents the first comprehensive assessment of the Petersen Ice Shelf and the Petersen Bay epishelf lake, and examines their current characteristics and changes to their structure between 1959 and 2012. The surface of the Petersen Ice Shelf is characterized by a rolling topography of ridges and troughs, which is balanced by a rolling basal topography, with thicker ice under the surface ridges and thinner ice under the surface troughs. Based on thickness measurements collected in 2011 and area measurements from August 2012, the Petersen Ice Shelf has a surface area of 19.32 km2 and a mean thickness of 29 m, with the greatest thicknesses (>100 m) occurring at the fronts of tributary glaciers feeding into the ice shelf. The tributary glaciers along the northern coast of Petersen Bay contributed an estimated area-averaged 7.89 to 13.55 cm yr-1 of ice to the ice shelf between 2011 and 2012. This input is counteracted by a mean surface ablation of 1.30 m yr-1 between 2011 and 2012, suggesting strongly negative current mass balance conditions on the ice shelf. The Petersen Ice Shelf remained relatively stable until 2005 when the first break-up in recent history occurred, removing >8 km2 of ice shelf surface area. This break-up led to the drainage of the epishelf lake once the ice shelf separated from the southern coast, providing a conduit through which the freshwater from the lake escaped. More break-ups occurred in summers 2008, 2011 and 2012, which resulted in a >31.2 km2 loss in surface area (~63% of June 2005 area). While ephemeral regions of freshwater have occurred along the southern coast of Petersen Bay since 2005 (with areas ranging from 0.32-0.53 km2), open water events and a channel along the southern coast have prevented the epishelf lake from reforming. Based on these past and present observations it is unlikely that Petersen Ice Shelf will continue to persist long into the future.
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Berger, Sophie. "Stability of Antarctic ice shelves: A case study of the Roi Baudouin Ice Shelf, Dronning Maud Land, East Antarctica." Doctoral thesis, Universite Libre de Bruxelles, 2017. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/258789.

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The Antarctic ice sheet is increasingly contributing to sea-level rise because of accelerated mass losses at its floating extensions -- its ice shelves. By floating while remaining attached to the grounded ice sheet, ice shelves buttress (i.e. restrain) the inland ice in such a way that ice-shelf losses lead to accelerated ice discharge in the ocean. This thesis investigates the stability of Antarctic ice shelves -- so crucial for the stability of the entire ice sheet -- using the Roi Baudouin Ice Shelf (RBIS), Dronning Maud Land, East Antarctica, as a case study. The RBIS has remained relatively stable over the last millennia and presents various kilometre-scale features (pinning point, ice-shelf channels and englacial lakes) with potential impact on its present and future stability.We first derive a horizontal velocity field, combining interferometry and speckle tracking with Synthetic Aperture Radar images from ERS 1/2 and ALOS-PALSAR, respectively. The resulting velocities and associated shear-strain rates represent the most detailed fields, currently available for the RBIS and clearly resolve small-scale features of the RBIS: significant slow-down and shearing are observed upstream of a small pinning point and ice converges at ice-shelf channels. We then combine our flow field with high-resolution elevations from TanDEM-X to infer the Basal Mass Balance (BMB) of the RBIS. This method relies on mass conservation in a Lagrangian frame and enables us to finely detect spatial variability in the BMB. We show that the BMB of the RBIS varies substantially on sub-kilometre scales. Our technique is promising and could easily be applied more widely.Additionally, the flow field is used to investigate how considering/ignoring small pinning points in observations (geometry and velocities) impacts data initialisation of poorly known parameters (e.g. basal friction, ice viscosity) and subsequent ice-sheet modelling with BISICLES. We find that overlooking the pinning point in the bathymetry leads to erroneous ice-shelf properties whereas accurately capturing the pinning point in velocities is of secondary importance. Finally, before concluding the thesis, we discuss the stability of the RBIS and its neighbouring ice shelves. Most studies agree that the ice shelf has remained stable over the last decades to millennia and would likely remain so in the absence of external forcing. We however point out to three potential triggers of instabilities: (i) large quantities of surface meltwater are formed in the grounding zone and subsequently stored on the ice shelf, thereby providing fuel for hydrofracturing; (ii) ice-shelf channels are found to significantly incise the ice inland and (iii) a bathymetric trough beneath the RBIS forms a potential gateway for warm water intrusions the ice-shelf cavity, which could destabilise the ice shelf from below. We close with a short essay on the importance of outreach, where we argue that public engagement as a scientist should be considered as being part of science and should be valued for its worth. This chapter gives us the opportunity to present outreach activities undertaken in the frame of this thesis. We conclude that, just like ice shelves control Antarctic ice losses, science communication determines transfers of scientific expertise to public knowledge.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished
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Karstkarel, Nanka. "Changes in shelf ice extent in West Antarctica between 1840 and 1960 : analysing historical maps in a geographical information system... /." Groningen : Rijksuniversiteit Groningen, 2005. http://catalogue.bnf.fr/ark:/12148/cb40220277c.

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Stosius, Ralf. "Anwendung des stratifizierten Krigings auf ERS-1 und ERS-2 Radaraltimeterdaten zur Untersuchung von Eishöhenänderungen im Lambert Gletscher/Amery Eisschelf-System, Ostantarktis = Application of stratified kriging to ERS-1 and ERS-2 radar altimeter data to investigate ice elevation changes in the Lambert Glacier/Amery Ice Shelf system, East Antarctica /." Bremerhaven : Alfred-Wegener-Institut für Polar- und Meeresforschung, 2007. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=017109561&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.

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Bäßler, Michael. "Untersuchungen zu Topographie und Bewegungsverhalten für das Küstengebiet des Riiser-Larsen- und Brunt-Schelfeises mittels Radarfernerkundung." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-70201.

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Mit der Weiterentwicklung von Sensoren und Methoden hat die Satellitenfernerkundung innerhalb der letzten 20 Jahre nicht nur einen großen Stellenwert in der Polarforschung errungen, sondern vor allem die Herangehensweisen an eine Vielzahl glaziologischer Probleme grundlegend verändert. RADAR-Sensoren (Radio Detection and Ranging) sind dabei besonders bei der Erkundung vereister Regionen hilfreich und tragen stark zur Ableitung klimasensitiver Parameter im Bereich der Antarktis bei. Nach einem einführenden Überblick im ersten wird im zweiten Kapitel mit Darstellungen zur Nutzung von RADAR-Messungen für Fernerkundungszwecke begonnen. Die zur Erhöhung der räumlichen Auflösung verwendete SAR-Prozessierung (Synthetic Aperture Radar) wird daraufhin kurz umrissen, bevor zu den Grundlagen der interferometrischen Auswertung (InSAR) übergeleitet wird. Bei dieser werden Phasendifferenzen unterschiedlicher Aufnahmen für Messzwecke eingesetzt. In den Beschreibungen wird aufgezeigt, wie sich derartige Messungen für die Ermittlung von Oberflächentopographie und Fließverhalten in polaren Regionen nutzen lassen. Eine Darstellung der ebenfalls benötigten Methoden zur Bestimmung von Verschiebungen in Bildpaaren und das Messprinzip der Laseraltimetrie beenden diesen Theorieteil. Das dritte Kapitel der Arbeit ist der Vorstellung des Arbeitsgebietes und der genutzten Datensätze gewidmet. Nach der geographischen Einordnung des Untersuchungsgebietes werden die wichtigsten glaziologischen Gegebenheiten vorgestellt. In der sich anschließenden Beschreibung genutzter Datensätze werden vor allem die für diese Region verfügbaren Höhen- und Ozeangezeitenmodelle intensiver besprochen. Die Bestimmung der Oberflächentopographie durch differentielle SAR-Interferometrie (DInSAR) ist Thema des vierten Kapitels. Nachdem die nötigen technischen Aspekte des Prozessierungsablaufes knapp erläutert wurden, werden die Unterschiede bei der Doppeldifferenzbildung benachbarter und identischer Wiederholspuren herausgearbeitet. Danach wird am Beispiel gezeigt, wie mithilfe von ICESat-Daten (Ice, Cloud and Land Elevation Satellite) eine Basislinienverbesserung zur genaueren Höhenbestimmung durchgeführt werden kann. Die ursprünglich separat abgeleiteten Höhenmodelle werden dann zu einer gemeinsamen Lösung kombiniert, welche abschließend hinsichtlich ihrer Genauigkeit besprochen und anderen Modellen vergleichend gegenübergestellt wird. Die Ableitung von Fließgeschwindigkeiten mit dem Hintergrund einer späteren Berechnung von Massenflüssen ist Gegenstand des fünften Kapitels, wobei drei unterschiedliche Methoden genutzt werden. Im ersten Fall wird das für RADAR-Bilder typische, hochfrequente Rauschen zur Bestimmung von Verschiebungen in ALOS-Daten (Advanced Land Observing Satellite) genutzt. Mit dieser Methode können durchgehende Fließgeschwindigkeitsfelder vom aufliegenden Bereich über die Aufsetzzone bis auf das Schelfeis ermittelt werden. DesWeiteren werden aus ERS-Daten (European Remote Sensing Satellite), die über einen Zeitraum von reichlich 13 Jahren vorliegen, Verschiebungen durch die Verfolgung von unveränderten, aber sich bewegenden Eisstrukturen bestimmt. Bei der als Drittes angewendeten, interferometrischen Methode werden aufsteigende und absteigende Satellitenspuren kombiniert, um die Fließinformationen zu rekonstruieren. In den jeweiligen Sektionen wird neben der Vorstellung der Ergebnisse auch deren Genauigkeit diskutiert. Das letzte große, sechste Kapitel untergliedert sich in zwei Teile. Im ersten dieser beiden Abschnitte wird gezeigt, wie InSAR und DInSAR zur Lagekartierung der Aufsetzzone eingesetzt werden können. Dabei werden die auf diese Weise ermittelten Ergebnisse dargestellt und diskutiert. Im zweiten, umfangreicheren Teil werden die zuvor gewonnenen Höhen- und Geschwindigkeitsinformationen genutzt, um deren Einfluss aus den InSAR-Messungen zu eliminieren, wodurch vertikale Höhenunterschiede mittels InSAR bestimmt werden können. Dies ist besonders für den Bereich der Aufsetzzone und des Schelfeises von Interesse, da diese Areale teilweise oder vollständig von Ozeangezeiten beeinflusst werden. Nach einer Luftdruckkorrektion werden den ermittelten Höhenunterschieden (entlang selektierter Profile) die Prädiktionen zwölf verfügbarer Ozeangezeitenmodelle gegenübergestellt. Die RMS-Werte dieser Differenzen werden abschließend genutzt, um die Qualität der Ozeangezeitenmodelle für die Region des Arbeitsgebietes einzustufen. Zum Abschluss werden in einer Zusammenfassung noch einmal die wichtigsten Ergebnisse aller Kapitel resümiert und bewertet
The development of new satellite sensors within the last 20 years along with changes towards more sophisticated processing strategies has not only given a new impetus to remote sensing data in view of polar research but also changed how a variety of glaciological problems are being addressed today. Particularly RADAR (radio detection and ranging) sensors are well-suited for the observation of glaciated areas and have already helped to retrieve a vast amount of climate sensitive parameters from the area of Antarctica. After an introductive overview at the beginning, the second chapter continues with the description of how RADAR measurements can be used to generate remote sensing images. The principle of synthetic aperture RADAR (SAR) which allows a better focusing of the RADAR measurements and therewith a rigorous increase of the spatial resolution of the images is outlined generally before more precise descriptions explain how interferometric SAR (InSAR) analyses can be used for the determination of surface topography heights and area-wide flow velocities. Two other techniques, namely matching methods for the determination of shifts between two images as well as the laser satellite altimetry are explained at the end of this chapter which closes the theoretical basics. The next section introduces the area of interest along with data sets which were used for validation purposes. After a careful exposure of the geographical situation, single objects such as ice streams and ice shelves are described in more detail. The following part, the data set introduction, has besides the description of other measurements its focus on topography and ocean tide models which are available for the area of investigation. Chapter four deals with the estimation of surface topography heights from differential InSAR (DInSAR) analyses. Therein the major differences for the usage of similar repeat tracks in contrast to neighboring, overlapping tracks will be shown and thoroughly discussed. The example of one track will be used to demonstrate how the required baseline estimation can be achieved if ICESat (Ice, Cloud and Land Elevation Satellite) profiles are used as tie points. Afterwards, all separately derived height models will be combined to obtain one final solution followed by an error analysis. A comparison to other available elevation models visualizes the spatial resolution of the derived model. The utilization of three different methods for the estimation of surface flow velocities (with the background of possible mass flux determinations) is the topic of the fifth chapter. The first case describes the usage of the high frequent noise contained in RADAR images for the tracking of horizontal surface displacements. Based on ALOS (Advanced Land Observing Satellite) data a flow velocity field which extends from the interior of the ice sheet across the grounding zone up to the ice shelf will be presented. Secondly, geocoded ERS (European Remote Sensing Satellite) images covering a time span of more than 13 years are used to track the motions of well-structured flat areas (ice shelf and glacier tongue). In the third approach used descending and ascending satellite passes will be combined in conjunction with a surface parallel flow assumption to interferometrically derive flow velocities in grounded areas. In each section respective errors will be discussed in order to evaluate the accuracy of the performed measurements. The last bigger chapter, number six, is divided into two sections. In the first one the adoption of SAR and InSAR with respect to the mapping of the grounding line location will be demonstrated. Results of the entire working area will be presented and compared to other data. The second section deploys the results of topography heights and flow velocities to remove both effects from the InSAR measurements which then allows to also measure height changes. This is of particular interest for the floating areas of ice shelf which are fully affected by ocean tides as well as for the grounding zone locations which partially experience deformations due to these height changes. After the correction for air pressure, changes between the image acquisitions, height changes along selected profiles are compared to twelve different ocean tide models. The RMS values of the differences are then used to evaluate the quality of these models for the working area. The most important results and conclusions are summarized in the last chapter
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Moorman, Ruth. "Response of Antarctic ocean circulation to increased meltwater." Thesis, 2019. http://hdl.handle.net/1885/187134.

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The implications of ocean freshening from accelerating Antarctic land-ice loss are poorly understood, due to the scarcity of observations near the Antarctic coast, and the high spatial and temporal resolution required to resolve Antarctic continental shelf processes in ocean models. Here, a high-resolution global ocean--sea-ice model is used to investigate the response of Antarctic continental shelf circulation to increasing meltwater. Two freshwater perturbation experiments are conducted, using projected Antarctic ice-loss rates under RCP 4.5 and RCP 8.5 emissions scenarios at 2100.We find that surface freshening near the Antarctic coast increases stratification and reduces the formation of cold, dense waters on the Antarctic continental shelf that, in the current climate, drive abyssal ocean circulation and ventilation. In our simulations, the connection between the abyssal ocean and the cold Antarctic shelf collapses within 10 years following the application of projected 2100 meltwater forcing, as downwelling surface waters on the continental shelf are freshened by glacial runoff, leaving them too buoyant to sink to the abyssal ocean. Around Antarctica, coastal freshening increases lateral density gradients between the cool, fresh shelf and the warm, saline open ocean, strengthening frontal structures that separate the adjacent water-masses, and accelerating geostrophic currents that flow westward along the coast and along the continental shelf break. This process acts to homogenise shelf waters and increasingly isolate the cool continental shelf from the warmer open ocean, leading to a net cooling on the continental shelf. Acceleration of the circumpolar coastal current results in remote temperature feedbacks unique to these experiments; most notable being a strong cooling signal on the West Antarctic shelf, an historically warm region associated with high rates of ice shelf melt, generated by the advection of cold Weddell Sea shelf waters around the Antarctic Peninsula by the strengthening coastal current. However, shelf cooling is not a circumpolar response to freshening. Deep warm anomalies arise in the Ross Sea, Adelie Coast, and Prydz Bay continental shelf dense water source regions under enhanced meltwater forcing, as full depth convention collapses and surface cooling fluxes diminish. Warming is strongest in the Ross Sea, where the absence of strong frontal structures and zonal currents at the shelf break grants warm, open ocean waters uninhibited access to the shelf. On the Prydz Bay and Adelie Coast shelf, warming due to convective shutdown is counterbalanced by decreased shoreward advective heat transport, due to strengthening frontal structures at the shelf break. As such, we find that coastal freshening induces both warm and cool anomalies at different locations along the Antarctic continental shelf, suggesting that shelf freshening by meltwater can both accelerate ice shelf melt (a positive feedback) and inhibit melt (a negative feedback) depending on regional factors. These findings improve our understanding of the complex suite of climate effects associated with the melting of Antarctica's land-ice. Both the disruption of abyssal overturning and shifts in heat transport to ice shelves have implications for sea-level rise; as reduced deep ocean ventilation may increase oceanic heat content (effecting steric sea-level), and accelerating land-ice loss, in regions of warming, adds mass to the oceans (effecting eustatic sea-level).
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Bäßler, Michael. "Untersuchungen zu Topographie und Bewegungsverhalten für das Küstengebiet des Riiser-Larsen- und Brunt-Schelfeises mittels Radarfernerkundung: Untersuchungen zu Topographie und Bewegungsverhalten für das Küstengebiet des Riiser-Larsen- und Brunt-Schelfeises mittels Radarfernerkundung." Doctoral thesis, 2010. https://tud.qucosa.de/id/qucosa%3A25606.

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Mit der Weiterentwicklung von Sensoren und Methoden hat die Satellitenfernerkundung innerhalb der letzten 20 Jahre nicht nur einen großen Stellenwert in der Polarforschung errungen, sondern vor allem die Herangehensweisen an eine Vielzahl glaziologischer Probleme grundlegend verändert. RADAR-Sensoren (Radio Detection and Ranging) sind dabei besonders bei der Erkundung vereister Regionen hilfreich und tragen stark zur Ableitung klimasensitiver Parameter im Bereich der Antarktis bei. Nach einem einführenden Überblick im ersten wird im zweiten Kapitel mit Darstellungen zur Nutzung von RADAR-Messungen für Fernerkundungszwecke begonnen. Die zur Erhöhung der räumlichen Auflösung verwendete SAR-Prozessierung (Synthetic Aperture Radar) wird daraufhin kurz umrissen, bevor zu den Grundlagen der interferometrischen Auswertung (InSAR) übergeleitet wird. Bei dieser werden Phasendifferenzen unterschiedlicher Aufnahmen für Messzwecke eingesetzt. In den Beschreibungen wird aufgezeigt, wie sich derartige Messungen für die Ermittlung von Oberflächentopographie und Fließverhalten in polaren Regionen nutzen lassen. Eine Darstellung der ebenfalls benötigten Methoden zur Bestimmung von Verschiebungen in Bildpaaren und das Messprinzip der Laseraltimetrie beenden diesen Theorieteil. Das dritte Kapitel der Arbeit ist der Vorstellung des Arbeitsgebietes und der genutzten Datensätze gewidmet. Nach der geographischen Einordnung des Untersuchungsgebietes werden die wichtigsten glaziologischen Gegebenheiten vorgestellt. In der sich anschließenden Beschreibung genutzter Datensätze werden vor allem die für diese Region verfügbaren Höhen- und Ozeangezeitenmodelle intensiver besprochen. Die Bestimmung der Oberflächentopographie durch differentielle SAR-Interferometrie (DInSAR) ist Thema des vierten Kapitels. Nachdem die nötigen technischen Aspekte des Prozessierungsablaufes knapp erläutert wurden, werden die Unterschiede bei der Doppeldifferenzbildung benachbarter und identischer Wiederholspuren herausgearbeitet. Danach wird am Beispiel gezeigt, wie mithilfe von ICESat-Daten (Ice, Cloud and Land Elevation Satellite) eine Basislinienverbesserung zur genaueren Höhenbestimmung durchgeführt werden kann. Die ursprünglich separat abgeleiteten Höhenmodelle werden dann zu einer gemeinsamen Lösung kombiniert, welche abschließend hinsichtlich ihrer Genauigkeit besprochen und anderen Modellen vergleichend gegenübergestellt wird. Die Ableitung von Fließgeschwindigkeiten mit dem Hintergrund einer späteren Berechnung von Massenflüssen ist Gegenstand des fünften Kapitels, wobei drei unterschiedliche Methoden genutzt werden. Im ersten Fall wird das für RADAR-Bilder typische, hochfrequente Rauschen zur Bestimmung von Verschiebungen in ALOS-Daten (Advanced Land Observing Satellite) genutzt. Mit dieser Methode können durchgehende Fließgeschwindigkeitsfelder vom aufliegenden Bereich über die Aufsetzzone bis auf das Schelfeis ermittelt werden. DesWeiteren werden aus ERS-Daten (European Remote Sensing Satellite), die über einen Zeitraum von reichlich 13 Jahren vorliegen, Verschiebungen durch die Verfolgung von unveränderten, aber sich bewegenden Eisstrukturen bestimmt. Bei der als Drittes angewendeten, interferometrischen Methode werden aufsteigende und absteigende Satellitenspuren kombiniert, um die Fließinformationen zu rekonstruieren. In den jeweiligen Sektionen wird neben der Vorstellung der Ergebnisse auch deren Genauigkeit diskutiert. Das letzte große, sechste Kapitel untergliedert sich in zwei Teile. Im ersten dieser beiden Abschnitte wird gezeigt, wie InSAR und DInSAR zur Lagekartierung der Aufsetzzone eingesetzt werden können. Dabei werden die auf diese Weise ermittelten Ergebnisse dargestellt und diskutiert. Im zweiten, umfangreicheren Teil werden die zuvor gewonnenen Höhen- und Geschwindigkeitsinformationen genutzt, um deren Einfluss aus den InSAR-Messungen zu eliminieren, wodurch vertikale Höhenunterschiede mittels InSAR bestimmt werden können. Dies ist besonders für den Bereich der Aufsetzzone und des Schelfeises von Interesse, da diese Areale teilweise oder vollständig von Ozeangezeiten beeinflusst werden. Nach einer Luftdruckkorrektion werden den ermittelten Höhenunterschieden (entlang selektierter Profile) die Prädiktionen zwölf verfügbarer Ozeangezeitenmodelle gegenübergestellt. Die RMS-Werte dieser Differenzen werden abschließend genutzt, um die Qualität der Ozeangezeitenmodelle für die Region des Arbeitsgebietes einzustufen. Zum Abschluss werden in einer Zusammenfassung noch einmal die wichtigsten Ergebnisse aller Kapitel resümiert und bewertet.
The development of new satellite sensors within the last 20 years along with changes towards more sophisticated processing strategies has not only given a new impetus to remote sensing data in view of polar research but also changed how a variety of glaciological problems are being addressed today. Particularly RADAR (radio detection and ranging) sensors are well-suited for the observation of glaciated areas and have already helped to retrieve a vast amount of climate sensitive parameters from the area of Antarctica. After an introductive overview at the beginning, the second chapter continues with the description of how RADAR measurements can be used to generate remote sensing images. The principle of synthetic aperture RADAR (SAR) which allows a better focusing of the RADAR measurements and therewith a rigorous increase of the spatial resolution of the images is outlined generally before more precise descriptions explain how interferometric SAR (InSAR) analyses can be used for the determination of surface topography heights and area-wide flow velocities. Two other techniques, namely matching methods for the determination of shifts between two images as well as the laser satellite altimetry are explained at the end of this chapter which closes the theoretical basics. The next section introduces the area of interest along with data sets which were used for validation purposes. After a careful exposure of the geographical situation, single objects such as ice streams and ice shelves are described in more detail. The following part, the data set introduction, has besides the description of other measurements its focus on topography and ocean tide models which are available for the area of investigation. Chapter four deals with the estimation of surface topography heights from differential InSAR (DInSAR) analyses. Therein the major differences for the usage of similar repeat tracks in contrast to neighboring, overlapping tracks will be shown and thoroughly discussed. The example of one track will be used to demonstrate how the required baseline estimation can be achieved if ICESat (Ice, Cloud and Land Elevation Satellite) profiles are used as tie points. Afterwards, all separately derived height models will be combined to obtain one final solution followed by an error analysis. A comparison to other available elevation models visualizes the spatial resolution of the derived model. The utilization of three different methods for the estimation of surface flow velocities (with the background of possible mass flux determinations) is the topic of the fifth chapter. The first case describes the usage of the high frequent noise contained in RADAR images for the tracking of horizontal surface displacements. Based on ALOS (Advanced Land Observing Satellite) data a flow velocity field which extends from the interior of the ice sheet across the grounding zone up to the ice shelf will be presented. Secondly, geocoded ERS (European Remote Sensing Satellite) images covering a time span of more than 13 years are used to track the motions of well-structured flat areas (ice shelf and glacier tongue). In the third approach used descending and ascending satellite passes will be combined in conjunction with a surface parallel flow assumption to interferometrically derive flow velocities in grounded areas. In each section respective errors will be discussed in order to evaluate the accuracy of the performed measurements. The last bigger chapter, number six, is divided into two sections. In the first one the adoption of SAR and InSAR with respect to the mapping of the grounding line location will be demonstrated. Results of the entire working area will be presented and compared to other data. The second section deploys the results of topography heights and flow velocities to remove both effects from the InSAR measurements which then allows to also measure height changes. This is of particular interest for the floating areas of ice shelf which are fully affected by ocean tides as well as for the grounding zone locations which partially experience deformations due to these height changes. After the correction for air pressure, changes between the image acquisitions, height changes along selected profiles are compared to twelve different ocean tide models. The RMS values of the differences are then used to evaluate the quality of these models for the working area. The most important results and conclusions are summarized in the last chapter.
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Books on the topic "Ice shelf channel"

1

Stosius, Ralf. Anwendung des stratifizierten Krigings auf ERS-1 und ERS-2 Radaraltimeterdaten zur Untersuchung von Eishöhenänderungen im Lambert Gletscher/Amery Eisschelf-System, Ostantarktis =: Application of stratified kriging to ERS-1 and ERS-2 radar altimeter data to investigate ice elevation changes in the Lambert Glacier/Amery Ice Shelf system, East Antarctica. Bremerhaven: Alfred-Wegener-Institut für Polar- und Meeresforschung, 2007.

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Ice in channels and ice-rock mixtures in valleys on Mars: Did they slide on deformable rubble like Antarctic ice streams? [Washington, DC: National Aeronautics and Space Administration, 1998.

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Ice in channels and ice-rock mixtures in valleys on Mars: Did they slide on deformable rubble like Antarctic ice streams? [Washington, DC: National Aeronautics and Space Administration, 1998.

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Ice in channels and ice-rock mixtures in valleys on Mars: Did they slide on deformable rubble like Antarctic ice streams? [Washington, DC: National Aeronautics and Space Administration, 1998.

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United States. National Aeronautics and Space Administration., ed. Ice in channels and ice-rock mixtures in valleys on Mars: Did they slide on deformable rubble like Antarctic ice streams? [Washington, DC: National Aeronautics and Space Administration, 1998.

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Climate Change In Eurasian Arctic Shelf Seas Centennial Ice Cover Observations. Springer, 2009.

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Liam, Fernand, Brewer Peter G, Barry James, and ICES Workshop on the Significance of Changing Ocean CO₂ and pH in ICES Shelf Sea Ecosystems (2007 : London, England), eds. Changes in surface CO₂ and ocean pH in ICES shelf sea ecosystems. Copenhagen, Denmark: International Council for the Exploration of the Sea, 2008.

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1960-, Barber David G., Fortier Louis 1953-, and Michaud Josée 1969-, eds. On thin ice: A synthesis of the Canadian Arctic Shelf Exchange Study (CASES). Winnipeg: Aboriginal Issues Press, 2008.

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Cosgrove, Richard, and Jillian Garvey. Behavioural inferences from Late Pleistocene Aboriginal Australia. Edited by Umberto Albarella, Mauro Rizzetto, Hannah Russ, Kim Vickers, and Sarah Viner-Daniels. Oxford University Press, 2017. http://dx.doi.org/10.1093/oxfordhb/9780199686476.013.49.

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Detailed research into marsupial behavioural ecology and modelling of past Aboriginal exploitation of terrestrial fauna has been scarce. Poor bone preservation is one limiting factor in Australian archaeological sites, but so has been the lack of research concerning the ecology and physiology of Australia’s endemic fauna. Much research has focused on marine and fresh-water shell-fish found in coastal and inland midden sites. Detailed studies into areas such as seasonality of past human occupation and nutritional returns from terrestrial prey species have not had the same attention. This chapter reviews the current level of published Australian research into two aspects of faunal studies, seasonality and nutrition. It describes the patterns from well-researched faunal data excavated from the Ice Age sites in southwest Tasmania. Concentration is on the vertebrate fauna found in seven limestone cave sites to examine any temporal changes to seasonal butchery and identify any differences between seasonally occupied sites.
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Petrick, Gabriella M. Industrial Food. Edited by Jeffrey M. Pilcher. Oxford University Press, 2012. http://dx.doi.org/10.1093/oxfordhb/9780199729937.013.0015.

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The years between 1880 and 1930 have been characterized not only as "Hell with the lid taken off" but also as a consumer revolution. Until recently, however, little attention has been paid to how industrialization changed the foods available to Americans. This article examines what Americans were eating in the first half of the twentieth century. It first defines industrial foods as foods that are mass produced in a factory setting and require no or very little cooking to make them edible. These foods are also packaged which make them highly portable. Examples of industrial foods are commercially canned goods; frozen foods; ice cream; breads, cakes, and pies purchased at bakeries and/or groceries and supermarkets; cake mixes; hot and cold cereals; instant mashed potatoes; pastry/pie shell mixes; and jams and jellies. Industrial foods are considered products of the Cold War and the Baby Boom Generation, rather than the Gilded Age or the Progressive Era. This article also discusses home economics, food consumption, and the national diet.
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Book chapters on the topic "Ice shelf channel"

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Mueller, Derek, Luke Copland, and Martin O. Jeffries. "Changes in Canadian Arctic Ice Shelf Extent Since 1906." In Arctic Ice Shelves and Ice Islands, 109–48. Dordrecht: Springer Netherlands, 2017. http://dx.doi.org/10.1007/978-94-024-1101-0_5.

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Ishman, Scott E., and Phillip Szymcek. "Foraminiferal Distributions in the Former Larsen-A Ice Shelf and Prince Gustav Channel Region, Eastern Antarctic Peninsula Margin: A Baseline for Holocene Paleoenvironmental Change." In Antarctic Peninsula Climate Variability: Historical and Paleoenvironmental Perspectives, 239–60. Washington, D. C.: American Geophysical Union, 2013. http://dx.doi.org/10.1029/ar079p0239.

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Frolov, Ivan E., Zalman M. Gudkovich, Valery P. Karklin, Evgeny G. Kovalev, and Vasily M. Smolyanitsky. "Consistency among sea ice extent and atmospheric and hydrospheric processes." In Climate Change in Eurasian Arctic Shelf Seas, 37–87. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-540-85875-1_4.

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Frolov, Ivan E., Zalman M. Gudkovich, Valery P. Karklin, Evgeny G. Kovalev, and Vasily M. Smolyanitsky. "Arctic sea ice as an element of the global climate system." In Climate Change in Eurasian Arctic Shelf Seas, 1–6. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-540-85875-1_1.

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Frolov, Ivan E., Zalman M. Gudkovich, Valery P. Karklin, Evgeny G. Kovalev, and Vasily M. Smolyanitsky. "Variability of sea ice thickness and concentration in the twentieth century." In Climate Change in Eurasian Arctic Shelf Seas, 29–36. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-540-85875-1_3.

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Frolov, Ivan E., Zalman M. Gudkovich, Valery P. Karklin, Evgeny G. Kovalev, and Vasily M. Smolyanitsky. "Long-term changes in Arctic Seas ice extent during the twentieth century." In Climate Change in Eurasian Arctic Shelf Seas, 7–27. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-540-85875-1_2.

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Frolov, Ivan E., Zalman M. Gudkovich, Valery P. Karklin, Evgeny G. Kovalev, and Vasily M. Smolyanitsky. "Possible causes of changes in climate and in Arctic Seas ice extent." In Climate Change in Eurasian Arctic Shelf Seas, 89–112. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-540-85875-1_5.

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Frolov, Ivan E., Zalman M. Gudkovich, Valery P. Karklin, Evgeny G. Kovalev, and Vasily M. Smolyanitsky. "Assessment of possible changes in air temperature and sea-ice extent in the Arctic Seas in the twenty-first century." In Climate Change in Eurasian Arctic Shelf Seas, 113–29. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-540-85875-1_6.

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Herzfeld, Ute Christina. "Monitoring Changes in Antarctic Ice Surface Topography: The Example of the Lambert Glacier/Amery Ice Shelf System." In Atlas of Antarctica, 259–87. Berlin, Heidelberg: Springer Berlin Heidelberg, 2004. http://dx.doi.org/10.1007/978-3-642-18515-1_5.

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"Advancing an Ecosystem Approach in the Gulf of Maine." In Advancing an Ecosystem Approach in the Gulf of Maine, edited by Catherine L. Johnson and Jonathan A. Hare. American Fisheries Society, 2012. http://dx.doi.org/10.47886/9781934874301.ch15.

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<i>Abstract</i>.—Zooplankton communities perform a critical role as secondary producers in marine ecosystems. They are vulnerable to climate-induced changes in the marine environment, including temperature, stratification, and circulation, but the effects of these changes are difficult to discern without sustained ocean monitoring. The physical, chemical, and biological environment of the Gulf of Maine, including Georges Bank, is strongly influenced by inflow from the Scotian Shelf and through the Northeast Channel, and thus observations both in the Gulf of Maine and in upstream regions are necessary to understand plankton variability and change in the Gulf of Maine. Large-scale, quasi synoptic plankton surveys have been performed in the Gulf of Maine since Bigelow’s work at the beginning of the 20th century. More recently, ongoing plankton monitoring efforts include Continuous Plankton Recorder sampling in the Gulf of Maine and on the Scotian Shelf, U.S. National Marine Fisheries Service’s MARMAP (Marine Resources Monitoring, Assessment, and Prediction) and EcoMon (Ecosystem Monitoring) programs sampling the northeast U.S. Continental Shelf, including the Gulf of Maine, and Fisheries and Oceans Canada’s Atlantic Zone Monitoring Program on the Scotian Shelf and in the eastern Gulf of Maine. Here, we review and compare past and ongoing zooplankton monitoring programs in the Gulf of Maine region, including Georges Bank and the western Scotian Shelf, to facilitate retrospective analysis and broadscale synthesis of zooplankton dynamics in the Gulf of Maine. Additional sustained sampling at greater-than-monthly frequency at selected sites in the Gulf of Maine would be necessary to detect changes in phenology (i.e. seasonal timing of biological events). Sustained zooplankton sampling in critical nearshore fish habitats and in key feeding areas for upper trophic level organisms, such as marine mammals and seabirds, would yield significant insights into their dynamics. The ecosystem dynamics of the Gulf of Maine are strongly influenced by large-scale forcing and variability in upstream inflow. Improved coordination of sampling and data analysis among monitoring programs, effective data management, and use of multiple modeling approaches will all enhance the mechanistic understanding of the structure and function of the Gulf of Maine pelagic ecosystem.
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Conference papers on the topic "Ice shelf channel"

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Cicek, B., and H. Xie. "Elevation and Freeboard Changes of Ross Sea Ice and Ice Shelf using Icesat." In 2006 IEEE International Symposium on Geoscience and Remote Sensing. IEEE, 2006. http://dx.doi.org/10.1109/igarss.2006.463.

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Rack, W., H. Rott, T. Nagler, and P. Skvarca. "Areal changes and motion of northern Larsen Ice Shelf, Antarctic Peninsula." In IGARSS '98. Sensing and Managing the Environment. 1998 IEEE International Geoscience and Remote Sensing. Symposium Proceedings. (Cat. No.98CH36174). IEEE, 1998. http://dx.doi.org/10.1109/igarss.1998.703800.

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Park, Deukhee, Sanghyun Cha, Yuenjoong Lee, Chanwoo Park, Ohjo Kwon, and Jaeshin Lee. "135-Channel electronic-paper driver IC for electronic shelf label." In 2011 IEEE International Conference on Consumer Electronics (ICCE). IEEE, 2011. http://dx.doi.org/10.1109/icce.2011.5722873.

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Hassanipour, Fatemeh, and Jose´ Lage. "Enhanced Mini-Channel Forced Convection With Encapsulated Phase-Change Particles." In ASME 2008 Heat Transfer Summer Conference collocated with the Fluids Engineering, Energy Sustainability, and 3rd Energy Nanotechnology Conferences. ASMEDC, 2008. http://dx.doi.org/10.1115/ht2008-56037.

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In this study we propose a new cooling concept using encapsulated phase-change particles flowing in a parallel-plate mini-channel. This novel concept is inspired by the gas exchange process in alveolar capillaries, where red blood cells (RBCs) flow with blood plasma, yielding very high gas transfer efficiency. Another important characteristic of alveolar capillary blood flow, which is related to the high efficiency of the lungs, is the snug fitting of the RBCs into the capillary. Hence, we conjecture that using particles similar to RBCs, i.e. with diameter similar to the spacing between the parallel plates, is likely to lead to high heat transfer efficiency as well. We report here experimental results of preliminary tests performed with octadecane paraffin (C18H38), a phase-change material, encapsulated in a thin melamine shell, flowing with water through a heated parallel-plate channel test module. We measured the temperature distribution along the heated surface of the channel for various water flow rates, with and without particles, and varying the number of particles. Results are reported in terms of the channel heated surface average temperature and the average Nusselt number.
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Ahmed, Samir, Ahmed El-Habashi, and Vincent Lovko. "Impact on satellite retrievals of temporal changes in Karenia brevis harmful algal blooms in the West Florida Shelf." In Remote Sensing of the Ocean, Sea Ice, Coastal Waters, and Large Water Regions 2017, edited by Charles R. Bostater, Stelios P. Mertikas, Xavier Neyt, and Sergey Babichenko. SPIE, 2018. http://dx.doi.org/10.1117/12.2278612.

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Raman, Senthil Kumar. "Stress Evaluation of a Three-Point Supported Heat Exchanger." In ASME 2022 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/pvp2022-84588.

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Abstract This paper focuses on developing formula-based method to predict shell stresses in a high-pressure heat exchanger with three-point supports. It compares the results with Finite Element Analysis (FEA) based design procedure. High pressure heat exchanger is supported with two saddles on shell (fixed and sliding saddles) and one lug support on channel due to heavy thk. tubesheet and channel flanges. Heat exchanger vessel part is considered as a hollow circular beam and closed form solutions are derived using continuous beam theory. Three-dimensional (3D) Finite Element model is developed using Ansys® and three types of meshing options are considered i.e., tetrahedron mesh, hex dominant mesh, and shell element mesh. Linear static structural analysis is performed, and shell membrane plus bending stresses are extracted by linearizing the axial stresses along the Stress Classification Lines at four shell locations using PVRC 3D stress criteria (Bulletin WRC 429). Longitudinal membrane plus bending stresses are calculated for the severe most design load case: Internal pressure, superimposed tubesheet weight and ship motion acceleration loads. Stress values which are obtained by formula-based approach and FEA are compared at four shell locations and conclusions are drawn.
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Chen, Zhenpeng, Sheng Shen, Ziniu Hu, Xuan Lu, Qiaozhu Mei, and Xuanzhe Liu. "Emoji-Powered Representation Learning for Cross-Lingual Sentiment Classification (Extended Abstract)." In Twenty-Ninth International Joint Conference on Artificial Intelligence and Seventeenth Pacific Rim International Conference on Artificial Intelligence {IJCAI-PRICAI-20}. California: International Joint Conferences on Artificial Intelligence Organization, 2020. http://dx.doi.org/10.24963/ijcai.2020/649.

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Sentiment classification typically relies on a large amount of labeled data. In practice, the availability of labels is highly imbalanced among different languages. To tackle this problem, cross-lingual sentiment classification approaches aim to transfer knowledge learned from one language that has abundant labeled examples (i.e., the source language, usually English) to another language with fewer labels (i.e., the target language). The source and the target languages are usually bridged through off-the-shelf machine translation tools. Through such a channel, cross-language sentiment patterns can be successfully learned from English and transferred into the target languages. This approach, however, often fails to capture sentiment knowledge specific to the target language. In this paper, we employ emojis, which are widely available in many languages, as a new channel to learn both the cross-language and the language-specific sentiment patterns. We propose a novel representation learning method that uses emoji prediction as an instrument to learn respective sentiment-aware representations for each language. The learned representations are then integrated to facilitate cross-lingual sentiment classification.
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Zhang, Sheng, Shanbin Shi, Xiao Wu, Xiaodong Sun, and Richard Christensen. "Double-Wall Natural Draft Heat Exchanger Design for Tritium Control in FHRs." In 2017 25th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/icone25-67844.

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Tritium control is potentially a critical issue for Fluoride salt-cooled High-temperature Reactors (FHRs) and Molten Salt Reactors (MSRs). Tritium production rate in these reactors can be significantly higher compared to that in Light Water Reactors (LWRs). Tritium is highly permeable at high temperatures through reactor structures, especially. Therefore, heat exchangers with large heat transfer areas in FHRs and MSRs provide practical paths for the tritium generated in the primary salt migrating into the surroundings, such as Natural Draft Heat Exchangers (NDHXs) in the direct reactor auxiliary cooling system (DRACS), which are proposed as a passive decay heat removal system for these reactors. A double-wall heat exchanger design was proposed in the literature to significantly minimize the tritium release rate to the environment in FHRs. This unique shell and tube heat exchanger design adopts a three-fluid design concept and each of the heat exchanger tube consists of an inner tube and an outer tube. Each of these tube units forms three flow passages, i.e., the inner channel, annular channel, and outer channel. While this type of heat exchangers was proposed, few such heat exchangers have been designed in the literature, taking into account both heat and tritium mass transfer performance. In this study, a one-dimensional heat and mass transfer model was developed to assist the design of a double-wall NDHX for FHRs. In this model, the molten salt and air flow through the inner and outer channels, respectively. A selected sweep gas acting as a tritium removal medium flows in the annular channel and takes tritium away to minimize tritium leakage to the air flowing in the outer channel. The heat transfer model was benchmarked against a Computational Fluid Dynamics (CFD) code, i.e., ANSYS Fluent. Good agreement was obtained between the model simulation and Fluent analysis. In addition, the heat and mass transfer models combined with non-dominated sorting in generic algorithms (NSGA) were applied to investigate a potential NDHX design in Advanced High-Temperature Reactor (AHTR), a pre-conceptual FHR design developed by the Oak Ridge National Laboratory. A double-wall NDHX design using inner and outer fluted tubes was therefore optimized and compared with a single-wall design in terms of performance and economics.
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Kumar, Navin, and Debjyoti Banerjee. "Experimental Validation of Numerical Predictions for the Transient Performance of a Simple Latent Heat Storage Unit (LHSU) Utilizing Phase Change Material (PCM) and 3-D Printing." In ASME 2017 Heat Transfer Summer Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/ht2017-5045.

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Experimental validation was performed in this study to verify the efficacy of numerical models for predicting the location of solid-liquid interface in an axi-symmetric configuration during both melting and solidification in a Latent Heat Storage Unit (LHSU). Development of analytical solutions for predicting the location of the solid-liquid interface is often intractable in LHSU due to non-linear temperature distribution in the Phase Change Material (PCM). This is further complicated by the moving boundary problem with free convection within the liquid phase of the PCM. Analytical solutions available in the contemporary literature are based on simplified transient heat conduction models and often fail to reliably predict the charging and discharging time constants for LHSU with complex configurations. This study is designed with the goal of developing more sophisticated numerical models for the estimation of transient thermal performance of an LHSU with a simple configuration involving a shell and tube heat exchanger (HX). The LHSU utilized in this study is realized by integrating various types of Phase Change Materials (PCM) contained in the shell side of a HX. The LHSU is charged or discharged by pumping hot or cold fluids in the tube side of the HX (i.e., by pumping water at a fixed inlet temperature from a commercial chiller apparatus). This study enabled the characterization of the transient response of a LHSU subjected to conduction and forced convection heat transfer. The PCM used in this material was paraffin wax (PURETEMP 29). The HX in the LHSU consisted of a single pass straight tube (½ inch copper pipe) mounted within a single shell configuration. The shell was fabricated from plastic material using additive manufacturing (i.e., “3D Printing”). The temperature variation during melting and solidification of the PCM were measured at different radial and axial locations within the cylindrical shell that was mounted vertically. Temperature measurements were performed at different mass flowrate ranging from 0.004 Kg/sec to 0.007 Kg/sec for the same fluid temperature. The water bath temperatures were maintained at a constant temperature of 40°C for melting and 15°C for solidification. The experiment results show that the transient response of the LHSU for charging and discharging (i.e., time required for melting and solidification of the PCM) vary significantly. Comparison of the experimental data with analytical results (involving quasi-stationary models for phase change) demonstrate that natural convection is the dominant mode during the melting process, while conduction is the dominant mode during the solidification process.
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Vabø, Jon Gustav, Evan Thomas Delaney, Tom Savel, and Norbert Dolle. "Novel Application of Artificial Intelligence with Potential to Transform Well Planning Workflows on the Norwegian Continental Shelf." In SPE Annual Technical Conference and Exhibition. SPE, 2021. http://dx.doi.org/10.2118/206339-ms.

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Abstract This paper describes the transformational application of Artificial Intelligence (AI) in Equinor's annual well planning and maturation process. Well planning is a complex decision-making process, like many other processes in the industry. There are thousands of choices, conflicting business drivers, lots of uncertainty, and hidden bias. These complexities all add up, which makes good decision making very hard. In this application, AI has been used for automated and unbiased evaluation of the full solution space, with the objective to optimize the selection of drilling campaigns while taking into account complex issues such as anti-collision with existing wells, drilling hazards and trade-offs between cost, value and risk. Designing drillable well trajectories involves a sequence of decisions, which makes the process very suitable for AI algorithms. Different solver architectures, or algorithms, can be used to play this game. This is similar to how companies such as Google-owned DeepMind develop customized solvers for games such as Go and StarCraft. The chosen method is a Tree Search algorithm with an evolutionary layer on top, providing a good balance in terms of performance (i.e., speed) vs. exploration capability (i.e., it looks "wide" in the option space). The algorithm has been deployed in a full stack web-based application that allows users to follow an end-2-end workflow: from defining well trajectory design rules and constraints to running the AI engine and evaluating results to the optimization of multi-well drilling campaigns based on risk, value and cost objectives. The full-size paper describes different Norwegian Continental Shelf (NCS) use cases of this AI assisted well trajectory planning. Results to-date indicate significant CAPEX savings potential and step-change improvements in decision speed (months to days) compared to routine manual workflows. There are very limited real transformative examples of Artificial Intelligence in multi- disciplinary workflows. This paper therefore gives a unique insight how a combination of data science, domain expertise and end user feedback can lead to powerful and transformative AI solutions – implemented at scale within an existing organization.
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Reports on the topic "Ice shelf channel"

1

Coastal-Change and Glaciological Map of the Larsen Ice Shelf Area, Antarctica, 1940-2005. US Geological Survey, 2008. http://dx.doi.org/10.3133/i2600b.

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Coastal-change and glaciological map of the Ronne Ice Shelf area, Antarctica, 1974-2002. US Geological Survey, 2005. http://dx.doi.org/10.3133/i2600d.

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Coastal-change and glaciological map of the Amery Ice Shelf area, Antarctica: 1961–2004. US Geological Survey, 2013. http://dx.doi.org/10.3133/i2600q.

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Coastal-Change and Glaciological Map of the Northern Ross Ice Shelf Area, Antarctica: 1962-2004. US Geological Survey, 2007. http://dx.doi.org/10.3133/i2600h.

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