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  • 1
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    Signatur: ZSP-201-78/2
    In: CRREL Report, 78-2
    Beschreibung / Inhaltsverzeichnis: Many of the technical questions relating to iceberg transport are given brief, but quantitative, consideration. These include iceberg genesis and properties, the mechanical stability of icebergs at sea, towing forces and tug characteristics, drag coefficients, ablation rates, and handling and processing the iceberg at both the pick-up site and at the final destination. In particular the paper attempts to make technical information on glaciological and ice engineering aspects of the problem more readily available to the interested planner or engineer. Specific conclusions include: (1) No unprotected iceberg, no matter how long or wide, would be likely to survive the ablation caused by a long trip to low latitudes. (2) Icebergs that have a horizontal dimension exceeding 2 km may well be prone to breakup by long wavelength swells. (3) To avoid the dangers associated with an iceberg capsizing, the width of a 200-m thick iceberg should always be more than 300 m. (4) For towing efficiency the length/width ratio of a towed iceberg should be appreciably greater than unity. (5) For a pilot project, the selected iceberg would have to be quite small, if for no other reason than the practical availability of tug power.
    Materialart: Schriftenreihen ausleihbar
    Seiten: v, 31 Seiten , Illustrationen
    Serie: CRREL Report 78-2
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Introduction Sources and properties of tabular icebergs Sources Characteristics of ice shelves near the ice front Characteristics of tabular icebergs Towing Geophysical and engineering considerations Tug characteristics Handling and processing Cutting and boring with thermal devices Penetration with electrothermal devices Electrothermal cutting Making vertical cuts by pre-split blasting Primary fragmentation by blasting Primary fragmentation by mechanical sawing Comminuting ice with machines Slurry pipelines Conclusion Literature cited
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    Signatur: ZSP-201-77/29
    In: CRREL Report, 77-29
    Beschreibung / Inhaltsverzeichnis: Results of measurements of salinity, grain size, substructure dimensions and crystal fabrics of the undeformed 2.15-m-thick annual sea ice sheet near Narwhal Island, Alaska, are presented. A notable observation was the formation of a dominant c-axis horizontal structure in all ice below 14 cm, including transformation to a pronounced east-west alignment of the c-axes by a depth of 66 cm. This study confirms earlier reports of the occurrence of very strong horizontal c-axis alignments in arctic fast ice.
    Materialart: Schriftenreihen ausleihbar
    Seiten: iii, 8 Seiten , Illustrationen
    Serie: CRREL Report 77-29
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Introduction Sampling and analytical procedures Results Discussion Conclusions Literature cited
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Signatur: ZSP-201-76/18
    In: CRREL Report, 76-18
    Beschreibung / Inhaltsverzeichnis: Three surface elevation and ice thickness profiles obtained during the 1972 Arctic Ice Dynamics Joint Experiment on a multiyear ice floe were analyzed to obtain relationships between surface elevation, thickness and physical properties of the ice. It was found that for ice freeboards from 0.10 m to 1.05 m above sea level a linear relationship between ice density and freeboard could be postulated. The equation for the regression line is: Ice density = -194f' + 974 kg/cu m where f' is the ice freeboard plus snow depth in ice equivalent at the point in question. This statistical relationship is consistent with observed physical properties, which indicate that as the ice freeboard increases, ice salinity decreases and the higher freeboard or thicker ice therefore decreases in density. Using this variable density with freeboard relationship, a model was constructed to predict ice thickness, given ice freeboard and snow depth alone. This prediction is desirable, since snow depth and freeboard are relatively easy to obtain, whereas ice thickness can usually be obtained only by drilling through the ice. The model was compared with two other models. It was found that the variable density prediction model gave the best approximation to observed ice thickness, with a standard error between the measured and predicted value of about 0.4 m, compared with errors from 50 to 100% higher for the other two models.
    Materialart: Schriftenreihen ausleihbar
    Seiten: v, 25 Seiten , Illustrationen
    Serie: CRREL Report 76-18
    Sprache: Englisch
    Anmerkung: Contents Abstract Preface Summary Introduction Previous work Results Models for predicting thickness from ice freeboard Comparison between measured and predicted thicknesses Spectral behavior of measured and predicted profiles Comparisons of ice thickness using airborne laser profilometry Conclusions Literature cited Appendix A: Misgivings on isostatic imbalance as a mechanism for sea ice cracking
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Monographie ausleihbar
    Monographie ausleihbar
    Bellingham : SPIE Optical Engineering Press
    Signatur: M 97.0224
    Materialart: Monographie ausleihbar
    Seiten: xiii, 570 S.
    ISBN: 0780334108
    Serie: SPIE/IEEE series on imaging science & engineering
    Klassifikation:
    C.2.9.
    Sprache: Englisch
    Standort: Kompaktmagazin oben
    Zweigbibliothek: GFZ Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    Signatur: ZSP-201-79/8
    In: CRREL Report, 79-8
    Beschreibung / Inhaltsverzeichnis: Sea ice ridging statistics obtained from a series of laser surface roughnessprofiles are examined. Each set of profiles consists of six 200-km-long flight tracks oriented approximately perpendicular to the coastline of the Chukchi and Beaufort Seas. The landward ends of the profiles were located at Point Lay, Wainwright, Barrow, Lonely, Cross Island and Barter Island. The flights were made in February, April, August, and December 1976, and one additional profile was obtained north of Cross Island during March 1978. It was found that although there is a systematic variation in mean ridge height (h) with season (with the highest values occurring in late winter), there is no systematic spatial variation in h at a given time. The number of ridges/km (micron) is also high during the late winter, with the highest values occurring in the Barter and Cross Island profiles . In most profiles, the ice 20 to 60 km from the coast is more highly deformed (higher micron values) than the ice either nearer the coast or farther seaward. The Wadhams model for the distribution of ridge heights gives better agreement with observed values in the higher ridge categories than does the Hibler model. Estimates of the spatial recurrence frequency of large pressure ridges are made by using the Wadhams model and also by using an extreme value approach. In the latter, the distribution of the lagest ridges per 20 km of laser track was found to be essentially normal
    Materialart: Schriftenreihen ausleihbar
    Seiten: iv, 28 Seiten , Illustrationen
    Serie: CRREL Report 79-8
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Introduction Data collection and processing Analysis General Variations in ridging Ridge height distributions Occurrence of high ridges The tail of the distribution Extreme values Applications to offshore design Conclusions Literature cited Appendix A. Tabulated ice ridge data
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    Signatur: ZSP-201-78/13
    In: CRREL Report, 78-13
    Beschreibung / Inhaltsverzeichnis: Field observations of the growth fabrics of the fast and near-fast ice along the coasts of the Beaufort and Chukchi Seas show that, at depths of more than 60 cm below the upper ice surface, the sea ice crystals show striking alignments within the horizontal plane. At one site this alignment was well developed at a depth of 15 cm and in all cases the degree of preferred orientation increased with depth, with the strongest orientations occurring at the bottom of the ice sheet. In general the c-axes of the crystals were aligned roughly E-W parallel to the coast. In the vicinity of islands the alignment roughly paralleled the outlines of the islands and in narrow passes between islands the alignment paralleled the channel. Our observations, as well as similar observations made in the Kara Sea by Cherepanov, can be explained if it is assumed that the c-axes of the crystals are aligned parallel to the 'long-term' current direction at the sea ice/sea water interface. The alignments are believed to be the result of geometric selection among the growing crystals, with the most favored orientation being that in which the current flows normal to the (0001) plates of ice that make up the dendritic ice/water interface characteristics of sea ice. It is hypothesized that current flow in this direction reduces the thickness of the solute boundary layer as well as the salinity in the liquid at the interface. This lowered salinity allows crystals in the favored orientation to extend farther into the melt than neighboring crystals with less favored orientations. In addition the current tends to induce a continuous flux of supercooled seawater against the sides of the crystals that extend ahead of the interface.
    Materialart: Schriftenreihen ausleihbar
    Seiten: v, 29 Seiten , Illustrationen
    Serie: CRREL Report 78-13
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Introduction Locale and techniques Observations Vertical variations in crystal orientation Regional variations in crystal orientation Summary of observations Causes Initial ice skim Earth’s magnetic field Currents Conclusions and consequences Literature cited
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    Signatur: ZSP-202-310
    In: Research report
    Beschreibung / Inhaltsverzeichnis: CONTENTS: Introduction. - Field sites and procedures. - Results. - Discussion. - Conclusions. - Literature cited. - Appendix A: Tabulation of AIDJEX core data. - Appendix B: Tabulation of average salinity/ice thickness data. - Abstract.
    Beschreibung / Inhaltsverzeichnis: The salinity distribution in multiyear sea ice is dependent on the ice topography and cannot be adequately represented by a single average profile. The cores collected from areas beneath surface hummocks generally showed a systematic increase in salinity with depth from 0 0/00 at tne surface to about 4 0/00 at the base. The cores collected from areas beneath surface depressions were much more saline and displayed large salinity fluctuations. Salinity observations from sea ice of varying thicknesses and ages collected at various arctic and subarctic locations revealed a strong correlation between the average salinity of the ice, S, and the ice thickness, h. For salinity samples collected from cold sea ice at the end of the growth season, this relationship can be represented by two linear equations: S = 14.24 - 19.39h (h? 0.4 m) ; S = 7.88 - 1.59h (h 〉 0.4 m) . It is suggested that the pronounced break in slope at 0.4 m is due to a change in the dominant brine drainage mechanism from brine expulsion to gravity drainage. A linear regression for the data collected during the melt season gives S = 1.58 + 0.18h. An annual cyclic variation of the mean salinity probably exists for multiyear sea ice. The mean salinity should reach a maximum at the end of the growth season and a minimum at the end of the melt season.
    Materialart: Schriftenreihen ausleihbar
    Seiten: iii, 23 Seiten , Illustrationen
    Serie: Research report / Cold Regions Research and Engineering Laboratory, CRREL, US Army Material Command 310
    Sprache: Englisch
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Washington, DC : United States Gov. Print. Off.
    Dazugehörige Bände
    Signatur: SR 90.0001(1046-O)
    In: U.S. Geological Survey bulletin
    Materialart: Schriftenreihen ausleihbar
    Seiten: IV S., S. 385-413 + 1 pl.
    Serie: U.S. Geological Survey bulletin 1046-O
    Sprache: Englisch
    Standort: Kompaktmagazin unten
    Zweigbibliothek: GFZ Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Washington, DC : United States Gov. Print. Off.
    Dazugehörige Bände
    Signatur: SR 90.0002(908)
    In: Professional paper
    Materialart: Schriftenreihen ausleihbar
    Seiten: VII, 84 S. + 1 pl.
    Serie: U.S. Geological Survey professional paper 908
    Sprache: Englisch
    Standort: Kompaktmagazin unten
    Zweigbibliothek: GFZ Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Washington, DC : United States Gov. Print. Off.
    Dazugehörige Bände
    Signatur: SR 90.0001(1074-A)
    In: U.S. Geological Survey bulletin
    Materialart: Schriftenreihen ausleihbar
    Seiten: III, 5 S. + 1 pl.
    Serie: U.S. Geological Survey bulletin 1074-A
    Sprache: Englisch
    Standort: Kompaktmagazin unten
    Zweigbibliothek: GFZ Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
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