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  • 1
    Call number: ZSP-202-337
    In: Research report
    Description / Table of Contents: Contents: Introduction. - Surface ice observations. - Imagery interpretation. - Side-looking airborne radar. - Infrared. - Conclusions. - Literature cited.
    Description / Table of Contents: Ice conditions during mid-January 1974 in the Gulf of St. Lawrence and in the estuaty as far upstream as Rimouski are described utilitizing side-looking airborne radar, infrared and photographic imagery. The interpretations were verified by simultaneous surface observations on the ice by investigators operating from the CSS Dawson. The ice examined was undergoing rapid drift and deformation and showed a wide variety of thin ice (0-40 cm) features formed under the influence of strong winds and currents. These observations should serve as a guide in interpreting ice conditions in similar areas where ground truth data are not available.
    Type of Medium: Series available for loan
    Pages: 41 Seiten , Illustrationen
    Series Statement: Research report / Cold Regions Research and Engineering Laboratory, CRREL, US Army Material Command 337
    Language: English
    Branch Library: AWI Library
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  • 2
    Series available for loan
    Series available for loan
    Hanover, NH : Corps of Engineers, U.S. Army, Cold Regions Research and Engineering Laboratory,
    Associated volumes
    Call number: ZSP-202-329
    In: Research report
    Description / Table of Contents: CONTENTS: General Introduction. - Part I. Spatial and temporal variations in sea ice deformatfon. - Introduction. - Approach. - Site location and data collection procedures. - Data analysis. - Strain results. - Comparison of mesoscale deformation with macroscale deformation. - Nature of the ice pack rotation. - Conciusion. - Literature cited. - Part Il. Comparison of mesoscale strain measurements with linear drift theory predictions. - Introduction. - List of symbols. - Linear drift equations. - Ice drift solutions. - Comparison of theory with mesoscale measurements. - A more general linear constitutive law. - Conclusions. - Literature cited. - Appendix Relative magnitudes of differential drift forces. - Abstract.
    Description / Table of Contents: Measurements of mesoscale sea ice deformation over a region approximately 20 km in diameter were made over a five-week period in the spring of 1972 at the main AIDJEX camp in the Beaufort Sea. They have been analyzed to determine nonlinearities in the ice velocity field (due to the discrete small-scale nature of the ice pack), as well as a continuum mode of deformation represented by a least squares strain rate tensor and vorticity. The deformation rate time series between Julian day 88 and 113 exhibited net areal changes as large as 3% and deformation rates up to 0.16% per hour. In the principal axis coordinate system, the strain rate typically exhibited a much larger compression (or extension) along one axis than along the other. Persistent cycles at ~12-hour wavelengths were observed in the divergence rate. A comparison of the average residual error with the average strain rate magnitude indicated that strains measured on a scale of 10 km or greater can serve as a valid measure of the continuum motion of the sea ice. This conclusion is also substantiated by a comparison between the mesoscale deformation, and macroscale deformation measured over a ~100-km-diameter region. Vorticity calculations indicate that at low temporal frequencies ( 〈 0.04 hr^-1 ) the whole mesoscale array rotates essentially as an entity and consequently the low frequency vorticity can accurately be estimated from the rotation of a single floe. (Part I) A comparison of mesoscale strain measurements with the atmospheric pressure field and the wind velocity field indicated that the ice divergence rate and vorticity followed the local pressure and wind divergence with significant correlation. For low atmospheric pressures and converging winds, the divergence rate was negative with the vorticity being counterclockwise. The inverse behavior was observed for high pressures and diverging winds. This behavior agreed with predictions based upon the infinite boundary solution of a linearized drift theory in the absence of gradient current effects and using the constitutive law proposed by Glen for pack ice. The best least squares values of the constitutive law parameters [Eta] and [Zeta] were found to be given by ~10^12 kg sec^-1. Using typical divergence rates, these values yielded compressive stresses of the magnitude of 10^5 N m^-1, which are similar to values suggested by the Parmerter and Coon ridge model. In general, the infinite boundary solution of the linear drift equation indicates that in a low pressure region that is reasonably localized in space, the ice would be expected to converge for high compactness (winter) and diverge for low compactness (summer). Calculations were also carried out using a more general linear viscoelastic constitutive law that includes memory effects and that includes a generalized Hooke's law as well as the Glen law as special cases. A best fit of this more general calculation with strain measurements indicates, overall, a better agreement with viscous behavior than with elastic behavior, with the frequency behavior of the estimated "viscosities" similar to the Glen law behavior at temporal frequencies less than ~0.01 hr^-1 (Part II)
    Type of Medium: Series available for loan
    Pages: v, 37 Seiten , Illustrationen
    Series Statement: Research report / Cold Regions Research and Engineering Laboratory, CRREL, US Army Material Command 329
    Language: English
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  • 3
    Call number: SR 90.0001(1046-O)
    In: U.S. Geological Survey bulletin
    Type of Medium: Series available for loan
    Pages: IV S., S. 385-413 + 1 pl.
    Series Statement: U.S. Geological Survey bulletin 1046-O
    Language: English
    Location: Lower compact magazine
    Branch Library: GFZ Library
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  • 4
    Series available for loan
    Series available for loan
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Associated volumes
    Call number: ZSP-201-79/8
    In: CRREL Report, 79-8
    Description / Table of Contents: 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
    Type of Medium: Series available for loan
    Pages: iv, 28 Seiten , Illustrationen
    Series Statement: CRREL Report 79-8
    Language: English
    Note: 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
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  • 5
    Series available for loan
    Series available for loan
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Associated volumes
    Call number: ZSP-202-117
    In: Research report / Cold Regions Research and Engineering Laboratory, 117
    Description / Table of Contents: Summary: An experiment was designed to investigate operator-variance in the determination of the plastic limit of cohesive soils, independent of sample preparation and hydration time. A standard sample was prepared by dry-mixing commercial clay, "Grundite", with a pure silt. After the sample was hydrated for 3 weeks, five random samples were taken and five replicates performed on each sample. Analysis of variance (AOV) shows that there is no reason to doubt that the sample is homogeneous at the 0.05 level of significance. Random samples were then distributed to five zones of operators, where a zone is defined as a group of operators with similar backgrounds and engineering interests. Two operators from each group performed five replicates. The AOV model used in the analysis is mixed with the upper level fixed and the two lower levels random. The estimated "within" and "between" operator variances are 0. 45 and 4. 18 respectively. The estimated "between zones" contribution to the total sum of squares is negative. No correlation was found between an operator's internal variance and his deviation from the grand mean. On the basis of this experiment, no reason-exists to doubt that an "untrained" operator can obtain results comparable to those of professional operators. The major factor contributing to the total sample variance is the inconsistency between the individual operators who, although able to duplicate their own determinations, do not call the same end point. To minimize between operator variance, a readily prepared standard sample is suggested with which any operator can calibrate his plastic limit determinations against the expected national average.
    Type of Medium: Series available for loan
    Pages: iv, 8 Seiten , Illustrationen
    Series Statement: Research report / Cold Regions Research and Engineering Laboratory 117
    Language: English
    Note: CONTENTS Preface Summary ­Introduction Sample preparation Sample homogeneity Distribution of samples Analysis Conclusions and suggested standardization References
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  • 6
    Series available for loan
    Series available for loan
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Associated volumes
    Call number: ZSP-201-81/19
    In: CRREL Report, 81-19
    Description / Table of Contents: Field observations support the interpretation that differences in the strength of radar returns from the ice covers of lakes on the North Slope of Alaska can be used to determine where the lake is frozen completely to the bottom. An ice/frozen soil interface is indicated by a weak return and an ice/ water interface by a strong return. The immediate value of this result is that SLAR (side-looking airborne radar) imagery can now be used to prepare maps of large areas of the North Slope showing where the lakes are shallower or deeper than 1.7m (the approximate draft of the lake ice at the time of the SLAR flights). The bathymetry of these shallow lakes is largely unknown and is not obvious from their sizes or outlines. Such information could be very useful, for example in finding suitable year-round water supplies.
    Type of Medium: Series available for loan
    Pages: iii, 17 Seiten , Illustrationen
    Series Statement: CRREL Report 81-19
    Language: English
    Note: CONTENTS Abstract Preface Introduction The experiment Results Maps of completely frozen North Slope lakes Literature cited
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  • 7
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    Series available for loan
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Associated volumes
    Call number: ZSP-202-80
    In: Research report / Cold Regions Research and Engineering Laboratory, 80
    Description / Table of Contents: From the Introduction: During the last few years, there has been an increased interest in developing a rational explanation for the rather considerable variation in such bulk properties of sea ice as its strength, density, thermal conductivity, latent heat of melting, and coefficient of thermal expansion. Of these properties, sea-ice strength has received by far the most attention for practical reasons.
    Type of Medium: Series available for loan
    Pages: iv, 30, A6, B10, C2, D5 Seiten , Illustrationen
    Series Statement: Research report / Cold Regions Research and Engineering Laboratory 80
    Language: English
    Note: CONTENTS Preface Summary Introduction Experimentation Method of growing salt ice Strength test procedures Bulk properties of salt ice Phase relations Density and air content Strength results Strength of fresh-water ice Strength of NaCl ice as a function of brine volume Strength of NaCl· 2H2O ice as a function of the relative volume of solid salt Effect of thermal history on salt-ice strength Phase hysteresis Geometric hysteresis Effect of short-term cooling on the strength of fresh-water and NaCl·2H2O ice Effect of the volume of inclosed air on the strength of salt ice Conclusions NaCl ice Sea ice References Appendix A: Volume of brine and NaCl· 2H2O in NaCl ice as a function of salinity and temperature Appendix B: Ring test results Normal test sequences Appendix C: Ring test results Hysteresis test sequences Appendix .b: Ring test results Thermal history test sequences
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  • 8
    Call number: ZSP-201-83/21
    In: CRREL Report, 83-21
    Description / Table of Contents: The probability density function of the gouge depths into the sediment is represented by a simple negative exponential over four decades of gouge frequency. The exceedance probability function is, therefore, e to the -lambda d, where d is the gouge depth in meters and lambda is a constant. The value of lambda shows a general decrease with increasing water depth, from 9/m in shallow water to less than 3/m in water 30 to 35 m deep. The deepest gouge observed was 3.6 m, from a sample of 20,354 gouges that have depths greater than or equal to 0.2 m. The dominant gouge orientations are usually unimodal and reasonably clustered, with the most frequent alignments roughly parallel to the general trend to the coastline. The value of N(bar) sub 1, the mean number of gouges (deeper than 0.2 m) per kilometer measured normal to the trend of the gouges, varies from 0.2 for protected lagoons to 80 in water between 20 and 38 m deep in unprotected offshore regions. The distribution of the spacings between gouges as measured along a sampling track is a negative exponential. The form of the frequency distribution of N sub 1 varies with water depth and is exponential for lagoons and shallow offshore areas, previously skewed for 10 to 20 m depths off the barrier islands, and near-normal for deeper water. As a Poisson distribution gives a reasonable fit to the N sub 1 distributions for all water depths, it is suggested that gouging can be taken as approximating a Poisson process in both space and time. The distributions of the largest values per kilometer of gouge depths, gouge widths, and the heights of the lateral embankment of sediments plowed from the gouges are also investigated.
    Type of Medium: Series available for loan
    Pages: 40 Seiten , Illustrationen, 1 Karte
    Series Statement: CRREL Report 83-21
    Language: English
    Note: CONTENTS Abstract Preface Introduction Background and environmental setting Data collection and terminology Data analysis Gouge depths Gouge orientation Gouge frequency Extreme value analysis Applications to offshore design Gouge depth Extreme value statistics Burial depths Conclusion Literature cited Appendix A: Detailed bathymetric map of the Alaskan portion of the Beaufort Sea
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  • 9
    Series available for loan
    Series available for loan
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Associated volumes
    Call number: ZSP-202-101
    In: Research report / Cold Regions Research and Engineering Laboratory, 101
    Description / Table of Contents: Partial Summary: This paper is a pilot study of interrelations between structural features readily observed in horizontal thin sections of sea ice under low magnification. The core studied was 31.4 cm in length and was collected from Elson Lagoon at Point Barrow, Alaska on 26 October 1960.
    Type of Medium: Series available for loan
    Pages: iv, 11 Seiten , Illustrationen
    Series Statement: Research report / Cold Regions Research and Engineering Laboratory 101
    Language: English
    Note: CONTENTS Preface Summary Introduction Petrographic characteristics Intercrystalline features Intracrystalline features References
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  • 10
    Series available for loan
    Series available for loan
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Associated volumes
    Call number: ZSP-201-78/13
    In: CRREL Report, 78-13
    Description / Table of Contents: 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.
    Type of Medium: Series available for loan
    Pages: v, 29 Seiten , Illustrationen
    Series Statement: CRREL Report 78-13
    Language: English
    Note: 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
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