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  • Books  (140)
  • MDPI - Multidisciplinary Digital Publishing Institute  (51)
  • Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory  (49)
  • Taylor & Francis  (40)
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  • 1
    Call number: ZSP-201-76/24
    In: CRREL Report, 76-24
    Description / Table of Contents: Chemical analysis of surface snows and deeper ice core samples from Milcent, Greenland, indicates a marine origin for Na and Cl and a terrestrial origin for Al, Mn and V. Pre-1900 enrichment factors, based on average crustal composition, are high for Zn and Hg and appear to be related to their volatility. A comparison of pre-1900 and 1971-1973 concentrations of V and Hg shows no decided increase from industrial production; however, the abundance of Zn (relative to Al) increased three-fold during this time period. The chemical composition of ancient ice is extremely useful in interpreting modern aerosols.
    Type of Medium: Series available for loan
    Pages: ii, 6 Seiten , Illustrationen
    Series Statement: CRREL Report 76-24
    Language: English
    Location: AWI Archive
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  • 2
    Series available for loan
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    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Associated volumes
    Call number: ZSP-202-316
    In: Research report
    Description / Table of Contents: Measurements of the concentrations of Na+, K+, Mg++ and Ca++ were made on 28 samples from the 255-m-deep ice core from Little America V. All concentrations decrease sharply with depth from the firn-ice transition at 52 m to somewhere between 125 m and 150 m. From 150 m to 250 m the cationic concentrations are relatively constant. This is interpreted to indicate that the ice above 125 m fell as snow on the Ross Ice Shelf and that ice below 150 m originated inland on Marie Byrd Land.
    Type of Medium: Series available for loan
    Pages: ii, 7 S. : graph. Darst.
    Series Statement: Research report / Cold Regions Research and Engineering Laboratory, CRREL, US Army Material Command 316
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  • 3
    Call number: ZSP-202-347
    In: Research report / Cold Regions Research and Engineering Laboratory, 347
    Description / Table of Contents: CONTENTS: Abstract. - Preface. - Introduction. - Experimental. - Results and discussion. - Applications. - Literature cited.
    Description / Table of Contents: Chemical analysis of century-old ice from continuous 5 to 7 year intervals of three ice cores from south and central Greenland (Dye 3, Milcent and Crete) show maximum concentrations of Na, Mg,Ca, K, and Al during early spring and minimum concentrations during late summer and early fall. Peak spring values are as much as 10 times greater than fall values. Because of the large seasonal chemical variations, samples used for depth-age or annual deposition rate studies must represent accumulation from exactly one year or whole multiples of a year. The seasonal chemical variations seem promising as a new method of defining annual layers and thus dating old ice cores.
    Type of Medium: Series available for loan
    Pages: iii, 5 Seiten , Illustrationen
    Series Statement: Research report / Cold Regions Research and Engineering Laboratory 347
    Language: English
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  • 4
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    Series available for loan
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Associated volumes
    Call number: ZSP-201-80/23
    In: CRREL Report, 80-23
    Description / Table of Contents: The contribution of brine layers to observed reflective anisotropy of sea ice at 100 MHz is quantitatively assessed. The sea ice is considered to be a stratified, inhomogeneous, anisotropic dielectric consisting of pure ice containing ordered arrays of conducting inclusions (brine layers). Below the transition zone, the ice is assumed to have constant azimuthal c-axis orientation within the horizontal plane, so that the orientation of brine layers is uniform. The brine layers are also assumed to become increasingly well-defined with depth, since adjacent brine inclusions tend to fuse together with increasing temperature. A theoretical explanation for observed reflective anisotropy is proposed in terms of an isotropic electric flux penetration into the brine layers. Penetration anisotropy and brine layer geometry are linked to anisotropy in the complex dielectric constant of sea ice. In order to illustrate the above effects we present a numerical method of approximating the reflected power of a plane wave pulse incident on a slab of sea ice. Mixture dielectric constants are calculated for two polarizations of the incident wave: 1) the electric field parallel to the c-axis direction, and 2) the electric field perpendicular to the c-axis direction. These dielectric constants are then used to calculate power reflection coefficients for the two polarizations. Significant bottom reflection (R ~ 0.08) occurs when the polariza-tion is parallel to the c-axis. However, when the polarization is perpendicular to the c-axis, the return may be almost completely extinguished (R 〈 0.001). This extinction is due primarily to absorptive loss associated with the conduct-ing inclusions and secondarily to an impedance match at the ice/water interface that results in transmission of the wave to the water without reflection.
    Type of Medium: Series available for loan
    Pages: vi, 15 Seiten , Illustrationen
    Series Statement: CRREL Report 80-23
    Language: English
    Note: CONTENTS Abstract Preface List of symbols Introduction Anisotropy and sea ice macrostructure Anisotropy and sea ice microstructure A theory of anisotropic radar return from sea ice Anisotropic electric flux penetration into brine layers Implications of normal exclusion, tangential penetration, and brine layer geometry for dielectric behavior of sea ice Modeling of electromagnetic reflection from a stratified, anisotropic, inhomogeneous lossy medium Calculation of mixture complex dielectric constants Calculation of interfacial power reflection coefficients Calculation of bulk power reflection coefficients Calculation of attenuated power reflection coefficients Beam spread Results Anisotropic bottom reflections Anisotropic complex dielectric constants Sensitivity of parameters Internal reflection: the bumps Discussion Conclusions Literature cited
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  • 5
    Call number: ZSP-201-80/20
    In: CRREL Report, 80-20
    Description / Table of Contents: Results of impulse radar studies of sea ice give support to the concept of a sea ice model in which the ice bottom is composed of an array of lossy parallel plate waveguides. The fundametal relation between the average bulk brine volume of sea ice and its electrical and strength properties is discussed as is the remote detection of under-ice current alignment. It was found that 1) the average effective bulk dielectric constant is dependent upon the average bulk brine volume of the sea ice; 2) sea ice anisotropy, arising from a bottom structure of crystal platelets with a preferred c-axis horizontal alignment, can be detected by radio echo sounding measurements made not only on the ice surface but also from an airborne platform; 3) the effective coefficient of reflection from the seaiIce bottom decreases with increasing average effective bulk dielectric constant of the ice, decreases with increasing bulk brine volume, and is typically one to two orders of magnitude lower dhan the coefficient of reflection from the ice surface; and 4) the losses In sea ice increase with increasing average bulk brine volume.
    Type of Medium: Series available for loan
    Pages: v, 18 Seiten , Illustrationen
    Series Statement: CRREL Report 80-24
    Language: English
    Note: CONTENTS Abstract Preface Introduction Field program Results and discussion Conclusions Literature cited Appendix: Data analysis procedures
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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-201-80/17
    In: CRREL Report, 80-17
    Description / Table of Contents: Construction pads made of snow were used to build two sections of the Trans Alaska Pipeline and a small gas pipeline during the winter of 1975-76. Construction during the winter has become increasingly common in the Arctic. Surface travel and the use of heavy construction equipment on the unprotected tundra have been severely restricted, even during the winter, so the use of temporary winter roads and construction pads built of snow and ice has been advocated and is being adopted. The three snow construction pads mentioned above were the first snow roads and construction pads used on a large scale in Alaska. Snow roads and construction pads have two objectives: to protect the underlying vegetation and upper layers of the ground, and to provide a hard, smooth surface for travel and the operation of equipment. Several types have been built, and a brief discussion is given of their history and classification systems. The three snow construction pads used in construction of the Trans-Alaska Pipeline and the small gas pipeline in 1975-76 were visited and observed while in use. The Globe Creek snow pad, about 50 miles north of Fairbanks, was built primarily of manufactured snow hauled to the site and watered. With very high densities this pad withstood heavy traffic and use by heavy construction equipment except on one steep slope. There, the use of tracked vehicles and vehicles without front wheel drive disaggregated the snow on and near the surface so that vehicles without front wheel drive were unable to climb the hill. The Toolik snow pad, just north of the Brooks Range, was built of compacted snow and proved capable of supporting the heaviest traffic and construction equipment. The fuel gasline snow pad ran from the northern Brooks Range to the Arctic Coast and also proved capable of supporting the necessary traffic. Both the Toolik snow pad and the fuel gasline snow pad failed in very early May because of unseasonably warm and clear weather before the associated construction projects were completed. However, the three snow pads must be considered successful. Common problems were the lack of snow, slopes, unseasonably warm spring weather, and inexperience on the part of contractors and construction personnel.
    Type of Medium: Series available for loan
    Pages: v, 28 Seiten , Illustrationen
    Series Statement: CRREL Report 80-17
    Language: English
    Note: CONTENTS Abstract Preface Introduction History of snow and ice roads Classification of snow and ice roads Snow pads used by Alyeska during the winter of 1975-1976 The Globe Creek snow pad The Toolik snow pad The gasline snow pad Summary and conclusions Literature cited
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  • 7
    Series available for loan
    Series available for loan
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Associated volumes
    Call number: ZSP-202-291
    In: Research report
    Description / Table of Contents: CONTENTS: Introduction. - Study lake. - Previous work at Post Pond. - Methods and procedures. - Results and discussion. - Summer stratification. - Autumnal mixing and thermocline disappearance. - Winter period of ice cover. - Spring circulation. - Summary and conclusions. - Literature cited. - Appendix A: Ice sample analysis. - Abstract.
    Description / Table of Contents: The temperature structure of Post Pond, a small (46.6 hectares), mid-latitude, dimictic lake in west-central New Hampshire, was studied during autumn,winter and spring of 1968-1969. The lake was instrumented over its maximum depth (11.7 m) with a string of 24 thermocouples which recorded hourly temperatures. Temperatures in 9 m of sediments underlying the lake were measured with a thermistor probe. Secondary and tertiary thermocline development in the epilimnion occurred during short warming periods in the early autumn. The autumn overturn lasted 25 days, whereas the spring overturn lasted only 4 days. The entire lake mixed isothermally in the autumn to 3.2°C. During the period of ice cover, the lower 5 m of water gained approximately 51.5 cal/cm^2, which was supplied by stored heat in the bottom sediments. A steady-state thermal gradient of 0.07°C/m was found for the deeper sediments underlying the lake during ice cover. Late winter cooling of bottom water under the ice cover may be the result of snowmelt in areas adjacent to the lake causing activation of groundwater influx. Melting of the clear ice portion of the ice cover was primarily the result of heat supplied to the lake from snowmelt water, and occurred on the underside of the ice sheet. Thermal instability of the water mass persisted for 9 days during peak snowmelt runoff; this can be partially explained by an increase in dissolved solids with depth.
    Type of Medium: Series available for loan
    Pages: 23 Seiten , Illustrationen
    Series Statement: Research report / Cold Regions Research and Engineering Laboratory, CRREL, US Army Material Command 291
    Language: English
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  • 8
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    Series available for loan
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Associated volumes
    Call number: ZSP-201-82/42
    In: CRREL Report, 82-42
    Description / Table of Contents: A high-resolution impulse radar profiling system was evaluated for 1) detecting the existence of sea ice which coring has revealed to exist on the bottom of the Ross Ice Shelf at Site J-9, 2) detecting the preferred horizontal c-axis azi-muthal direction of the sea ice crystals, using the voltage amplitude of the radar reflection from the sea ice bottom, and 3) determining the direction of the currents under an Antarctic ice shelf. A field program was conducted consisting of a surface radar survey on the Ross Ice Shelf at Site J-9 and surface and airborne radar profiling on the McMurdo Ice Shelf. The CRREL impulse radar system, operating at a center frequency of either 80 MHz or 20 MHz, was unable to detect the shelf bottom at Site J-9, which drilling revealed to be 416 m below the snow surface. The radar system was used to profile the McMurdo Ice Shelf both from the snow surface and from the air; a shelf thickness of about 275 m was easily detected. Theoretical considerations indicate that the bulk conductivity of the ice shelf at Site J1-9 was higher than originally anticipated, and this limited the radar sounding depth to about 405 m when operating at a frequency of 20 MHz.
    Type of Medium: Series available for loan
    Pages: iv, 19 Seiten , Illustrationen
    Series Statement: CRREL Report 82-42
    Language: English
    Note: CONTENTS Abstract Introduction Profiling system Theoretical considerations Field program Discussion Literature cited
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  • 9
    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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  • 10
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    Series available for loan
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Associated volumes
    Call number: ZSP-201-83/18
    In: CRREL Report, 83-18
    Description / Table of Contents: An evaluation of an impulse radar system for detecting cavities under concrete pavement is discussed, and field results are presented. It was found that a dual antenna mode of surveying was ideal for void detection. In this mode one antenna operated in a transceive mode and a second, offset from the first, operated in a receive-only mode. This arrangement allowed a refraction-type profile survey to be performed, which enabled subpavement voids to be easily detected. Field trails were held at Plattsburgh Air Force Base, where 28 cavities were detected and mapped. Drilling of holes verified that a cavity existed and allowed cavity depth to be measured. The cavities varied from 1.5 in. to 23 in, depth and were up to 20 ft. long.
    Type of Medium: Series available for loan
    Pages: 49 Seiten , Illustrationen
    Series Statement: CRREL Report 83-18
    Language: English
    Note: CONTENTS Abstract Preface Introduction Plattsburgh Air Force Base Radar sounding system Survey procedure Cavity inspection Radar cavity detection test Radar profile results Falling-weight deflectometer tests Discussion and conclusions Literature cited
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