Journal of the Japanese Society of Snow and Ice
Online ISSN : 1883-6267
Print ISSN : 0373-1006
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Volume 62, Issue 6
Displaying 1-4 of 4 articles from this issue
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  • Normal stress dependence of ice-ice friction coefficients
    Naoki MIZUKAMI, Norikazu MAENO
    2000 Volume 62 Issue 6 Pages 515-521
    Published: November 15, 2000
    Released on J-STAGE: September 04, 2009
    DOIhttps://doi.org/10.5331/seppyo.62.515
    JOURNAL FREE ACCESS
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    The ice-ice friction coefficient was measured as a function of normal stress (1.217.3 kPa), temperature (-0.5-20°C) and velocity (4×10-3, 4.5×10-2, 4×10-1m/s). The friction coefficient was found to decrease with increasing normal stress and became almost constant at larger normal stresses than about 6 kPa at all the temperatures and velocities studied. Though the overall dependence could be expressed as, μ ∝ P-0.32 where μ and P are respectively the ice-ice friction coefficient and normal stress, the Mohr-Coulomb relation, μ=μO+A/P, was utilized in our data analysis, where μO and A are the Coulomb friction coefficient and adhesion strength, respectively. The temperature dependence of μO showed a minimum around-5°C. The value of μO decreased with increasing velocity, suggesting the formation of water film by friction heat at these low sliding velocities. The value of adhesion strength was of the order of 10250 Pa and increased with lowering temperature or increasing velocity.
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  • Evaluation of frequency band and polarization of microwave radiometer for observation of first-year ice in the Okhotsk Sea
    Masashige NAKAYAMA, Kohei CHO, Haruhisa SHIMODA, Toshibumi SAKATA, Tom ...
    2000 Volume 62 Issue 6 Pages 523-535
    Published: November 15, 2000
    Released on J-STAGE: September 04, 2009
    DOIhttps://doi.org/10.5331/seppyo.62.523
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    Relevant frequencies and polarization are investigated for observation of first-year ice using airborne microwave radiometer in the Okhotsk Sea. The 89.0GHz could distinguish the sea ice cover and open water area. In addition, the discrimination of sea ice and open water derived from SSM/I data is successful for first-year ice cover in the Okhotsk Sea.
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  • Study on ice thickness estimation on Lake Saroma to develop a method to be applied sea ice in the Sea of Okhotsk using SAR data
    Kazuki NAKAMURA, Fumihiko NISHIO, Hiroyuki WAKABAYASHI
    2000 Volume 62 Issue 6 Pages 537-548
    Published: November 15, 2000
    Released on J-STAGE: September 04, 2009
    DOIhttps://doi.org/10.5331/seppyo.62.537
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    In order to evaluate the possibility of measurement of sea ice thickness in the Sea of Okhotsk, a “Sea ice observation and experiment in the Sea of Okhotsk” campaign has been carried out on Lake Saroma, Hokkaido since 1993. Lake Saroma consists of sea water of almost the same salinity as connected to the Sea of Okhotsk, and is covered with sea ice in the winter. The salinity, surface roughness and layer structure of ice are similar to those of thin first-year sea ice produced in the Sea of Okhotsk. The relationship between ice thickness and backscattering coefficients obtained by SAR data shows a negative correlation.
    In general, the backscattering from a saline ice such as first-year ice is dominated by surface scattering. If the roughness of the ice surface is uniform, backscatter eventually depends on the dielectric constant of the ice. When the air temperature is lower than the sea ice freezing point of-1.8 degrees centigrade, ice surface temperature is decreasing as the ice thickness is thickening, and then the surface temperature is lowering, it is caused by brine volume decrease within the ice. It is, therefore, considered that the backscattering coefficient is decreased as the dielectric constant decreases because the average dielectric constant as the brine volume decreases. It is possible to retrieve the ice thickness using SAR whenever the snow cover and surface roughness of the ice are uniform.
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  • Glaciological Investigation at Sofiyskiy Glacier, Russian Altai Mountains
    Yoshiyuki FUJII, Fumihiko NISHIO, Takao KAMEDA
    2000 Volume 62 Issue 6 Pages 549-556
    Published: November 15, 2000
    Released on J-STAGE: September 04, 2009
    DOIhttps://doi.org/10.5331/seppyo.62.549
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    Glaciological invesitgation was carried out at the accumulation area (3450m a.s.l.) of Sofiyskiy Glacier, Altai Republic, Russian Federation from July 15 to 24, 2000. The purposes of this study are to evaluate the suitability of the site for estimating past climate and environment changes through ice core study, to solve the logistic problems including helicopter operation in the Altai region, and to discuss future collaborative research with scientists in the Russian Federation. This paper describes in situ observational results of 12.3 m ice core, snow stratigraphy of 3m pit and meteorological observations on the site. It was found that ice temperature from the surface to 8m depth was 0°C and the minimum temperature was -0.11°C at 10m depth. Fourteen brown-colored layers were observed from the surface to 12.3m depth. Air temperature varies from -4 to +5.5°C and wind speed is in the range between 0 and 5m/s. Wind direction was almost the same (W to SW).
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