Journal of the Japanese Society of Snow and Ice
Online ISSN : 1883-6267
Print ISSN : 0373-1006
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Volume 80, Issue 5
Displaying 1-5 of 5 articles from this issue
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  • Simple prediction method of frost on contact wire
    Yasushi KAMATA, Masaya SHISHIDO, Kazuyoshi NEZU
    2018 Volume 80 Issue 5 Pages 427-440
    Published: 2018
    Released on J-STAGE: March 01, 2023
    DOIhttps://doi.org/10.5331/seppyo.80.5_427
    JOURNAL OPEN ACCESS
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    To investigate the contact wire frosting phenomena, we analyzed meteorological conditions under which the frost was observed. As a result, probability of the frosting generation was high, when the following conditions occurred at the same time: air temperature was less than 0.5℃，humidity was more than 80 %, wind velocity was less than 1ms−1 and net radiation was−120〜−70Wm−2. It was ascertained that the water vapor concentration was supersaturated in the neighborhood of the contact wire surface in such conditions and water vapor concentration was almost same through the night on the day of typical contact wire frosting. Based on the observed climatic conditions and generation mechanism of the frost, we examined a predicting method of generation of the contact wire frosting by using air temperature and humidity in the evening, and the forecasted weather condition and the minimum temperature in the next morning. We confirmed that hit rates by this method were high. When using this method to frost-remove train service determination, it was expected that efficient operation would be possible.
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  • Estimation of snow density for evaluatingsnow load by consideringtemperature
    Hiroki MATSUSHITA
    2018 Volume 80 Issue 5 Pages 441-450
    Published: 2018
    Released on J-STAGE: March 01, 2023
    DOIhttps://doi.org/10.5331/seppyo.80.5_441
    JOURNAL OPEN ACCESS
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    Snow density is used to design avalanche protection structures and buildings in snowy regions. It has thus far been derived from relational equations that use only snow depth. However, the density of actual snow cover varies due to regional conditions, such as temperature. To propose a method of estimating snow density using regional snow cover characteristics, we focused on snow and air temperature as factors influencing snow density. A multiple regression analysis with the average density of snow cover as the dependent variable was conducted based on the results of snow pit observations at nine places in Niigata and Nagano prefectures. An equation with snow depth and the average temperature of snow cover as independent variables was obtained. This equation can be used to estimate snow density according to snow temperature even for the same snow depth.
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  • Artificial snow used in environmental test facilities and its example of engineering applications
    Shinsuke KOJIMA
    2018 Volume 80 Issue 5 Pages 451-459
    Published: 2018
    Released on J-STAGE: March 01, 2023
    DOIhttps://doi.org/10.5331/seppyo.80.5_451
    JOURNAL OPEN ACCESS
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    [in Japanese]
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  • Research on snow related damage of overhead transmission facilities ─ Research results of CRIEPI in recent years ─
    Hisato MATSUMIYA, Yuzuru EGUCHI, Takashi NISHIHARA
    2018 Volume 80 Issue 5 Pages 461-474
    Published: 2018
    Released on J-STAGE: March 01, 2023
    DOIhttps://doi.org/10.5331/seppyo.80.5_461
    JOURNAL OPEN ACCESS
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    [in Japanese]
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  • Summer melting observation at the marginal region of the Antarctic ice sheet by microwave radiometer
    Nuerasimuguli ALIMASI, Hiroyuki ENOMOTO, Naohiko HIRASAWA
    2018 Volume 80 Issue 5 Pages 481-499
    Published: 2018
    Released on J-STAGE: March 01, 2023
    DOIhttps://doi.org/10.5331/seppyo.80.5_481
    JOURNAL OPEN ACCESS
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    This study introduces temporal and spatial variations of microwave radiation at the slope area of Antarctica based on in situ microwave observations. The observations were conducted by using portable microwave radiometers of 6, 18, and 36 GHz in January 2017. The continuous observation at S17 showed a rapid increase of brightness temperature of all frequencies in daytime. Snow melting seems to have caused this increase. The largest increase of brightness temperature was observed with the low frequency band of 6 GHz horizontal polarization. The amount of increase was 70 K. The higher frequencies of 36 and 18 GHz showed an earlier increase, followed by the increase at the low frequency of 6 GHz. This time difference is expected because the lower frequency may be influenced by emission from the deeper snow layer. As determined from observation along the 80km traverse route between S17 and H128, the brightness temperature increased generally toward the inland; however, the lowest brightness temperature was observed locally around S17. The refrozen ice layers in the coastal snow layers seem to have caused the low emission at S17. Although the satellite microwave observation could reveal the general decrease of brightness temperature from coast to inland, the local low brightness temperature around S17 was not revealed clearly. The satellite observation showed a 5K increase when the in situ observation recorded a large increase of 70 K. These results imply that the satellite observation missed some local and temporal variations.
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