Bulletin of Glaciological Research
Online ISSN : 1884-8044
Print ISSN : 1345-3807
ISSN-L : 1345-3807
Volume 30
Displaying 1-5 of 5 articles from this issue
  • Masamu ANIYA, Pedro SKVARCA
    2012 Volume 30 Pages 1-8
    Published: 2012
    Released on J-STAGE: April 26, 2012
    Glaciar Perito Moreno, with an area of 258km², is located on the eastern side of the Hielo Patagónico Sur (Southern Patagonia Icefield) at about 50°29′S and 73°04′W. Currently, it terminates in Lago Argentino, thereby dividing the lake into Canal de los Tmpanos to the north and Brazo Rico to the south. The glacier has repeatedly made small advances and retreats in the 20th century; however, it can be regarded as rather stable since the 1920. Based on 14C dating of 22 wood and one organic samples, we inferred that Glaciar Perito Moreno made two Little Ice Age (LIA) advances, one at ca. AD 1650 and the other about AD 1820-50. These two dates fit very well into the general framework of the LIA of the HPS.
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  • Kazuya AKIYAMA, Masaaki HANAOKA, Toshiya TAKESHI
    2012 Volume 30 Pages 9-23
    Published: 2012
    Released on J-STAGE: June 06, 2012
    Observation stations were established on the east side of Mt. Gongendake, central Japan, in a warm snowy region where air temperature often exceeds 0°C in winter. Meteorological data were measured and avalanche events were recorded using a seismometer and three video cameras. Over four winters, 1504 avalanche tremors and 727 avalanche video images were recorded. The video images included 83 dry surface avalanches, four dry full-depth avalanches, 157 wet surface avalanches, and 483 wet full-depth avalanches. Among these avalanches, 431 were on slope S1, where a disastrous avalanche occurred on January 26, 1986. Wet avalanches represented about 88% of the avalanches and took place when the air temperature was high. Approximately 92% of dry surface avalanches occurred while snow was falling. When dry surface avalanches occurred, calculated snow stability index (SI) values were below 4 and conditions for avalanche release from within the snow cover were satisfied. Wet avalanches occurred frequently during and after March, when the air temperature continuously exceeded 0°C, and even occurred in January and February when the air temperature was high. Wet full-depth avalanches increased in frequency as snowmelt increased. Starting in mid-March, most avalanches were wet full-depth avalanches, whereas in April only wet full-depth avalanches occurred.
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  • Keisuke SUZUKI, Katsutaka YOKOYAMA, Hiroshi ICHIYANAGI
    2012 Volume 30 Pages 25-32
    Published: 2012
    Released on J-STAGE: June 12, 2012
    In order to elucidate the spatial variation of chemicals deposited with snowfall in central Japan and the chemical characteristics of the snowpack in the mountainous area, samples from new surface snow and from snow pits were collected during the 2000-2001 winter season. There is a clear relationship between rising electric conductivity (EC) and falling pH for the new surface snow samples. The Na+ concentration correlates well with the Cl- and Mg2+ concentrations for new surface snow, suggesting that the contributions of sources other than sea salt are negligible. Thus, sea water is the predominant source of Na+, Cl-, and Mg2+ in new surface snow in central Japan. The ratio of Cl-/anions in new surface snow correlates well with latitude;there is a higher ratio of Cl-/anions at the sampling locations near the Sea of Japan. On the other hand, the ratio of NO3-/nssSO42- is high in the southern locations. The pH value for the snow pit samples is determined by the acid index. The colored layers deposited during the Kosa event are characterized by high EC, high pH, and high ion concentrations. The EC and Cl- concentration in new surface snow along roads are higher on the coastal plain than farther inland. On the other hand, the pH and ratio of NO3-/nssSO42- are lower on the coast than farther inland.
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  • Koich WATANABE, Daiki NISHIMOTO, Sachie ISHITA, Nagisa EDA, Yoshitoshi ...
    2012 Volume 30 Pages 33-40
    Published: 2012
    Released on J-STAGE: June 22, 2012
    Measurements of the concentrations of formaldehyde (HCHO) and hydrogen peroxide (H2O2) as well as major ions in the snow pit (6.5m deep) at Murododaira (altitude, 2450m), Mt. Tateyama near the coast of the Japan Sea in Central Japan, were performed in April 2011. The peaks of HCHO corresponded to the high nssSO42- layers above a 3.0m depth. The concentrations of deposited HCHO might have been relatively well preserved in the spring layers. HCHO with sulfate aerosols may be transported to Mt. Tateyama from the Asian mainland. The highest concentration of H2O2 was detected in the granular snow (coarse grain, melt forms) layer. The concentrations of H2O2 were low in the layers of compacted snow (fine grain, rounded grains) and solid-type depth hoar (faceted crystals). Post-depositional modification of H2O2 may be more significant than that of HCHO in snow in an alpine region.
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  • Nuerasimuguli ALIMASI, Shuhei TAKAHASHI, Hiroyuki ENOMOTO
    2012 Volume 30 Pages 41-51
    Published: 2012
    Released on J-STAGE: September 17, 2012
    Road surface freezing is a serious problem for road traffic in the winter in cold regions. This is especially true in mountainous regions, where the winter season is longer and roads are frequently covered with snow and/or ice. We sought to develop a detector for road-freezing conditions, consisting of optical sensors and an infrared thermometer. The measurement system has a light source with an incident angle of 45° and two photodiodes set with receiving angles of 0° (at the zenith) and 45° to measure the diffuse reflection and the specular reflection (mirror reflection). Using observations from a portable measurement system, road conditions (dry, wet, 'sherbet,' compacted snow, glossy compacted snow, black ice) were distinguished well in relation to the specular reflectance RS and the diffusive reflection RD. A mobile measurement system was installed at the rear of a car, and continuous observations were made along Route 39 around Sekihoku Pass, Hokkaido. The observed reflection data showed reasonable results for wet and sherbet surfaces along the lower parts of the course and for compacted snow and glossy compacted snow around Sekihoku Pass. The ratio of specular reflectance to diffuse reflectance, γSD (=RS/RD), enhanced the indication of the existence of black ice on the road surface, because RS was large and RD was small.
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