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Volume 78 (2016)
- Issue 6 Pages 365-
- Issue 5 Pages 255-
- Issue 4 Pages 185-
- Issue 3 Pages 127-
- Issue 2 Pages 89-
- Issue 1 Pages 3-
Volume 78, Issue 5
Displaying 1-8 of 8 articles from this issue
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Masaru MATSUZAWA2016 Volume 78 Issue 5 Pages 255-268
Published: 2016
Released on J-STAGE: March 01, 2023
JOURNAL OPEN ACCESSThe quantitative assessment of snowstorm hazards is necessary for the effective implementation of blowing-snow control measures. Snow transport rate is used as a hazard index, but it is difficult to measure this rate directly. Thus, the snow transport rate has been estimated by using its correlation with wind velocity expressed by an empirical equation. However, that empirical equation does not account for snowfall intensity. In evaluating snow transport rates in Japan and in other regions with heavy snowfall, snowfall intensity needs to be taken into consideration. This paper describes a method for estimating snow transport rates during blowing snow with snowfall, and it examines the applicability of the method. The snow transport rate as a whole at a specific site is assumed to be a sum of the transport rates of snow particles in the suspension layer and in the saltation layer. For the suspension layer, the transport rate of snow particles is calculated by vertically integrating a product obtained by multiplying the spatial density of drifting snow, which consist of suspended particles and falling snow particles, by the wind velocity. For the saltation layer, an empirical equation of Kobayashi (1972) is used for calculating the transport rate of snow particles. The snow transport rates estimated by using the method described in this paper are largely consistent with the measured snow transport rate.View full abstractDownload PDF (2094K) -
Momota IMAMURA, Kazuo TAKEDA, Yuki HINOKAWA, Yoshihiro NOBORI, Masato ...2016 Volume 78 Issue 5 Pages 269-279
Published: 2016
Released on J-STAGE: March 01, 2023
JOURNAL OPEN ACCESSIn order to evaluate the influence of ground freezing on the growth of larch (Larix Kaempferi)， a correlation analysis was conducted between tree ring width and meteorological factors in Tokachi district, eastern Hokkaido in Japan, which is characterized by low temperatures and thin snow cover in winter. The results show that the changes of tree ring width standardized among the 20 trees sampled in this study area have a correlation coefficient of 0.646. The TRI (Tree Ring Index) using a 32 years series, shows a negative relation with the annual maximum frost depth with a correlation coefficient of −0.451 (p<0. 01), however it did not have any correlation with the freezing index. It instead shows a weak correlation (0.312, p=0.08) with the annual maximum snow depth. The average value of annual maximum frost depth is 0.25 m, which is equal to the distribution range of larch tree rootlets. Taking into account that the surface soil around larch roots is frost-susceptible, frost heave increases the risk of rootlets damage increasing annual maximum frost depth. The rootlet damage suppresses growth of larch so that the width of tree ring decreases. Based on these findings, growth of trees in this region is closely related to soil frost depth and snow depth.View full abstractDownload PDF (1749K) -
Yuka OOTA, Akihiro HACHIKUBO, Satoshi TAKEYA2016 Volume 78 Issue 5 Pages 281-290
Published: 2016
Released on J-STAGE: March 01, 2023
JOURNAL OPEN ACCESSSubmicron-order pores, such as diatoms in sea-bottom sediments, have large specific surface area and affect the formation and dissociation processes of methane hydrates. We formed synthetic methane hydrates in mesopores of silica gel and diatomaceous earth, and we observed their dissociation process by using calorimetric techniques. The dissociation heat from the methane hydrate in mesopores to gas and ice was about 15% less than that of bulk methane hydrate. Isotopic fractionation of carbon and hydrogen in methane during the formation of hydrate was also investigated. The δD of the hydrate-bound methane was 5.5±0.8‰ lower than that of residual methane in the formation processes, which agrees well with the results of bulk methane hydrate reported in previous research. The δ13C of the hydrate-bound methane was 1.1±0.6‰ higher than that of residual methane; no difference was found in the case of bulk methane hydrate.View full abstractDownload PDF (1749K) -
Yuki SHIBATA, Katsuhisa KAWASHIMA, Hiroto SUZUKI2016 Volume 78 Issue 5 Pages 291-306
Published: 2016
Released on J-STAGE: March 01, 2023
JOURNAL OPEN ACCESSLong-term variations and trends in the annual maximum snow depth and snow cover duration were analyzed for Niigata Prefecture between the winters of 1941/42 and 2012/13. Analysis was conducted on daily snow depth data from 17 snow observation sites, ranging in altitude from 4m to 507 m, and both the simple linear regression analysis and the Mann-Kendall test were utilized as means to detect trends. Statistical significance of the trend in this study was evaluated at a level of significance of 5%. The results showed that the annual maximum snow depth is on a decreasing trend in the plain area, which has an altitude of 30m or less, while no significant trend is seen in the mountainous area. The rates of decrease range from 2.3 to 12.8cm every 10 years. It is considered that decreases in winter precipitation and rises in winter temperature are likely to be related to the decreasing trend in the annual maximum snow depth. In addition, a decreasing trend in the snow cover duration was observed at the stations analyzed in this study, which have an altitude of 350m or less; rates of decrease range from 1.7 to 7.5 days every 10 years. In the plain area at an altitude of 30m or less, this decreasing trend is believed to be primarily due to the significant increase in air temperature in February and March.View full abstractDownload PDF (3226K) -
Koichi WATANABE, Taiki HIRAI, Keisuke NAKAGAWA, Kouji OGAWA, Yoshitosh ...2016 Volume 78 Issue 5 Pages 307-315
Published: 2016
Released on J-STAGE: March 01, 2023
JOURNAL OPEN ACCESSThe concentrations of Na+and Cl− in the snow cover at Murododaira, Mt. Tateyama each April from 2009 to 2014 were compared. The ratios of Cl− to Na+ were similar to the ratio in seawater from 2009 to 2011, whereas there were many snow samples in which the ratios were higher than the ratio in seawater after 2012. The excessive Cl− might have been due to activated fumarolic activity at Jigokudani, Midagahara. High Cl− layers which did not correspond to Na+ peaks were detected in the 2014 snow cover. The concentrations of nssSO42− were not high in the high Cl− layers. The volcanic gases may not affect nssSO42− in the snow cover. To discuss the transport and depositional processes of anthropogenic pollutants, such as nssSO42−, the chemical data at Murododaira after 2012 may also be available.View full abstractDownload PDF (1956K) -
Hiroyuki OBANAWA, Katsuhisa KAWASHIMA, Takane MATSUMOTO, Tsutomu IYOBE ...2016 Volume 78 Issue 5 Pages 317-328
Published: 2016
Released on J-STAGE: March 02, 2023
JOURNAL OPEN ACCESSWe conducted an aerial survey of mountain slopes during the snow season and after snow melting, and constructed multitemporal 3-dimensional topographic models. Our aerial photogrammetric method uses a small UAV (Unmanned Aerial Vehicle) carrying a compact camera, and SfM-MVS (Structure from Motion-Multi View Stereo) software. We estimated the snow distribution from the difference between the two periods. The estimated snow depth was compared with the actual depth measured with a snow probe, and the difference was found to be 8% on average. Making reliable profiles of the topography and the snow depth, and then estimating the total snow volume within an arbitrary area, is possible because the spatial resolutions of the snow depth and topographic data estimated by this method are very high. This method has great potential for the evaluation of snow avalanche risks, as highresolution parameters can be obtained with high frequency, allowing for rapid and precise calculation of avalanche risk even in inaccessible areas. However, the method is not suitable for application to a wide area, continuous observations over a long period, or operation in bad weather such as rain, strong winds or low temperatures.View full abstractDownload PDF (4996K) -
Tatsuo SEKIGUCHI, Takayuki ABE, Osamu ABE, Kazuya AKIYAMA2016 Volume 78 Issue 5 Pages 329-337
Published: 2016
Released on J-STAGE: March 01, 2023
JOURNAL OPEN ACCESS -
Masayoshi NAKAWO2016 Volume 78 Issue 5 Pages 339-348
Published: 2016
Released on J-STAGE: March 01, 2023
JOURNAL OPEN ACCESS
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