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Volume 64, Issue 1
Displaying 1-11 of 11 articles from this issue
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Yasoichi ENDO, Yuji KOMINAMI, Katsumi YAMANOI, Shoji NIWANO2002 Volume 64 Issue 1 Pages 3-13
Published: January 15, 2002
Released on J-STAGE: August 07, 2009
JOURNAL FREE ACCESSThe depth and density of new snow deposited during a given time interval are important practical information for avalanche forecasting, snow removal on roads and other applications. But, the depth of new snow cannot be measured automatically; it is obtained by measuring manually the depth of snow deposited on a snow board, which is cleared and set on the snow surface at regular intervals. Hence, Kominami et al.(1998)derived a method to compute the depth of daily new snow based on a viscous compression model of snow, by using values of total snow depth and precipitation measured hourly by an ultrasonic snow-depth meter and a rain- and snow-gauge respectively. In this paper, we compute the depth and density of hourly new snow by the method, and compare these with the values measured on a snow board in three winters from 1994-95 to 1996-97. The result shows that the computed values were fairly close to the measured values. The standard deviation of the computed depth was 0.88cm and the maximum difference was 4.3cm. The standard deviation of the computed density was 16 kg·m-3 for computed hourly snow depth of more than 2 cm. We have shown that the errors of hourly new snow depth mainly result from errors of total snow depth measured with an ultrasonic snow-depth meter, not from the viscous compression model.View full abstractDownload PDF (2693K) -
Shigeo SUIZU2002 Volume 64 Issue 1 Pages 15-24
Published: January 15, 2002
Released on J-STAGE: August 07, 2009
JOURNAL FREE ACCESSDry snow avalanches occur due to heavy snowfalls or weak layers in the snowpacks.The stability index(=shear strength/shear stress)of snow can indicate the hazard evaluation and forecast of dry snow avalanches. The stability index of new snow, settling due to its own weight, can be calculated by using viscous compression theory, snowfall amount and snow temperature. The model for the stability index has been developed. It can estimate the time series and distributions of snowfalls, air temperatures and stability indices by using meteorological data and digital elevation models. The model was applied to an extensive area and it showed good accord with the occurrence of avalanches. The model is useful in indicating the hazard evaluation and forecast of avalanches due to heavy snowfall. The model is practical because the input data comprise only public data.View full abstractDownload PDF (1386K) -
Prediction of impact pressure waves for snow blocks with low densityOsamu ABE, Shun'ichi KOBAYASHI, Atsushi SATO, Hideomi NAKAMURA, Tsutom ...2002 Volume 64 Issue 1 Pages 25-31
Published: January 15, 2002
Released on J-STAGE: February 05, 2010
JOURNAL FREE ACCESSA previous paper investigated the impact of snow blocks against walls, posts and disks. However, impact pressure waves remain to be elucidated. In this paper, the impact pressure waves of snow blocks against a wall and a disk are simulated using Rankine-Hugoniot's relation with a new aspect. The new aspect is in the densification of pulverized snow in a plastic region, i.e., pulverized snow is compressed by the impulse after impact. Using this method, an impact pressure wave can be calculated from the impact velocity and the initial snow density up to 380 kg/m3. In this case, the density of pulverized snow at the front of the plastic wave is estimated from the impact velocity, the initial snow density and the maximum impact pressure. The results show that the density of pulverized snow at the front jumps to 1.45 times the initial snow density.View full abstractDownload PDF (837K) -
Shinji IKEDA2002 Volume 64 Issue 1 Pages 33-37
Published: January 15, 2002
Released on J-STAGE: August 07, 2009
JOURNAL FREE ACCESS -
Kaoru IZUMI, Shun'ichi KOBAYASHI, Tomoharu NAGASAKI, Yasoichi ENDO, Ka ...2002 Volume 64 Issue 1 Pages 39-47
Published: January 15, 2002
Released on J-STAGE: February 05, 2010
JOURNAL FREE ACCESS -
Remi MOTOYAMA, Fumitaka YANAGISAWA, Naofumi AKATA, Yuuichirou SUZUKI, ...2002 Volume 64 Issue 1 Pages 49-58
Published: January 15, 2002
Released on J-STAGE: February 05, 2010
JOURNAL FREE ACCESSAcidification of rain and snow is one of the most serious environmental problems in the world today. Sulfur isotope ratios considered to be related to this acidification, have been used as tracers. It has been reported that the sulfur isotope ratio of non-sea salt sulfate in winter is higher than that during other seasons, and that in the winter wet deposits contain sulfur released by the combustion of coal in East Asia. Sulfur isotope ratios of non-sea salt sulfate in wet depositions were measured at Sakata, northern Japan. The deposition rate of non-sea salt sulfate increases in winter. The sulfur isotope ratios of non-sea salt sulfate ranged from- 1 to+14‰and showed seasonal variation, with an increase in winter. This seasonal variation suggests that non-sea salt sulfate in wet deposition is derived from a source, having a higher sulfur isotope ratio in winter than in other seasons.In order to clarify the sources of non-sea salt sulfate in wet deposits, sulfur isotope ratios were measured for coals used in East Asia (China and Russia).The average sulfur isotope ratio of coals used in 30-20°N is-3.8±6.3‰, that of coals used in 60-30°N is+7.4±8.8‰, and that of northeastern Chinese coals (42-39°N)is+9.6±10.8‰.The sulfur isotope ratios of non-sea salt sulfate collected in Japan in the winter were in agreement with the sulfur isotope values for coals in northeastern China. The northwest Siberia monsoon dominates Japan in the winter. The air mass at the 850hPa level appears to have passed over Northeast Asia. Sulfur oxides produced by coal combustion in Northeast Asia have their highest contribution in winter.View full abstractDownload PDF (3902K) -
Tutomu KOKAWA, Osamu ITOH, Tohru WATANABE2002 Volume 64 Issue 1 Pages 59-68
Published: January 15, 2002
Released on J-STAGE: August 07, 2009
JOURNAL FREE ACCESSSnow and cold facilitate the construction of an ice shell. Such an ice shell is thin.Because of its high structural efficiency, it can cover a larger area than classical snow-ice structures such as“Igloo”and“Kamakura”. It creates a fantastic, beautiful space providing a unique environment in snowy and cold regions.
Since 1997 Tomamu, Hokkaido has been the site for many ice shells used as architectural leisure spaces for tourists. These ice shells have thus far had less than 15-m spans. In hopes of constructing a larger ice shell to be used as a winter multi-purpose hall, we have tested a 20-m span ice dome 6.5m in height. Two test-domes were completed, one in 1999, and one in 2000.These test-domes had a high structural efficiency compared with a previous test-dome constructed in 1985 that had geometrical and material imperfections because of unskilled snow blowing operation.
This paper describes the construction experiment and creep behavior of 2000'test-dome, and concludes, that construction of a 20-m span ice dome, to be used during winter in Hokkaido, is possible.View full abstractDownload PDF (5017K) -
Masahiro KAJIKAWA, Eiko NARITA, Keiko ICHINOSEKI, Teiko KUDO, Rumiko S ...2002 Volume 64 Issue 1 Pages 69-76
Published: January 15, 2002
Released on J-STAGE: February 05, 2010
JOURNAL FREE ACCESSTo study the growth process of snowflakes, the composition factors (the number, shape and diameter of component snow crystals) were observed using a separation method of snowflakes.
For a given number of component crystals, the larger the average diameter of the crystals, the larger the diameter of the snowflakes is. The diameter of snowflakes can be expressed as a power of the number of crystals with the average diameter of crystals as a parameter.
When several crystals make a snowflake, its external form is planar, whereas with more than about ten crystals it nears a spherical form. It was confirmed that dendritic type crystals make larger snowflakes than radiating type crystals for the same number of crystals, because the average diameter of the former crystals is larger than the latter.View full abstractDownload PDF (1092K) -
Masaru MATSUZAWA, Masao TAKEUCHI2002 Volume 64 Issue 1 Pages 77-85
Published: January 15, 2002
Released on J-STAGE: February 05, 2010
JOURNAL FREE ACCESSProvision of real-time information on the distribution of poor visibility caused by blowing snow will enable drivers to select safer routes. Visibility meters currently are used to monitor visibility on roads. However, too few such devices are installed to adequately monitor the regional distribution of blowing snow. This has led us to seek estimation methods for the degree of poor visibility based on wind velocity and snowfall intensity, data that are available relatively easily. First, based on findings of past studies on mass flux of snow (Mf) and visibility (Vis) we established that log (Vis)=-0.733·log(Mf)+2.845 when the visibility is 3000 m or less. We then attempted to establish methods to obtain snow concentration based on the fact that the mass flux of snow is snow concentration multiplied by wind velocity. For this, we used two specific scenarios in order to estimate snow concentration based on wind velocity and snowfall intensity: the case in which the wind velocity at 10 m above the ground was 8.5 m/s or greater and the temperature was -2°C or lower; and the case in which the wind velocity at 10 m above the ground was less than 8.5 m/s and snow was falling. The visibility estimated by our formulae corresponded fairly well to measured values, which indicates that our visibility estimation method can be used for regional monitoring of poor visibility on roads.View full abstractDownload PDF (1206K) -
Takeshi SATO, Osamu ABE, Kenji KOSUGI, Yasuaki NOHGUCHI2002 Volume 64 Issue 1 Pages 87-95
Published: January 15, 2002
Released on J-STAGE: February 05, 2010
JOURNAL FREE ACCESSThe hardness of snow can be measured quickly with a portable load gauge to which a circular attachment is fixed. The maximum resistance during the penetration of the attachment into the snow is measured and the hardness is obtained by dividing it by the area of the attachment. The resultant hardness of snow, PR, is almost independent of the direction of penetration(horizontal/vertical).It does not depend on the speed of the attachment just before the penetration into the snow within a range of a few cm/s-1m/s. The relationship between the hardness, PR15, which is obtained using the standard attachment whose diameter is 15mm, and the hardness, KR, obtained with the Kinosita-type hardness meter, is given by KR =0.1PR151.5. If an attachment with a diameter of d (mm) is used, PR15 can be calculated from the measured hardness, PR, by PR15 = PR/ (0.5+8/d). These equations, where the unit of the hardness is kPa, allow us to convert the hardness measured with the load gauge into the hardness measured with the Kinosita-type hardness meter. These conversion equations may depend on the response time of the load gauge and the penetration depth of the attachment.View full abstractDownload PDF (1160K) -
Factors affecting highway disasters caused by blowing snowMasao TAKEUCHI2002 Volume 64 Issue 1 Pages 97-105
Published: January 15, 2002
Released on J-STAGE: February 05, 2010
JOURNAL FREE ACCESSDisasters caused by blowing snow cause damage to highway traffic, including motorists, vehicles, road and its facilities.
There are many factors related to disasters because of the unique characteristics of highway traffic and the structure of the blowing snow, which is complicated. To prevent disasters, it is important to comprehend these factors.
Highways suffer damage in such ways as traffic closures and accidents, the causes including reduced visibility and snowdrift.Many factors affect the extent of damage suffered. For example, a long fetch increases snow transportation, increasing the causative factor of reduced visibility. Snow accretion on signs obstructs traffic safety information for motorists.
A block diagram composed of these factors shows the structure of a blowing snow disaster.View full abstractDownload PDF (1378K)
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