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Volume 77 (2015)
- Issue 6 Pages 475-
- Issue 5 Pages 397-
- Issue 4 Pages 285-
- Issue 3 Pages 233-
- Issue 2 Pages 173-
- Issue 1 Pages 5-
Volume 77, Issue 4
Displaying 1-5 of 5 articles from this issue
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Masaaki ISHIZAKA, Takeshi FUJINO, Hiroki MOTOYOSHI, Sento NAKAI, Kazuk ...2015 Volume 77 Issue 4 Pages 285-302
Published: 2015
Released on J-STAGE: March 01, 2023
JOURNAL OPEN ACCESSTwo extratropical cyclones, passing along the Pacific Ocean side of Japan Island around February 8 and 14, 2014, brought heavy snowfall, serious damages, and frequent occurrence of avalanches over the Kanto-Koshin areas. During the snowfall periods of the two cyclones, we carried out radar observation, continuous measurements of size and fall speed of falling snows, and classification of snow crystals in Niigata district. The observations revealed that in the both cases the main snow types were aggregates of plate, closs plate, and bullet, which grow in the temperature lower than−20℃. This types was different from the types during ordinary winter monsoon. The radar observations also revealed that heights of top echoes were 5 km or more, which were higher than ordinary winter monsoon, 4 km or lower. It is also ascertained by the data analysis with meso-scale meteorological model that at high altitudes above 5 km temperature was lower than−20℃ and relative humidity was higher than 90% (ice super-saturation), and the high humidity region had expanded to lower altitude according to the lows approached, that satisfied the conditions for formation and maintenance of low temperature-type snow crystals. Moreover these low temperature-type snow crystals are suggested to relate to the frequent occurrence of avalanches in Kanto-Koshin areas, not only because similar events had reported in a previous article, but because glass-like snow including columnar crystals were observed near an avalanche area.View full abstractDownload PDF (6031K) -
Masuyoshi MATSUDA, Takaaki SHIMIZU2015 Volume 77 Issue 4 Pages 303-311
Published: 2015
Released on J-STAGE: March 01, 2023
JOURNAL OPEN ACCESSFrom February 8 to 9 and 14 to 15 in 2014, Tokyo was covered with 27-cm-deep snow (Tokyo Meteorological Agency). Owing to heavy snow load, many buildings were damaged on February 15. During the two periods of snowfall, we measured the snow density in central Tokyo and obtained values of 122 and 130 kg m−3 on February 8 and 258 and 270 kg m−3 on February 14. The damage that occurred on February 15 was explained by a two-fold difference in snow density between the two periods, which was caused by the fact that the snowfall changed to the rainfall through the sleet-fall. From February 14 to 15, rain water remained within the snow cover, whereas from February 8 to 9, there was no rain water. On February 14, we measured the snow density on both the ground and the roof of a 170-m-tall high-rise building in Otemachi. We observed a snow density of 270 kg m-3 on the ground at positive temperature in the Celsius scale and a snow density of 144 kg m−3 on the rooftop at a negative temperature in the Celsius scale, which constitutes a large difference in density. In a region with snowfall as less frequent as in Tokyo, it was clarified that the amount of snow-load is best approximated by the cumulative precipitation because snow cover occurs. This approximation method was applied for Tokyo, Kumagaya, and Kofu, where the snow-load was calculated using time-series hourly data of snow depth and precipitation for the past 24 winters. The return periods of snow-load were then obtained for the three cities. In conclusion, the peak snow-load of 941Nm−2 （=96mm）on February 15 in Tokyo was estimated to occur once in 240 years.View full abstractDownload PDF (3749K) -
Katsuhisa KAWASHIMA, Takane MATSUMOTO, Tsutomu IYOBE, Kaoru IZUMI2015 Volume 77 Issue 4 Pages 313-325
Published: 2015
Released on J-STAGE: March 01, 2023
JOURNAL OPEN ACCESSA remarkable regionality in snow damages was seen during the heavy snowfall event that occurred in the Kanto-Koshin district on February 14-15, 2014. Since the areal differences in the predominant precipitation type may be related to this regionality, the estimates of the precipitation type （dry snowfall, wet snowfall, rain） in the Kanto-Koshin district were made at hourly intervals using AMeDAS data. Consequently, it was estimated that snowfall on February 14 was dry in most of the districts, and that wet snowfall and rain appeared to a limited extent on the Pacific coast and Boso Peninsula. The data show that wet snowfall and rain gradually spread from east （Chiba and Ibaraki Prefectures） to west during the morning of February 15. The quantitatively predominant precipitation type was dry snowfall in the Nagano, Yamanashi, and Gunma Prefectures, dry and wet snowfall in the Tokyo metropolitan area, wet snowfall in the Kanagawa, Saitama, and Tochigi Prefectures, and wet snowfall and rain in the Chiba and Ibaraki Prefectures. Considering the relationship between snow damage and predominant precipitation type, the ratio of dry precipitation to total precipitation during the February 14-15 snowfall event was found to depend on the type of snow damage.View full abstractDownload PDF (2197K) -
Takane MATSUMOTO, Katsuhisa KAWASHIMA, Tsutomu IYOBE2015 Volume 77 Issue 4 Pages 327-337
Published: 2015
Released on J-STAGE: March 01, 2023
JOURNAL OPEN ACCESSHeavy snowfall due to a cyclone passing along southern Honshu Island during February14-15, 2014, caused severe snow accretion damage to Cryptomeria japonica plantations in southwestern Tochigi Prefecture, central Japan. Most of damaged trees were on the east slopes of the Ashio Mountains at 200-650m above sea level (a.s.l.), and the damage type included stem breakage, canopy breakage, and bending. Dry snowfall that began in the afternoon of February 14 in this area became heavy wet snow in the early morning of February15 and was accompanied by increases in air temperature. In some parts of this area, the total amount of wet snow had a 100mm water equivalent. Snow accretion damage occurred in the morning of February 15 when the snowfall intensity was at its maximum. Although severe north winds were observed in the northern and central parts of Tochigi Prefecture on the morning of February 15, the wind speed on the slopes of the Ashio Mountains was relatively low. These conditions imply that the primary factor causing the snow accretion damage to C. japonica plantations in this area was heavy, wet snowfall.View full abstractDownload PDF (2485K) -
Makoto NASHIMOTO, Yukio IIDA, Takashi ISHII, Takuya KOBAYASHI, Toru TA ...2015 Volume 77 Issue 4 Pages 339-349
Published: 2015
Released on J-STAGE: March 01, 2023
JOURNAL OPEN ACCESS
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