All issues
Volume 79 (2017)
- Issue 6 Pages 483-
- Issue 5 Pages 403-
- Issue 4 Pages 319-
- Issue 2 Pages 211-
- Issue 1 Pages 3-
Volume 79, Issue 6
Displaying 1-10 of 10 articles from this issue
- |<
- <
- 1
- >
- >|
-
Hiroyuki HIRASHIMA, Takafumi KATUSHIMA2017 Volume 79 Issue 6 Pages 483-495
Published: 2017
Released on J-STAGE: March 01, 2023
JOURNAL OPEN ACCESS -
Satoru ADACHI, Satoru YAMAGUCHI, Toshihiro OZEKI, Katsumi KOSE2017 Volume 79 Issue 6 Pages 497-509
Published: 2017
Released on J-STAGE: March 01, 2023
JOURNAL OPEN ACCESS -
Takafumi KATSUSHIMA, Satoru ADACHI, Satoru YAMAGUCHI, Hiroyuki HIRASHI ...2017 Volume 79 Issue 6 Pages 511-524
Published: 2017
Released on J-STAGE: March 01, 2023
JOURNAL OPEN ACCESSWe conducted experiments on one-dimensional water infiltration into dry snow to validate a numerical model for it. We observed the wetting front using a near-infrared camera. We used four different particle sizes of sieved snow samples and several supplied water flux. The experimental results were numerically analyzed by using Richardʼs model and a model implementing water entry pressure. The results showed that a model based on Richardʼs equation simulate water infiltration into finer dry snow. However, this model overestimates advancing rate of the wetting front for coarser dry snow such that a slower wetting front movement and higher water content are observed at an early period. The model included the effect of water-entry values that acted as the threshold for capillary pressure, reproduced the actual phenomenon. However, the simulated wetting front velocity obtained using the model was lesser than that obtained during the experiment.View full abstractDownload PDF (1617K) -
Masashi NIWANO, Teruo AOKI, Akihiro HASHIMOTO, Satoru YAMAGUCHI, Tomon ...2017 Volume 79 Issue 6 Pages 525-538
Published: 2017
Released on J-STAGE: March 01, 2023
JOURNAL OPEN ACCESSWe present performance of the physical snowpack model SMAP, which was applied to Japan Meteorological Agency (JMA)ʼs AMeDAS (Automated Meteorological Data Acquisition System) sites in Niigata, Japan during the 2015-2016 winter to simulate temporal evolution of snow depth. Input precipitation, air temperature, and wind speed data for the SMAP model were obtained from in-situ AMeDAS data, where precipitation were corrected considering catch efficiency of each rain gauge. Before performing this correction, it is necessary to discriminate measured precipitation into snow and rain. In the present study, air temperature was employed as a criterion for the discrimination (Tdisc), and three input precipitation data were created by modulating Tdisc within the realistic range: 0, 0.5, and 1℃．Other necessary data to drive the SMAP model (downward shortwave and longwave radiant fluxes, cloud fraction, relative humidity, and air pressure) were prepared by running the JMA Nonhydrostatic Mesoscale Model. The best performance of the SMAP model in terms of snow depth at Nagaoka was obtained when Tdisc was set to be 0.5℃; however, the best scores were obtained when Tdisc was 0℃ at most of the sites. We also found that the SMAP model simulations in Niigata during the period were very sensitive to the choice of Tdisc: average differences in simulated snow depths for the cases Tdisc=0 and 1℃ reached 0.41m at Koide. On the other hand, the difference was at most 0.10m at Sekiyama, suggesting that sensitivities to Tdisc of model simulations are different from place to place. By investigating the winter precipitation curve at each site, it was clarified that the above-mentioned sensitivities were controlled by the winter total precipitation amount, as well as the representative air temperature at which precipitation frequently occurred during the winter period.View full abstractDownload PDF (3925K) -
Wataru SHIMADA, Tomoyuki MOTEGI, Satoru YAMAGUCHI, Kenji KOSUGI, Osamu ...2017 Volume 79 Issue 6 Pages 539-548
Published: 2017
Released on J-STAGE: March 01, 2023
JOURNAL OPEN ACCESSWe experimentally formed snow dimples on artificial snow layers via a snow- and rainfall device and observed these in cross-section. Time sequences of density, water content, and thermo-graphic images show local and little water penetrations in the low-density layer under the water-saturated layer during the initial stage. After these penetrations were observed across the cross-section, snow dimples formed on the snow surface. Initial water penetrations at 0ºC affected the growth of snow particles and their aperture. This metamorphism of snow under the water-saturated layer caused both the decrease of the water entry capillary pressure and the increase of the volume of impounded water. Consequently, high penetration in the metamorphosed snow layer rapidly changed to granular snow, forming snow dimples on the snow surface.View full abstractDownload PDF (2382K) -
Tomomi NAKASHIMA, Nozomu TAKEUCHI2017 Volume 79 Issue 6 Pages 549-563
Published: 2017
Released on J-STAGE: March 01, 2023
JOURNAL OPEN ACCESSSnow algae are photosynthetic microbes that grow on a melting snow surface. The various pigments in their cells can colour the snow red or green. In this study, our aim was to determine the spatial and temporal variations in the algal pigments. Hence, we collected coloured snow during the melting seasons of 2014 and 2015 at Mount (Mt.) Tateyama in Toyama prefecture, Japan. The absorption spectra of snow extracts differed among the samples, and showed peaks of chlorophylls and carotenoids. The spectra could be classified into four types based on the peaks, which corresponded to the relative abundance of pigments in algal cells. Spatial and seasonal variations were observed among the samples. Microscopic observations revealed seven morphotypes of algal cells and the proportion of each cell type significantly differed among the four spectral types. This indicates that the variations in the spectra are due to dominant algal taxa and/or pigments contained in the algal cells. The factor underlying the differences in the spectra remains unclear; nevertheless, the results indicate spatial and seasonal variations in algal pigment composition of red snow at Mt. Tateyama.View full abstractDownload PDF (2490K) -
Kengo SATO, Kenji KOSUGI2017 Volume 79 Issue 6 Pages 565-571
Published: 2017
Released on J-STAGE: March 01, 2023
JOURNAL OPEN ACCESSWe introduce a device that employs a forced air ventilation technique to rapidly produce wet snow from dry dendritic artificial snow. The dry snow is spread in a wet snow making box that has perforated plates at the top and bottom; each hole has a diameter of 5mm. The bottom of the wet snow making box is connected to a thermostatic box that maintains the air temperature at 4℃. Then，air is sucked in from the upper surface of the wet snow making box to uniformly ventilate all layers of the dry snow. Using this device，wet snow with a liquid water content of 1-3% can be produced from dry snow at −10℃ within about 10 min. The most significant merit of this device is that the wet snow produced retains the shape of the dendritic crystals. Using both natural and artificial snow as a starting material, this device can produce wet snow via a facile, rapid, and highly reproducible process. Therefore, it can contribute to improving the efficiency and accuracy of artificial snow accretion experiments.View full abstractDownload PDF (2333K) -
Wataru SHIMADA, Izumi ASAJI, Hideharu HONOKI2017 Volume 79 Issue 6 Pages 573-579
Published: 2017
Released on J-STAGE: March 01, 2023
JOURNAL OPEN ACCESSWe observed both snow dimples and water channels through cross-sectional investigation of snow layers at Murodo-daira, Mt. Tateyama, on April 15-17, 2017. These snow dimples were formed by metamorphism from lightly compacted snow to granular snow or an ice layer created by water penetration. Furthermore, examination of the stratigraphy around the water channel revealed rapid formation of many ice layers and granular snow layers in a thickly compacted snow layer. Analysis of both air temperature at Mt. Jodo and live-camera images at Murodo-daira indicate that these phenomena were formed by precipitation events on April 8 and 11 and were subsequently buried by snowfall.View full abstractDownload PDF (4259K) -
Gorow WAKAHAMA2017 Volume 79 Issue 6 Pages 581-600
Published: 2017
Released on J-STAGE: March 01, 2023
JOURNAL OPEN ACCESS -
Kazuo TAKEDA2017 Volume 79 Issue 6 Pages 601-609
Published: 2017
Released on J-STAGE: March 01, 2023
JOURNAL OPEN ACCESS
- |<
- <
- 1
- >
- >|