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Toyama-shi, Japan

Fujita K.,Nagoya University | Hiyama K.,Nagoya University | Iida H.,Tateyama Caldera SABO Museum | Ageta Y.,Nagoya University
Water Resources Research | Year: 2010

We describe four decades of temporal fluctuations in the ablation of the Hamaguri-yuki snow patch in the northern Japan Alps. Annual ablation depth through the melting season shows a significant correlation with the initial depth (at the beginning of the melting season), whereas a less significant correlation is found with a temperature index that is generally believed to correlate well with ablation. The scale effect of the snow patch, which appears to modify the wind speed over the patch, has a more significant effect on snow ablation than does the radiation shadowing effect of surrounding mountains. In the case of a thinner and therefore smaller initial springtime snow patch, the speed of the local wind may be reduced over the snow surface, thereby suppressing ablation, whereas wind speed is not reduced (and ablation is not suppressed) in the case of a thicker snow patch. This self-regulating feedback means that over the past four decades, the thickness of the snow patch has fluctuated in a manner that is largely independent of summertime temperature. Our findings also suggest that the self-regulating feedback, which influences ablation, allows some small wind-drifted glaciers to survive, whereas previous studies reported enhanced accumulation at such glaciers via a similar topographic effect on wind speed and suppressed ablation via the shading effect of surrounding mountains on solar radiation. © 2010 by the American Geophysical Union.

Sugiyama S.,Hokkaido University | Fukui K.,Tateyama Caldera SABO Museum | Fujita K.,Nagoya University | Tone K.,Hokkaido University | Yamaguchi S.,Japan National Research Institute for Earth Science and Disaster Prevention
Annals of Glaciology | Year: 2013

To investigate recent glacier changes in the Himalayan region, we carried out GPS and ground-penetrating radar (GPR) measurements at Yala Glacier, a benchmark glacier in Nepal. Glacier surface elevation and ice thickness were surveyed along a 1.5km profile from the glacier top to the terminus. Ice flow velocity was measured at five locations by surveying stakes for either 1 year or 4 day periods. Obtained surface elevation and ice velocity were compared with those measured in 1982 and 1996. The mean ice thickness along the radar profile was 36m in 2009 and the ice has been thinning at rates of-0.690.25 and-0.750.24ma-1 during the periods 1982-96 and 1996-2009, respectively. The thinning rate increases down-glacier, reaching a magnitude up to-1.8ma-1 near the terminus from 1996 to 2009. The ice velocity has reduced by >70% from 1982 to 2009 in the lower half of the glacier. By assuming a constant driving stress over the glacier, the total ice volume in 2009 was estimated as 0.061km3. Our results indicate that Yala Glacier has lost 40% of its ice volume over the last 27 years and that the rate of the mass loss has accelerated over the last decade.

Sugiyama S.,Hokkaido University | Enomoto H.,Kitami Institute of Technology | Fujita S.,Japan National Institute of Polar Research | Fukui K.,Tateyama Caldera SABO Museum | And 2 more authors.
Annals of Glaciology | Year: 2010

As a joint contribution of Japan and Sweden to the International Polar Year 2007-09, a field expedition between Syowa and Wasa stations in East Antarctica was carried out in the 2007/08 austral summer season. Along the 2800km long expedition route, the dielectric permittivity of the upper 1m snow layer was measured at intervals of approximately 50km using a snow fork, a parallel-wire transmission-line resonator. More than 2000 measurements were performed under carefully calibrated conditions, mostly in the interior of Antarctica. The permittivity ε' was a function of snow density as in previous studies on dry snow, but the values were significantly smaller than those reported before. In the light of the dielectric mixture theory, the relatively smaller ε' obtained in this study can be attributed to the snow structures characteristic in the studied region. Our data suggest that the permittivity of snow in the Antarctic interior is significantly affected by weak bonding between snow grains, which is due to depth-hoar formation in the extremely low-temperature conditions.

Uemura R.,University of Ryukyus | Masaka K.,University of Ryukyus | Fukui K.,Tateyama Caldera SABO Museum | Iizuka Y.,Hokkaido University | And 2 more authors.
Geophysical Research Letters | Year: 2016

The sulfur stable isotopic values (δ34S) of sulfate aerosols can be used to assess oxidation pathways and contributions from various sources, such as marine biogenic sulfur, volcanoes, and sea salt. However, because of a lack of observations, the spatial distribution of δ34S values in Antarctic sulfate aerosols remains unclear. Here we present the first sulfur isotopic values from surface snow samples along a latitudinal transect in eastern Dronning Maud Land, East Antarctica. The δ34S values of sulfate showed remarkably uniform values, in the range of 14.8–16.9‰, and no significant decrease toward the inland part of the transect was noted. These results suggest that net isotopic fractionation during long-range transport is insignificant. Thus, the δ34S values can be used to infer source contributions. The δ34S values suggest that marine biogenic sulfur is the dominant source of sulfate aerosols, with a fractional contribution of 84 ± 16%. ©2016. The Authors.

Arimoto I.,Tokyo University of Agriculture and Technology | Goto Y.,Tateyama Caldera SABO Museum | Nagai C.,Tokyo University of Agriculture and Technology | Furubayashi K.,NPO Study Group of Ptarmigan Conservation
Mammal Study | Year: 2011

We examined food habits and home-range elevations of Japanese black bears (Ursus thibetanus japonicus) in relation to Fagaceae mast production in Toyama Prefecture. Nine bears (four males and five females) fitted with GPS collars were tracked for various periods from July to December in 20052007. We investigated the food habits of each bear using traces found at GPS-fix locations. Bears selectively fed on Fagus crenata mast when F. crenata and Quercus crispula mast was abundant and consumed Q. crispula and Q. serrata mast when F. crenata mast was scarce. When both F. crenata and Q. crispula mast was scarce, bears fed on multiple alternatives, such as Diospyros kaki. Home-range elevations of bears also differed among years in response to vertical distributions of available foods. Individual bears captured in the Q. serrata zone (lower elevation) and F. crenata zone (higher elevation) tended to eat Q. serrata and Q. crispula acorns, respectively, when F. crenata mast was not available. Therefore, food habits and home-range elevations of bears were influenced greatly by fluctuations in Fagaceae mast production and the species' vertical distribution, as well as by factors such as food preference for F. crenata mast and food resource distribution around the home ranges. © the Mammalogical Society of Japan.

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