研究者詳細 - 藤田　耕史

論文 - 藤田　耕史

分割表示 211 件中 101 - 120 件目／全件表示 >>

The state and fate of Himalayan glaciers 査読有り

Bolch T, Kulkarni A, Kääb A, Huggel C, Paul F, Cogley JG, Frey H, Kargel JS, Fujita K, Scheel M, Stoffel M, Bajracharya S

Science 336 巻 ( 6079 ) 頁： 310-314 2012年4月

Variations in discharge from the Qilian mountains, northwest China, and its effect on the agricultural communities of the Heihe basin, over the last two millennia 査読有り

Sakai A, Inoue M, Fujita K, Narama C, Kubota J, Nakawo M, Yao TD

Water History 4 巻 ( 2 ) 頁： 177-196 2012年4月

The rates of sea salt sulfatization in the atmosphere and surface snow of inland Antarctica 査読有り

Iizuka Y, Tsuchimoto A, Hoshina Y, Sakurai T, Hansson M, Karlin T, Fujita K, Nakazawa F, Motoyama H, Fujita S

Journal of Geophysical Research - Atmospheres 117 巻頁： D04308 2012年2月

Distribution of debris thickness and its effect on ice melt at Hailuogou glacier, southeastern Tibetan Plateau, using in situ surveys and ASTER imagery 査読有り

Zhang Y, Fujita K, Liu SY, Liu Q, Nuimura T

Journal of Glaciology 57 巻 ( 206 ) 頁： 1147-1157 2011年12月

Spatial and temporal variability of snow accumulation rate on the East Antarctic ice divide between Dome Fuji and EPICA DML 査読有り

Fujita S, Holmlund P, Andersson I, Brown I, Enomoto H, Fujii Y, Fujita K, Fukui K, Furukawa T, Hansson M, Hara K, Hoshina Y, Igarashi M, Iizuka Y, Imura S, Ingvander S, Karlin T, Motoyama H, Nakazawa F, Oerter H, Sjöberg LE, Sugiyama S, Surdyk S, Ström J, Uemura R, Wilhelms F

The Cryosphere 5 巻 ( 4 ) 頁： 1057-1081 2011年11月

Glacial lake inventory of Bhutan using ALOS data: Part I: methods and preliminary results 査読有り

Ukita J, Narama C, Tadono T, Yamanokuchi T, Tomiyama N, Kawamoto S, Abe C, Uda T, Yabuki H, Fujita K, Nishimura K

Annals of Glaciology 52 巻 ( 58 ) 頁： 65-71 2011年8月

Spatially heterogeneous wastage of Himalayan glaciers 査読有り

Fujita K, Nuimura T

Proceedings of the National Academy of Sciences of the United States of America 108 巻 ( 34 ) 頁： 14011-14014 2011年8月

Favorable climatic regime for maintaining the present-day geometry of the Gregoriev Glacier, Inner Tien Shan 査読有り

Fujita K, Takeuchi N, Nikitin SA, Surazakov AB, Okamoto S, Aizen VB, Kubota J

The Cryosphere 5 巻 ( 3 ) 頁： 539-549 2011年7月

Temporal changes in elevation of the debris-covered ablation area of Khumbu Glacier in the Nepal Himalaya since 1978 査読有り

Nuimura T, Fujita K, Fukui K, Asahi K, Aryal R, Ageta Y

Arctic, Antarctic, and Alpine Research 43 巻 ( 2 ) 頁： 246-255 2011年5月

Establishing the timing of chemical deposition events on Belukha glacier, Altai Mountains, Russia, using pollen analysis 査読有り

Nakazawa F, Miyake T, Fujita K, Takeuchi N, Uetake J, Fujiki T, Aizen VB, Nakawo M

Arctic, Antarctic, and Alpine Research 43 巻 ( 1 ) 頁： 66-72 2011年3月

Climate Change: Another Antarctic rhythm 招待有り

Fujita K

Nature 471 巻 ( 7336 ) 頁： 45-46 2011年3月

Evidence for propagation of cold-adapted yeast in an ice core from a Siberian Altai glacier 査読有り

Uetake J, Kohshima S, Nakazawa F, Takeuchi N, Fujita K, Miyake T, Narita H, Aizen VB, Nakawo M

Journal of Geophysical Research - Biogeosciences 116 巻頁： G01019 2011年2月

Reevaluation of the reconstruction of summer temperatures from melt features in Belukha ice cores, Siberian Altai 査読有り

Okamoto S, Fujita K, Narita H, Uetake J, Takeuchi N, Miyake T, Nakazawa F, Aizen VB, Nikitin SA, Nakawo M

Journal of Geophysical Research - Atmospheres 116 巻頁： D02110 2011年1月

Self-regulated fluctuations in the ablation of a snow patch over four decades 査読有り

Fujita K, Hiyama K, Iida H, Ageta Y

Water Resources Research 46 巻頁： W11541 2010年11月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）

We describe four decades of temporal fluctuations in the ablation of the Hamaguriyuki 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.

Reconstructions of annual discharge and equilibrium line altitude of glaciers at Qilian Shan, northwest China, from 1978 to 2002. 査読有り

Sakai A, Fujita K, Narama C, Kubota J, Nakawo M, Yao TD

Hydrological Processes, 24(19), . 24 巻 ( 19 ) 頁： 2798-2806 2010年9月

記述言語：英語掲載種別：研究論文（学術雑誌）

Discharge was calculated from a mountainous area, including discharge from glaciers, in the Qilian Shan (Qilian Mountains) of northwest China. The studied Yingluoxia basin is 9983 km2 in area, with glaciers making up 0·3% of the basin. The calculation method was based on the heat balance, requiring only daily temperature and precipitation. Calculated annual discharge from the basin corresponded well with the observed data. Calculated annual discharge from glaciers was 3·6% of the total discharge from the basin.

The temporal trend of the calculated equilibrium line altitude (ELA) at the July 1st Glacier (western side of the Yingluoxia basin) was similar to that of the observed ELA. The calculated annual mass balance of glaciers within the Yingluoxia basin has a larger negative value than the other glaciers in China, as the ratio of accumulation area to the total glacier area in the Yingluoxia basin is much lower than in neighbouring basins to the west.
doi:10.1002/hyp.7700

ヒマラヤにおける氷河縮小の実態をさぐる招待有り

藤田耕史

遺伝 64 巻 ( 5 ) 頁： 68-74 2010年9月

Characteristics of high-precipitation events in Dronning Maud Land, Antarctica. 査読有り

Schlosser E, Manning KW, Powers JG, Duda MG, Birnbaum G, Fujita K

Journal of Geophysical Research - Atmospheres 115 巻頁： D14107 2010年7月

記述言語：英語掲載種別：研究論文（学術雑誌）

High-resolution Antarctic Mesoscale Prediction System archive data were used to investigate high-precipitation events at the deep ice core drilling site Kohnen Station, Dronning Maud Land, Antarctica, during the period 2001–2006. The precipitation is found to be highly episodic, with, on average, approximately eight high-precipitation events per year that can bring more than half of the total annual accumulation. The duration of the events varies between 1 day and about 1 week. On most days in the remaining time of the year, however, daily precipitation sums are about one order of magnitude smaller than that for the high-precipitation events. Synoptic weather patterns causing these events were directly connected to frontal systems of cyclones in only 20% of the 51 investigated cases. The majority of the events occurred in connection with (blocking) anticyclones and correspondingly amplified Rossby waves, which lead to advection of warm, moist air from relatively low latitudes. Possible changes in the seasonality and frequency of these events in a different climate can lead to a bias in ice core properties and might also strongly influence the mass balance of the Antarctic continent and thus global sea level change.
doi:10.1029/2009JD013410

Estimated impact of black carbon deposition during pre-monsoon season from Nepal Climate Observatory - Pyramid data and snow albedo changes over Himalayan glaciers. 査読有り

Yasunari TJ, Bonasoni P, Laj P, Fujita K, Vuillermoz E, Marinoni A, Cristofanelli P, Duchi R, Tartari G, Lau KM

Atmospheric Chemistry and Physics 10 巻頁： 6603-6615 2010年7月

記述言語：英語掲載種別：研究論文（学術雑誌）

The possible minimal range of reduction in snow surface albedo due to dry deposition of black carbon (BC) in the pre-monsoon period (March–May) was estimated as a lower bound together with the estimation of its accuracy, based on atmospheric observations at the Nepal Climate Observatory – Pyramid (NCO-P) sited at 5079 m a.s.l. in the Himalayan region. A total BC deposition rate was estimated as 2.89 μg m-2 day-1 providing a total deposition of 266 μg m-2 for March–May at the site, based on a calculation with a minimal deposition velocity of 1.0×10-4 m s-1 with atmospheric data of equivalent BC concentration. Main BC size at NCO-P site was determined as 103.1–669.8 nm by correlation analyses between equivalent BC concentration and particulate size distributions in the atmosphere. The BC deposition from the size distribution data was also estimated. It was found that 8.7% of the estimated dry deposition corresponds to the estimated BC deposition from equivalent BC concentration data. If all the BC is deposited uniformly on the top 2-cm pure snow, the corresponding BC concentration is 26.0–68.2 μg kg-1, assuming snow density variations of 195–512 kg m-3 of Yala Glacier close to NCO-P site. Such a concentration of BC in snow could result in 2.0–5.2% albedo reductions. By assuming these albedo reductions continue throughout the year, and then applying simple numerical experiments with a glacier mass balance model, we estimated reductions would lead to runoff increases of 70–204 mm of water. This runoff is the equivalent of 11.6–33.9% of the annual discharge of a typical Tibetan glacier. Our estimates of BC concentration in snow surface for pre-monsoon season is comparable to those at similar altitudes in the Himalayan region, where glaciers and perpetual snow regions begin, in the vicinity of NCO-P. Our estimates from only BC are likely to represent a lower bound for snow albedo reductions, because we used

Formation conditions of supraglacial lakes on debris-covered glaciers in the Himalayas. 査読有り

Sakai A, Fujita K

Journal of Glaciology 56 巻 ( 195 ) 頁： 177-181 2010年4月

Multi-decadal ice-velocity and elevation changes of a monsoonal maritime glacier: Hailuogou glacier, China. 査読有り

Zhang Y, Fujita K, Liu SY, Liu Q, Wang X

Journal of Glaciology 56 巻 ( 195 ) 頁： 65-74 2010年4月

記述言語：英語掲載種別：研究論文（学術雑誌）

Digital elevation models (DEMs) of the ablation area of Hailuogou glacier, China, produced from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data obtained in 2009, differential GPS (DGPS) data surveyed in 2008 and aerial photographs acquired in 1966 and 1989 are differenced to estimate long- and short-term glacier surface elevation change (dh/dt). The mean dh/dt of the ablation area over 43 years (1966-2009) is -1.1 ± 0.4 m a-1. Since 1989 the thinning has accelerated significantly. Ice velocities measured by DGPS at 28 fixed stakes implanted in the ablation area increase with distance from the glacier terminus, ranging from 41.0 m a-1 approaching the glacier terminus to a maximum of 205.0 m a-1 at the base of an icefall. Our results reveal that the overall average ice velocity in the ablation area has undergone significant temporal variability over the past several decades. Changes in glacier surface elevation in the ablation area result from the combined effects of climate change and glacier dynamics, which are driven by different factors for different regions and periods.

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