Bulletin of Glaciological Research
Online ISSN : 1884-8044
Print ISSN : 1345-3807
ISSN-L : 1345-3807
29 巻
選択された号の論文の4件中1~4を表示しています
Report
  • 安仁屋 政武, SKVARCA Pedro, 杉山 慎, 青木 賢人, 松元 高峰, 安間 了, 内藤 望, 榎本 浩之, 堀 和明, MA ...
    2011 年 29 巻 p. 1-17
    発行日: 2011年
    公開日: 2011/05/23
    ジャーナル フリー
    The Glaciological Research Project in Patagonia (GRPP) 2006-2009 was carried out with several objectives at Glaciar Perito Moreno of the Hielo Patagónico Sur (HPS), in the area of the Hielo Patagónico Norte (HPN) and along the Pacific coast. At Glaciar Perito Moreno, hot water drilling was carried out at about 5km upstream from the terminus, reaching the glacier bottom at ca. 515m, in order to monitor subglacial water pressure. Good positive correlations among air temperature, subglacial water pressure and glacier flow speed were found. Based on 14C dating of tree and organic samples, it is proposed that Glaciar Perito Moreno made two Little Ice Age (LIA) advances at AD1600-1700 and ca. 130-100y BP (AD1820-50). Fan deltas located at the mouth of big rivers around Lago General Carrera (Buenos Aires) and Lago Cochrane (Pueyrredon), in the area east of the HPN, were investigated to elucidate their development. The variations of 21 outlet glaciers of the HPN elucidated from aerial surveys for 2004/05-2008/09 revealed an areal loss of 8.67km2 in four years. A general slowing down of retreats was observed with a few exceptions. Meteorological measurements at Glaciar Exploradores of the HPN from 2005 to 2009 indicate that air temperature ranged from 17.4°C to -10.5°C. The total annual precipitation was about 3000mm. Glacier surface melt was observed at two spots. Sediment and water discharges from the glacier showed that while water discharge fluctuated a lot, suspended sediment concentration was rather stable in summer. A single channel seismic profiling during the JAMSTEC MR08-06 cruise identified a probable submerged moraine formed before the last glacial maximum (LGM) in the Golfo de Penas, south of Taitao Peninsula. Piston coring along the Chilean coast further indicates that ice-rafted debris recorded the LGM and earlier Late Pleistocene events of the glacial advance.
Article
  • Surendra ADHIKARI, Shawn J. MARSHALL, Philippe HUYBRECHTS
    2011 年 29 巻 p. 19-29
    発行日: 2011年
    公開日: 2011/06/30
    ジャーナル フリー
    Observations indicate that over the past few decades, valley glaciers and ice caps in the Nepalese Himalaya have been continuously shrinking in response to climate warming. The response timescales of these glaciers are not yet well understood. Considering the case of Glacier AX010, this paper examines several methods for estimating the rate of glacier response to changes in climate. In spite of having simple model physics and requiring only a few and often available field data, simpler analytical methods yield reasonable estimates of timescale. Detailed analytical and numerical ice-flow models suggest that the response times for Glacier AX010 are on the order of 50 years. These magnitudes are slightly larger than field evidence indicates for typical valley glaciers, indicating that Glacier AX010 responds relatively slowly to changing climate. Nonetheless, sustained century-scale warming as forecasted for the Nepalese Himalaya would provide sufficient time for Glacier AX010 to respond to this climatic disequilibrium. Given the fact that the glacier already lacks a persistent accumulation zone, we foresee a complete retreat of the glacier by 2100.
Report
  • 田中 大祐, 徳山 祐美, 寺田 陽平, 国持 孝太, 水牧 千佳, 田村 尚子, 若林 雅行, 青木 一真, 島田 亙, 田中 仁志, 中 ...
    2011 年 29 巻 p. 31-39
    発行日: 2011年
    公開日: 2011/06/30
    ジャーナル フリー
    Asian dust particles transported from Asian desert areas are trapped in spring snow on the western plateau of Mt. Tateyama, Japan. We investigated bacterial communities in snow layers containing Asian dust, and other underlying snow layers, on Mt. Tateyama during 2008 and 2009. Several genera of bacteria were present among isolates obtained from Asian dust-containing snow layers, including the presumed dust-associated bacterial genus Bacillus. In particular, we detected isolates with identical 16S rDNA sequences (AB500941) over 2 consecutive years, and these isolates were most closely related to Bacillus subtilis. PCR-denaturing gradient gel electrophoresis (DGGE) analysis showed that bacterial community profiles in the Asian dust-containing snow layers were similar over the 2 years. The bacterial communities differed between the Asian dust-containing layers and other layers. Total bacterial cell counts ranged from 6.85×10² to 2.39×105 cells ml-1, with higher values in the Asian dust-containing layers than in the other layers. A backward trajectory analysis showed that the possible source of Asian dust was similar each year. The bacterial community composition of the Asian dust-containing layers presumably reflected the long-distance transportation of microorganisms from dust source regions.
  • KADOTA Tsutomu (門田 勤), Davaa GOMBO, Purevdagva KALSAN, Davaadorj NAMGU ...
    2011 年 29 巻 p. 41-50
    発行日: 2011年
    公開日: 2011/11/04
    ジャーナル フリー
    Glaciological research has been conducted in the Mongolian Altai since 2003 in order to understand the present state of the glaciers. Three different types of glaciers were surveyed, namely Potanin Glacier in the Tavan Bogd mountain range, Glaciers D002 and D036 in the Tsambagarav Massif. The maximum ice thickness varied from 229m (Potanin Glacier; valley glacier) and 178m (D002; mountain glacier) to 79m (D036; ice cap). The surface flow velocity of Potanin Glacier varied from 0.8-2.6m a-1 at the tongue to 17-31m a-1 in the middle part, and it was higher in summer than in winter. On the other hand, that of D002 gradually increased from 12.6m a-1 at the tongue to 28.4m a-1 at the middle part and was almost constant throughout the year. Large surface lowering was observed at the tongue of the Potanin Glacier, with values of 9.5-15.8m lowering from September 2004 to September 2009. In contrast, at the tongue of D002, the surface level lowered by 2.8-8.3m from June 2005 to September 2008. The retreat distance of the Potanin Glacier was 90m during the period from September 2003 to September 2009, whereas D002 showed a retreat of 20m from June 2005 to September 2008. A rough estimate shows that the Potanin Glacier may experience a sizable retreat of 3km within 100 years, a distance which is larger than that observed in the past 55 years (0.9km).
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