2011 年 29 巻 p. 41-50
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).