Pollen analyses were carried out on samples from a snow pit and an ice core in the saddle of the Gangjoe La Glacier in the Bhutan Himalayas in 2002. The main purpose of this study was to implement an ice core analysis to investigate the recent snow depositional environment at the upstream part, particularly to understand melting status. The total sample length was 6.60m. Three pollen concentration peaks were observed at the ice core depths of 0.46-0.56, 1.44-1.54, and 2.52-2.56m. These peaks contained pollen, from various taxa, that had scattered in the study region between March and October. On the other hand, air temperature data showed that the summer melting season on the glacier was from June to September. Therefore, we assumed that snow deposited from approximately March to September over the past three years was lost due to summer melting. The ice layers between the pollen concentration peaks seemed to correspond to snow accumulation from September to March of the following year. These results provided a clue to better understand melting and snow depositional conditions at the study site.

View full abstract

Glaciological surveys and glacier balance studies in the Mongolian Altai Mountains are necessary for understanding the impact of climate change within the area.　Such studies are important globally because the data can help expand the range of monitoring of the worldwide glacier observation network.　We estimated the glacier-wide surface mass balance (ΔM) of the Potanin Glacier in the Mongolian Altai Mountains by means of stake observations, pollen analyses, and pit observations.　We estimated ΔM as －0.97, －1.23, and －0.17 m w.e. (water equivalents) for the years 2005, 2008, and 2009, respectively.　The high negative value of mass balance observed in 2008 was due to lower amounts of solid precipitation and higher summer temperatures in comparison with 2005 and 2009.　A comparison of the Potanin Glacier with the Maliy Aktru Glacier in the Russian Altai Mountains, both locate in the slightly drier and warmer climate region, revealed that the two glaciers experienced similar mass balance fluctuations between 2005 and 2009, which was probably because these two glaciers are from the same regional climate system.　However, the ΔM of the Potanin Glacier in 2008 (－1.23) was more negative than that of the Maliy Aktru Glacier (－0.87).　Thus, we concluded that the lower value of ΔM at the Potanin Glacier compared with that of the Maliy Aktru Glacier was due to the smaller accumulation area ratio (AAR) as the higher equilibrium line altitude of the glacier.

View full abstract