naito_etal_2001.html

Bulletin of Glaciological Research 18 (2001) 1-8
©Japanese Society of Snow and Ice

Response sensitivities of a summer-accumulation type glacier to climate changes indicated with a glacier fluctuation model

Nozomu NAITO¹, Yutaka AGETA¹, Masayoshi NAKAWO¹, Edwin D. WADDINGTON², Charles F. RAYMOND² and Howard CONWAY²
1 Institute for Hydrospheric-Atmospheric Sciences, Nagoya University, Nagoya 464-8601 JAPAN
2 Geophysics Program, University of Washington, Box 351650, Seattle, Washington 98195-1650 USA

Abstract

Sensitivities of a summer-accumulation type glacier in response to changes in air temperature and precipitation are investigated using a glacier fluctuation model. The model couples glacier dynamics to empirical mass balance equations obtained for a typical summer-accumulation type glacier in the eastern Nepal Himalayas. The geometry and seasonal variations in air temperature and precipitation are simplified in order to examine the principal characteristics of the sensitivities. The magnitude of the volume change and the volume response time are discussed and compared with those for a hypothetical winter-accumulation type glacier of equivalent geometry.
The volume change of a summer-accumulation type glacier is roughly twice as large in its magnitude for an air temperature change as for an equally probable precipitation change in east Nepal. Moreover, the volume response time of the glacier is shorter for the temperature change than for the precipitation change. Accordingly, we suggest that air temperature changes rather than precipitation changes are mainly responsible for the fluctuations of summer-accumulation type glaciers in east Nepal, as long as the likelihood of future shifts in air temperature and precipitation scale with their modern standard deviations. The summer-accumulation type glacier responds more quickly to a temperature change than does the winter-accumulation type glacier, and its magnitude of the volume response is smaller for a precipitation change than the winter-accumulation type glacier. There is a significant shortening of the response time for increasing magnitude of glacier shrinkage.