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Modelling Changes in Glacier Mass Balance That May Occur as a Result of Climate Changes
Roger J. Braithwaite and Yu Zhang
Geografiska Annaler. Series A, Physical Geography
Vol. 81, No. 4, Methods of Mass Balance Measurements and Modelling (1999), pp. 489-496
Stable URL: http://www.jstor.org/stable/521488
Page Count: 8
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Projections of changes in glacier mass balance caused by climate changes involve modelling present mass balance in terms of climate and then perturbing the climate variables to calculate future mass balance. The simplest model involves linear regression of mass balance time series on temperature and precipitation data at stations close to the glacier but we prefer the degree-day model. This model uses temperature and precipitation to calculate snow accumulation, snow and ice melting, and possible refreezing of meltwater at regular altitude intervals on a glacier. Model parameters are still somewhat uncertain and are established for individual glaciers by tuning the model mass balance as a function of altitude to fit observed data. The model has been applied to 37 glaciers in different parts of the world so far and some details are given for Storglaciären to illustrate the approach. The sensitivity of modelled mass balance to a +1°C temperature increase shows a wide range for the 37 glaciers from about 0.1 to 1.3 m water a-1. Sub-polar glaciers have lower temperature sensitivities, and maritime and tropical glaciers have higher sensitivities.
Geografiska Annaler. Series A, Physical Geography © 1999 Swedish Society for Anthropology and Geography