Negative Ablation on Storglaciären
Abstract
Initial surface mass balance calculations for 2012 on Storglaciären suggested considerable accumulation of snow through the summer at higher elevations, despite a lack of supporting observations. This phenomenon was initially suspected to be caused by an error in either the winter's density measurements or the parameterised end of summer density. Analysis and measurement did not agree with either of these explanations. Snow depth measurements taken on a near-by glacier for other purposes indicated that at least 1.4m of new snow had fallen after the winter survey in April. Taking this into consideration reduced the apparent negative ablation considerably but not entirely. The lack of recorded snow fall throughout the summer ablation season strongly suggests that a higher figure, closer to 2m, of new snow must have fallen between the last winter accumulation survey and the first summer ablation survey. A distributed melt model was developed from temperature observations across the glacier and the disparity between the model's results and field observations for the April to July melt was used to estimate unobserved accumulation. Whilst the unmeasured snowfall has no impact on the net balance, the winter balance and calculations of meltwater discharge are hugely underestimated. This problem is not restricted to the year 2012 nor to Storglaciären; the majority of mass balance programmes will be similarly affected. We therefore recommend estimating unobserved accumulation using the melt model method where accurate winter balance values are needed.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2013
- Bibcode:
- 2013AGUFM.C21A0619M
- Keywords:
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- 0776 CRYOSPHERE Glaciology;
- 0720 CRYOSPHERE Glaciers;
- 0762 CRYOSPHERE Mass balance 0764 Energy balance