Brief communication: On area- and slope-related thickness estimates and volume calculations for unmeasured glaciers
Geography Department, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
Received: 04 Dec 2015 – Accepted for review: 10 Dec 2015 – Discussion started: 15 Jan 2016
Abstract. Area- and slope-related techniques have been used to estimate thicknesses and to calculate volumes of unmeasured glaciers on the basis of glacier outlines and corresponding glacier surface areas in glacier inventories. The present communication critically reflects key aspects involved with the application of these approaches to field data. Area-related empirical statistics are known to only provide order-of-magnitude estimates if applied to individual glaciers or glacier ensembles spanning less than several orders of magnitude. Even at this scale, however, problems exist with respect to calibration/validation, error propagation, artefacts (immediate mass loss in case of coalescing/disintegrating composite glaciers) and shortcomings (no detection of ice below sea level or below lake levels on land in view of glacier contributions to sea-level rise). 3-D-flux/stress/slope-related approaches and numerical models are better constrained by calibration/validation with field measurements. They help with overcoming the problems of 2-D-area-related statistics in that they allow for calculating detailed glacier bed topographies at all scales, from individual glaciers to global ensembles. Corresponding results are available today and can be further improved.
Haeberli, W.: Brief communication: On area- and slope-related thickness estimates and volume calculations for unmeasured glaciers, The Cryosphere Discuss., doi:10.5194/tc-2015-222, in review, 2016.