Area- and slope-related approaches for estimating thicknesses and calculating volumes of unmeasured glaciers are compared with respect to statistical regression/correlation, area definition, error propagation, calibration/validation and average versus distributed values. Slope-related techniques and numerical modeling making full use of 3-D-information are better constrained and provide realistic glacier-bed topographies. Corresponding results are available at local to regional and global scales
Area- and slope-related approaches for estimating thicknesses and calculating volumes of...
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.
Area- and slope-related approaches for estimating thicknesses and calculating volumes of unmeasured glaciers are compared with respect to statistical regression/correlation, area definition, error propagation, calibration/validation and average versus distributed values. Slope-related techniques and numerical modeling making full use of 3-D-information are better constrained and provide realistic glacier-bed topographies. Corresponding results are available at local to regional and global scales
Area- and slope-related approaches for estimating thicknesses and calculating volumes of...