Glaciers, ice caps and ice sheets constitute a large reservoir in the global hydrological cycle and provide a coupling between climate and sea-level. Observations of glacial change is important for constraining their contribution to sea-level fluctuations and to better understand the interactions between glaciers and climate. This thesis focuses on glacier observations through measurements of elevation change.
The research in this thesis is oriented towards the methodological detection of elevation changes using remote sensing techniques. The quality of glacier elevation change measurements is dependent on controlling the potential errors and biases within the data. Therefore, one aspect is focused on a universal co-registration method for elevation products and further identification and correction of biases that remain, specifically in satellite stereo products.
For glaciological studies, elevation changes require conversion into volume and mass changes. This is sometimes complicated when the data available is not spatially continuous and/or temporally consistent. Therefore, another aspect of this thesis explores methods for estimating regional glacier volume change. Specifically, Svalbard glacial contribution to sea-level has been estimated using regionalization techniques from scattered elevation measurements over roughly two time epochs. We observed that Svalbard glaciers over the past few decades have had a negative mass balance, contributing approximately 0.026 mm per year to the oceans. During the past few years, the sea-level contribution from Svalbard glaciers decreased slightly to 0.013 mm per year.
Interpretations of elevation changes are convoluted by their dependence on climatic and dynamic forces operating on glacier systems. The last aspect of this thesis experiments with surface mass balance modelling for quantifying the climatic component of an elevation change. Combining this with observed elevation changes using theory of mass continuity can yield estimates of the calving flux of icebergs into the ocean. We observed on one particular fast flowing glacier in Svalbard that the average calving flux in the 1966-1990 epoch increased in the 1990-2007 epoch.
List of papers. Paper II is removed due to copyright restrictions.
Nuth C., Moholdt G., Kohler J., Hagen J.O., Kääb A (2010) Svalbard glacier elevation changes and contribution to sea level rise.
Journal of Geophysical Reasearch- Earth Surface. 115, F01008
Moholdt G., Nuth C., Hagen J.O., Kohler J. (2010) Recent elevation changes of Svalbard glaciers derived from ICESat laser altimetry.
Remote Sensing of Environment. 114(11), 15 November 2010, Pages 2756-2767.
Nuth, C. and Kääb, A. (2010) What is in an elevation difference? Accuracy and corrections of satellite elevation data sets for quantification of glacier changes.
The Cryosphere Discussions. 4, 2013-2077, 2010
doi:10.5194/tcd-4-2013-2010Published under a Creative Commons Attribution License.
Nuth C., Schuler T.V., Kohler J., Altena B. and Hagen J.O.
Estimating the long term calving flux of Kronebreen, Svalbard, from geodetic elevation changes and mass balance modelling. Manuscript, published in:
Journal of Glaciology, Vol. 58, No. 207, 2012
doi:10.3189/2012JoG11J036 Copyright IGS