The Cryosphere Discuss., 6, 5405-5420, 2012
www.the-cryosphere-discuss.net/6/5405/2012/
doi:10.5194/tcd-6-5405-2012
© Author(s) 2012. This work is distributed
under the Creative Commons Attribution 3.0 License.
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This discussion paper has been under review for the journal The Cryosphere (TC). A final paper in TC is not foreseen.
Glacier volume estimation as an ill-posed boundary value problem
D. B. Bahr1,2, W. T. Pfeffer2, and G. Kaser1
1Institute of Meteorology and Geophysics, University of Innsbruck, Innrain 52, 6020 Innsbruck, Austria
2Institute of Arctic and Alpine Research, UCB 450, University of Colorado at Boulder, Boulder, CO, USA

Abstract. Estimating a glacier's volume by inferring properties at depth from properties observed at the surface creates an instability that grows exponentially with the size of the glacier. Random errors from this instability can overwhelm the volume calculation unless problematic short spatial wavelengths are specifically excluded. Volume-area scaling inherently filters these short wavelengths and automatically eliminates the instability, but typical numerical inversions must filter the correct wavelengths explicitly. The world's total glacier and ice cap (GIC) volume is calculated from the sum of hundreds of thousands of ice masses, dramatically reducing the random error from the "ill-posed" instability. However, the variance of the total GIC volume estimate will be exponentially larger if the instability is not carefully controlled. When all other considerations are equal, greater confidence should be placed in total volume estimates that eliminate the ill-posed instability versus those estimates that do not.

Citation: Bahr, D. B., Pfeffer, W. T., and Kaser, G.: Glacier volume estimation as an ill-posed boundary value problem, The Cryosphere Discuss., 6, 5405-5420, doi:10.5194/tcd-6-5405-2012, 2012.
 
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