http://hdl.handle.net/20.500.12128/368
Tytuł: | Application of a two-step approach for mapping ice thickness to various glacier types on Svalbard |
Autor: | Furst, Johannes Jakob Gillet-Chaulet, Fabien Benham, Toby J. Dowdeswell, Julian A. Grabiec, Mariusz Navarro, Francisco Pettersson, Rickard Moholdt, Geir Nuth, Christopher Sass, Bjorn Aas, Kjetil Fettweis, Xavier Lang, Charlotte Seehaus, Thorsten Braun, Matthias |
Słowa kluczowe: | Ice thickness; Mapping method |
Data wydania: | 2017 |
Źródło: | Cryosphere, Vol. 11, iss. 5 (2017), s. 2003-2032 |
Abstrakt: | The basal topography is largely unknown beneath most glaciers and ice caps, and many attempts have been made to estimate a thickness field from other more accessible information at the surface. Here, we present a two-step reconstruction approach for ice thickness that solves mass conservation over single or several connected drainage basins. The approach is applied to a variety of test geometries with abundant thickness measurements including marine- and land-terminating glaciers as well as a 2400-km2 ice cap on Svalbard. The input requirements are kept to a minimum for the first step. In this step, a geometrically controlled, non-local flux solution is converted into thickness values relying on the shallow ice approximation (SIA). In a second step, the thickness field is updated along fast-flowing glacier trunks on the basis of velocity observations. Both steps account for available thickness measurements. Each thickness field is presented together with an error-estimate map based on a formal propagation of input uncertainties. These error estimates point out that the thickness field is least constrained near ice divides or in other stagnant areas. Withholding a share of the thickness measurements, error estimates tend to overestimate mismatch values in a median sense. We also have to accept an aggregate uncertainty of at least 25-% in the reconstructed thickness field for glaciers with very sparse or no observations. For Vestfonna ice cap (VIC), a previous ice volume estimate based on the same measurement record as used here has to be corrected upward by 22-%. We also find that a 13-% area fraction of the ice cap is in fact grounded below sea level. The former 5-% estimate from a direct measurement interpolation exceeds an aggregate maximum range of 6-23-% as inferred from the error estimates here. |
URI: | http://hdl.handle.net/20.500.12128/368 |
DOI: | 10.5194/tc-11-2003-2017 |
ISSN: | 1994-0416 |
Pojawia się w kolekcji: | Artykuły (WNP) |
Plik | Opis | Rozmiar | Format | |
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Furst_Application_of_a_two-step_approach_for_mapping_ice_thickness.pdf | 25,35 MB | Adobe PDF | Przejrzyj / Otwórz | |
Furst_Application_of_a_two-step_approach_for_mapping_ice_thickness.pdf | 25,35 MB | Adobe PDF | Przejrzyj / Otwórz |
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