Application of a two-step approach for mapping ice thickness to various glacier types on Svalbard [Elektronisk resurs]
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Fuerst, Johannes Jakob (författare)
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Gillet-Chaulet, Fabien (författare)
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Benham, Toby J. (författare)
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Dowdeswell, Julian A. (författare)
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Grabiec, Mariusz (författare)
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Navarro, Francisco (författare)
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Pettersson, Rickard (författare)
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Moholdt, Geir (författare)
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Nuth, Christopher (författare)
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Sass, Björn (författare)
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Aas, Kjetil (författare)
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Fettweis, Xavier (författare)
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Lang, Charlotte (författare)
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Seehaus, Thorsten (författare)
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Braun, Matthias (författare)
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Uppsala universitet Teknisk-naturvetenskapliga vetenskapsområdet (utgivare)
- 2017
- Engelska.
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Ingår i: The Cryosphere. - 1994-0416. ; 11:5, 2003-2032
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Sammanfattning
Ämnesord
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- 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 landterminating glaciers as well as a 2400 km(2) 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.
Ämnesord
- Natural Sciences (hsv)
- Earth and Related Environmental Sciences (hsv)
- Geology (hsv)
- Naturvetenskap (hsv)
- Geovetenskap och miljövetenskap (hsv)
- Geologi (hsv)
- Natural Sciences (hsv)
- Earth and Related Environmental Sciences (hsv)
- Physical Geography (hsv)
- Naturvetenskap (hsv)
- Geovetenskap och miljövetenskap (hsv)
- Naturgeografi (hsv)
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