Application of a two-step approach for mapping ice thickness to various glacier types on Svalbard

Beitrag in einer Fachzeitschrift
(Originalarbeit)


Details zur Publikation

Autor(en): Fürst J, Gillet-Chaulet F, Benham T, Dowdeswell J, Grabiec M, Navarro FJ, Pettersson R, Moholdt G, Nuth C, Saß B, Aas K, Fettweis X, Lang C, Seehaus T, Braun MH, Braun M
Zeitschrift: Cryosphere
Jahr der Veröffentlichung: 2017
Band: 11
Heftnummer: 5
Seitenbereich: 2003-2032
ISSN: 1994-0416
eISSN: 1994-0424
Sprache: Englisch


Abstract


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.



FAU-Autoren / FAU-Herausgeber

Braun, Matthias Prof. Dr.
Professur für Geographie (Fernerkundung und GIS)
Fürst, Johannes Dr.
Institut für Geographie
Saß, Björn
Professur für Geographie (Fernerkundung und GIS)
Seehaus, Thorsten Dr.
Professur für Geographie (Fernerkundung und GIS)


Autor(en) der externen Einrichtung(en)
Norsk Polarinstitutt / Norwegian Polar Institute
University of Oslo


Zitierweisen

APA:
Fürst, J., Gillet-Chaulet, F., Benham, T., Dowdeswell, J., Grabiec, M., Navarro, F.J.,... Braun, M. (2017). Application of a two-step approach for mapping ice thickness to various glacier types on Svalbard. Cryosphere, 11(5), 2003-2032. https://dx.doi.org/10.5194/tc-11-2003-2017

MLA:
Fürst, Johannes, et al. "Application of a two-step approach for mapping ice thickness to various glacier types on Svalbard." Cryosphere 11.5 (2017): 2003-2032.

BibTeX: 

Zuletzt aktualisiert 2018-07-11 um 20:50