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SAR-Interferometric flow velocities of two tidewater glaciers in NW Spitsbergen

Zbigniew Perski(1) and Manfred Stober(2)

(1) University of Silesia, Bedzinska 60, 41-200 Sosnowiec, Poland
(2) University of Applied Sciences, Schellingstr. 24, 70174 Stuttgart, Germany

Abstract

This paper presents the results of flow velocity studies of two large tidewater glaciers in Svalbard, Aavatsmarkbreen and Comfortlessbreen. This study is part of the international GECALVEX project and interferometric analysis have been performed thanhs to ESA project CP1-1076. During the field campaigns of July 2000 and April 2001 the GPS data of flow velocities and elevation have been registered, using static and kinematic methods. Also the flow velocity for the glaciers have been calculated from SAR interferometric satellite measurements using both ascending and descending satellite passes.

Assuming that the glacier flow is superficial, the flow velocity was calculated using satellite passes (both ascending and descending). Two ERS SAR data sets have been used in this study: (a) three scenes acquired in March 1994 during 2nd ice mission of ERS-1 (ascending) (b) two scenes acquired in April 1996 during a tandem mission by ERS-1 and ERS-2 (descending) Dataset (a) has been processed using 3-pass method although, for set, (b) a 2-pass method was applied with external DEM application in order to reduce the topographic effect. To calculate flow velocity field from from ascending and descending observations, a precise topographic information is required. As input data, the glacier slope and flow direction (this only in a case of calculations with single pass) must be known to a high level of accuracy. To prepare such data and to reduce the effect of topography on the interferogram (b) the 20-m DEM provided by Cartographic Branch of the Norwegian Polar Institute (NP) have been applied. Additional problem have been identified in as much as the DEM presents very detailed and accurate height information for the ground but its accuracy for the glacier surfaces leaves much to be desired. Elevation data for glaciers was collected mostly in 1936 from photogrammetric surveys. Additionally, owning the interpolation errors of up to 50 m in respect of the sparse data elevation points, the quality of DEM on glaciers has been degraded.

To try to avoid this problem, the NP DEM have been updated for Aavatsmarkbreen and Comfortlessbreen areas using field GPS elevation data acquired in 2001. The front position was also updated using optical satellite ASTER image acquired in 2001. The updated DEM have been also compared with elevation data calculated from 3-pass interferometry. The interferometric flow velocity calculations have been then validated with results from field static GPS measurements.

 

Full paper

Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry