Surface and bed morphology of Hansbreen, a tidewater glacier in Spitsbergen

Abstract

Hansbreen, a medium size tidewater glacier in Southern Spitsbergen (Svalbard) is one of the most intensively studied glaciers in the Arctic. This work presents new digital elevation models of its surface and basal topography based on data collected during GPS/GPR campaigns conducted in the spring seasons of 2005 and 2008, as well as on other recent topographic/bathymetric sources. The mean thickness of the glacier is calculated as 171 m and its volume is estimated to be 9.6 (±0.1) km 3 . The main feature of the bedrock morphology is a vast depression that is overdeepened below sea level and extends as far as 11 km upstream from the glacier front. This depression is divided into four individual bas− ins by distinct sills that are related to the main geological/tectonic features of the area. The bedrock morphology affects considerably the glacier's surface topography. The influence of bedrock and surface relief on the subglacial drainage system geometry is discussed. Vast depressions on the glacier surface favor concentration of meltwater and development of moulin systems.

Ice Volume Estimates from Ground-Penetrating Radar Surveys, Wedel Jarlsberg Land Glaciers, Svalbard

“…We then performed volume estimates using constant RWVs for the entire glacier, between 165 and 170 m µs −1 , at 1 m µs −1 intervals, and found that the constant RWV that produces the glacier volume closest to that computed using different velocities for distinct media is 166 m µs −1 . This value is within the range of column-averaged RWVs measured on Hansbreen by the authors using the CMP method (Jania et al, 2005;Grabiec et al, 2012). The corresponding volume is 10.75 ± 0.73 km 3 , equivalent, within error bounds, to the volume given above.…”

“…The volume of Hansbreen presented here is about 1 km 3 (9%) larger than that recently published by Grabiec et al (2012), who used the same set of radar profiles. The main reason is that the outlines of this glacier in the Randolph Glacier Inventory (used here) and in Grabiec et al (2012) differ substantially at the ice divide between Paierlbreen and Hansbreen, implying a difference in the surface area of Hansbreen, which is some 8 km 2 larger in the Randolph Glacier Inventory.…”

“…The main reason is that the outlines of this glacier in the Randolph Glacier Inventory (used here) and in Grabiec et al (2012) differ substantially at the ice divide between Paierlbreen and Hansbreen, implying a difference in the surface area of Hansbreen, which is some 8 km 2 larger in the Randolph Glacier Inventory. Additionally, Grabiec et al (2012) ) for the time-to-depth conversion, producing smaller ice thicknesses, which also contribute to make the glacier volume smaller.…”

“…To our knowledge, the hydrothermal structure of the glaciers studied in this paper has only been discussed in the literature for Hansbreen (e.g., Dowdeswell et al, 1984aDowdeswell et al, , 1984bMacheret et al, 1993;Jania, 1996;Jania et al, 1996;Moore et al, 1999;Pälli et al, 2003;Grabiec et al, 2012), Recherchebreen (e.g., Macheret and Zhuravlev, 1982;Dowdeswell et al, 1984aDowdeswell et al, , 1984b, Werenskioldbreen (e.g., Macheret and Zhuravlev, 1982;Dowdeswell et al, 1984aDowdeswell et al, , 1984bPälli et al, 2003), and Ariebreen (Lapazaran et al, 2013), all of them polythermal except the latter, which is entirely made of cold ice. On the basis of the presence or absence of scattering in the radargrams as an indicator of temperate or cold glacier ice (Navarro and Eisen, 2010), we here interpret that all other glaciers in our data set (Austre Torellbreen, Paierlbreen, Renardbreen, and Scottbreen) have a polythermal structure.…”

Icings and their role as an important element of the cryosphere in High Arctic glacier forefields

“…This supposition is supported by the presence of icings in the forefield of glaciers. A similar thermal regime has been reported for other Svalbard glaciers (Jania et # -after www.placenames.npolar.no; $ -without Agnorbreen; * -area in 2015; ** -area in 2014; *** -area in 2010, 1 -total area where icings were observed in the selected years; 2 -area in the years 2008-2015Hodgkins et al 1999;Degard et al 2007;Willis et al 2007;Grabiec et al 2012).…”