We combined ground-based pulsed radar data collected in 20082009 with airborne radio-echo sounding data acquired in 1983 and 1986 over Vestfonna ice cap, Svalbard. The airborne dataset mainly covers the fast-flowing outlet glaciers and the marginal zone, while the ground-based data explicitly cover the interior part of the ice cap. The data presented here are thus the first complete estimate of bed topography and ice thickness. The subglacial landscape undulates with elevations between -160 and +410 m above sea level. The mean ice thickness is 186 m and the total ice area and volume are 2402 km2 and 442 +/- 0.6 km3, respectively. This is a much smaller volume than those derived from empirical volume-area scaling relationships currently used to estimate regional-to-global glacier volumes. This difference may depend on local conditions for Vestfonna and emphasizes the need to include more volume observations in the derivations of volume-area scaling parameters. We also derive basal reflectivity as a proxy for thermal conditions at the bed. Basal reflectivity values suggest that fast-flowing outlet glaciers are underlain by temperate conditions. The geometric boundaries and basal conditions for Vestfonna will be critical additions to the development of numerical models of the ice cap and to the estimation of more accurate area-volume scaling parameters.
ISI Document Delivery No.: 857QK Times Cited: 8 Cited Reference Count: 66 Pettersson, Rickard Christoffersen, Poul Dowdeswell, Julian A. Pohjola, Veijo A. Hubbard, Alun Strozzi, Tazio Christoffersen, Poul/C-7328-2013 Christoffersen, Poul/0000-0003-2643-8724 UK Natural Environment Research Council (NERC) [NE/F011466/1]; Swedish National Research Council (VR) [2008-2379]; Stiftelsen [Ymer-80]; IPY-KINNVIKA [2011b]; Swedish Polar Secretariat This work was supported by the UK Natural Environment Research Council (NERC) grant NE/F011466/1, Swedish National Research Council (VR) grant 2008-2379 and Stiftelsen Ymer-80. Logistical support was provided by the IPY-KINNVIKA project (see Pohjola et al. (2011b) for IPY-KINNVIKA support organizations) and the Swedish Polar Secretariat. We thank Ola Brandt and an anonymous referee for valuable comments. Adrian McCallum, Robert McNabb and Emilie Beaudon are thanked for invaluable help in field. SPOT imagery was provided by the SPIRIT Program (c) CNES 2008-2009 and SPOT Image 2008. The ESA GlobGlacier project (ALOS PALSAR data courtesy AOPOL.4086, (c) JAXA) is acknowledged. This is Nordic Centre of excellence SVALI publication no 2. 8 Wiley-blackwell Hoboken Si Geography, Physical; Geology