Recent fluctuations in the extent of the firn area of Austfonna, Svalbard, inferred from GPR

• Published in: Annals of glaciology Vol. 50; no. 50; pp. 155 - 162
• Main Authors: Dunse, Thorben, Schuler, Thomas Vikhamar, Hagen, Jon Ove, Eiken, Trond, Brandt, Ola, Høgda, Kjell Arild
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 2009
• Subjects: Norway, Svalbard
• ISSN: 0260-3055; 1727-5644
• DOI: 10.3189/172756409787769780

In spring during 2004–07 we conducted ground-penetrating radar (GPR) measurements on the Austfonna ice cap, Svalbard, with the original aim of mapping the thickness and distribution of winter snow. Here, we further exploit the information content of the data and derive a multi-year sequence of glacier-facies distribution that provides valuable spatial information about the total surface mass balance (SMB) of the ice cap, beyond the usually evaluated winter balance. We find that following an initial decrease in the extent of the firn area (2003–04), the firn line lowered within two subsequent years by ∼40–100m elevation in the north and west and 150–230m in the south and east of the ice cap, corresponding to a lateral expansion of the firn area along the profiles by up to 7.3 and 13.3 km, respectively. The growth of the firn area is in line with stake measurements from Etonbreen that indicate a trend towards less negative SMB over the corresponding period.