Extreme icing event in snowpack at High Arctic site

Thursday, 18 December 2014
Jack Kohler, Norwegian Polar Institute, Tromsø, Norway
Winter snow is a key factor affecting many aspects of polar ecosystems. For example, winter snow thickness, ice layers formed within and, more particularly, at the base of the snowpack, have all been linked to fluctuations in in High Arctic animal populations in Svalbard. At a field site in northwestern Svalbard, measurements of snow and snow properties (e.g. ice layers) have been made along a series of transects around the peninsula Brøggerhalvøya. These measurements are typically made over a 1-2 day period in April/May, and have been performed annually since 2002. The typical procedure is to sound at 100-200 m intervals along the transects, digging snow pits at regular intervals to determine the snowpack stratigraphy, in particular the basal ice layer thickness, if present. In a few years these measurements have been supplemented with 900 MHZ ground-penetrating radar (GPR) profiles. In January-February 2012 there was an extreme warm period across all of Svalbard, with temperatures well above freezing (up to 7°C) across the entire archipelago and record-breaking precipitation (nearly 10 cm of rain falling in one day at Ny-Ålesund). This extreme event led to a pervasive ground-ice layer 5-20 cm thick across most of the low-lying terrain around Brøggerhalvøya. I compare measurements made in this year to those made in other years, including a comparison of GPR profiles made in 2012 and in 2007, a year with very little ground-ice.