Melting Characteristics of Snow Cover on Tidewater Glaciers in Hornsund Fjord, Svalbard

Abstract

Abstract:In recent years, the Svalbard area, especially its southern section, has been characterised by an exceptionally thin snow cover, which has a significant impact of the annual mass balance of glaciers. The objective of this study was to determine melting processes of the snow cover deposited on 11 glaciers that terminate into Hornsund Fjord during the melting period of 2014. The study included analyses of snow pits and snow cores, meteorological data collected from automatic weather stations and Polish Polar Station Hornsund, and supervised classification of six Landsat 8 images for assessing the progress of snow cover melting. The calculated Snow-Covered Area (SCA) varied from 98% at the beginning of the melting season to 43% at the end of August. The melting vertical gradient on Hansbreen was −0.34 m 100 m −1 , leading to surface melting of −1.4 cm water equivalent (w.e.) day −1 in the ablation zone (c. 200 m a.s.l. (above sea level)) and −0.7 cm w.e. day −1 in the accumulation zone (c. 400 m a.s.l.). Furthermore, the study identified several observed features such as low snow depth in the accumulation zone of the Hornsund glaciers, a large proportion of the snow layers (12-27%) produced by rain-on-snow events, and a frequent occurrence of summer thermal inversions (80% annually), indicating that the area is experiencing intensive climate changes.

The Role of Winter Rain in the Glacial System on Svalbard

“…Increased snow density resulted particularly from winter rain-on-snow events and winter thaw periods leading to the formation of high-density layers within the snowpack. In recent years, the number of layers in the general structure of the snowpack was greater, as was also observed for other glaciers in Wedel Jarlsberg Land [23,25]. On Hansbreen, the contribution of the high-density layer in the snowpack structure changed gradually along with altitude, from ca 16% in the accumulation zone (H9) to ca 25% in the ablation zone (H4).…”

“…The most frequent below-freezing-point conditions are interrupted by several thaw periods [20]. Rain-on-snow events, frequently co-occurring with warm spells in winter, are recorded in the Hansbreen snowpack structure as ice formations [15,24,25].…”

“…They can be identified even in high-elevation glacial zones [23]. Although such spells were observed in the Hornsund region in the late 1980s [24], they have become substantially more frequent in recent years, not only in the research area, but throughout the Arctic [15,25,[70][71][72][73][74]. In southern Spitsbergen, these events are typical of the S + SWc circulation type [21], for which the greatest amounts of liquid precipitation are recorded [75].…”

Changes of glacier facies on Hornsund glaciers (Svalbard) during the decade 2007–2017

“…The average Equilibrium-Line Altitude (ELA) of Hansbreen was detected at 342 m a.s.l. in 2014 (Laska et al 2017a). The snow accumulation at the main trunk of the glacier is asymmetrical, favouring the western over the eastern side (e.g.…”

“…Although glacier zones have been detected by analysis of multispectral images during the ablation season (e.g. Hall et al 1987;Pope and Rees, 2014;Laska et al 2017a;Sobota and Wójcik 2020), for detection of their annual changes and possible support of mass balance studies Synthetic Aperture Radar (SAR) data are advantageous. SAR is an active system operating in the microwave range of the electromagnetic spectrum.…”