Seasonal snow cover on frozen ground: Energy balance calculations of a permafrost site near Ny-Ålesund, Spitsbergen

Abstract

We apply an energy balance model to the snow cover for snowpack accumulation and ablation at a continuous permafrost site on Spitsbergen for the snow-covered periods from fall 1998 to winter 2000. The model includes net radiative, turbulent, ground, snow, and rain heat flux. The balance yields two distinct types of snow ablation: winter and spring ablation. Energy transferred by sensible heat and rain input reduces the snow cover during the winter, creating internal ice lenses and basal ice. The snowpack ablates during spring in two stages in both years. During the first stage, surface melt and subsequent internal freezing compact and reduce the snow cover, but no runoff is produced. This phase lasts more than twice as long as the second stage. During the second stage, which takes 14 days in both years, melt rates from the snowpack are represented well using the energy balance model. Ground heat fluxes are comparable during spring in both years, but the long persistence of the snow cover in 2000 delays the thawing of the ground. Due to the duration of the snow cover during spring snow melt of both years, the total energy supplied to the ground is significant, between 30 and 50% of the total energy supplied by net radiation.