Understanding links between snow cover and mass balance using a dense monitoring network in a small Arctic glacier basin (Austre Lovénbreen, Svalbard 79°N)

Résumé En

Glacier ice is the result of successive transformations of snow. All glaciers are therefore strongly linked with seasonal snowfalls. The frequency of snowfalls, the quantities involved, and the quality of snow all have an influence on the dynamics of glaciers. Snow cover is the prime source of new ice, but it also has a protective role in ablation areas of glaciers. From an hydrological point of view, snow also constitutes an important part of the outflows of glacier basins. A monitoring protocol based on a network of stakes and complemented with regular snow drilling campaigns has been carried out for 5 years on the Austre Lovénbreen (Spistbergen, 79 N). Overall, 36 measurement points have been dis- tributed at regular intervals over the 4.5 km 2 glacier surface. For each of these points the snow cover was measured at a period close to its yearly maximum (usually late April) and expressed in terms of snow height and water equivalent. Mass balance was also recorded yearly at the end of September. Results show that there is a strong link between the annual snow maximum and the resulting mass balance. Areas with the strongest ablation are the ones displaying the highest variability. This is particularly true on years when the snow cover at lower elevations disappears early in the season, exposing ice. In the up- per reaches of the glacier, the links between snow cover and the resulting balance measurements are not clearly structured. Variability seems related to orientation and more or less sheltered position of the accumulation cirques. On most of the remaining glacier area, and especially near the equilibrium line altitude, snow cover and mass balance display a strong correlation