Glaciological and meteorological investigations of an Alpine debris-covered glacier: the case study of Amola Glacier (Italy)

Abstract

Debris-covered glaciers are common in many regions of the world, and accurately modelling their melt is of increasing importance for water resources planning, and biological and ecological research. In this study, we investigate meteorological and glaciological conditions and estimate the melt of Amola Glacier (a small debris-covered glacier in the Adamello-Presanella Massif, Italian Alps) using an empirical approach, based on shortwave radiation, surface temperature, debris thickness and thermal resistance. Meteorological conditions are determined from a supraglacial automatic weather station, while the model is calibrated using i) field data acquired during the ablation season 2020, including a network of ablation stakes and thermistors, ii) modelled solar radiation and iii) thermal imagery from Landsat 8 TIRS.The analysis of glacier meteorological conditions shows a high prevalence of cloud-covered (50.60% of daytime observations) and humid conditions, with a high daily air temperature range (22.24 °C). Analysis of thermistor data suggests that a linear thermal gradient of the debris layer can be assumed when the model is run at daily resolution. Modelled debris thickness, surface temperatures and melt capture patterns observed on the field, including the decrease in debris thickness and increasing melt with elevation and their variability across the glacier surface. The root mean square error between measured and observed melt is 0.16 m, corresponding to 22% of the average observed melt, in line with the performance of empirical models for debris-free and debris-covered ice. The model could thus be used to provide a first estimate of debris-covered ice melt for glaciers in the Adamello region. Improvements to the model would require measuring all energy fluxes on the glacier from a weather station and investigating their spatial distribution on the glacier surface.