Abstract ID: 28.7353 | Accepted as Poster | Poster | 2025-02-27 13:00 - 14:30 | Ágnes‐Heller‐Haus/Small Lecture Room

In this work we apply a modified version of the energy-balance model to assess Land Surface Temperature (LST) in a debris covered glacier. We tested literature energy balance model, to compute the energy fluxes between atmosphere, debris and ice. During summer of 2024, a field campaign in the Belvedere glacier, in the Piedmont side of the Pennine Alps, was led by personnel of Climate-LAB. A complete weather station, a series of thermistors placed among 0-100 cm of depth, and several ablation stakes have been placed. These data were employed to run and validate energy-balance model at punctual scale at the location of the weather station. The thickness of the debris cover was estimated by applying linear regression, identifying the 0°C point. Energy model is described as the balance of: net solar radiation S, latent heat LE, sensible heat H and ground-soil heat G fluxes. These contributes correspond to an energy cumulation M, stored by the ground during the day and released during the night hours. Traditional approaches only consider the conduction mechanism, i.e. the conductive heat soil flux Gcond, for the heat through supraglacial debris. Analysing the results of our field campaign, it has shown that there is also the contribute of a first order term, that we consider related to convection, Gconv. We also observed relevant variation of the wind speed, causing large variability in the sensible heat. Hence, we perform a sensitivity analysis with respect to wind speed and convective term. In particular we considered the corresponding average day-night values, and we considered the convection in heat soil flux. We obtained four scenarios: i) VW-CC: Variable Wind velocity and Conduction+Convection; ii) VW-C: Variable Wind velocity and Conduction; iii) CW-CC: Constant Wind velocity and Conduction+Convection; iv) CW-C: Constant Wind velocity and Conduction. Best statistical indices occur for the scenario CW-CC, with R2 = 0.95, Bias= 0.05 °C and s.d. =1.5 °C. Overall, the energy-balance model is robust in the representation of observed LST, but it shows some error during the peak of temperature in the central hours of the day, and sometimes also a relevant overestimate (ca. 2 °C) of minimum night temperature. This study highlights the influence of conductive heat fluxes and the impact of low wind patterns on the assessment of sensible heat. These insights contribute to improving energy balance modeling and understanding the dynamics of debris-covered glaciers.