Brief Communication: Inferring Glacier Equilibrium Line Altitudes in Central Europe with FROST

Abstract. Glaciers in Central Europe are projected to almost disappear by 2100. To improve projections, glacier models must be calibrated to match observations. Using the open-source Framework for assimilating Remote-sensing Observations for Surface mass balance Tuning (FROST), we infer equilibrium-line altitudes and surface mass balance parameters for all Alpine glaciers during 2000–2019 through an Ensemble Kalman Filter. The method combines an elevation-dependent surface mass balance model with ice dynamics from Instructed Glacier Model (IGM). Validation against in-situ mass balance and end-of-summer snowline data (correlations of 0.76 and 0.62) shows that FROST enables satellite-based regional estimates of glacier equilibrium conditions.