https://doi.org/10.5194/tc-2020-367 Preprint. Discussion started: 21 January 2021 c Author(s) 2021. CC BY 4.0 License. Firn changes at Colle Gnifetti revealed with a high-resolution process-based physical model approach Enrico Mattea1, Horst Machguth1, Marlene Kronenberg1, Ward van Pelt2, Manuela Bassi3, and Martin Hoelzle1 1Department of Geosciences, University of Fribourg, Fribourg, Switzerland 2Department of Earth Sciences, Uppsala University, Uppsala, Sweden 3Department of Forecasting Systems, Regional Agency for Environmental Protection of Piedmont, Turin, Italy Correspondence: Enrico Mattea (
[email protected]) Abstract. Our changing climate is expected to affect ice core records as cold firn progressively transitions to a temperate state. Thus there is a need to improve understanding and further develop quantitative process modeling, to better predict cold firn evolution under a range of climate scenarios. Here we present the application of a distributed, fully coupled energy balance model, to simulate high-alpine cold firn at Colle Gnifetti over the period 2003–2018. For the first time, we force such a model 5 with high-resolution, long-term and extensively quality-checked meteorological data measured in closest vicinity of the firn site, at the Capanna Margherita (4560 m a.s.l.). The model incorporates the spatial variability of snow accumulation rates, and is calibrated using several, partly unpublished high-altitude measurements from the Monte Rosa area. The simulation reveals a very good overall agreement in the comparison with a large archive of firn temperature profiles. The rate of firn warming at 20 m depth is estimated at 0.44 ◦C per decade.