openAMUNDSEN v 0.8.3: an open source snow-hydrological model for mountain regions

Abstract. openAMUNDSEN (= the open source version of the Alpine MUltiscale Numerical Distributed Simulation ENgine) is a fully distributed model, designed primarily for calculating the seasonal evolution of a snow cover and melt rates in mountain regions. It resolves the mass and energy balance of snow covered surfaces and layers of the snowpack beneath, thereby including the most important processes that are relevant in such regions. The potential model applications are very versatile; typically, it is applied in areas ranging from the point scale to the regional scale (i.e., up to some thousands of square kilometers), using a spatial resolution of 10–1000 m and a temporal resolution of 1–3 h or daily. Temporal horizons may vary between single events and climate change scenarios. The openAMUNDSEN model has been applied for manyfold applications already which are referenced herein. It features a spatial interpolation of meteorological observations, several layers of snow with different density and liquid water content, wind-induced lateral redistribution, snow-canopy interaction, glacier ice response to climate and more. The model can be configured according to each specific application case. A basic consideration for its development was to include a variety of process descriptions of different complexity to set up individual model runs which best match a compromise between physical detail, transferability, simplicity as well as performance for a certain region in the European Alps, typically a (preferably gauged) hydrological catchment. The Python model code and example data are available for the public as open source project (Hanzer et al., 2023).