openAMUNDSEN v1.0: 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 snow-hydrological model, designed primarily for calculating the seasonal evolution of snow cover and melt rates in mountain regions. It resolves the mass and energy balance of snow-covered surfaces and layers of the snowpack, thereby including the most important processes that are relevant in complex mountain topography. 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 already been used for many applications, which are referenced herein. It features a spatial interpolation of meteorological observations, several layers of snow with different density and liquid-water contents, wind-induced lateral redistributions, snow–canopy interactions, glacier ice responses 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, and computational performance for a certain region in the European Alps, typically a (preferably gauged) hydrological catchment. The Python model code and example data are available as an open-source project on GitHub (https://github.com/openamundsen/openamundsen, last access: 1 June 2024).