Assessment on the continuous measurements of snow water equivalent on the Monte Rosa massif (Italy) performed with state-of-the-art sensors in the 2023-24 winter season

The effects of anthropogenic climate change are particularly evident in mountainous regions, where the warming rate is higher than the global average. In this framework, the Alps have recently experienced multiple seasons characterized by a deficit of solid precipitation compared to the historical records. This deficit resulted in a critical situation regarding the status of the snowpack in the Alpine Region. Since the vast majority of the hydrological assets present in Northern Italy are highly dependent on the snow melting from the Alps, a lack of solid precipitation during the snow season could lead to dire impacts on the hydrological balance of the region, as it has already happened during the snow-drought events occurred in the years 2022 and 2023. Therefore, it is of the outmost importance to accurately assess the amount of water present in the snowpack of the Alps, especially at high elevation, where observations are lacking. The snow water equivalent (SWE) represents the equivalent amount of liquid water stored in the snowpack. It is usually measured in situ during campaigns carried out by researchers and technicians. However, the measurements obtained in the field with this method may lack temporal density and continuity. To address this problem, it is widespread practice to derive the SWE from models which account for the snow density and the snow height. Recently, instruments have been developed to perform continuous measurements of the SWE even in remote areas. Here we present the SWE data of the 2023-24 season retrieved from a high elevation monitoring station located on the Monte Rosa massif in the Western Italian Alps. The station (45°52’30’’ N; 7°52’18’’ E; 2900 m a.s.l.) is equipped with two sensors which measure the SWE adopting different techniques. The first, developed by Finapp Srl, is based on the Cosmic Ray Neutron Sensing (CRNS) technology, and retrieves hourly measures of the SWE integrated on a circular area with a diameter of roughly 20 m. The second sensor, developed by ANavS GmbH, employs antennas with Global Satellite Navigation System (GNSS) to evaluate the daily SWE in a solid angle with an amplitude in the order of ten degrees. The data from the sensors are compared with each other and with SWE values obtained during field campaigns and by means of model simulations (with data obtained using the model SNOWPACK) to assess the performance of the installed instruments. The main goal is to determine the feasibility and the limits of these kinds of solutions, with the aim of extending the framework adopted for this work to remote Alpine sites that would benefit from the possibility of retaining continuous monitoring of the snowpack status.