26 Sep 2023
 | 26 Sep 2023
Status: this preprint is currently under review for the journal HESS.

Climatology of Snow Depth and Water Equivalent measurements in the Italian Alps (1967–2020)

Roberto Ranzi, Paolo Colosio, and Giorgio Galeati

Abstract. A climatology of SWE based on data collected at 299 gauging sites was performed for the Italian Alps over the 1967–2020 period, when the Italian National Electric board conducted routinely and with homogeneous methods snow depth and density measurements. Six hydrological sub-regions were investigated spanning from the eastern Alps to the western Alps at altitudes ranging from 1000 m to 3000 m asl. Measures were conducted at fixed dates at the beginning of each month from 1 February to 1 June and on 15 April. To our knowledge this is the most comprehensive and homogeneous dataset of measured snow depth and density for the Italian Alps. Significant decreasing trends over the years at fixed dates and elevation classes were identified for both snow depth (−0.12 m decade−1 on average) and snow water equivalent (−37 mm decade−1 on average) in most of the six investigated areas. The analysis of bulk snow density data showed a temporal evolution along the snow accumulation and melt season, but no altitudinal trends were found. A Moving Average and Running Trend Analysis (MARTA triangles), combined with a Pettitt’s test change-point detection, highlighted a decreasing change of snow climatology occurring around the end of the 1980s. Correlation with climatic indexes indicate significant negative values of Pearson correlation coefficient with winter North Atlantic Oscillation (NAO) and positive values with winter West Mediterrean oscillation (WeMO) for some areas and elevation classes. Results of this climatology are synthesized in a temporal polynomial model useful for climatological studies and water resources management in mountain areas.

Roberto Ranzi et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on hess-2023-223', Xavier Fettweis, 18 Oct 2023
  • RC2: 'Comment on hess-2023-223', Anonymous Referee #2, 30 Oct 2023
  • CC1: 'Review on hess-2023-223', Marijn van Dijk, 03 Nov 2023
  • CC2: 'Comment on hess-2023-223', Rick Haanschoten, 07 Nov 2023
  • CC3: 'Comment on hess-2023-223', Thijs Merkx, 07 Nov 2023

Roberto Ranzi et al.

Roberto Ranzi et al.


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Short summary
We studied temporal trends and variability of snow depth and snow water equivalent (SWE) in six regions of the Italian Alps. We applied different statistical analysis to a dataset of homogeneous and continuous measurements of snow depth and snow water equivalent, temporally spanning from 1967 to 2020, and discuss the results with meteo-climatic data. Our results quantify the decrease of SWE in the study area, confirming the impacts of climate modifications on the cryosphere in the Alps.