Historical snowfall precipitation data in the Apennine Mountains, Italy - V02

This database includes a large collection of quality-controlled and homogenized historical snow records measured between January 1951 and December 2001 across the Italian Apennines. The spatial coverage extends from the Ligurian Apennines in northern Italy to the Calabrian Apennines in southern Italy and also includes monitoring stations located in the mountainous areas of Sardinia and Sicily. Most of the data were manually digitized from the Hydrological Yearbooks of the Italian National Hydrological and Mareographic Service (hereafter, NHMS), the institution responsible for hydro-meteorological data collection in Italy from 1917 to 2002. Additional data were provided by the Regional Agency for Prevention, Environment and Energy of Emilia-Romagna (ARPAE) and the Regional Agency for Environmental Protection of Calabria (ARPACAL). More specifically, the rescued dataset includes monthly observations of three different variables: · Snow cover duration (SCD), defined as the total number of days in a given month with a snow depth on the ground greater than or equal to 1 cm. This variable is available for 223 stations located between 288 and 1430 m above sea level (ASL). · Number of days with snowfall (NDS), defined as the total number of days in a given month on which the accumulated snowfall - that is, the amount of fresh snow recorded since the previous observation - is at least 1 cm. This variable is available for 228 stations located between 288 and 1430 m ASL. · Height of new snow (HN), defined as the monthly amount of fresh snow, expressed in centimetres. Each monthly value corresponds to the sum of the daily HN observations recorded during the relevant month. This variable is available for 170 stations located between 288 and 2165 m ASL. The data digitization, quality-control and homogenization procedures are the same as those adopted for the previous version of the database. The quality-control process consists of several statistical tests: a gross-error test, which flags values falling outside physically acceptable limits; a consistency test, based on inter-variable comparisons; and a tolerance test, aimed at detecting potential outliers. The homogeneity of the rescued time series was assessed using the Climatol method (Guijarro, 2018). This method employs the Standard Normal Homogeneity Test (Alexandersson, 1986) to identify potential break points and a linear-regression approach to adjust detected inhomogeneities (Easterling and Peterson, 1995). Climatol was also used to estimate and fill missing values. The database is organised into three separate folders, one for each snow variable. Each folder contains two files: one providing the main metadata for the available monitoring stations - including station code, station name, latitude and longitude in decimal degrees, and elevation above sea level in metres - and another containing the corresponding monthly time series. All time series have a monthly temporal resolution and cover the period from January 1951 to December 2001. The original data sources represented by the NHMS Hydrological Yearbooks are freely accessible as scanned documents in Portable Document Format through the website of the Italian Institute for Environmental Protection and Research (ISPRA): http://www.bio.isprambiente.it/annalipdf Additional information on the data rescue, quality-control and homogenization procedures can be found in: Capozzi, V., Serrapica, F., Rocco, A., Annella, C., and Budillon, G. (2025): Historical snow measurements in the central and southern Apennine Mountains: climatology, variability, and trend, The Cryosphere, 19, 565–595, https://doi.org/10.5194/tc-19-565-2025. For further information: [email protected]