Empirical modelling of snow cover duration patterns in complex terrains of Italy

Nazzareno Diodato,Gianni Bellocchi,Fredrik Charpentier Ljungqvist

doi:10.1007/s00704-021-03867-8

Abstract

Snow cover duration is a crucial climate change indicator. However, measurements of days with snow cover on the ground (DSG) are limited, especially in complex terrains, and existing measurements are fragmentary and cover only relatively short time periods. Here, we provide observational and modelling evidence that it is possible to produce reliable time-series of DSG for Italy based on instrumental measurements, and historical documentary data derived from various sources, from a limited set of stations and areas in the central-southern Apennines (CSA) of Italy. The adopted modelling approach reveals that DSG estimates in most settings in Italy can be driven by climate factors occurring in the CSA. Taking into account spatial scale-dependence, a parsimonious model was developed by incorporating elevation, winter and spring temperatures, a large-scale circulation index (the Atlantic Multidecadal Variability, AMV) and a snow-severity index, with in situ DSG data, based on a core snow cover dataset covering 97 years (88% coverage in the 1907–2018 period and the rest, discontinuously from 1683 to 1895, from historical data of the Benevento station). The model was validated on the basis of the identification of contemporary snow cover patterns and historical evidence of summer snow cover in high massifs. Beyond the CSA, validation obtained across terrains of varying complexity in both the northern and southern sectors of the peninsula indicate that the model holds potential for applications in a broad range of geographical settings and climatic situations of Italy. This article advances the study of past, present and future DSG changes in the central Mediterranean region.

Highlights

Quando Orion dal cielo Declinando imperversa, E pioggia e nevi e gelo Sopra la terra ottenebrata versa, me spinto ne la iniqua stagione, infermo il piede, tra il fango e tra l’obliqua furia de’ carri la città gir vedeWhen Orion from heaven Declining raging, And rain and snow and frost Over the darkened earth pours, pushed me into the iniquitous season, foot infirm, between the mud and the oblique fury of the chariots the town seesGiuseppe Parini, La caduta, 1785, published by Reina 1825, p. 207Injured by a fall on a snowy and icy ground, the Italian poet Giuseppe Parini (1729–1799) begins his ode La caduta (“The fall”) with the epic description of an eighteenth century winter season in his city (Milan, northern Italy)
We developed the hypothesis of Diodato and Bellocchi (2020) stating that site- or area-specific estimates of snowfall in peninsular Italy can be obtained from temperature variations in the Benevento Valley (BNV) because this valley is located at the transition between central and southern Apennines and captures the temperature variations of the Italian peninsular sector
The mean absolute error (MAE), used to quantify the amount of error, was equal to 6.0 day year−1, which is lower than the standard error of the estimates (8.8 day year−1)

Summary

Introduction

Quando Orion dal cielo Declinando imperversa, E pioggia e nevi e gelo Sopra la terra ottenebrata versa, me spinto ne la iniqua stagione, infermo il piede, tra il fango e tra l’obliqua furia de’ carri la città gir vedeWhen Orion from heaven Declining raging, And rain and snow and frost Over the darkened earth pours, pushed me into the iniquitous season, foot infirm, between the mud and the oblique fury of the chariots the town seesGiuseppe Parini, La caduta, 1785, published by Reina 1825, p. 207 (our translation into English)Injured by a fall on a snowy and icy ground, the Italian poet Giuseppe Parini (1729–1799) begins his ode La caduta (“The fall”) with the epic description of an eighteenth century winter season in his city (Milan, northern Italy). Alterations in snow cover may, in turn, influence mountain ecosystem hydrology (Gobiet et al 2014), biological and chemical processes in soil and water (Magnani et al 2017), crop phenology and plant composition (Rogora et al 2018) In this context, the inter-annual variability of cool-season precipitation is important at middle to high latitudes, where winter precipitation likely occurs as snow at high elevations through orographic enhancement (e.g., Dettinger et al 1998; Selkowitz et al 2002; Terzago et al 2012; Luce et al 2013). These determinants are important for the validation of climate models and a better understanding of the interactions among the different spheres (geosphere, biosphere, atmosphere, hydrosphere and cryosphere) of the Earth’s system (Brown 2014)

Methods

Results

Conclusion