MODIS (2001-2022) snow cover variability over the Italian territory

Study region The Italian territory including the southern part of the Alps and the Apennine chain. Study focus The snow cover variables (duration - SCD, onset - SOD, end - SED) have been analysed between 2000 and 2022 using MODIS data to study their spatial distribution and temporal evolution. The snow cover extent (SCE) obtained from ERA5-Land has been used to evaluate trends over a longer period (since 1950s). New hydrological insights for the region The spatial distribution of SCD shows a dependence on elevation (76 % variance explained); high variability at each elevation is also seen, underlining the importance of other parameters (e.g., slope, aspect, longitude, latitude). A similar pattern is observed for SOD and SED. The SCD series for Italy shows very high interannual variability resulting in a significant negative trend (between -5.1 and -0.6 days decade(-1)) at elevations > 3500 m a.s.l., owing to the signal observed over the Alps. A good agreement (correlation=0.91) is found between the temporal evolution of SCD from MODIS and the SCE obtained from ERA5-Land allowing to evaluate the trend since the 1950s which was found negative (-4 % decade(-1)) and significant over the Italian territory owing to the decreasing SCE in the Alpine region. The obtained results are important in view of the socioeconomic importance of snow cover for the considered area for agriculture, human consumption, tourism and industry sector.