Snowfall and snow cover evolution in the Eastern Pre-Pyrenees (NE Iberian Peninsula)

J Bonsoms,M Oliva,F Salvador-Franch

doi:10.18172/cig.4879

Abstract

Snow cover has significant impacts on geoecological dynamics as well as on socio-economical systems. An accurate quantification of snow precipitation patterns in mountain regions is needed to better understand the spatio-temporal implications of snow cover. The objective of this work is to characterize the patterns of solid precipitation and snow cover in two high Mediterranean massifs. To this purpose, we analyse instrumental data series of snowfall and snow depth of Port del Comte (2316 m a.s.l.) and Cadí-Nord (2134 m). Both stations are situated in the eastern Pre-Pyrenees and include 14 consecutive snow seasons from November to May, allowing to (i) explore the dependence of the main drivers of snowpack: temperature and snowfall; (ii) find out the most frequent circulation weather types associated with high intensity snowfall events, and finally (iii) investigate the role of the North Atlantic Oceanic (NAO) teleconnection pattern explaining snow cover evolution during the winter season. Data show that snowfall is controlled by similar weather types in both stations that resulted in similar snowfall averages: 205 cm and 258 cm at Port del Comte and Cadí-Nord, respectively. Nevertheless, local factors interfere with the amount of snow depth recorded, which is moderately different between stations. Whereas Cadí-Nord records a seasonal mean of 66 cm, Port del Comte records a smaller quantity of 25 cm with a high interannual and seasonal variability. In fact, snowfall recurrence, snow amount or duration in the ground is considerably variable among years (CV>20). In these stations, snow cover duration is determined by the precipitation in the form of snow falling during the previous months. Snowfalls in moderate to severe episodes (>15 cm in 24 h) are mainly driven by Atlantic flows, mostly from NW. In addition, NAO pattern is negatively correlated with snowfall in November and December months (R>-0.50), showing a weaker and not statistically significant correlation during the rest of the winter season.

Highlights

Solid precipitation and the consequent accumulation as snowpack is crucial for the stability of the global climate system
We present an accurate characterization of the snowfall and snow depth at Port del Comte and Cadí-Nord over 14 consecutive seasons, together with an analysis of the relationship between snowpack during the late season and the main meteorological drivers and the role of the North Atlantic Oceanic (NAO)
Local factors introduce some singularities at each site; Cadí-Nord snow station is located in a place affected by weak WSW winds that do not favour snow drift, whereas Port del Comte snow station is situated in an open area, exposed to WNW air flows that affect effectively the redistribution of the snow cover

Summary

Introduction

Solid precipitation and the consequent accumulation as snowpack is crucial for the stability of the global climate system. Snow presence and abundance favours human activities in winter, for example, guaranteeing the opening of ski resorts, a major business in the Pyrenees area, or in springtime, providing hydroelectricity, hydric resources for agriculture or water for settlements and population (e.g., Lasanta et al, 2005). These dependencies will increase in the future, when droughts will be more frequent and severe, and water availability will be more demanding across the Mediterranean basin (García-Ruiz et al, 2011)

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