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

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 (CV20). 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.

Increase of the Energy Available for Snow Ablation in the Pyrenees (1959 – 2020) and its Relation to Atmospheric Circulation

“…The elevation increases towards the center of the mountain range, where the highest peaks are found (Aneto, 3404 m asl), and decreases towards the edges. The climate of the Pyrenees is ruled by the southward displacement of the jet stream during winter, and anticyclonic conditions during summer (Bonsoms et al, 2021b;and references therein). The Pyrenees present a wide range of climate regimes due to the different exposure of the massifs to the main air masses and the rough orography of the region.…”

“…W, NW, N and NE advections control the snow accumulation on the northern slopes of the central-eastern zone, whereas precipitation shadow effects decrease the Atlantic low-pressures system influence in the eastern area (Bonsoms et al, 2021a), as well as in the valley bottoms (González et al, 2021). In addition, the climate becomes gradually more continental towards the southern slopes of the eastern range, where the snow regime shows a marked interannual variability (Bonsoms et al, 2021b). The above-mentioned climatic contrasts eventually drive the snow climatology on the mountain range.…”

“…This is because snow studies in the Pyrenees are constrained by temporal and spatial availability of in-situ climate and snow data. In some sectors of the mountain range, such as in the high elevation areas of the southern slopes of the Pre-Pyrenees, instrumental records started in the early 2000s (e.g., Bonsoms et al, 2021b). This makes challenging comparing data in different areas.…”

“…Those CTs often produces precipitation, instead of positive Q m and snow ablation conditions. CT 3 and 6 are associated with high amounts of snow over the southern slopes of the western and central Pyrenees (e.g., López-Moreno and Serrano-Vicente, 2006), whereas CT 6 contribute to positive HN and torrential rainfall in the southern slopes of the eastern Pyrenees (Bonsoms et al, 2021b;and references therein). CT 8 brings the highest contribution of snowfall on the northern slopes of the high elevation areas of the western and central (Navarro-Serrano and López-Moreno, 2017), central-eastern (Esteban et al, 2005) and eastern Pyrenees (Bonsoms et al, 2021a).…”

Reconstructing the Snow Avalanche of Coll de Pal 2018 (SE Pyrenees)

“…According to the Emergency Events Database, EM-DAT [2], snowfall and snow avalanches are considered natural hazard belonging to hydrometeorological events. Snow avalanches have caused, and cause, important damages, especially in mountain areas; thus, hazard assessment and prevention to reduce the associated risk become mandatory [3][4][5][6][7][8][9][10][11][12][13][14].…”