title: Snowfall in the northwest Iberian Peninsula: synoptic circulation patterns and their influence on snow day trends.
abstract: In recent decades, a decrease in snowfall attributed to the effects of global warming (among other causes) has become evident. However, it is reasonable to investigate meteorological causes for such decrease, by analyzing changes in synoptic scale patterns. On the Iberian Peninsula, the Castilla y León region in the northwest consists of a central plateau surrounded by mountain ranges. This creates snowfalls that are considered both an important water resource and a transportation risk. In this work, we develop a classification of synoptic situations that produced important snowfalls at observation stations in the major cities of Castilla y León from 1960 to 2011. We used principal component analysis (PCA) and cluster techniques to define four synoptic patterns conducive to snowfall in the region. Once we confirmed homogeneity of the series and serial correlation of the snowfallday records at the stations from 1960 to 2011, we carried out a Mann-Kendall test. The results show a negative trend at most stations, so there are a decreased number of snowfall days. Finally, variations in these meteorological variables were related to changes in the frequencies of snow events belonging to each synoptic pattern favorable for snowfall production at the observatory locations.
authors.affiliation: University of León, Instituto de Medio Ambiente (IMA), 24006 León, Spain.
authors.forename: Andrés
authors.initials: A
authors.lastname: Merino
authors.affiliation: University of León, Instituto de Medio Ambiente (IMA), 24006 León, Spain.
authors.forename: Sergio
authors.initials: S
authors.lastname: Fernández
authors.affiliation: University of León, Instituto de Medio Ambiente (IMA), 24006 León, Spain.
authors.forename: Lucía
authors.initials: L
authors.lastname: Hermida
authors.affiliation: University of León, Instituto de Medio Ambiente (IMA), 24006 León, Spain.
authors.forename: Laura
authors.initials: L
authors.lastname: López
authors.affiliation: University of León, Instituto de Medio Ambiente (IMA), 24006 León, Spain.
authors.forename: José Luis
authors.initials: JL
authors.lastname: Sánchez
authors.affiliation: University of León, Instituto de Medio Ambiente (IMA), 24006 León, Spain.
authors.forename: Eduardo
authors.initials: E
authors.lastname: García-Ortega
authors.affiliation: University of León, Instituto de Medio Ambiente (IMA), 24006 León, Spain.
authors.forename: Estíbaliz
authors.initials: E
authors.lastname: Gascón
mesh_terms: D004784:Environmental Monitoring; D008685:Meteorological Concepts; D012914:Snow