Air-mass trajectories and extreme episodes: Snowfalls on the natural region of the south-east coast of the Iberian Peninsula (1900–2005)

Abstract

This paper analyses and characterizes snowfall events in one of the hottest, most arid areas in continental Europe. Our information was taken from a snowfall database that was partly our own, covering a period of over 100 years. The FLEXTRA model of air-mass back-trajectories was applied together with our own subjective synoptic classification. Data from the ECMWF Reanalysis of the 20th Century (ERAsingle bond20C) were used for the calculation and clustering of the back-trajectories and the establishment of synoptic weather types. The snowfall events were classified into 8 synoptic types and 4 first-level and 8 s-level back-trajectories. The meteorological scenario for these extreme events was marked by mixed structures at altitude with a main NE/SW axis and dipoles on the surface dominated by powerful North Atlantic anti-cyclones and back-trajectories from the NE at the three levels analysed (500, 1500 and 5000 m.a.s.l.).