Cloud-to-Ground lightning and thunderstorm activity over Asturias, Spain

Abstract

Cloud-to-Ground (CG) lightning data from 2000 to 2013 were used to study certain characteristics of thunderstorms in the Spanish region of Asturias (northern section of the Iberian Peninsula). The average CG- flash density and number of days with thunderstorms (defined as days with number of CG-flashes ≥ 2) was found to be 0.64 fl km-² yr-1 and 64 td yr-1 respectively. Both variables exhibited maximum values in the warm period of the year, especially in late spring (June), indicating that thermal instability is the main factor in the development of thunderstorms in the area studied. Convective activity in Asturias tends to be concentrated over mountainous areas. The maxium activity of CG-flashes was found in June and July (associates to the thermal instability) and the mininum in February (convection associated with dynamic processes such as fronts). The Pearson correlation coefficient between altitude and CG- flash density was 0.95 for altitudes between 50 m and 1,900m. The number of CG-lightning flashes per day was related to the intensity, polarity and multiplicity of the thunderstorm. The observed annual average values of intensity (multiplicity) were 22.8 kA (2.04) for negative CG lightning and 42.1 kA (1.13) for positive CG lightning.