Temporal and spatial characterization of cloud-to-ground lightning activity over Iberian Peninsula

Abstract

The quantitative assessment of the impact on society of weather and climate extremes is challenging and recent years have seen a tremendous increase in economic losses from weather hazards. Is necessary to know the changes in the frequency and/or intensity of extreme events to evaluate the trend in losses. So the lightning activity plays a fundamental role as a cause of weather-related deaths, property damages and power system breakdowns. The temporal and spatial distribution of cloud-to-ground lightning activity in the Iberian Peninsula have been studied, using data of years 1992-1994,0ver 2.2 million cloud-to-ground lightning flashes were recorded. The highest lightning activity was found in the summer (79% of all lightning events in the months May to September and the diurnal variation shows a single peak with the maximum at 1700 local time. Just over 11% of all lightning flashes are observed between 0700 and 1100 local time; which represents the contribution of frontal thunderstorms to lightning activity. The lightning polarity changes throughout the year: during the warmer months positive flashes contribute only 5.9 °/0 whereas this percentage increases to 13.1‘Yo in the colder months. The geographical distribution of cloud-to-ground flashes shows a clear relationship with orography, with maximum lightning activity over Pirineos. The average maximum flash density is found to be 3,3 flashes km-zyr-l,