LIGHTNING GROUND FLASH DENSITY
The above figure shows the result of an analysis obtained from cloud to ground lightning flashes as recorded by the Italian Lightning Recording System operated by CESI-SIRF. The data processed by CESI-SIRT are taken from year 1995 to the present. The detection system was launched in 1994 and is capable of recording lightning flashes to ground in real time and evaluating their principal electrical characteristics. It covers all Italian national territory including Sicily and Sardinia. Since 1996, the system covers mainland with a standardized detection reliability of 90% and an impact accuracy of 500m. In 1999 it was extended to cover also the islands.
Density of lightning flashes to the ground NG
The ground flash density Ng is the number of lightning flashes per km2 and year. These values are provided by the above mentioned recording system from all the flashes detected by the corrresponding lightning localization system (LLS) that covers the territory.
The detection data registered by the LLS must be collected and processed, in order to calculate the annual number of dangerous events Nx according to EN 62305-2.
It is sufficient to provide the geographical coordinates (latitude/longitude) to retrieve the corresponding value of Ng. The ground flash density values are drawn from the SIRF database.