Lightning occurrence in relation with elevation, terrain slope, and vegetation cover in the Mediterranean

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Abstract

[1] In the frame of this paper, 1-year of lightning data from the experimental network ZEUS operated by National Observatory of Athens is analyzed. The area of interest is the Mediterranean and surrounding countries. At a first stage, the ZEUS data are compared with the data provided by the UK Met Office long-range lightning detection network for the warm period of the year. It was found that although ZEUS system underestimates the nighttime and early morning activity, during the rest of the day ZEUS system detects increased number of lightning compared to ATD that suffers from saturation when the number of flashes exceeds a certain threshold. Furthermore, the possible relationship between lightning and elevation, terrain slope and vegetation is investigated. The analysis showed that during spring and summer there is a positive relationship of lightning activity with elevation, while this feature is not evident during the rest of the year. The lightning activity was found to be positively correlated with the elevation slope throughout the year except winter. As it concerns the vegetation cover, it was found that over bareground the lightning “yield” is low during the whole year, while the inverse is true for woodland areas. During the warm period of the year, due to drying of the Mediterranean surfaces, the forested and wooded areas that keep soil moisture present increased lightning “yield” in contrast with the shrubland areas that, for the same period, present a decreased lightning yield.

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