Monthly and Diurnal Trends in Lightning over the Mediterranean Sea: A Thunder Hours Analysis

Lightning data are often used to measure the location and intensity of thunderstorms. This study presents data from the Earth Networks Global Lightning Detection Network (ENGLN) in the form of thunder hours. A thunder hour is defined as an hour during which thunder can be heard by a human observer at a given location and represents an intuitive measure of thunderstorm frequency. Thunder hour information derived from ENGLN data over 5 years (January 2015 - December 2019) is aggregated for each month over the Mediterranean Sea region to study the spatial distribution of thunderstorms there at different times of day and during different months of the year. The timing and distribution of Mediterranean thunderstorms are shown to be related to sea surface temperatures. We use meteorological observations, model data, and storm reports to study the modes of convection producing these thunder hours signatures. The maritime thunder hours signal appears in August in the central Mediterranean and then begins shifting eastward. Thunderstorm frequency in the Ionian Sea region peaks during October-November, while, over the sea south of Turkey, most thunderstorm activity occurs during December-March. Thunderstorm frequency over the entire Mediterranean is smallest between May-July.