Lightning occurrence data observed with lightning location systems of electric power companies in Japan: 1992–2008

17 years of lightning data from 1992 to 2008 obtained with lightning location system of 9 electric power companies in Japan have been summarized and analyzed. The recent annual number of lightning flashes of which current is more than 10 kA in Japan is around one million and the 50% value of cumulative distribution of lightning peak currents is about 20kA. The variation of lightning occurrence characteristics by areas, seasons and so on are clarified. The relationship between lightning occurrence and climate, detection efficiency and the version of lightning detection systems are discussed.