Lightning occurrence data observed with lightning location systems in Japan: 1992-1995

Cloud-to-ground lightning occurrence for years 1992-1995 has been analyzed using the data obtained with nine different lightning location systems in Japan. A total of more than 2 million lightning strokes are observed for the four years and the number of annual lightning strokes is closely related to the weather conditions in summer. Lightning occurs all over Japan in summer but occurrence of lightning is concentrated in the coastal area of the Sea of Japan in winter. Data of thunderdays are compared with the data observed by the Japan Meteorological Agency. The relationship between number of lightning strokes and thunderdays is also obtained. It changes season by season and it is very difficult to express the relations with a single formula.