Frequency of upward lightning from tall structures in winter in Japan

In Japan, transmission lines or wind turbines in the coastal area of the Sea of Japan have suffered from higher frequencies of serious troubles by lightning in winter than those in summer. The thunderstorm days in this area are comparable in winter to those of summer; however, the number of lightning strokes observed by lightning location systems (LLS) in winter is much smaller. In winter, concentration of lightning hits to tall structures is observed by LLS in the coastal area of the Sea of Japan. Out of the observation by LLS, the authors propose an experimental formula to estimate the frequency of upward lightning occurring on tall structures in winter in Japan.