Lightning strokes forming hot spots observed by LLS in winter in Japan

Hot spots, where lightning strokes located by LLS (Lightning location system) concentrate, are formed almost in winter only in Japan in the coastal area of the Sea of Japan. The lightning strokes forming a hot spot are inferred to be related to upward lightning strokes which frequently damage wind turbines and electrical facilities in winter. Characteristics of lightning strokes forming a hot spot are investigated by using directly ob-served current, electric field waveforms and LLS data.