Charge Structure of Winter Thunderstorm in Japan: a Review and an Update

Abstract

It is well-known that winter lightning has many special characteristics, and the charge structure of winter thunderstorm has been under debate for tens of years. This paper reviews past studies on charge structure of winter thunderstorm and presents new results with the observation of lightning mapping array (LMA). The results show that compared to summer thunderstorm, winter thunderstorm can exhibit extremely complicated charge structures. Dipole and tripole structures of both positive and negative polarities have all been observed. Relatively large thunderstorms can exhibit different charge structures in different regions, and as a thunderstorm develops, its charge structure can also have significant changes. One common feature of the charge structures observed is that the charge regions are mainly around the -10°C and -20°C temperature level, in agreement with the non-inductive electrification mechanism. Another common feature of the charge structures is that its horizontal extension is usually much larger than its vertical extension. Besides, the vertical distance between the two charge layers in opposite polarity is usually small, around 1 or 2km. All these factors combined may conduce to the high percentage of positive CG, the high percentage of bipolar CG and the superbolts observed in the winter storms in Japan.