On the Probability of Thunderstorms Self-triggering Upward Lightning from Tall Towers

Abstract:
This study focuses on the further implementation of the Self-Consistent Leader Inception and Propagation Model -SLIMto evaluate the probability of thunderstorms to self-trigger upward lightning. Three tall structures have been analysed: the Morro do Cachimbo station in Brazil, the KNBN FM antenna in Rapid City in the United States and the Säntis tower in Switzerland. Topographic and meteorological data have been used used as input for the evaluation of the physical conditions required for triggering upward lightning under stationary thundercloud fields. It has been found that the calculated probability of storms self-triggering upward lightning agrees well with the observations for the Morro do Cachimbo and the Säntis Towers. This results agrees with previous analyses performed before with SLIM for the Gaisberg and a wind turbine and a protection mast in Uchinada, Japan. However, it is found that the probability of selftriggered upward lightning cannot be calculated with the described procedure for structures where other-triggered upward lightning is dominant such as for the towers in Rapid City. It is suggested that self-triggered upward lightning cannot take place in storms in which upward lightning can be initiated instead by other nearby lightning events.