Abstract:

In order to calculate the historical average annual cloud-to-ground lightning flashes density in the southwest of Shandong Province, the correlation between thunderstorm days and lightning days was analyzed firstly, then the thunderstorm days and cloud-to-ground lightning flashes density within audible range were fitted and carried on further based on group, and the relative errors were analyzed. Finally, the spatial distribution of historical averaged cloud-ground lightning density was drawn in the southwest of Shandong Province. The results show that the thunderstorm days were closely related to the lightning days within distances of 6-22 km from the meteorological stations, and the correlation coefficients of them presented a single peak curve within different radius of the observatory, the audible range of thunder was 14 km. The fitting result between thunderstorm days and cloud-ground lightning density was superior to the normal formula, and it was more representative of the historical average annual cloud-to-ground lightning flashes density. The adjacent area with the same mechanism for thunderstorm, cloud-to-ground lightning flashes density calculated by the fitting formula by using thunderstorm days was consistent with the actual values. The historical average cloud-ground lightning density presented a funnel-shape with high values in the southwest and northeast and low values in the middle, and the regional difference was significant.