Lightning location system accuracy determined from strikes to trees

Lightning strikes to 41 trees are used to estimate the accuracy of the Finnish Lightning Location System (LLS). With some limitations, the data set is large enough to estimate the validity of the uncertainty ellipse which is provided by the LLS. Such an estimation does not appear to have been done before for natural lightning. The method may give slightly overoptimistic results because extreme outliers have been removed. However, using a two-part quality control system, the flash causing the damage could be identified with high reliability. It is shown that the uncertainty ellipse given by the LLS is statistically consistent with the distribution of lightning location errors inferred from tree strikes.