A decade of high‐latitude lightning location: Effects of the evolving location network in Finland

[1] The present lightning location system of the Finnish Meteorological Institute has been in operation since 1998. We present statistics from the 10-year period 1998–2007. The main emphasis of this study is to give a comprehensive analysis of the development of the location system. Our results complement previous studies by providing 10-year lightning statistics from high latitudes in Europe (60–70°N). The changes in the detection efficiency have also been discussed. Our results indicate that in Finland (1) the median (average) peak currents in 2007 were −11.3 (−16.0) kA and +13.3 (+20.7) kA for negative and positive flashes, (2) the percentage of positive flashes in 2007 was 17%, (3) the average multiplicity for negative (positive) flashes in 2007 was 2.1 (1.2), (4) the median semimajor axis of the 50% location error ellipse in 2007 was 600 m (for 92% of flashes it was below 5 km), and (5) the average number of sensors reporting a flash in 2007 was 6.3. The network has experienced several configuration changes, leading to a more stable and better performing system, but these technical changes have also caused significant changes in the statistics of the measured lightning data. Clearly, lightning statistics over a 10-year period cannot be handled without considering the impact of technical changes on the detection network.