Average auroral occurrence in 2000-2013

Percentages of yearly auroral occurrence come from visual inpection of keograms. The number of nights with aurora are scaled by the number of nights in operation per year and per station. Stations from south to north are Hankalsalmi (HAN), Sodankylä (SOD), Kilpisjärvi (KIL), Longyearbyen (LYR) and Ny-Ålesund (NAL). HAN camera was moved to Nyrölä (about 30 km west of Hankasalmi) in 2005. KIL camera was upgraded into an emCCD device in 2007. Since that year was spent in learning the way to operate the new system and no high-quality data were recorded yet, the KIL percentage for 2007 is calculated from Muonio station station.