Long-Term Trends and Gleissberg Cycles in Aurora Borealis Records (1600-aEuro parts per thousand 2015)

摘要

The long-term spatial and temporal variation of aurora borealis events from 1600 to the present were studied using catalogues and other records of these phenomena. Geographic and geomagnetic coordinates were assigned to approximately 45 000 auroral events with more than 160 000 observations. They were analysed separately for three large-scale areas: i) Europe and North Africa, ii) North America, and iii) Asia. Variations in the cumulative numbers of auroral events with latitude (in both geographic and geomagnetic coordinates) were used to distinguish between the two main solar sources: coronal mass ejections and high-speed streams from coronal holes. We find significant long-term variations in the space-time distribution of auroras. We mainly identify these with four Gleissberg solar activity cycles whose overall characteristics we examine. The Asian observations are crucial in this context, and therefore merit further studies and verifications.