Occurrence of great magnetic storms on 6–8 March 1582

Abstract

Abstract Although knowing the occurrence frequency of severe space weather events is important for the modern society, it is insufficiently known due to the lack of magnetic or sunspot observations, before the Carrington event in 1859, which is known as one of the largest events of the last two centuries. Here we show that a severe magnetic storm occurred on 8 March 1582, based on auroral records in East Asia. The equatorward boundary of auroral visibility reached 28.8° magnetic latitude. The equatorward boundary of the auroral oval is estimated to be 33.0° invariant latitude (ILAT), which is comparable to the storms on 25/26 September 1909 (∼31.6° ILAT, minimum Dst of −595 nT), 28/29 August 1859 (∼36.5° ILAT), and 13/14 March 1989 (∼40° ILAT, minimum Dst of −589 nT). Assuming that the equatorward boundary is a proxy for the scale of magnetic storms, we presume that the storm in March 1582 was severe. We also found, by combining Euroepan records, that the storm in March 1582 lasted at least three days. The auroral oval stayed at mid-latitude for the first two days and moved to low latitude (in East Asia) for the last day. It is plausible that the storm was caused by a series of ICMEs (interplanetary coronal mass ejections). We can reasonably speculate that the first ICME could have cleaned up interplanetary space to make the following ICMEs more geoeffective, as probably occurred in the Carrington and Halloween storms.