Occurrenceof Great Magnetic Stormson 6–8March1582
https://arxiv.org/pdf/1905.08017.pdf
ABSTRACTAlthough knowing the occurrence frequency of severe space weather events isimportantfor a modern society,itis insufficiently known due to thelack of magnetic or sunspot observations, before the Carrington event in 1859 known as one of the largest events during the last two centuries. Here, we show that a severe magnetic stormoccurred on 8March1582based onauroral records in East Asia. Theequatorward boundary of auroral visibility reached 28.8° magnetic latitude. The equatorward boundary of the auroral ovalis estimatedto be 33.0° invariant latitude (ILAT), which iscomparable to thestorms on25/26 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 boundaryisa proxy for the scale of magnetic storms, we presume that thestorm on March1582wassevere. We also found that the storm on March 1582lasted,at least,for three daysby combining European records. The auroral oval stayed at mid-latitudefor 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 a first ICME could havecleanedup interplanetary space to make the following ICMEs more geo-effective, as probably occurred in the Carrington and Halloween storms.