Absolute magnitude of 373 geomagnetic storms lasting more than 48h with absolute magnitude (dst) larger than 100 in 1957-2014.
Note
For a detailed article presenting the derivation of the Dst index, see http://wdc.kugi.kyoto-u.ac.jp/dstdir/dst2/onDstindex.html
References
World Data Center for Geomagnetism, Kyoto, M. Nose, T. Iyemori, M. Sugiura, T. Kamei (2015), Geomagnetic Dst index, doi:10.17593/14515-74000.