| Storm Sudden Commencements (ssc) 1868 to present: STORM1 and STORM2 Lists: (Some text
here is taken from the International Association of Geomagnetism and Aeronomy (IAGA)
Bulletin 39) 1868-1967 data (STORM1.SSC) are from IAGA Bulletin 33. These data are
based on 3 observatories. Only one of them was at low latitude; the other two, with
an invariant magnetic latitude of 50 degrees, were strongly sensitive to the auroral
effect. 1968-1975 data (STORM2.SSC) are from IAGA Bulletin 39. These data are much
more reliable. The monthly reports from all observatories guarantee that very few
events are omitted. With the examination of five low-latitude records, the changes
of rhythm could be evaluated much better, and events were kept of rejected on a more
rational basis. However, it is probable that, for statistical use, both lists will
be relatively homogeneous. Indeed, Alibag was the low-latitude observatory of the
100-year list and belongs, in the 1968-1975 list, to the group form which the amplitudes
are close to the average of five observatories. 1976-1982 data are from IAGA Bulletin
32 series. These data are reduced in the same manner as the 1968-1975 data. 1983-present
data are from the monthly ISGI Bulletins (DeBilt, Netherlands - 1983-1987 data; Institut
de Physique du Globe, Paris, France - 1988-present data. |