Concept information
Preferred term
Sudden Commencement (SC)
Broader concept
Description
- Sudden commencement followed by a magnetic storm/an increase in activity (SSC - Storm Sudden Commencement) or by no further disturbance (SI - Sudden Impulse). A SC is basically an unexpected sharp increase in the Northern (X) magnetic component of a considered observatory. Usually, but not always a SC is the precursor to a geomagnetic storm (defined by, for example, a minimum of the Dst index). It has to be noted that more emphasis is put on the change of rhythm in the magnetic activity than on the amplitude of the possible succeeding magnetic storm. The SC list is available from 1868 onwards and made available by Observatori de l'Ebre (Spain). The SC list is formally recognised and endorsed since 1975 by International Association of Geomagnetism and Aeronomy (IAGA).
In other languages
-
French
URI
https://service.poleterresolide.fr/voc/variable/V0020100
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