Open AccessSeasonal variations in the occurrence of geomagnetic storms
Author(s) -
John R. Taylor,
M. Lester,
T. K. Yeoman
Publication year - 1996
Publication title -
annales geophysicae
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.522
H-Index - 93
eISSN - 1432-0576
pISSN - 0992-7689
DOI - 10.1007/s00585-996-0286-1
Subject(s) - geomagnetic storm , storm , atmospheric sciences , solar wind , latitude , seasonality , environmental science , climatology , geology , physics , magnetic field , oceanography , biology , geodesy , ecology , quantum mechanics
Seasonal variations in the onset of magneticstorms are investigated. For the purposes of this study storms have been definedas events in which Dst falls below –50 nT for at least four consecutivehours. The storms have been classified as either storm sudden commencements (SSCs;storms initiated by a sudden commencement) or as storm gradual commencements (SGCs;all other storms). It is found that the semi-annual variation of magneticactivity is reflected in the occurrence statistics of SGC events only,indicative that the solar wind origin is different for SSCs and SGCs. It issuggested that the heliospheric latitude model of seasonal magnetic activity isrelatively ineffective in modulating the previously observed seasonal variationsin the occurrence of magnetic storms