Open AccessTwo‐step development of geomagnetic storms
Author(s) -
Kamide Y.,
Yokoyama N.,
Gonzalez W.,
Tsurutani B. T.,
Daglis I. A.,
Brekke A.,
Masuda S.
Publication year - 1998
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/97ja03337
Subject(s) - ring current , geomagnetic storm , solar wind , storm , magnetosphere , interplanetary magnetic field , interplanetary spaceflight , earth's magnetic field , physics , geophysics , current (fluid) , ionospheric dynamo region , atmospheric sciences , geology , magnetic field , meteorology , quantum mechanics , thermodynamics
Using the Dst index, more than 1200 geomagnetic storms, from weak to intense, spanning over three solar cycles have been examined statistically. Interplanetary magnetic field (IMF) and solar wind data have also been used in the study. It is found that for more than 50% of intense magnetic storms, the main phase undergoes a two‐step growth in the ring current. That is, before the ring current has decayed significantly to the prestorm level, anew major particle injection occurs, leading to a further development of the ring current, and making Dst decrease a second time. Thus intense magnetic storms may often be the result of two closely spaced moderate storms. The corresponding signature in the interplanetary medium is the arrival of double‐structured southward IMF at the magnetosphere.