Open AccessEffects of solar polarity reversals on geoeffective plasma streams
Author(s) -
Baranyi T.,
Ludmány A.
Publication year - 2003
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 - 10.1029/2002ja009553
Subject(s) - solar wind , physics , interplanetary magnetic field , dipole , magnetosphere , ionosphere , atmospheric sciences , astrophysics , geophysics , plasma , quantum mechanics
The present work focuses on the annual/semiannual behavior of those parameters which can be considered to be the most relevant factors from the point of view of geoeffectiveness. These are the interplanetary magnetic field (IMF) components, B z and B y (in both the Geocentric Solar Magnetospheric (GSM) system and Geocentric Solar Ecliptic (GSE) system), the bulk speed of the plasma, and the number of hours spent by the Earth in domains of either positive or negative GSM B y . In all cases, monthly mean values were used. As a criterion of geoeffectiveness, we adopted the values Kp > 3. The consecutive solar dipole cycles were separately studied, and definite differences were found between the annual variations of the mean values. When the solar dipole is opposite to the terrestrial one, the mean B z does not exhibit the Russell‐McPherron effect in the GSM system because there are strong inverse annual variations in the GSE system. However, the Russell‐McPherron effect can be detected in the occurrence of the negative and positive GSM B y values. The case is opposite in those years when the solar and terrestrial dipoles are parallel: the Russell‐McPherron effect is detectable in the opposite annual variations of the mean GSM B z but not in the occurrence of GSM B y values. The mean bulk speed of geoeffective events also shows a dipole cycle dependence in its average value, and it shows a semiannual character in the parallel years.