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1 INPE - Instituto Nacional de Pesquisas Espaciais

Abstract : The smoothed values of the minima of sunspot number Rz and the geomagnetic index aa were compared for sunspot cycles 12?23. In one cycle, aamin occurred earlier than Rzmin, but remained at that low from a few months before Rzmin to a few months after Rzmin. In two cycles, Rzmin and aamin coincided within a month or two. In nine cycles, aamin occurred more than three months later than Rzmin. The aamin coincided with the minima of some solar radio emission indices originating in the solar corona. For sunspot cycles 21, 22, 23, the minimum of solar wind velocity V occurred 0?9 months later than the aamin. The minimum of solar wind total magnetic field B occurred near Rzmin. The solar wind ion density N had maxima instead of minima near Rzmin, and again near Rzmax, indicating a ~5-year periodicity, instead of an 11-year periodicity. The maxima of aa, V and B occurred near Rzmax and-or later in the declining phase of Rz. The aa index was very well correlated with the functions BV and BV 2.





Author: R. P. Kane -

Source: https://hal.archives-ouvertes.fr/



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