Data of the daily interplanetary magnetic field (IMF), and the geomagnetic indices (aa, Ap, Kp, and DST) have been used to examine the asymmetry between the solar field north and south of the heliospheric current sheet, over the period (1975-2013). It important to note that during the positive polarity epochs: (T) refers to Toward the South of the heliospheric current sheet (Southern Hemisphere), and (A) refers to Away from North of the heliospheric current sheet (Northern Hemisphere). While, during the negative polarity epochs the opposite will be happened. The present study finds no clear indication of the presence of north-south asymmetry in the field magnitude, and also there is no magnetic solar cycle dependence that is evident. During the considered period, the north-south asymmetry for the considered parameters reaches maximum values around the declining phase or near to the minimum of the solar cycle. The geomagnetic indices have a clear asymmetry during the positive solar magnetic polarity period (qA > 0) and have a northern dominance during cycles (22 & 23) and southern dominance during cycles (21 & 24). From the power spectrum density, the considered parameters showed significant peaks which appeared in the north-south asymmetry but the 10.7 yr solar cycle was absent. In addition, the main periodicity of the asymmetry may be 5.2, 4.0 and 3.3 years that exist in the parameters with higher confidence levels. Finally, one can conclude that the asymmetry of the interplanetary parameters and the geomagnetic indices may provide multiple causes for producing the observed asymmetric modulations of cosmic rays.
Data of the solar and interplanetary parameters (IMF magnitude B, Solar wind speed V, Proton density n, and the Proton temperature T) during the period from 1975 to 2013, have been used to examine the asymmetry between the solar field north and south of the eliospheric current sheet (HCS). In this work, the asymmetry of the IMF magnitude is obvious, and has no magnetic solar cycle dependence over the considered epochs. The solar wind speed V is faster by about 26.9 km/s for toward polarity days than for away polarity days when the IMF points away from the Sun north of the current sheet and toward the Sun south of it. In addition, the solar plasma was more dense, hotter, and faster north of the HCS than south of it during cycles 22, and 23. Large asymmetries in V, n, and T occurred in 1994. Finally, we conclude that the asymmetry is real, and is a good indicator in studying the solar activity.
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