MAGNETOSPHERIC DISTURBANCES IN GNEVYSHEV GAPS: CASE OF SOLAR CYCLES 20 TO 24

Time dependence of many solar activity factors and related phenomena shows a highest double-peak structure around sunspot maximum during the maximum phase of the 11-year solar cycle. Highly variable conditions on the Sun persist throughout the phase maximum of solar activity. A distinctive minimum around this phase maximum, called the Gnevyshev Gap or GG forms a kind of separating matrix between ascending and descending phases of a solar cycle (SC). This article gives some details on the disturbances experienced by our magnetic shield (Earths magnetosphere) during the last five complete solar cycles. Using a statistical approach, solar parameters and magnetic indices were analyzed over a discontinuous period of 125 days, having recorded the High-Speed Solar Wind (HSSW). As they pass through the interplanetary medium, highly energetic HSSW particles become hostile to all humanity and its society, which has become too technological. Our results show that solar activity is influenced by factors specific to each SC, but general structure of daily variations remains stable in GG. An asymmetry between the activity of the poloidal component of the solar magnetic field and that of HSSW was revealed over all solar cycles 20 to 24. Of these cycles, SC_22 was the most magnetically dipolar and the cycle with the most non-polar coronal holes. The time dependence of HSSW also shows two trends (increasing and decreasing). The gradually increasing HSSW trend induces North/South fluctuations in the Bz component of the Interplanetary Magnetic Field (IMF-Bz). These fluctuations are due to the emergence of new active regions of the Sun in the early morning and late night. On the other hand, rapidly decreasing HSSW trend inflicts southern stability on IMF-Bz. Whatever the period of solar cycle, IMF-Bz and E_M (convective electric field) progress inversely. This suggests that in GG, solar wind/Earth magnetosphere interaction is not responsible for magnetospheric plasma circulation. Thus, GG offers a crucial period of relative calm in the terrestrial solar system, ensuring the absence of harmful phenomena in the terrestrial environment.