The solar sources of 884 geomagnetic storms have been studied for the solar cycles 23 and 24 , regardless of their size ranges; using the Kp index and the NOAA G criteria (minor to extreme storms). It claims from our investigation that fast solar wind streams (HSSWs) is the main factor of small (G1) and medium (G2) storms and occur mostly on the descending phase of the solar cycle. Fast solar wind has contributed to about 59% of G1 storms; 50% of G2; 29% G3; and 10% G4 storm. Large storms (G3 to G5) are the effects of coronal mass ejections (CMEs) and they are observed mainly during the maximum and the descending phases of the solar cycle. About 10% of G1 storms, 26% of G2 storms, 59% of G3 (strong) storms, 87% of G4 (severe) storms, and 100% of G5 (extreme) storms were the effect of CMEs. Magnetic clouds contributed 11% of G1 storms, 15% of G2 storms, 9% of G3 storms, and 3% of G4 storms. A comparative statistical occurrence shows that the number of storms decreased during solar cycle 24 when compared with the solar cycle 23. These results showed that the magnetospheric energy transfer decreased in solar cycle 24 and that the magnetosphere was under the influence of intense solar magnetic fields in solar cycle 23. The phenomenon observed in these investigations highlight a drop in solar plasma geoeffectiveness since the long minimum that followed the solar cycle 23.
To better understand the geomagnetic conditions and the particularities of solar cycles 23 and 24, we present analysis from morphological variations of solar and geomagnetic activities parameters IMF-Bz, the interplanetary electric field (E), the proton density (N), Dst (disturbance storm time), Polar cap (PC) indices (PCN and PCS), and geomagnetic activity index aa. The occurrences of the different classes of geomagnetic activity established by Zerbo et al. (2012), through the daily averages of the Aa index are also presented for the period 1996-2019 covering the solar cycle 23 and 24. This investigation reveals: (1) a decrease in solar activity and geomagnetic activity during the last decade; (2) the solar cycle 23 was a magnetically disturbed solar cycle with 41.52% disturbed days versus 72.35% very quiet conditions for the solar cycle 24; (3) the most important numbers of intense and severe storm or magnetic substorm conditions (E, PC index, Dst < -100 nT) are recorded during the solar cycle 23; (4) solar cycle 24 presents similar characteristics as solar cycles 12 and 14 and has also experienced spotless days at its maximum phase; (5) solar cycle 24 experienced low solar activity compared to solar cycle 23. The two solar cycles can be qualified as antagonistic cycles.
In this paper, we analyzed diurnal and annual seasonal variations of solar wind parameters such as interplanetary magnetic field (IMF), proton density (N), solar wind speed (V) and solar wind dynamic pressure (Pdym), during the solar cycles 23 and 24. Our study shows that strong geomagnetic disturbances are observed at the equinoxes during both solar cycles. The highest proton densities are observed at solstices during both solar cycles. The greatest solar wind speeds are observed at the equinoxes of solar cycle 23 and at the solstices of solar cycle 24. The highest solar wind dynamic pressures are observed at the solstices of both solar cycles. We also observed an asymmetrical evolution of the seasonal diurnal values of the solar wind parameters during the two cycles, except for the proton density. Our investigations also highlight the fact that the seasonal diurnal values of the solar wind parameters are significant at solar cycle 23 compared to solar cycle 24 characterized by a global weak in solar plasma conditions since the deep minimum that followed the solar cycle 23 leading to an absence of a persistent polar coronal hole. The drop observed in polar field and solar winds parameters during solar cycle 24 is reproduced on seasons (solstices and equinoxes). The solar cycle 23 and 24 appear to be two magnetically opposite solar cycles regardless the time scales.
This study investigates climatic parameters (rainfall, and temperature) over Burkina Faso and the possible role of solar activity and its induced energies. Through morphological investigations, we analyzed solar activity indices (sunspot number, IMF, PC index, Cosmic rays) over the last three solar cycles . Results about interplanetary heating show that joule heating is well correlated with the dynamic pressure of the solar plasma. Climate parameters (rainfall, Temperature) variabilities are modulated by disturbances in solar activity: 1) quiet solar characterized by a drop in solar plasma's parameters is associated with important cloud cover and consequently bring important rainfall which chills terrestrial atmosphere, 2) active solar characterized by important input energy is associated with weak incident cosmic ray consequently with low cloudiness which brings warming. Thus, the possible natural link can be suggested between solar activity and climatic parameters even if it is not the only factor of global warming.
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