![]() Partial ring currents during the main phase of a geomagnetic storm cause a longitudinal asymmetry in the magnetic field at the earth’s surface at low and mid latitudes. CME-driven storms pose more of a problem for Earth-based electrical systems CIR-driven storms pose more of a problem for space-based assets. Further, the magnetosphere is more likely to be preconditioned with dense plasmas prior to CIR-driven storms than it is prior to CME-driven storms. CME-driven storms are brief, have denser plasma sheets, have strong ring currents and Dst, have solar energetic particle events, and can produce great auroras and dangerous geomagnetically induced currents CIR-driven storms are of longer duration, have hotter plasmas and stronger spacecraft charging, and produce high fluxes of relativistic electrons. (CME-driven includes driving by CME sheaths, by magnetic clouds, and by ejecta CIR-driven includes driving by the associated recurring high-speed streams.) These differences involve the bow shock, the magnetosheath, the radiation belts, the ring current, the aurora, the Earth's plasma sheet, magnetospheric convection, ULF pulsations, spacecraft charging in the magnetosphere, and the saturation of the polar cap potential. Twenty one differences between CME-driven geomagnetic storms and CIR-driven geomagnetic storms are tabulated. These HILDCAA events, although without an intense and remarkable interplanetary cause, such as those leading to storms, show very high levels of geomagnetic activity in the auroral region and may cause the acceleration of relativistic electrons. In this paper, we address the main differences and similarities in the Dst profile and auroral shape of these storms, and compare them with another kind of geomagnetic activity: HILDCAA events. However, the characteristics of these storms are different, depending on the type of the driving interplanetary structure and Bs profile. Both ICMEs and CIRs lead to geomagnetic storms when these structures reach the Earth's magnetosphere, in case they have a significant southward oriented Bz component (Bs). From these coronal holes emanate high speed solar wind streams, which interact with the slow solar wind, forming interplanetary structures called Corotating Interaction Regions (CIRs). During the descending and solar minimum phases, the coronal holes in the Sun become the most remarkable features. Around the solar maximum phase, the predominant features are coronal mass ejections (CMEs), and their interplanetary counterparts, the ICMEs. The model than being used to predict Dst index for operational purposes and obtained the RMSE from 1 August to 31 October 2021 was ‘∼5 – 20 nT during quiet days and ∼18 – 45 nT during disturb days.Īlong the 11-year solar cycle, the dominant structures in the Sun and its effects in the interplanetary medium change significantly. By using 39 geomagnetic storms data during 1997 to 2000 as training data and 7 geomagnetic storms data during 2000 to 2001 as testing data that have not been used in the training, the correlation between target and ouput was 0.97. Solar wind parameters and interplanetary magnetic field (IMF) Bz has been used as exogenous input for the model. This paper described a 24 hours Dst index prediction using a nonlinear autoregressive exogenous (NARX) method. ![]() Dst index prediction is needed as an effort to mitigate the impact of geomagnetic storms. The geomagnetic storms themselves could harm technological systems on earth. The index shows the strength and duration of a geomagnetic storm. Disturbance Storm Time (Dst) index is an index which measured the decrease in the horizontal component of the Earth’s magnetic field near the magnetic equator due to increases in the magnetospheric ring current. ![]()
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