Abstract:
The sun’s activity governs the interaction of the magnetosphere with the solar wind and
Earth’s magnetic field. The influence of the magnetosphere is known as a geomagnetic
storm. The main purpose of studying geomagnetic storms is to understand the current
passing through the ionosphere. The geomagnetic storms that occurred during solar
cycles 23 and 24 were analyzed using the southward interplanetary magnetic field (IMF
(Bz)), the interplanetary electric field of the ring current (IEF), the solar wind velocity
(SW), and the Dst index from the OMNI data explorer. As the results reveal at the high
solar activity, CME-driven geomagnetic storms are more prominent than CIR-driven
geomagnetic storms. Moreover, it is clear from the observations of geomagnetic storm
events that the occurrence of geomagnetic storms is highly correlated with the southward
turning of Bz, the z component of IMF. The magnitude of turning of Bz in a southward
direction from a northward direction depends highly upon the severity of the storm.
Moderate and intense geomagnetic storms were observed during the years 1996-2019,
while they were absent of intense storms during the years 2007-2010. 15 great storms
and 7 super storms were observed from 1996 to 2007, while a single great and not super
storm were observed during the years 2008 to 2019. The only one great storm was
observed in March 17 2015.