A STATISTICAL STUDY IN THE 24TH SOLAR CYCLE ON CORONAL MASS EJECTION AND MAGNETIC CLOUD AND THEIR GEOEFFECTIVENESS

A detailed study on the impact of Coronal Mass Ejections (CMEs) and Magnetic Clouds (MCs) on geomagnetic activity during the 24th solar cycle, from December 2009 to December 2019, has been conducted. The collected data on CMEs associated with geomagnetic storms, defined by a Dst index less than -50 nT, has been grouped into two categories: geoeffective events and non-geoeffective events. Most of the observed CMEs are of the halo type, and they are mostly found in the western hemisphere. Halo and partial halo CMEs are likely to be the main contributors to high-intensity geomagnetic storms. A weak anti-correlation (R=0.54) was found between the speed of CMEs and the Dst index for geoeffective events. However, a stronger correlation (R=0.51) was observed between CME speed and solar wind speed, while a moderate correlation (R=0.16) was noted between the Dst index and solar wind speed. The correlation between the Dst index and the southward component of the magnetic field (Bz) was found to be weak (R=0.17). The analysis showed that intense and prolonged southward magnetic field components along with high-speed solar wind are the key factors behind geomagnetic storms. It was also noted that geomagnetic storms are only weakly influenced by the speed of CMEs. Keywords: Coronal mass ejections; Solar Wind; Interplanetary Magnetic Field; Geomagnetic Storms.