Abstract

An investigation of moderately intense geomagnetic storms (50 nT>Dst≥-150 nT) observed between 1997 and 2007 with coronal mass ejections (CMEs) and interplanetary magnetic field was carried out. We found that 54.91% geomagnetic storms are associated with halo and partial halo coronal mass ejections. The association rates of halo and partial halo coronal mass ejections were found to be 63.16 and 36.84% respectively. It was also inferred that CMEs related geomagnetic storms are associated with X-ray solar flares of different categories. The association rates of class X, class M, class C and class B X-ray solar flares were 13.67, 26.32, 44.21 and 15.79% respectively. Furthermore, it was concluded that moderately intense geomagnetic storms are closely related to disturbances in interplanetary magnetic field. Positive correlation with correlation coefficient 0.48 was found between magnitude of moderately intense geomagnetic storms and maximum (peak) value of average interplanetary magnetic field. The correlation coefficient of 0.40 between magnitude of moderately intense geomagnetic storms and magnitude of associated jump in interplanetary magnetic field (JIMF) events was obtained. Positive correlation with correlation coefficient 0.49 was also found between magnitude of moderately intense geomagnetic storms and magnitude of maximum (peak) value of southward component of interplanetary magnetic field. The correlation coefficient of 0.37 between magnitude of moderately intense geomagnetic storms and magnitude of southward component of interplanetary magnetic field was also obtained.

Key words: Moderately intense geomagnetic storms, coronal mass ejections, X-ray solar flares, interplanetary magnetic field.