Space weather disturbances and their geoeffectiveness during solar cycle 23 and 24

We present the findings of a study of the sequence of solar activity that eventually resulted in 80 large geomagnetic storms (distinguished by minimum Dst -100nT to -200nT), 11 super geomagnetic storms (Dst -200nT to -300nT), and 6 super great geomagnetic storms (Dst -300nT) that occurred between 1996 and 2012. Large storms were discovered to be mostly caused by solar flares (M- and X-class), while corotating interaction region (CIR) was also a significant contributor to several of these storms. During the peak and declining phases of solar cycle 23, all extremely powerful storms were observed (2000-2004). It has been noted that coronal mass ejections (CMEs) and flares were always related with super and super tremendous storms (100%). M-class and X-class flares frequently accompany superstorms associated to CMEs. It is observed that 66.6% (4/6) super great geomagnetic storms (Dst ≤ -300nT) were associated with CMEs and solar flares. The number of storms related to X-class flares or CMEs were 50% (3/6). X-class flare/CMEs are found to be responsible for super geomagnetic storms.