Effect of solar features and interplanetary parameters on geomagnetosphere during solar cycle-23

Abstract

The dependence of geomagnetic activity on solar features and interplanetary (IP) parameters is investigated. Sixty-seven intense (−200 nT ≤ Dst < −100 nT) and seventeen superintense (Dst < −200 nT) geomagnetic storms (GMSs) have been studied from January 1996 to April 2006. The number of intense and superintense GMSs show three distinct peaks during the 11-year period of 23rd solar cycle. The largest number of high strength GMSs are observed during maximum phase of solar cycle. Halo and partial halo CMEs are likely to be the major cause for these GMSs of high intensity. No relationship is observed between storm duration and the number of CMEs involved in its occurrence. The intensity of the GMS is also independent of the number of CMEs causing the occurrence of storm. These geoeffective CMEs show western and northern bias. Majority of the geoeffective CMEs are associated with X-ray solar flares (SFs). Solar and IP parameters, e.g., VCME, VSW, B, Bz (GSE and GSM coordinates) and their products, e.g., VSW · B and VSW · Bz are observed and correlated to predict the occurrence of intense GMSs. VCME does not seem to be the appropriate parameter with the correlation coefficient, r = −0.2 with Dst index, whereas the correlation coefficient, r = −0.57, −0.65, 0.75, −0.68 and 0.77 of the parameters VSW, B, Bz, VSW · B and VSW · Bz respectively, with Dst indicating that VSW · Bz and Bz may be treated as the significant contributors in determining the strength of GMSs.