Abstract: We present a statistical analysis of the peak values of geomagnetic activity indices ( Kp, ap, AE and Dst ) with the interplanetary plasma and field parameters (T,D,V,P, and Bt , Bz , E, and B) along with their product functions (BV,BzV and B2V ) during major geomagnetic storms. We find that peak values of Dst, Kp,ap, and AE are in good correlation with E, V, BV,BzV,B2V,Bt,Bz. We have obtained specifically high values of correlation between Dst and product functions of plasma parameters (R=-0.75 for BV, R=0.78 for BzV and R=-0.77 for B2V ).This study provides statistical prove that occurrence of intense GMSs depends mainly upon magnetic field, velocity and their product functions(BV, BzV and B2V).Therefore these parameters may act as reliable indicators for predicting GMSs and their strength. We have also analysed the GMSs data during different phases of the solar cycles 23& 24 and concluded that CMEs are more important drivers of GMSs during the maximum phase of solar cycle while CIR are more significant drivers of GMSs during the decay phase.
Keywords: Geomagnetic Storms, interplanetary field parameters, interplanetary plasma parameters, Geomagnetic Indices.