Variability of Solar Wind Dynamic Pressure with Solar Wind Parameters During Intense and Severe Storms

The solar wind dynamic pressure (P) variability with plasma flow speed (V) and the Interplanetary Magnetic Field (IMF) Bz for the storm's initial and main phases, as well as during peak plasma flow speed value periods, have been presented. Nine intense and eleven severe storms were used for our analysis. The strong P versus V relationship during the storm's initial phase was linked to the accelerated ring current build-up. The weak P versus V relationship during storms main phase was attributed to ring current energy losses, which may have originated from different sources. The solar wind dynamic pressure have a strong relationship with the southward IMF Bz during the main phase of a storm, typically when the plasma flow speed value is very large, exceeding the 550km/s value, and the Dst < -250 nT. An enhancement in P during enhanced solar wind speed flow and under a steady flow southward Bz was observed, which always led to intense storm.