Correlation between the variations of cosmic ray geomagnetic thresholds and interplanetary parameters during various phases of solar disturbance in November 2004

The geomagnetic cutoff rigidity R (momentum per unit charge) is the threshold rigidity below which the particle flux becomes zero due to geomagnetic shielding. The properties of the geomagnetic screen vary greatly during magnetic storms, depending on the dynamic interaction of the solar wind (SW) magnetic fields with the magnetospheric fields and currents. The correlation between the variations of geomagnetic cutoff rigidity ΔR and interplanetary parameters and geomagnetic activity indexes during various phases of the superstorm on November 7 – 8, 2004 has been calculated. On the scale of the entire storm the most geoeffеctive parameters were Dst, Kp, and SW speed, while other parameters, including total interplanetary magnetic field B and Bz component, were effective at different phases of the storm.