Longitudinal Expansion of Compressional Disturbances at Middle Latitudes on Ground during CME Events

Two strong magnetic storms observed during CME events in November 2001 and 2003 are considered in this study. Magnetic field data from L'Aquila (Italy), Bay St Louis and Boulder (USA), Alibag (India) and other observatories are analyzed where amplitude, possible time lag and expansion characteristics of the geomagnetic field variations among observatories at middle and low latitudes are examined. Special attention to the long-range interactions of the magnetic field disturbances during strong geomagnetic storms is paid. A strong long-range interaction (Brownian motion) of the geomagnetic disturbances is discovered and the differences that emerge are assigned to the observed time lag between magnetic observatories.