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On January 17 - 22, 2005 Events in Space Weather

Authors: Dorotovic, I., Kudela, K., Lorenc, M., Rybanský, M.

Ref.: Solar Physics accepted (2008)

Abstract: This contribution is a follow-up to a recent paper of Kuznetsov et al. (2006) on the GLE on January 20, 2005. We focused on a study of FD of January 17-18 and 21-22, 2005. The data from the neutron monitor at Lomnický štít (1 minute counts) and from the Geomagnetic Observatory in Hurbanovo, both in Slovakia, were used as the basis for our investigation. The data on magnetic field and solar wind from GOES 10 and 12, SOHO-CELIAS, ACE and WIND satellites were used for better understanding of the global evolution of the event. The magnetic field is transformed to the RTN system where only the disturbed part of the field is compared, i.e. a daily variation and a constant part are subtracted. The field reduction method is described. Our results are temporal vector diagrams of variation of all parameters at all positions from where we used the data. The amplitudes of |B| exceed 100 nT and variations during the arrival of the wavefront of CME take place in the same minute at the ground-based station and at GOES satellites. The character of the variations is as if there would be regions with the dominant electric charge of opposite sign, or electric currents with different orientation in the CME. On the basis of the values v_p and n_p and using certain assumptions we determined the mass of CME on January 17 and January 21, respectively, of 10^12 kg. A decrease of the cosmic ray level runs suddenly (during 10 minutes), starting, however, about 2 hours after a sudden change of the magnetic field.