Reflection of the solar wind parameters in the CR geomagnetic cutoff rigidity before a strong magnetic storm in November 2003

• Published in: Geomagnetism and Aeronomy 2008-12, Vol.48 (6), p.691-708
• Main Authors: Tyasto, M. I., Danilova, O. A., Dvornikov, V. M., Sdobnov, V. E.
• Format: Article
• Language: English
• Subjects: Aeronomy; Anisotropy; Earth and Environmental Science; Earth Sciences; Geophysics; Geophysics/Geodesy; Magnetic fields; Rigidity; Storms; Sun
• ISSN: 0016-7932; 1555-645X; 0016-7940
• DOI: 10.1134/S0016793208060017

The time variations in the CR geomagnetic cutoff rigidity and their relation to the interplanetary parameters and the Dst index during a strong magnetic storm of November 18–24, 2003, have been analyzed. The Tsyganenko (Ts03) model of a strongly disturbed magnetosphere [Tsyganenko, 2002a, 2002b; Tsyganenko et al., 2003] have been used to calculate effective geomagnetic thresholds with the help of the method for tracing CR particle trajectories in the magnetospheric magnetic field. The geomagnetic thresholds have been calculated using the method of global spectrographic survey (GSS), based on the data from the global network of CR stations, and the results have been compared with the effective geomagnetic cutoff rigidities. The daily anisotropy of effective geomagnetic thresholds during the Dst variation minimum have been estimated. The relation of the theoretical and experimental geomagnetic thresholds, obtained using the GSS method, to the interplanetary parameters and Dst variation is analyzed. The Dst variations, IMF B z , and solar wind density are most clearly defined in the geomagnetic thresholds during this storm. The correlation between B y and experimental geomagnetic thresholds is higher than such a correlation between this parameter and theoretical thresholds by a factor 2–3, which suggests that a real dawn-dusk asymmetry during this storm was stronger than such an asymmetry represented by the Ts03 model.