Mapping of Geomagnetic Cutoff Rigidity of Cosmic Rays during the Main Phase of the Magnetic Storm of November 20, 2003

• Published in: Geomagnetism and Aeronomy 2019-03, Vol.59 (2), p.147-154
• Main Authors: Danilova, O. A., Demina, I. M., Ptitsyna, N. G., Tyasto, M. I.
• Format: Article
• Language: English
• Subjects: Asymmetry; Cosmic rays; Daytime; Earth and Environmental Science; Earth Sciences; Geomagnetic storms; Geomagnetism; Geophysics/Geodesy; Latitude; Magnetic storms; Magnetospheres; Mapping; Night; Northern Hemisphere; Rigidity; Ring currents; Southern Hemisphere; Storms; Thresholds
• ISSN: 0016-7932; 1555-645X; 0016-7940
• DOI: 10.1134/S0016793219020051

In this work, geomagnetic cutoff rigidities are calculated in a model magnetosphere field on the world latitude–longitude 5° × 15° grid during the main phase of the magnetic storm of November 20, 2003. A decrease in geomagnetic thresholds (Δ R ) by up to 1.8 GV as compared to thresholds in the main field is observed in the maximum of the geomagnetic storm at 2000 UT at middle and low latitudes. In the equatorial part, Δ R amounts to 0.5–0.6 GV. It has been found that the global distribution of drops in the cutoff rigidities exhibits a North–South asymmetry, as well as day–night asymmetry. This is expressed by the fact that the Δ R maximum in the daytime sector is observed at a latitude of ~40° N in the Northern Hemisphere and ~60° S in the Southern Hemisphere. Conversely, the Δ R maximum is observed in the nighttime sector at a latitude of ~55° N in the Northern Hemisphere and ~45° S in the Southern Hemisphere. Moreover, the maximum Δ R values in the Northern Hemisphere in the daytime sector are higher than in the nighttime sector; in the Southern Hemisphere, the maximum Δ R values in the daytime sector are lower than in the nighttime sector. The observed magnetospheric effects in the global distribution of Δ R seem to be caused by the dominant impact of the partial ring current that develops in the main storm phase.