The Properties of Source Locations and Solar Cycle Distribution of GLEs During 1942–2017

Abstract

During 1942–2017, 72 ground level events (GLEs) have been registered. Source location and solar cycle distribution of GLEs during 1942–2017 have been investigated. The GLEs that occurred during 1942–2017 are mainly distributed in the longitudinal area ranged from E30 to W150. The northern hemisphere has many more GLEs than the southern hemisphere during Solar Cycles 19 and 20, while the northern hemisphere has slightly more GLEs than the southern hemisphere of the Sun during Solar Cycles 21 and 22. However, the southern hemisphere has more GLEs than the northern hemisphere during Solar Cycle 23. The latitudinal area ranged from N20 to N40 of the northern hemisphere of the Sun has many more GLEs than the latitudinal area ranging from S20 to S40 of the southern hemisphere of the Sun. The latitudinal area ranging from N0 to N20 of the northern hemisphere of the Sun has slightly more GLEs than the latitudinal area ranged from S0 to S20 of the southern hemisphere of the Sun. 46 GLEs came from the northern hemisphere, while 26 GLEs came from the southern hemisphere of the Sun, suggesting that GLEs dominated in the northern hemisphere of the Sun during 1942–2017. Statistical results show that 44.3% and 55.7% of the GLEs appeared in the ascending and descending phases of the solar cycles, respectively, and about 83% of the GLEs appeared during the period from the two years before solar cycle peak and the three years after solar cycle peak time. The number of GLEs during a solar cycle has a poor correlation with the amplitude of the solar cycle.

Appendix

Table 4 Ground-level events during 1942–2017.