| Full text | |
| Author(s): |
Marques de Souza Franco, Adriane
[1]
;
Hajra, Rajkumar
[2]
;
Echer, Ezequiel
[1]
;
Bolzan, Mauricio Jose Alves
[3]
Total Authors: 4
|
| Affiliation: | [1] Inst Nacl Pesquisas Espaciais INPE, Sao Jose Dos Campos - Brazil
[2] Indian Inst Technol Indore, Indore 453552 - India
[3] Fed Univ Jatai, Space Phys & Astron Lab, Jatai - Brazil
Total Affiliations: 3
|
| Document type: | Journal article |
| Source: | Annales Geophysicae; v. 39, n. 5, p. 929-943, OCT 18 2021. |
| Web of Science Citations: | 0 |
| Abstract | |
Seasonal features of geomagnetic activity and their solar-wind-interplanetary drivers are studied using more than five solar cycles of geomagnetic activity and solar wind observations. This study involves a total of 1296 geomagnetic storms of varying intensity identified using the Dst index from January 1963 to December 2019, a total of 75 863 substorms identified from the SuperMAG AL/SML index from January 1976 to December 2019 and a total of 145 high-intensity long-duration continuous auroral electrojet (AE) activity (HILDCAA) events identified using the AE index from January 1975 to December 2017. The occurrence rates of the substorms and geomagnetic storms, including moderate (-50nT >= Dst >-100nT) and intense (-100nT >= Dst >-250nT) storms, exhibit a significant semi-annual variation (periodicity similar to 6 months), while the super storms (Dst <= -250 nT) and HILDCAAs do not exhibit any clear seasonal feature. The geomagnetic activity indices Dst and ap exhibit a semi-annual variation, while AE exhibits an annual variation (periodicity similar to 1 year). The annual and semi-annual variations are attributed to the annual variation of the solar wind speed Vsw and the semi-annual variation of the coupling function VBs (where V = V-sw, and B-s is the southward component of the interplanetary magnetic field), respectively. We present a detailed analysis of the annual and semi-annual variations and their dependencies on the solar activity cycles separated as the odd, even, weak and strong solar cycles. (AU) | |
| FAPESP's process: | 18/21657-1 - Study of Jupiter magnetospheric auroral radio activity variability |
| Grantee: | Ezequiel Echer |
| Support Opportunities: | Regular Research Grants |