Harmonic content of Ap index
Abstract. Fourier spectral analysis is applied to the planetary geomagnetic index Ap for the February 2001, 2003, and 2017 time intervals. We investigate how Fourier coefficients change in time with respect to geomagnetic activity. A detailed analysis of the 13–14 February 2001 substorm revealed that higher harmonics were suppressed during the event, contrary to what was expected.
Authors
- Pranab Majumder
- Sanjay Karki (ORCID: https://orcid.org/0000-0001-7930-2893)
- M. Vandas (ORCID: https://orcid.org/0000-0001-9212-2133)
- Evgeny Romashets
- Tasmina Imam
- Tanvir Hasan
Institutions
- Lamar University (US)
- Czech Academy of Sciences, Astronomical Institute (CZ)
Publication Details
- Journal
- Annales Geophysicae
- Published
- 2026-07-28
- DOI
- https://doi.org/10.5194/angeo-44-689-2026
- Primary Topic
- Ionosphere and magnetosphere dynamics
- Type
- article
- Field-Weighted Citation Impact
- 0.00