Nonlinear and Causal Dynamics between Solar and Geomagnetic Activity Indices: Findings from Chaos and Causality Measures
17th Workshop on Solar Influences on the Magnetosphere, Ionosphere and Atmosphere, 2025, Primorsko, Bulgaria, 2 - 06 June 2025, pp.42-48, (Full Text)
- Publication Type: Conference Paper / Full Text
- Doi Number: 10.31401/ws.2025.proc.06
- City: Primorsko
- Country: Bulgaria
- Page Numbers: pp.42-48
- Keywords: Chaos, Nonlinear and Causality Analyses, Solar and Geomagnetic Activity
- Akdeniz University Affiliated: Yes
Abstract
This study aims to identify nonlinear/chaotic features and causal relationships among monthly SSN, F10.7, aa, and Dst indices over December 1963–March 2025. Phase-space is reconstructed via AMI-selected delay τ and FNN dimension E; we estimate the Hurst exponent H, the largest Lyapunov exponent λ, and the correlation dimension D2; and apply CCM with SSN as reference. H spans 0.84–0.93 (SSN≈0.93; F10.7≈0.93; aa≈0.88; Dst≈0.84), indicating strong persistence. λ ranges from ≈0.010 to ≈0.040 (highest for Dst, lowest for aa), implying deterministic chaos with finite prediction horizons. D2 varies between 3.37–3.86, consistent with low–moderate dimensional structure. CCM analysis shows a strong linear relationship between SSN–F10.7, while indicating a non-linear causal relationship between SSN and other indices. In conclusion, sunspot variability affects global geomagnetic activity continuously and nonlinearly on a monthly scale; this effect is most pronounced for aa and weaker for Dst.