Nonlinear and Causal Dynamics between Solar and Geomagnetic Activity Indices: Findings from Chaos and Causality Measures

KILÇIK A., Gerçeker K.

17th Workshop on Solar Influences on the Magnetosphere, Ionosphere and Atmosphere, 2025, Primorsko, Bulgaristan, 2 - 06 Haziran 2025, ss.42-48, (Tam Metin Bildiri) identifier

  • Yayın Türü: Bildiri / Tam Metin Bildiri
  • Doi Numarası: 10.31401/ws.2025.proc.06
  • Basıldığı Şehir: Primorsko
  • Basıldığı Ülke: Bulgaristan
  • Sayfa Sayıları: ss.42-48
  • Anahtar Kelimeler: Chaos, Nonlinear and Causality Analyses, Solar and Geomagnetic Activity
  • Akdeniz Üniversitesi Adresli: Evet

Özet

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.