Can the Sunโs long-term activity patterns be better understood through the mathematics of chaos?
This study investigates chaotic behaviour in solar activity using daily sunspot number, equivalent planetary amplitude, and solar radio flux data across six solar cycles, from cycle 19 to cycle 24.
The researchers applied nonlinear dynamical tools, including correlation dimension, Lyapunov exponents, approximate entropy, Hurst exponent, and the GottwaldโMelbourne 0โ1 test, to examine whether these solar and geospace parameters follow deterministic chaotic patterns.
The findings reveal the presence of low-dimensional deterministic chaos in all three parameters. Positive Lyapunov exponents, correlation-dimension values between 2.1 and 2.3, positive surrogate significance tests, and 0โ1 test results above 0.99 all confirmed chaotic behaviour.
The study also found strong persistence and long-term autocorrelation, with Hurst values between 0.8 and 1. Based on chaoticity indicators, the order of chaos was identified as Ap < SSN < F10.7obs, with solar radio flux showing the highest chaotic behaviour.
Across the six solar cycles, chaoticity increased from cycle 19 to cycle 24, linked to small perturbations in solar plasma flow, rotational shear, and changes in the strength and orientation of the Sunโs magnetic field.
This research contributes to solar physics, space-weather modelling, nonlinear dynamics, geospace analysis, solar-cycle prediction, and understanding how solar variability may affect satellite communication, navigation systems, and terrestrial technology.
๐ Read the full article here:
https://doi.org/10.46481/asr.2026.5.2.517
Published in: African Scientific Reports