Hysteresis in a Solar Activity Cycle

TL;DR

This study uses permutation entropy to analyze solar wind velocity data, revealing hysteresis and multistability phenomena over a solar activity cycle, which enhances understanding of solar wind dynamics.

Contribution

The paper introduces the application of permutation entropy to solar wind data, demonstrating hysteresis in solar wind complexity during the solar cycle.

Findings

Complexity of solar wind velocity exhibits hysteresis.

Permutation entropy effectively captures solar wind dynamics.

Multistability is present in solar wind behavior over the cycle.

Abstract

We analyze in situ measurements of solar wind velocity obtained by the Advanced Composition Explorer (ACE) spacecraft during the solar activity cycle 23. We calculated a robust complexity measure, the permutation entropy (S) of solar wind time series at different phases of a solar activity cycle. The permutation entropy measure is first tested on the known dynamical data before its application to solar wind time series. It is observed that complexity of solar wind velocity fluctuations at 1 AU shows hysteresis phenomenon while following the ascending and descending phases of the activity cycle. This indicates the presence of multistability in the dynamics governing the solar wind velocity over a solar activity cycle.