Kramers-Moyal analysis of interplanetary magnetic field fluctuations at sub-ion scales

TL;DR

This paper applies Kramers-Moyal analysis to high-resolution magnetic field data from the solar wind to characterize turbulence at sub-ion scales, testing the universality of Markovian properties in magnetic fluctuations.

Contribution

It introduces a multiscale Markov process analysis of solar wind magnetic fluctuations at sub-ion scales, extending previous near-Sun studies.

Findings

Magnetic field fluctuations exhibit Markovian behavior at sub-ion scales.

Kramers-Moyal coefficients effectively describe the turbulence dynamics.

Results support the universality of Markovian properties in solar wind turbulence.

Abstract

In the framework of statistical time series analysis of complex dynamics we present a multiscale characterization of solar wind turbulence in the near-Earth environment. The data analysis, based on the Markov-process theory, is meant to estimate the Kramers-Moyal coefficients associated with the measured magnetic field fluctuations. In fact, when the scale-to-scale dynamics can be successfully described as a Markov process, first- and second-order Kramers-Moyal coefficients provide a complete description of the dynamics in terms of Langevin stochastic process. The analysis is carried out by using high-resolution magnetic field measurements gathered by Cluster during a fast solar wind period on January 20, 2007. This analysis extends recent findings in the near-Sun environment with the aim of testing the universality of the Markovian nature of the magnetic field fluctuations in the sub-ion/kinetic domain.