Generalized similarity in finite range solar wind magnetohydrodynamic turbulence

TL;DR

This paper demonstrates that a single generalized scaling function characterizes finite-range anisotropic MHD turbulence in the solar wind, remaining invariant across different plasma conditions, including during an unusually inactive solar minimum.

Contribution

It introduces the concept of a universal generalized scaling function for finite-range turbulence in the solar wind, independent of plasma activity levels.

Findings

A single generalized scaling function describes the turbulence.

The scaling function is insensitive to plasma conditions.

Turbulence power decreases by a factor of two during inactive solar minimum.

Abstract

Extended or generalized similarity is a ubiquitous but not well understood feature of turbulence that is realized over a finite range of scales. ULYSSES spacecraft solar polar passes at solar minimum provide \textit{in situ} observations of evolving anisotropic magnetohydrodynamic turbulence in the solar wind under ideal conditions of fast quiet flow. We find a single generalized scaling function characterises this finite range turbulence and is insensitive to plasma conditions. The recent unusually inactive solar minimum -with turbulent fluctuations down by a factor of $\sim 2$ in power- provides a test of this invariance.