A robust empirical relationship between speed and turbulence energy in the near-Earth solar wind

TL;DR

This paper establishes an empirical law linking solar wind speed to turbulence energy, enabling turbulence estimation from low-resolution data for space weather and particle transport applications.

Contribution

It introduces a robust empirical relationship between solar wind speed and turbulence energy based on 25 years of near-Earth observations.

Findings

The empirical law accurately relates speed to turbulence energy.

The model allows turbulence estimation from low-resolution speed data.

Potential applications include space-weather forecasting and particle transport modeling.

Abstract

The connection between turbulence and solar-wind acceleration, long known in space physics, is further developed in this Letter by establishing a robust empirical law that relates the bulk-flow speed to the magnetohydrodynamic-scale fluctuation energy in the plasma. The model is based on analysis of twenty-five years of near-Earth observations by NASA's Advanced Composition Explorer. It provides a simple way to estimate turbulence energy from low-resolution speed data -- a practical approach that may be of utility when high-resolution measurements or advanced turbulence models are unavailable. Potential heliospheric applications include space-weather forecasting operations, remote imaging datasets, and energetic-particle transport models that require turbulence amplitudes to specify diffusion parameters.