Impact of Yaglom’s law anisotropy on the estimation of the turbulence energy transfer rate: A multipoint multiscale analysis

¹ Department of Physics and Astronomy, University of Delaware, Newark, DE 19716, USA
² Astronomical Institute of the Czech Academy of Sciences, Prague, Czechia
³ Institute of Atmospheric Physics of the Czech Academy of Sciences, Prague, Czechia
⁴ Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721, USA
⁵ IAPS – INAF Istituto di Astrofisica e Planetologia Spaziali, 00133 Roma, Italy
⁶ IRF Swedish Institute of Space Physics, Uppsala, Sweden
⁷ Laboratoire de Physique des Plasmas, CNRS, 91128 Palaiseau, France

^★ Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 28 September 2025
Accepted: 30 January 2026

Abstract

Context. Spectral anisotropy is a ubiquitous characteristic of turbulence in magnetized space plasma environments, as it occurs spontaneously due to the effect of a background magnetic field. This anisotropy significantly affects the turbulent energy cascade and modifies the scale-to-scale balance between different terms in the von Kármán-Howarth equation.

Aims. We investigate the effect of the induced lag-space anisotropy on the determination of the scale-dependent energy transfer rate.

Methods. We compared traditional single-spacecraft and novel multispacecraft approaches using hybrid particle-in-cell simulations and in situ observations from the Magnetospheric Multiscale (MMS) mission in the Earth’s magnetosheath.

Results. We show that the isotropy assumption, which is required for single-spacecraft measurements, leads to inaccuracies in the estimation of the turbulent cascade rate. On the other hand, the novel lag-polyhedra derivative ensemble method, which is specifically designed for the next generation of multipoint multiscale missions such as HelioSwarm and Plasma Observatory, can capture the anisotropy of the turbulent cascade.

Conclusions. These findings are used to interpret observations from the MMS mission in the Earth’s magnetosheath. They highlight the importance of accounting for anisotropy in space plasma diagnostics.