Statistical Energy Budget of the Solar Wind with Parker Solar Probe and Solar Orbiter : 1 - Unbalanced Total Energy Radial Evolution
Abstract
The magneto-hydrodynamic (MHD) description of the solar wind has long been regarded as one of the most successful frameworks for investigating solar wind heating and acceleration. Under a set of simplifying assumptions, it provides a reduced large-scale description that is widely used to study the energetic role of electromagnetic fluctuations in the solar wind energy budget. In practice, applying simplification to MHD can result in the loss of some physics compared to an exact set of equations. However, an observational energy budget can help us to verify whether any energetic information has been lost in the process of simplification. To do so, we directly test the validity of the large-scale non-linear ideal MHD energy budget with solar wind observations from Parker Solar Probe (PSP) and Solar Orbiter (SO). After verifying the reliability of the measurements through comparison with previous studies of similar solar wind properties, we test the conservation of the total energy predicted by the MHD theory. We find that the average total energy increases with radial distance by 56% (±9%) between 14 and 203 solar radii. The increase in kinetic energy is not sufficiently compensated by the decrease of the thermal and electromagnetic contributions. We investigate the major sources of observational uncertainty and find that they cannot account for the observed energy increase. These results suggest that the large-scale theoretical description may neglect an energetically significant contribution to solar wind acceleration. Assuming that such a contribution exists, we predict that this extra energy would scale with radial distance as r−0.54±0.38.
Related
- Delayed maximum energy solar energetic particle events: Statistical analysis from Solar Orbiter
- Effects of Alfvénicity on the compressible energy cascade in magnetohydrodynamic solar-wind turbulence: Evidence from Parker Solar Probe, Solar Orbiter, and WIND observations
- Radial Evolution of Turbulent Modes near the Sun Using Parker Solar Probe and Solar Orbiter Measurements
- Elemental Composition Evolution during the 2024 September 30 Solar Eruption: A Comparison of Hot and Cool Plasma Components with Solar Orbiter/SPICE, Hinode/EIS, and Chandrayaan-2/XSM
- Effects of Alfvénicity on the Compressible Energy Cascade in Magnetohydrodynamic Solar Wind Turbulence: Evidence from Parker Solar Probe, Solar Orbiter, and WIND observations
BibTeX
@misc{dakeyo2026statistical,
title = {{Statistical Energy Budget of the Solar Wind with Parker Solar Probe and Solar Orbiter : 1 - Unbalanced Total Energy Radial Evolution}},
author = {Jean-Baptiste Dakeyo and Pascal Démoulin and Victor Réville and Stuart Bale and Tamar Ervin and Milan Maksimovic and Olga Alexandrova and Mingzhe Liu and Roberto Livi and Nikos Sioulas and Orlando Romeo and Alexis Rouillard},
howpublished = {arXiv},
year = {2026},
month = aug,
doi = {10.48550/arxiv.2608.28873},
eprint = {2608.28873},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2608.28873},
note = {CC BY-NC-SA 4.0},
}
RIS
TY - UNPB
TI - Statistical Energy Budget of the Solar Wind with Parker Solar Probe and Solar Orbiter : 1 - Unbalanced Total Energy Radial Evolution
AU - Jean-Baptiste Dakeyo
AU - Pascal Démoulin
AU - Victor Réville
AU - Stuart Bale
AU - Tamar Ervin
AU - Milan Maksimovic
AU - Olga Alexandrova
AU - Mingzhe Liu
AU - Roberto Livi
AU - Nikos Sioulas
AU - Orlando Romeo
AU - Alexis Rouillard
PY - 2026
DA - 2026/08/28
PB - arXiv
DO - 10.48550/arxiv.2608.28873
UR - https://arxiv.org/abs/2608.28873
AB - The magneto-hydrodynamic (MHD) description of the solar wind has long been regarded as one of the most successful frameworks for investigating solar wind heating and acceleration. Under a set of simplifying assumptions, it provides a reduced large-scale description that is widely used to study the energetic role of electromagnetic fluctuations in the solar wind energy budget. In practice, applying simplification to MHD can result in the loss of some physics compared to an exact set of equations. However, an observational energy budget can help us to verify whether any energetic information has been lost in the process of simplification. To do so, we directly test the validity of the large-scale non-linear ideal MHD energy budget with solar wind observations from Parker Solar Probe (PSP) and Solar Orbiter (SO). After verifying the reliability of the measurements through comparison with previous studies of similar solar wind properties, we test the conservation of the total energy predicted by the MHD theory. We find that the average total energy increases with radial distance by 56% (±9%) between 14 and 203 solar radii. The increase in kinetic energy is not sufficiently compensated by the decrease of the thermal and electromagnetic contributions. We investigate the major sources of observational uncertainty and find that they cannot account for the observed energy increase. These results suggest that the large-scale theoretical description may neglect an energetically significant contribution to solar wind acceleration. Assuming that such a contribution exists, we predict that this extra energy would scale with radial distance as r^−0.54±0.38.
ER -