Statistical analysis of solar energetic particle rise times using Earth and Mars observations and constraints on particle transport parameters

Fuente: arXiv
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Auteurs principaux: Cao, Yihang, Guo, Jingnan, Wang, Yuming, Zou, Zhuxuan, Zhang, Yongjie, Li, Cunhui
Format: Preprint
Publié: 2026
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author Cao, Yihang
Guo, Jingnan
Wang, Yuming
Zou, Zhuxuan
Zhang, Yongjie
Li, Cunhui
author_facet Cao, Yihang
Guo, Jingnan
Wang, Yuming
Zou, Zhuxuan
Zhang, Yongjie
Li, Cunhui
contents The propagation of solar energetic particles (SEPs) in interplanetary space is modulated by solar wind turbulence, which significantly influences particle diffusion and energy evolution through scattering processes. Traditional analyses based on absolute flux measurements face inherent difficulties in disentangling source acceleration from subsequent transport, while temporal features such as onset and peak times are less affected and better suited for studying SEP transport. This study establishes a statistical relationship between the rise time of SEP events at different energies using multi-satellite observations at Earth and Mars. We use data from SOHO/ERNE and Tianwen-1/MEPA between November 2020 and March 2025, selecting 75 SEP events at 1 AU and 58 near Mars. For each energy range, onset times are determined by linear fitting, and peak times are extracted via a sliding median filter combined with Savitzky-Golay smoothing; the difference gives the SEP rise time. Comparing with the pure diffusion equation prediction, we examine the statistical behavior of rise time at Earth and Mars. Despite event selection uncertainties, SEP rise time follows a clear power-law relation with energy. The flatter power-law at Mars indicates weaker energy dependence with increasing solar distance. Using these empirical relations, we constrain the rigidity dependence of the parallel mean free path within the parallel diffusion model. Our results show that turbulence scattering at Mars approaches a rigidity-independent regime, reflecting turbulence evolution toward a dissipation-dominated state from Earth to Mars.
format Preprint
id arxiv_https___arxiv_org_abs_2605_01437
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Statistical analysis of solar energetic particle rise times using Earth and Mars observations and constraints on particle transport parameters
Cao, Yihang
Guo, Jingnan
Wang, Yuming
Zou, Zhuxuan
Zhang, Yongjie
Li, Cunhui
Space Physics
The propagation of solar energetic particles (SEPs) in interplanetary space is modulated by solar wind turbulence, which significantly influences particle diffusion and energy evolution through scattering processes. Traditional analyses based on absolute flux measurements face inherent difficulties in disentangling source acceleration from subsequent transport, while temporal features such as onset and peak times are less affected and better suited for studying SEP transport. This study establishes a statistical relationship between the rise time of SEP events at different energies using multi-satellite observations at Earth and Mars. We use data from SOHO/ERNE and Tianwen-1/MEPA between November 2020 and March 2025, selecting 75 SEP events at 1 AU and 58 near Mars. For each energy range, onset times are determined by linear fitting, and peak times are extracted via a sliding median filter combined with Savitzky-Golay smoothing; the difference gives the SEP rise time. Comparing with the pure diffusion equation prediction, we examine the statistical behavior of rise time at Earth and Mars. Despite event selection uncertainties, SEP rise time follows a clear power-law relation with energy. The flatter power-law at Mars indicates weaker energy dependence with increasing solar distance. Using these empirical relations, we constrain the rigidity dependence of the parallel mean free path within the parallel diffusion model. Our results show that turbulence scattering at Mars approaches a rigidity-independent regime, reflecting turbulence evolution toward a dissipation-dominated state from Earth to Mars.
title Statistical analysis of solar energetic particle rise times using Earth and Mars observations and constraints on particle transport parameters
topic Space Physics
url https://arxiv.org/abs/2605.01437