Würzburg 2018 – scientific programme

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EP: Fachverband Extraterrestrische Physik

EP 11: Sun and Heliosphere III - Particles

EP 11.1: Invited Talk

Thursday, March 22, 2018, 15:00–15:30, BSZ - Pabel HS

Recent advances in heliospheric transport of solar energetic particles — •Timo Laitinen and Silvia Dalla — Jeremiah Horrocks Institute, University of Central Lancashire, Preston, UK

Solar Energetic Particles (SEPs), accelerated during solar eruptions, are typically observed with in situ instruments in the interplanetary space. Their propagation from the Sun to the observer is controlled by the interplanetary magnetic field, which consists of a mean Parker spiral field and turbulent fluctuations. Recent multi-spacecraft SEP observations made with the STEREO, SOHO and ACE spacecraft have shown that SEPs have access to wide range of heliolongitudes, across the mean Parker field spiral field. Thorough analysis of the observations has implied that the wide SEP events are to significant extent caused by propagation of the particle across the mean field. In this presentation, we will review the current understanding of SEP propagation across the mean magnetic field in a turbulent heliosphere. In particular, we will discuss the often-used spatial cross-field diffusion model, and the recently-introduced model in which the particles follow non-diffusively the turbulently meandering field-lines before relaxing time-asymptotically to spatial cross-field diffusion. We will also consider the influence of the large-scale structure of the heliospheric field on the SEP event. We discuss the implications of the transport models to our understanding of the nature of wide SEP events.