Freiburg 2008 – wissenschaftliches Programm

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EP: Fachverband Extraterrestrische Physik

EP 4: The Sun and Heliosphere - Poster Session

EP 4.19: Poster

Montag, 3. März 2008, 17:30–19:00, Vorraum KGI-Aula

Perpendicular Transport in the Inner Heliosphere: A Quick and Dirty Approach — •Florian Lampa, Katrin Jahns, and May-Britt Kallenrode — Department of Physics, University of Osnabrueck, Barbarastraße 7, D-49076 Osnabrueck

In previous studies, particle transport in the inner heliosphere is regarded as one dimensional along the archimedian spiral; any perpendicular transport is neglected. We extend Roelof’s equation of focused transport to accommodate perpendicular transport in the plane of ecliptic. For typical ratios κ_⊥/κ_|| between 0.02 and 0.1 we find that cross-field transport is extremely efficient in smearing out any azimuthal gradients within a few hours – much faster than suggested by observations. We employ different scenarios to reduce perpendicular transport to maintain gradients, namely a diffusive shell around the Sun and an ad-hoc scaling of azimuthal transport with spiral angle Ψ. For the latter case we find that (a) azimuthal spread over some ten degrees occurs within a few hours, (b) the variation of maximum intensities with longitude is comparable to the ones inferred from multi-spacecraft observations, and (c) on a given field line intensity- and anisotropy-time profiles are modified such that fits with the 2D transport model give different combinations of injection profiles and mean free paths. Thus although the consideration of perpendicular transport in the inner heliosphere can account for quite a wide range for observations, this is not possible with currently assumed fixed ratios κ_⊥/κ_|| derived from random walk of field lines and non-linear guiding center theory.