Abstract
Theoretical considerations lead to a solar cosmic ray diffusion coefficient which varies with heliolongitude in a stream-structured solar wind. By solving numerically the time dependent convection-diffusion equation for the particle transport we investigate the effect of the azimuthal variation of the diffusion coefficient on intensity-time profiles as seen by a stationary observer. Depending on the position of the observer relative to the solar wind stream at the time of flare occurrence, completely different intensity-time profiles will be observed. When the spacecraft is at the time of the flare occurrence right at the leading edge of a solar wind stream, the large mean free path leads to rapid steepening of the initial phase of the intensity profile. The longitudinally decreasing mean free path ∼ 1 day in front of the leading edge will lead to intensity-time profiles similar to long-time injection events if the event occurs before the stationary observer enters the flux tubes with the decreasing diffusion coefficient.
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Scholer, M., Morfill, G. & Richter, A.K. Energetic solar particle events in a stream-structured solar wind. Sol Phys 64, 391–401 (1979). https://doi.org/10.1007/BF00151448
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DOI: https://doi.org/10.1007/BF00151448