G. Zimbardo et al., Magnetic field line transport in the heliosphere and energetic particle propagation from corotating interaction regions to high heliographic latitudes, ASTRO SP SC, 277(1-2), 2001, pp. 97-100
A numerical model of magnetic turbulence allows us to compute the diffusion
coefficients for different degrees of anisotropy, and in particular for th
e cases corresponding to the solar wind. We consider here the problem of th
e propagation of the energetic particles accelerated by corotating interact
ion regions (CIRs) and observed by Ulysses at high heliographic latitudes.
The excursion in latitude of a magnetic field line located at large heliosp
heric distance is evaluated with a Monte Carlo simulation. In the calculati
ons, the random `force' terms are proportional to the square root of the di
ffusion coefficient in each direction. By tracing a large number of field l
ines, we can devise how the particles would be seen by Ulysses. Good agreem
ent with the actual observations is found.