Predictions for the propagation of energetic particles from the sun to the earth: influence of the magnetic turbulence

Abstract

Energetic particle fluxes in the Earth's magnetosphere can seriously affect spacecraft operations as well as navigation and communication systems. To this end, and critical issue is to understand and predict whether particles accelerated at a solar flare will impinge on the Earth's magnetosphere. Energetic particle propagation depends on the magnetohydrodynamic turbulence in the solar wind. We present here a Monte Carlo simulation which traces the magnetic field line from the Earth to the solar corona, taking into account both the average Parker spiral magnetic field and the effects of magnetic turbulence. A proper evaluation of the diffusion coefficient is obtained by a numerical simulation of transport in anisotropic magnetic turbulence which takes into account the scaling of the fluctuation level and of the correlation lengths with the distance from the Sun. This numerical code allows to determine, from the observations of a solar flare at given heliographic latitude and longitude, whether energetic particles will come over the magnetosphere or not.