A study of the compatibility between observations and model simulations for Jovian and galactic electrons Original Research Article

The heliospheric modulation of galactic and Jovian electrons is studied using a newly developed complete three-dimensional, steady-state model based on Parkerʹs transport equation including a Jovian source. The modulation of low-energy electrons is a handy tool to establish and to construct a suitable diffusion tensor to assure compatibility between model computations and observations from the Ulysses, Voyager and Pioneer spacecraft. Electrons respond, e.g., directly to the energy dependence of the diffusion coefficients below ∼500 MeV in contrast to protons which experience large adiabatic energy losses below this energy. The model is used to illustrate how the low-energy electron intensities are affected at different latitudes when enhancing perpendicular diffusion in the polar direction. In particular, the electron intensity-time-profile along the Ulysses trajectory is calculated for various diffusion coefficients and compared to the 3 – 10 MeV electron flux observed by Ulysses. The results show how the relative contribution of low-energy galactic and Jovian electrons vary with respect to the total electron intensity for the various diffusion coefficients.