Abstract. The heliospheric modulation of galactic and Jovian electrons is studied using a fully threedimensional, steady state model based on Parker's transport equation including the 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 spacecraft. This is because electron modulation responds 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 study the latitudinal transport of both Jovian and 4-20 MeV galactic electrons by illustrating how the 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 assumptions for perpendicular diffusion in the polar direction and compared to the 3-10 MeV electron flux observed by Ulysses from launch up to the end of the first out of the ecliptic orbit. Comparison of the model computations and the observations give an indication as to the magnitude of this diffusion coefficient. The relative contributions of the Jovian and galactic electrons to the total electron intensity is shown along the Ulysses trajectory.

No abstract

No abstract

Abstract. Previously, the latitudinal transport of -7 MeV electrons was studied by comparing the results of a newly developed three-dimensional model, based on the numerical solution of Parker's transport equation including the Jovian source, with Ulysses observations. Here, the radial transport of-16 MeV electrons is studied by comparing the model results with the -16 MeV electron intensities observed by Pioneer 10 up to -70 AU. Electron modulation responds 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, and in addition, low-energy electrons do not experience significant drifts. The modulation of low-energy electrons is therefore a handy tool to find a diffusion tensor suitable to the heliospheric modulation of electrons. It is illustrated that the computed electron intensities are sensitive to the radial dependence of the diffusion coefficients in the inner heliosphere and that compatibility between the model and observations gives an indication as to the radial dependence of the diffusion coefficients. The effects of different perpendicular diffusion coefficients in the radial direction are also shown, and an upper limit for the value of this coefficient is proposed. Finally, the relative contributions of the Jovian and galactic electrons to the total electron intensity are shown along the Pioneer 10 trajectory, illustrating that the Jovian electrons dominate the total electron intensity at these low energies in the inner equatorial regions only up to -9 AU. From 15 AU outward, the Jovian contribution becomes less than 20%, decreasing rapidly as a function of increasing distance.

Abstract. In recent years the variability of the cosmic ray flux has become one of the main issues interpreting cosmogenic elements and especially their connection with climate. In this review, an interdisciplinary team of scientists brings together our knowledge of the evolution and modulation of the cosmic ray flux from its origin in the Milky Way, during its propagation through the heliosphere, up to its interaction with the Earth's magnetosphere, resulting, finally, in the production of cosmogenic isotopes in the Earth' atmosphere. The interpretation of the cosmogenic isotopes and the cosmic ray -cloud connection are also intensively discussed. Finally, we discuss some open questions.