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.

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 2000-2001Ulysses passed from the south to the north polar regions of the Sun in the inner heliosphere, providing a snapshot of the latitudinal structure of cosmic ray modulation and solar energetic particle populations during a period near solar maximum. Observations from the COSPIN suite of energetic charged particle telescopes show that latitude variations in the cosmic ray intensity in the inner heliosphere are nearly non-existent near solar maximum, whereas small but clear latitude gradients were observed during the similar phase of Ulysses' orbit near the 1994-95 solar minimum. At proton energies above ∼10 MeV and extending up to >70 MeV, the intensities are often dominated by Solar Energetic Particles (SEPs) accelerated near the Sun in association with intense solar flares and large Coronal Mass Ejections (CMEs). At lower energies the particle intensities are almost constantly enhanced above background, most likely as a result of a mix of SEPs and particles accelerated by interplanetary shocks. Simultaneous high-latitude Ulysses and near-Earth observations show that most events that produce large flux increases near Earth also produce flux increases at Ulysses, even at the highest latitudes attained. Particle anisotropies during particle onsets at Ulysses are typically directed outwards from the Sun, suggesting either acceleration extending to high latitudes or efficient cross-field propagation somewhere inside the orbit of Ulysses. Both cosmic ray and SEP observations are consistent with highly efficient transport of energetic charged particles between the equatorial and polar regions and across the mean interplanetary magnetic fields in the inner heliosphere.

Observations of galactic cosmic radiation and anomalous component nuclei with charged particle sensors on the Ulysses spacecraft showed that heliospheric magnetic field structure over the south solar pole does not permit substantially more direct access to the local interstellar cosmic ray spectrum than is possible in the equatorial zone. Fluxes of galactic cosmic rays and the anomalous component increased as a result of latitude gradients by less than 50% from the equator to -80 degrees . Thus, the modulated cosmic ray nucleon, electron, and anomalous component fluxes are nearly spherically symmetric in the inner solar system. The cosmic rays and the anomalous nuclear component underwent a continuous, -26 day recurrent modulation to -80.2 degrees , whereas all recurring magnetic field compressions and recurring streams in the solar wind disappeared above approximately 55 degrees S latitude.