Modulation effects of anisotropic perpendicular diffusion on cosmic ray electron intensities in the heliosphere

The modulation of cosmic ray electrons provides a useful tool to study the diffusion tensor applicable to heliospheric modulation. Electron modulation responds directly to the assumed energy dependence of the diffusion coeffi cients below similar to 500 MeV in contrast to protons which experience lar ge adiabatic energy losses below this energy. As a result of this and becau se drifts become unimportant for electrons at these low energies, conclusio ns can be made about the appropriate diffusion coefficients. Using a modula tion model, we illustrate the role of anisotropic perpendicular diffusion o n electron modulation. In general, we find that perpendicular diffusion dom inates electron modulation below similar to 100 MeV. Enhancing it in the po lar direction typically produced an increase in modulation for both the A > 0 (e.g., similar to 1990 to similar to 2000) and A < 0 (e.g., similar to 1 980 to similar to 1990) solar magnetic polarity cycles. It also causes the radial dependence of the intensity to become more uniform throughout the he liosphere, and causes a significant reduction in the latitude dependence of the intensities at all radial distances, with the largest effects in the i nner heliosphere and at low energies. This agrees with studies of cosmic ra y protons, which suggest that perpendicular diffusion enhanced in the polar direction of the heliosphere is required in conventional drift models to e xplain the small latitudinal gradients observed for protons on board the Ul ysses spacecraft. The role of enhanced perpendicular diffusion was further investigated by examining electron modulation as a function of the "tilt an gle" alpha of the wavy current sheet. In general, a reduction occurred betw een the modulation differences caused by drifts as a function of alpha for both polarity cycles. This work illustrates that anisotropic perpendicular diffusion has profound effects on the modulation of galactic cosmic ray ele ctrons during both polarity cycles.