Fig. 4. Local pitch angle diffusion coefficients Dαα for sulfur and oxygen ions.

The diffusion coefficients Dαα are calculated using the PADIE code (see the Supplementary Materials) from a combination of H⁺, O⁺ (or S⁺⁺), and S⁺ waves calculated locally at B ~ 6 and 3 nT, respectively, interacting with O⁺ (or S⁺⁺) and S⁺ ions. The black numbers above the x axis show the maximum latitude a particle with this pitch angle will reach before mirroring. The left panels show the wave interaction with O⁺ (or S⁺⁺) ions, and the right panels show the interaction with S⁺ ions.