Relation of solar proton latitude profiles to outer radiation zone electron measurements

Charged particle detectors on the Alouette 2 satellite have been used to study various features of solar proton (1–8 Mev) latitude profiles during relatively quiet magnetic conditions, One feature of these profiles that is observed frequently is a flux enhancement close to the cutoff latitude for these particles. The high-latitude limit of the enhancement, denoted by Λϵ, shows a good correlation with Λb, the background boundary for outer-zone electrons (E > 35 kev). The region of enhanced flux, when it occurs, usually extends down to the latitude cutoff or ‘knee’, which exhibits approximately the same dependence on local time as Λϵ (or Λb) but is displaced 6° or 7° toward lower latitudes. Arguments are given that indicate the enhanced fluxes occur on closed field lines, and it is suggested that solar protons from the tail scatter across closed field lines and the flux enhancements may result from small differences in the probabilities for scattering into and out of the closed field line region. The position of the latitude ‘knee’ as a function of local time and the pitch-angle distributions close to the ‘knee’ are discussed in relation to cutoff theories.