Variations of proton energy and pitch angle spectra in the upper atmosphere

Abstract

An isotropic pitch angle distribution over the upper hemisphere of auroral prǒtons above the atmosphere seems to be a general feature of the flux penetrating into the atmosphere. Due to experimental difficulties it is hard to measure the proton flux at all heights in the atmosphere, and therefore in this report calculations of the energy and pitch angle distributions are performed. The calculations are based on non-linear energy degradation as the protons penetrate into the atmosphere approximated by CIRA Mean Reference Atmosphere (1972), and are intended to act as a guide for further studies. It is found that pitch angle distribution changes in the atmosphere. The protons with small pitch angles get less attenuated than the protons with large pitch angles.