Energetic electron precipitation from the inner zone

Abstract

Energetic electron precipitation flux from the Earth's inner radiation belt (L≤2) is usually below the detection threshold of current satellite instrumentation. Theoretical estimates of the longitudinally and interhemispherically averaged rate of precipitation have been obtained by evaluating the equilibrium electron pitch angle distribution in the loss cone due to pitch angle scattering. The results are normalized to CRRES MEA measurements of the trapped flux. An energy deposition code is employed to evaluate ion production rates in the middle atmosphere. We demonstrate that inner zone electron precipitation is an important mesospheric energy source for L≥1.35 and that it can be the dominant ionization source at altitudes between 60 and 80 km. For E≳1MeV the energetic electron deposition declines monotonically with decreasing L, in agreement with the trend implied by observations at L≥2.