A survey of electron cyclotron waves in the magnetosphere and the diffuse auroral electron precipitation

Abstract

Natural electron cyclotron harmonic emissions in the outer magnetosphere are often cited as the electron scattering mechanism which results in the diffuse auroral precipitation. A survey is presented of the characteristics of these waves using data from both the SCATHA and Active Magnetospheric Particle Tracer Explorers (AMPTE) IRM plasma wave instruments. The emissions were observed most often in the 0300–0600 LT sector at L ∼ 4–8 and magnetic latitudes in the range ±10°. In this region, emissions exceeding 35 µV m −1 were detected only 25% of the time, and those exceeding 12 µV m −1 were detected 60% of the time. In agreement with Belmont et al. (1983), these amounts are grossly insufficient to account for the diffuse auroral electron precipitation by quasi‐linear pitch angle diffusion.