ARE EQUATORIAL ELECTRON CYCLOTRON WAVES RESPONSIBLE FOR DIFFUSE AURORAL ELECTRON PRECIPITATION?

The electrostatic wave amplitude statistics performed on the basis of data collected by the GEOS 2 spacecraft in the nightside plasma sheet is presented. The wave amplitude variation with latitude in the region of the magnetic equation is discussed. Theoretical calculations taking into account the wave confinement within a few degrees of latitude from the magnetic equator are given, and an analytical expression of the minimum wave amplitude required to cause strong pitch angle diffusion for plasma sheet electrons is derived. This analytical expression allows for easy evaluation of the dependence of the results on parameters such as the latitudinal wave extension or others that are not accessible to observations, such as the wave number spectrum. Finally, the statistical and theoretical results are compared and discussed.