Low-frequency fluctuations of the electric field in the equatorial ionosphere

Abstract

High time resolutions radar measurements of ionospheric electric fields have recently permitted studies of low-frequency hydromagnetic waves, but most of the research had depended on electron drift velocity from data obtained from the Scandinavian Twin Auroral Radar Experiment (STARE), taken at high latitudes (λm ~+70°) and used to study oscillations with periods of 200-300 s. At high latitudes, the low-frequency pulsations provide important information of the magnetospheric plasma process 1-3, but, at low latitudes, coupling of the ionosphere and magnetosphere remain unexplored. The purpose of our study is to examine the fluctuations in the electric field on a time scale longer than ion cyclotron periods, which have not been studied at low latitudes. We report here observations of these waves with periods larger than 45s from the high time-resolution data taken at Jicamarca, Perú.