EMIC waves growth and guiding in the presence of cold plasma density irregularities

Abstract

Intense electromagnetic ion cyclotron (EMIC) waves are observed within plasmaspheric plumes during geomagnetic storms and are believed to be a significant driver of loss of both ring current protons and radiation belt electrons. In this study, we use ray tracing together with path‐integrated linear growth calculations to analyze the amplification and propagation of EMIC waves within cold plasma density irregularities characteristic of the plasmaspheric plume. All waves are launched at the equator in the range of L = 5 to 7, and wave amplification is analyzed as a function of frequency and initial wave normal angle. These results are compared to a baseline case without irregularities, which show that guiding is possible for irregularity sizes on the order of the EMIC wavelength. Results suggest that typical structures with density levels above and below the average value can result in both areas of increased as well as suppressed wave activity.