Electromagnetic Ion Cyclotron Wave Energy Propagation in the Magnetosphere: Dynamic Poynting Spectra Results

Previous studies of electromagnetic ion cyclotron (EMIC) waves in the equatorial middle magnetosphere using Poynting vector calculations from the CRRES spacecraft, (dE and dB wave fields) have shown that the waves with frequencies below the helium cyclotron frequency f (He⁺) propagate essentially in field-aligned directions away from the equator. Ray angles are typically less than 30° with respect to the magnetic field direction. A new study is underway on the energy propagation characteristics of 110 EMIC wave events from CRRES using a newly developed dynamic spectral analysis technique to display the Poynting vector. Analysis includes waves with f > f (He⁺) and a number showing harmonic structure and an association with cold plasma density cavities or gradients. In general results from the larger CRRES dataset confirm that field aligned energy propagation is primarily away from the equatorial region and bouncing wave packets are not observed.