On the origin of whistler mode radiation in the plasmasphere

The origin of whistler mode radiation in the plasmasphere is examined from 3 years of plasma wave observations from the Dynamics Explorer and the Imager for Magnetopause‐to‐Aurora Global Exploration spacecraft. These data are used to construct plasma wave intensity maps of whistler mode radiation in the plasmasphere. The highest average intensities of the radiation in the wave maps show source locations and/or sites of wave amplification. Each type of wave is classified on the basis of its magnetic latitude and longitude rather than any spectral feature. Equatorial electromagnetic (EM) emissions (∼30–330 Hz), plasmaspheric hiss (∼330 Hz to 3.3 kHz), chorus (∼2–6 kHz), and VLF transmitters (∼10–50 kHz) are the main types of waves that are clearly delineated in the plasma wave maps. Observations of the equatorial EM emissions show that the most intense region is on or near the magnetic equator in the afternoon sector and that during times of negative Bz (interplanetary magnetic field) the maximum intensity moves from L values of 3 to