Hiss Waves Near the South Atlantic Anomaly in the Inner Plasmasphere

Plasmaspheric hiss is an important electromagnetic wave with a broad frequency range from 10 Hz to several kHz. In this study, we statistically investigate the distribution of the plasmaspheric hiss wave near the South Atlantic Anomaly (SAA) using data from the Van Allen Probes. We first detect power peaks of hiss waves with frequencies below 600 Hz near the SAA in the ‐shell region from 1.1 to 2.0. The results show stronger hiss wave power on the dayside and in boreal summer. For frequencies below 300 Hz, power peaks are observed across the ‐shell regions , while for frequencies between 300 Hz and 600 Hz, these peaks become confined to lower ‐shell regions . The power peaks and their seasonal variations are probably due to variations in the crossover and cutoff frequencies, which are caused by differences in magnetic field and variations in ion composition ratios, respectively.