Abstract. Plasmaspheric hiss was observed by Van Allen Probe B in association
with energetic electron injections in the outer plasmasphere. The energy of
injected electrons coincides with the minimum resonant energy calculated for
the observed hiss wave frequency. Interestingly, the variations in hiss wave
intensity, electron flux and ultra low frequency (ULF) wave intensity exhibit remarkable
correlations, while plasma density is not correlated with any of these
parameters. Our study provides direct evidence for the first time that the
injected anisotropic electron population, which is modulated by ULF waves,
modulates the hiss intensity in the outer plasmasphere. This also implies
that the plasmaspheric hiss observed by Van Allen Probe B in the outer
plasmasphere (L > ∼ 5.5) is locally amplified.
Meanwhile, Van Allen Probe A observed hiss emission at lower L shells
(< 5), which was not associated with electron injections but
primarily modulated by the plasma density. The features observed by Van Allen
Probe A suggest that the observed hiss deep inside the plasmasphere may have
propagated from higher L shells.
