AbstractExohiss waves are whistler mode hiss observed in the plasmatrough region. We present a case study of exohiss waves and the corresponding background plasma distributions observed by the Van Allen Probes in the dayside low‐latitude region. The analysis of wave Poynting fluxes, suprathermal electron fluxes, and cold electron densities supports the scenario that exohiss leaks from the plasmasphere into the plasmatrough. Quasilinear calculations further reveal that exohiss can potentially cause the resonant scattering loss of radiation belt electrons ∼<MeV on a comparable time scale to that associated with the storm time plasmaspheric hiss. These results clearly illustrate that exohiss may need to be taken into account in future radiation belt models.
