Shock-induced disappearance and subsequent recovery of plasmaspheric hiss: Coordinated observations of RBSP, THEMIS and POES satellites

Author
Keywords
Abstract
Plasmaspheric hiss is an extremely low frequency whistler-mode emission contributing significantly to the loss of radiation belt electrons. There are two main competing mechanisms for the generation of plasmaspheric hiss: excitation by local instability in the outer plasmasphere and origination from chorus outside the plasmasphere. Here, on the basis of the analysis of an event of shock-induced disappearance and subsequent recovery of plasmaspheric hiss observed by RBSP, THEMIS and POES missions, we attempt to identify its dominant generation mechanism. In the pre-shock plasmasphere, the local electron instability was relatively weak and the hiss waves with bidirectional Poynting fluxes mainly originated from the dayside chorus waves. On arrival of the shock, the removal of pre-existing dayside chorus and the insignificant variation of low-frequency wave instability caused the prompt disappearance of hiss waves. In the next few hours, the local instability in the plasmasphere was greatly enhanced due to the substorm injection of hot electrons. The enhancement of local instability likely played a dominant role in the temporary recovery of hiss with unidirectional Poynting fluxes. These temporarily recovered hiss waves were generated near the equator and then propagated toward higher latitudes. In contrast, both the enhancement of local instability and the recurrence of pre-noon chorus contributed to the substantial recovery of hiss with bidirectional Poynting fluxes.
Year of Publication
2017
Journal
Journal of Geophysical Research: Space Physics
Date Published
10/2017
URL
http://onlinelibrary.wiley.com/doi/10.1002/2017JA024470/full
DOI
10.1002/2017JA024470