The plasmapause marks the limit of the plasmasphere and is characterized by a sudden change in plasma density. This can influence the other regions of the magnetosphere, including due to different waves circulating inside and outside the plasmasphere. In the present work, we first compare the positions of the plasmapause measured by the NASA Van Allen Probes in 2015 with those of the Space Weather Integrated Forecasting Framework plasmasphere model (SPM). Using the Van Allen Probes and other satellite observations like PROBA-V, we investigate the links that can exist with the radiation belt boundaries. The inward motion of the outer radiation belt associated with sudden flux enhancements of energetic electrons can indeed be directly related to the plasmapause erosion during geomagnetic storms, suggesting possible links. Moreover, the position of the plasmapause projected in the ionosphere is compared with the ionospheric convection boundary. The equatorward motion of the plasmapause projected in the ionosphere is related to the equatorward edge motion of the auroral oval that goes to lower latitudes during storms due to the geomagnetic perturbation, like the low altitude plasmapause and the outer radiation belt. The links between these different regions are investigated during quiet periods, for which the plasmaspheremore »
Superfast precipitation of energetic electrons in the radiation belts of the Earth
Energetic electron precipitation from Earth’s outer radiation belt heats the upper atmosphere and alters its chemical properties. The precipitating flux intensity, typically modelled using inputs from high-altitude, equatorial spacecraft, dictates the radiation belt’s energy contribution to the atmosphere and the strength of space-atmosphere coupling. The classical quasi-linear theory of electron precipitation through moderately fast diffusive interactions with plasma waves predicts that precipitating electron fluxes cannot exceed fluxes of electrons trapped in the radiation belt, setting an apparent upper limit for electron precipitation. Here we show from low-altitude satellite observations, that ~100 keV electron precipitation rates often exceed this apparent upper limit. We demonstrate that such superfast precipitation is caused by nonlinear electron interactions with intense plasma waves, which have not been previously incorporated in radiation belt models. The high occurrence rate of superfast precipitation suggests that it is important for modelling both radiation belt fluxes and space-atmosphere coupling.
- Publication Date:
- NSF-PAR ID:
- 10364413
- Journal Name:
- Nature Communications
- Volume:
- 13
- Issue:
- 1
- ISSN:
- 2041-1723
- Publisher:
- Nature Publishing Group
- Sponsoring Org:
- National Science Foundation
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