The Effect of Compression Induced Chorus Waves on 10-100 s eV Electron Precipitation

On 7 January 2014, a solar storm erupted, which eventually compressed the Earth's magnetosphere leading to the generation of chorus waves. These waves enhanced local wave-particle interactions and led to the precipitation of electrons from 10 s eV to 100 s keV. This paper shows observations of a low energy cutoff in the precipitation spectrum from Van Allen Probe B Helium Oxygen Proton Electron measurements. This low energy cutoff is well replicated by the predicted loss calculated from pitch angle diffusion coefficients from wave and plasma observations on Probe B. To our knowledge, this is the first time a single spacecraft has been used to demonstrate an accurate theoretical prediction for chorus wave-induced precipitation and its low energy cutoff. The specific properties of the precipitating soft electron spectrum have implications for ionospheric activity, with the lowest energies mainly contributing to thermospheric and ionospheric upwelling, which influences satellite drag and ionospheric outflow.

Automated summary

On 7 January 2014, a solar storm caused compression of Earth's magnetosphere and resulted in the generation and enhancement of chorus waves. These waves induced the precipitation of electrons from 10 s eV to 100 s keV. This study provides observations of a low energy cutoff in the precipitation spectrum, which is accurately predicted by theoretical calculations using wave and plasma data from Van Allen Probe B. This is the first time a single spacecraft has demonstrated the accuracy of theoretical predictions for chorus wave-induced precipitation and its low energy cutoff.