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. Plain Language Summary: On 7 January 2014, a large storm erupted from the Sun. This storm encountered the Earth and compressed the magnetosphere a few days later. The compression of the magnetosphere led to the creation of chorus waves, a wave‐type known to interact only with electrons with specific energies. In this case, the waves interacted with electrons in the magnetosphere's outer radiation belt. They caused the loss of electrons from 10 s eV to 100 s keV into the ionosphere and upper atmosphere. This paper uses theory to determine which energies we expect will interact with the observed chorus wave. We use the Helium Oxygen Proton Electron instrument from the Van Allen Probes to see if our predictions are correct. We care about these processes because the loss of these electrons can affect ionospheric activity. Key Points: Upper band chorus waves can have a minimum resonant energy in the 10 s eV energy rangeChanges in the minimum resonant energy can change the cut off for what lower energy particles will be lostThe lower energy cut off can be observed in the Van Allen Probes Helium Oxygen Proton Electron data [ABSTRACT FROM AUTHOR]