Valérie Coumans

High resolution FUV observations of proton aurora

[1] We present new FUV observations of Doppler-shifted Lyman-α emissions from proton aurora obtained from the High Resolution Ionospheric and Thermospheric Spectrograph (HITS) aboard the Advanced Research and Global Observation Satellite (ARGOS). The HITS instrument observes the Doppler-shifted H Lyman-α emissions from proton precipitation with 1.5 A resolution. The high spectral resolution of these measurements allows the auroral Lyman-α emissions to be separated from the intense geocoronal background. The measured proton aurora Doppler spectra are modeled using a Monte Carlo simulation of proton flux transport. The forward modeling performed with this code allows us to infer the characteristic energies of the incident protons from the measured Lyman-α Doppler spectra. The inferred characteristics of dayside versus nightside proton precipitation are compared and used to identify the magnetospheric regions from which the particles likely originated.