Satellite and ground-based observations of a large-scale electron precipitation event

Energetic electron precipitation into the atmosphere is determined using subionospheric VLF measurements, DEMETER satellite electron spectra, and modelling techniques for a 24-hour period during the January 2005 geomagnetic storms. Large-scale observations using VLF measurements of multiple subionospheric paths to Sodankylä, Finland, are combined with detailed in situ measurements from the DEMETER satellite to determine the spatial extent, flux, and energy distribution of the precipitation. By providing a better picture of both the intensity and size of the precipitation region, we obtain a more complete picture of the net impact that such an event has on the atmosphere.