Reconstruction of precipitated electron fluxes using auroral data

Precipitations of auroral electrons characterize the relationship of the magnetosphere and the upper atmosphere, therefore state of near-Earth space depending on their localization and their intensity. One of the main gaps in both data and modelling is the monitoring of the precipitation of low-energy (0.02 – 35 keV) particles in the ionosphere. These particles are responsible of the surface charging on satellites, which lead to trigger electrostatic discharge (ESD) on components. This impact is the most recurrent in space and need to better understand. The method present here, allows an alternative to particle detectors that do not have access to this area.

From optical data, it can be very interesting to reconstruct low energy electron flux in the aurora region. Therefore, the interpretation of the auroral intensities is made using the Transsolo code, a kinetic code which use as input the electron flux and the solar EUV flux on the dayside. It calculates the transport of the suprathermal electrons along a line of sight or a vertical and the subsequent auroral emissions. A optimization method is worked to trying to retrieve electron flux from optical measurements.

The study present here is based on ALIS network data which provides very useful data (Brandstorm, 2003). Tomographic data of the volume emission rate are built from ALIS measurements (Gustavsson, 2000). From tomographic data and transsolo simulations, we adapt the optimization method to reconstruct energetic particles flux. We focus on measurements of the event of 05 March 2008 at 18:41:30 UT and 18:42:40 UT acquired by 5 stations and centred above Skibotn city. Results are presented in the form of maps of mean energy and total energy (corresponding to the energy flux) depending on geographic coordinates.