Parallel electric fields:: variations in space and time on auroral field lines

We present results from a particle-fluid simulation of auroral electrons and discuss the distribution of parallel electric fields along aurora] field lines and the processes occurring during the build up of these electric fields. Neglecting field-aligned ion dynamics, the main potential drop has a width of about 5000 km and is centered at an altitude of roughly 5000 km. We find that the gradient in the potential becomes steeper and the build up of the potential drop becomes faster if the temperature of the magnetospheric electrons is lower.