Comparison of the characteristic energy of precipitating electrons derived from ground-based and DMSP satellite data

Energy maps are important for ionosphere- magnetosphere coupling studies, because quantitative de- termination of field-aligned currents requires knowledge of the conductances and their spatial gradients. By combin- ing imaging riometer absorption and all-sky auroral optical data it is possible to produce high temporal and spatial reso- lution maps of the Maxwellian characteristic energy of pre- cipitating electrons within a 240◊240 km 2 common field of view. These data have been calibrated by inverting EIS- CAT electron density profiles into equivalent energy spec- tra. In this paper energy maps produced by ground-based instruments (optical and riometer) are compared with DMSP satellite data during geomagnetic conjunctions. For the pe- riod 1995-2002, twelve satellite passes over the ground- based instruments' field of view for the cloud-free condi- tions have been considered. Four of the satellite conjunctions occurred during moderate geomagnetic, steady-state condi- tions and without any ion precipitation. In these cases with Maxwellian satellite spectra, there is 71% agreement be- tween the characteristic energies derived from the satellite and the ground-based energy map method.