High-energy electron fluxes derived from EISCAT electron density profiles

Two different methods for deriving the flux-energy spectrum of precipitating electrons from EISCAT electron density profiles are compared. The first method uses ionisation rates calculated from electron densities using an average effective recombination model followed by direct inversion using matrix algebra. The second method uses a seasonally and solar-zenith dependent model of D-region ion-chemistry to relate spectral hardness to the height of maximum absorption of 30 MHz radio waves, and the total absorption to the total flux. Incremental absorption profiles calculated from EISCAT electron density profiles can then be used to find the corresponding flux-energy spectra. The results of the two methods are compared with each other and with measured electron fluxes from a rocket experiment. The first method is found to give good results for electron energies less than a few tens of keV but not for higher energies where the recombination coefficient model is inadequate. The second method is found to give more reliable results for high energy electrons, 20-300 keV, but is not sensitive to lower energies..