Ionospheric electron density profiles inverted from a spectral riometer measurement

The first implementation of the so‐called spectral riometertechnique for the ionospheric electron density profile estimation is presented. In contrast to the traditional riometer operating at a single frequency, this experiment monitors the cosmic radio noise at 244 frequencies, ranging between 10 and 80 MHz, by using the new Kilpisjärvi Atmospheric Imaging Receiver Array radio telescope. The received power at each time and frequency is compared to the corresponding quiet‐day value, resulting in the cosmic radio noise absorption spectrum as a measurement of ionization in the ionosphere. In this study, the observed absorption spectrum is used to invert the corresponding electron density profile by applying a simple parameterized electron precipitation model. By comparing the inverted electron density profiles to a simultaneous and nearly colocated European Incoherent Scatter VHF radar measurement on 13–14 November 2012, we show that the spectral riometry approach is capable of producing realistic electron density profiles under conditions of substorm‐related electron precipitation. Spectral riometer measurement is introduced and implemented for the first timeA novel inversion of the ionospheric electron density profile is presentedA good general agreement with the EISCAT reference data is found