I'm happy to announce that our proof-of-concept study on the electron density profile estimation based on the KAIRA spectral riometry measurement has been finally published in the Geophysical Research Letters, please have a look:
Kero, A., J. Vierinen, D. McKay-Bukowski, C.-F. Enell, M. Sinor, L. Roininen, and Y. Ogawa (2014), Ionospheric electron density profiles inverted from a spectral riometer measurement, Geophys. Res. Lett., 41, doi:10.1002/2014GL060986
By comparing our spectral riometry results to a simultaneous EISCAT VHF measurement, we were able to show that the methodology works, at least under conditions of relatively strong ionisation. This builds confidence towards continuous monitoring of height-dependent D-region ionisation by spectral riometry.