Could negative ion production explain the polar mesosphere winter echo (PMWE) modulation in active HF heating experiments

Kero, A., C.-F. Enell, A. J. Kavanagh, J. Vierinen, I. Virtanen, E. Turunen, Geophys. Res. Lett., 35, L23102, doi:10.1029/2008GL035798 2008