On mechanisms for high-frequency pump-enhanced optical emissions at 557.7 and 630.0 nm from atomic oxygen in the high-latitude F-region ionosphere. - Leyser, Thomas B.; Sergienko, Tima; Brändström, Urban; Gustavsson, Björn; Rietveld, Michael T. (Annales Geophysicae (ANGEO) (09927689), 2023)