Unambiguous evidence of HF pump-enhanced airglow at auroral latitudes

Simultaneous observations by up to three low-light imaging stations belongi ng to the Auroral Large Imaging System (ALIS) have provided the first stron g evidence of high-frequency (HF) pump-enhanced airglow at auroral latitude s. The airglow was enhanced by an ordinary mode 4.04 MHz electromagnetic wa ve with an effective radiated power (ERP) of about 210 MW that was transmit ted from the EISCAT-Heating facility near Troms phi, Norway. While often ob served at low or mid-latitudes, and despite numerous earlier experiments, n o unambiguous observations of pump-enhanced airglow have been reported at a uroral latitudes. On February 16, 1999, the first successful results were o btained, and this paper concentrates on discussing optical data from this e vent. Triangulated estimations of the altitude and position of the enhanced airglow are also presented. Auroral-latitude observations of HF pump-enhan ced airglow are important in order to better understand the underlying exci tation mechanisms.