Analysis of excitation of the 630.0 nm airglow during a heating experimentin Tromso on February 16, 1999

During an ionospheric heating experiment in Tromso during February 1999, ar tificial 630.0 nm airglow enhancements have been observed by the auroral la rge imaging system (ALIS). The airglow enhancements took place in the F reg ion of the ionosphere near the heating wave reflection point. Two possible mechanisms are proposed for the explanation of this phenomenon. The first i s the excitation of the O(D-1) state by the energetic electrons from the ta il of the artificially heated thermal electron gas, and the second is the e xcitation of this state by the plasma instability accelerated electrons. Th e detailed spatial and temporal characteristics of the red line airglow are obtained from the ALIS measurements. An analysis of these characteristics based on the models of thermal response of the ionosphere and the atmospher ic optical emissions allows us to draw conclusions about the mechanism of t he interaction between the heating radio wave and the ionospheric plasma. ( C) 2000 Elsevier Science Ltd. All rights reserved.