Variation of the green line oxygen airglow emission rate as a precursor indicative of wintertime absorption anomaly of HF radio waves

Airglow emission of the E layer was observed from the ground at nighttime during the Winter Anomaly Campaign at Arenosillo, Spain, winter 1975/76. A comparison of these optical data with the HF waves ionospheric absorption values of the following day indicates that a special kind of variation of the airglow emission can be used as a precursor indicative for an increase of the ionospheric D region absorption on the following day.