Correlations between atomic oxygen airglow and radio wave absorption in winter

The correlation at latitude 37°N between zenith brightness of 557.7 nm atomic oxygen airglow and short wave radio wave absorption was investigated. A correlation seems to exist only when the amount of absorption is relatively low and does not exceed a certain critical value. Electron density profiles measured when the radio wave absorption was slightly below the critical value, slightly above it, and winter-anomalous show that the main contribution to absorption is shifted to lower heights when absorption increases and becomes winter-anomalous. Results of DC probe measurements suggest that the atmospheric temperature increases when this change occurs.