Energy spectrum for auroral-zone X rays: 2. Spectral variability and auroral absorption

Simultaneous measurements of bremsstrahlung x rays and ionospheric absorption in the auroral zone demonstrate the importance of spectral variability in energetic electron precipitation for the interpretation of D-region effects. Although the observations are generally consistent with present knowledge of upper atmospheric processes, they suggest a less dominant role for nighttime detachment below 70–80 km than has previously been assumed.