Electron measurements bearing on the energy and particle balance of the upperFregion

Electron temperature and density profiles measured between 120 and 630 kilometers at midday at Wallops Island on March 2, 1966, are presented and interpreted. The temperature profile exhibits a strong positive gradient (24°/km) below 150 kilometers followed by a smooth transition to a much smaller positive gradient (1.5°/km) above 300 kilometers. Between 300 and 400 kilometers, the electron concentration decreases with a scale height of about 100 kilometers, which is significantly lower than the diffusive equilibrium scale height for the observed temperatures. Furthermore, the scale height more than doubles between 400 and 500 kilometers. This change in scale height in a region where the mean ion mass and the electron temperature are nearly constant is also inconsistent with diffusive equilibrium and suggests that some dynamic process was occurring at the time of the flight. A simultaneous solution of the particle and energy continuity equations for the F region is carried out with the aid of inputs and boundary conditions from measurements of neutral composition, neutral gas temperature, and ion composition from the same vehicle. This analysis permits us to conclude that the upper F region was not in diffusive equilibrium between 300 and 500 kilometers and that the low plasma scale height at these altitudes was consistent with either a neutral atmospheric wind or a rapid temporal variation in O+.