Electron concentrations and electron and ion temperatures in the F region for magnetically quiet and disturbed conditions

Abstract

Incoherent backscatter measurements of the F-region electron concentrations and electron and ion temperatures were made at Arecibo during the sudden commencement magnetic storm of June 15-16, 1965, and a few magnetically quiet days in the same season. The results obtained are used to describe the quiet and disturbed day diurnal behavior of the shape of the electron concentration profile, the contours of constant plasma frequency, the plasma density scale heights in the topside ionosphere, and the electron and ion temperatures. Storm-day deviations of some of the important F-region parameters were also calculated, and their temporal variations are presented. In response to the strong magnetic storm, the electron concentrations in the topside ionosphere are enhanced by a factor of 1.5-2.0 and the nighttime plasma density scale heights by a factor of 2.0-3.0. The electron temperatures under disturbed conditions are 200-300°K higher than the quiet day values during nighttime, whereas the daytime changes are within the limits of day to day variations. The changes in the ion temperatures, which are found to be appreciable during the daytime, suggest that under disturbed conditions the ion temperature is coupled to the neutral temperature to a greater height level than during quiet conditions. A significant amount of storm-associated heating of the nighttime F region is evident from the electron-to-ion temperature ratios that are found to be above 1.5 throughout the night in the height range 225-450 km.