Millstone Hill Thomson Scatter Results for 1964

Abstract

Thomson scatter (incoherent backscatter) observations of the ionosphere were made at Millstone Hill at a wavelength of 68 cm during 1964, for 30-hour periods every two weeks. These data have been employed to derive the mean hourly F-region (200 to 700 km) electron density profile and electron and ion temperature curves in each month. The results are presented in this report, together with the derived seasonal variation of electron density (at 0600, 1200, 1800 and 2400 hours local time) and the average daytime (0900 to 1500) and nighttime (2100 to 0300) electron and ion temperature behavior. Separate measurements with a 23-cm radar permitted the temperature results reported to be extended to lower altitudes (~130 km) and, in addition, provided information concerning the ionic constituents between 130 and 230 km. Although 1964 was at sunspot minimum, the seasonal variation in f[subscript o]F2 was quite evident. It is shown that this feature is strictly associated with the peak of the layer and that densities above 400-km altitude are highest at the equinoxes. No seasonal variations of temperature are found which might be large enough to account for the phenomenon. At night the peak densities are highest in summer, and the temperatures at all altitudes highest in winter. This last effect is believed largely due to heat conducted from the protonosphere, which in winter continues to be heated by photoelectron escape from the conjugate ionosphere which remains sunlit throughout the night.