Millstone Hill Thomson Scatter Results for 1967

Abstract

This report summarizes results for the electron density distribution and electron temperature of the F-region obtained during 1967 using the Millstone Hill (42.6“N, 71.5°W) Thomson (incoherent) scatter radar system. These data, for the height interval of approximately 200 to 800 km, were gathered over 24-hour observing periods twice per calendar month. The time required to obtain a complete electron density and temperature profile over this height interval was 30 minutes. The results show a far wider range of behavior than that encountered in previous years. This is attributed to the increase in magnetic activity as sunspot maximum is approached. On magnetically quiet days, the characteristic behavior observed previously for electron density manifests itself. Winter days exhibit a maximum at all levels near noon and a weaker maximum at the layer peak in the early morning (0200 to 0400 EST), while summer days exhibit a maximum near sunset and only a small day-to-night change in density near the layer peak. Two days exhibited a pattern of behavior, first noted in 1965, that appears characteristic of many storms. This consists of an increase in density on the afternoon of the first day of the storm followed by a marked decrease the next morning. Other days show instances of nocturnal heating and erratic behavior of the F-region electron density at night. We believe that on several occasions in 1967 the plasmapause boundary moved south of Millstone giving rise to a rapid fall in f[subscript o]F2 and to much of the irregular behavior observed at night.