| dc.description.abstract | This report presents F-region electron densities, and electron and ion temperatures observed during the year 1965 at the Millstone Hill Radar Observatory (42.6°N. 71.5“W) by the UHF Thomson (incoherent) scatter radar. The measurements were made over 48-hour periods that were usually scheduled to include the International Geophysical World days near the center of each month. Geomagnetic storm sudden commencements occurred during two of the observing periods, but do not appear to have given rise to marked variation of the densities or temperatures. On the other band, measurements made during the progress of a major storm (15-19 June 1965) exhibit large changes compared with the behavior observed in the following month. The remaining months were magnetically quiet, and the density and temperature behavior were similar to those observed in 1964. Millstone is a midlatitude station exhibiting a characteristic “winter” and "summer” daytime density variation. The transition between these two types occurs rapidly around equinox, without any corresponding seasonal change in the F-region thermal structure. Current ideas concerning the mechanisms responsible for this and other features of diurnal and seasonal variations arc discussed. | en_US |
