%0 Journal Article
%F self-archiving-INPE-MCTIC-GOV-BR
%A Mendonça, Fernando de,
%@affiliation Comissão Nacional de Atividades Espaciais
%T Ionospheric electron content and variations measured by doppler shifts in satellite transmissions
%B Journal of Geophysical Research
%D 1962
%V 67
%N 6
%8 June
%X A method is derived for calculating ionospheric electron content by comparison of the Doppler shifts imparted to two harmonically related frequencies transmitted from a satellite. This Doppler method is applied in the analysis of many passages of the satellite Transit 2-A (1960η1) during the months of July through October 1960. The observations were made at Stanford, California, on the frequencies of 54 Mc/s and its sixth harmonic. Differences in the electron content of 25 per cent between two subionospheric points separated by as little as 1000 km were observed on several passages during magnetically quiet days. On some magnetically disturbed days these differences increased to over 50 per cent for the same separation. A very strong magnetic storm is shown to decrease the early-afternoon electron content to almost a normal nighttime value over the range of latitudes surveyed. Other less intense storms are observed to decrease the electron content to the north and to increase it to the south of the observer. The day-to-day variations of electron content at a given latitude on magnetically quiet days are observed to be about ±15 per cent from the mean; however, less frequently, variations as large as ±50 per cent were observed. Unlike the variations on the magnetically disturbed days, these variations did not seem to modify the horizontal gradients normally found.
%P 2315-2337
%O google Acadêmico: 68
%O Web of Scince: 11
%@language en
%9 journal article