Results of Ionospheric Observation at Syowa Base, Antarctica, during the Solar Eclipse

Abstract

During the solar eclipse on August 11, 1961, the continuous recording of h'-f observation was made in vertical incidence at Syowa Base in Antarctica, and in spite of the period of very low solar zenith angle, it was possible to find the effect of the eclipse on the ionograms. The recordings at this time were obtained of only the F2 region in the ionosphere, and the variation of electron density during the solar eclipse at a certain height of the F2 region was more remarkable than the variation of the critical frequency. The results of analysis of the observations are summarized as follows: (i) Electron in the F2 region seems to decrease by the attachment process, and the order of magnitude of the attachment coefficient can be estimated at 1.5×10^ to 2.0×10^sec^ at 300km. (ii) On the assumption of the above-mentioned values as the attachment coefficient, the computed values of an electron density during the eclipse show a good agreement with the observational values up to the maximum phase of the eclipse, but beyond the maximum phase, the observational values continue to increase rapidly in electron density until after the end of eclipse. It may be suggested that the phenomena of electron increase are due to an effect such as the ionization of charged particles, (iii) In our observation, the value of scale height obtained, as the attachment process of electron to (O_2) oxygen, is about 30 km at 300 km levels of the F2 layer.