Radio Observations of the Bureau of Standards during the Solar Eclipse of August 31, 1932

Radio observations of the heights of the several layers of the ionosphere were made at Washington, D.C., and Sydney, Nova Scotia, by the pulse method during the afternoon of the solar eclipse of August 31, 1932, and during the afternoons of several days preceding and following. At Washington three separate groups of determinations were made: (1) Measurements of the maximum ionization of the E layer during the afternoon; (2) continual series of measurements of virtual height during the afternoon at 4200 kilocycles which was ordinarily just above the F1critical frequency for the ordinary ray; (3) measurements of the critical frequency of the F2layer during the afternoon. At Sydney, determinations similar to (1) were made and continuous records of virtual height were obtained at 2400 and 3000 kilocycles. Separate equipment was used for each of these groups of determinations so that measurements could be made rapidly and continuously. It was found that the ionization of the E layer decreased to about 30 per cent of its normal value at the time of the eclipse maximum, the variation taking place approximately in phase with the eclipse. The ionization of the F1layer likewise decreased in almost exactly the same manner, reaching a value of about 40 per cent of its normal ionization at about the eclipse maximum. When analyzed by the method presented in this paper, observations of other investigators are found to agree well with these results.