Effects of sudden commencements on solar protons at the synchronous orbit

Increases in solar proton flux coincident with sudden commencements have been observed by detectors aboard the geostationary ATS-1 satellite during 1967 and 1968. The flux increases are of short duration (<30 min) and are of magnetospheric origin. Decay of the proton flux after the sudden commencement enhancement (sce) is consistent with pitch angle scattering by hydromagnetic waves.