The Twelve-Year Periodicities of the Decametric Radiation of Jupiter


  • Thomas D. Carr,

  • Alex G. Smith,

  • Frank F. Donivan,

  • Henry I. Register


Three parameters of Jupiter's decametric radiation which apparently undergo cyclic variations with periods of the order of a decade are the mean occurrence probability for an apparition, the central meridian longitude of the main source, and the effective width of the main source (or Source A). Observational results indicate that the oscillation in each parameter is caused by the apparent change in Jupiter's aspect as it orbits the sun and that the period in each case is therefore 11.86 yr. It was found that the average rotation period over an 11.86 year interval is 9h 55m 29.73s±0.04s. This is probably the rotation period of Jupiter's magnetic field.