Direct evidence for solar wind control of Jupiter’s hectometer‐wavelength radio emission

Observations of the solar wind close to Jupiter by the Voyager 1 and Voyager 2 spacecraft in 1978 and 1979 are compared with the hectometer‐wavelength radio emission from the planet. A significant positive correlation is found between variations in the solar wind plasma density at Jupiter and the level of Jovian radio emission output. During the 173‐day interval studied for the Voyager 2 data the radio emission displayed a long‐term periodicity of about 13 days, identical to that shown by the solar wind density at Jupiter and consistent with the magnetic sector structure association already proposed for ground‐based observations of the decameter‐wavelength emission.