Association of corotating magnetic sector structure with Jupiter's decameter-wave radio emission

Chree (superposed epoch) analyses of Jupiter's decameter-wave radio emission taken from the new Thieman (1979) catalog show highly significant correlation with solar activity, indicated by the geomagnetic Ap index. The correlation effects can be explained in terms of corotating interplanetary magnetic sector features. At times when the solar wind velocity is relatively low, about 300 to 350 km/s, a sector boundary can encounter the earth and Jupiter almost simultaneously during the period immediately before opposition. After opposition this will not normally occur, as the solar wind velocities necessary are too low. The correlation effects are much enhanced for the three apparitions of 1962--1964, during which a relatively stable and long-lived sector pattern was present. Chree analyses for this period indicate periodicities, equal to approximately half the solar rotation period, in the Jupiter data