ULYSSES RADIO AND PLASMA-WAVE OBSERVATIONS AT HIGH SOUTHERN HELIOGRAPHIC LATITUDES

Ulysses spacecraft radio and plasma wave observations indicate that so me variations in the intensity and occurrence rate of electric and mag netic wave events are functions of heliographic latitude, distance fro m the sun, and phase of the solar cycle. At high heliographic latitude s, solar type III radio emissions did not descend to the local plasma frequency, in contrast to the emission frequencies of some bursts obse rved in the ecliptic, Short-duration bursts of electrostatic and elect romagnetic waves were often found in association with depressions in m agnetic field amplitude, known as magnetic holes. Extensive wave activ ity observed in magnetic clouds may exist because of unusually large e lectron-ion temperature ratios. The lower number of intense in situ wa ve events at high latitudes was likely due to the decreased variabilit y of the high-latitude solar wind.