A NEW COMPONENT OF JOVIAN KILOMETRIC RADIO-EMISSION

Evidence is presented for a new Jovian radio emission component in the frequency range from approximately 40 to approximately 200 kHz observed during the Ulysses-Jupiter outbound pass at high Jovian southern latitudes along the dusk terminator. The new radio component (referred to as sKOM) occurs in the same frequency range as the observed broadband kilometric (bKOM) radio emission, but its characteristics are distinctly different. It has the opposite polarizati on, is about 100 times weaker, and has a characteristically smooth intensity profile. It is consistently observed in the longitudinal range from approximately 120-degrees to approximately 230-degrees central meridian longitude, where the intermittent bKOM is often absent, and is found to originate in the Jovian magnetosphere about 5R(J) from Jupiter and at a latitude of about 35-degrees-S. Its observed right-hand circular polarization suggests that it is generat ed in the O mode in the source region.