Mikhail V. Panchenko

New periodicity in Jovian decametric radio emission

[1]xa0We report on the finding of a new periodicity in the Jovian decametric radio emission (DAM). Periodic bursts of non-Io component of DAM which recur with a period 1.5% longer than the Jupiter rotation (System III) have been found in the dynamic radio spectra acquired by STEREO/WAVES, Wind/WAVES and Cassini/RPWS during the years 2002–2008. Typically, the bursts appear very periodically over several Jovian days with a decreasing intensity and they display a negative frequency drift. All the bursts were detected within the same sector of Jovian Central Meridian Longitude (III), between 300° and 60° (via 360°) of CML (III), close to the region of the non-Io-C source. No correlation has been found with the position of Io. Considering the simultaneous stereoscopic observations onboard STEREO-A and STEREO-B, as well as Wind and Cassini we can conclude that the sources of the periodic bursts most probably sub-corotate with Jupiter.

Daily variations of auroral kilometric radiation observed by STEREO

[1]xa0Daily variations of terrestrial auroral kilometric radiation (AKR) are considered; an effect that is detected in STEREO/WAVES data. It has been found that the intensities of the AKR emitted from Northern and Southern sources are modulated with a period of ∼24 hours. The occurrence frequency of the AKR has been shown to be strongly dependent on the orientation of the rotating oblique magnetic dipole of the Earth relative to the Sun. AKR is found to occur more often and emit in a broader frequency range when the axis of the terrestrial magnetic dipole in the given hemisphere is oriented toward the nightside. We suggest that the observed ∼24 h variations of AKR are connected with diurnal changes of the ambient plasma density in the auroral region.