Premium
Coupled SKR Emissions in Saturn's Northern and Southern Ionospheres
Author(s) -
Kivelson Margaret G.,
Jia Xianzhe
Publication year - 2018
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2017gl075425
Subject(s) - saturn , ionosphere , northern hemisphere , physics , southern hemisphere , rotation period , jovian , electron , electron precipitation , atmospheric sciences , magnetosphere , geology , astrophysics , geophysics , astronomy , magnetic field , planet , stars , quantum mechanics
Abstract Kilometric radiation (SKR) emitted above Saturn's auroral ionosphere is modulated in intensity at periods close to the planetary rotation period; SKR periods differ slightly for sources in the north and in the south. Although there is good evidence that the signals are generated independently in the two hemispheres, it is also well established that during southern summer power emitted from the northern hemisphere is modulated in intensity not only at the northern period but also at the southern period, an observation that requires an explanation. We examine the idea that the signal in the north at the southern period is a secondary effect of the strong field‐aligned current system centered at 270° that drives the southern signal. Basing our analysis on studies of field‐aligned current systems in the terrestrial and Jovian magnetospheres, we argue that the parallel electric fields that drive electrons into the southern auroral ionosphere and generate SKR are, at least in part, bidirectional and thus capable of accelerating electrons toward the opposite hemisphere where the secondary signal is detected with intensity lower than that of the locally generated signal. This interpretation implies that the atmospheric process that modulates the periodic responses can operate independently in each hemisphere.