Dawn-dusk oscillation of Saturn's conjugate auroral ovals

Abstract

We present observations of the oscillation of the dawn-dusk locations of Saturn's northern and southern UV auroral ovals obtained using the Hubble Space Telescope during the 2009 equinoctial campaign. We determine the dawn-dusk locations of the centers of the southern and northern auroral ovals from the mean of the dawnward and duskward extents of the emission, and order the computed locations by the phases of the respective SKR oscillations for each hemisphere. We show that statistically significant ∼1-2 oscillations of the dawn-dusk location of the auroral ovals are evident, with the duskward displacement being in lagging quadrature with the SKR power. These results, the first to indicate that the location of the northern auroral oval oscillates, show that the cause of the oscillation is an external magnetospheric current system, and the sense of the oscillations is consistent with the expected displacement caused by magnetic perturbations observed throughout Saturn's magnetosphere. © 2010 by the American Geophysical Union.