Joe Kinrade

Measurements of FUV auroral intensity can be used to derive estimates of Saturn's ionospheric Pedersen conductance which can be enhanced above the solar EUV-driven background by up to 20 times following energetic auroral precipitation [Galand+ 2011]. Local time profiles of the auroral intensity reveal spatial and temporal variation in the enhanced ionospheric conductance in response to magnetospheric dynamics. Seasonal variation in large-scale current flows linking the ionosphere and magnetosphere has been observed in Saturn’s polar regions using Cassini magnetic field measurements, implying stronger conductivity in the summer hemisphere than in winter [Bradley+ 2018]. We first aim to answer the question, ‘How do Saturn’s auroral intensities vary with season?’ by applying statistical auroral boundaries - based on the full Cassini UVIS image set [Bader+ 2019] - to auroral images, in order to obtain local time intensity profiles under different seasons in both hemispheres. We then test for evidence of a modest increase in northern conductance between equinox and summer solstice owing to the increasing solar illumination over 2009-2017. We will also examine whether there is any difference between the average conductances predicted in this way for the northern and southern solstice conditions, and how this compares to the south:north conductance ratio of 1.2 associated with the magnetic field asymmetry.