Long‐term modulations of Saturn's auroral radio emissions by the solar wind and seasonal variations controlled by the solar ultraviolet flux

摘要: [1] Saturn's auroral activities have been suggested to be controlled by the seasonal variations of polar ionospheric conductivities and atmospheric conditions associated with solar extreme ultraviolet (EUV) flux. However, they not yet explained self-consistently only EUV effects. This study investigates long-term Saturnian Kilometric Radiation (SKR) as a proxy activities, which were observed Cassini's Radio Plasma Wave Science experiment mostly during southern summer (DOY (day year) 001 2004 DOY 193 2010). We deduced height distribution SKR source region in Northern (winter) Southern (summer) Hemispheres from remote sensing spectra. The peak spectral density was found up 100 times greater than that northern SKR, altitude flux similar (∼ 0.8 Rs) Hemispheres. densities both hemispheres became comparable each other around equinox August 2009. These results suggest stronger winter related effect, is opposite trend Earth's kilometric radiation. A correlation analysis performed for flux, wind parameters extrapolated orbit an magnetohydrodynamical simulation focusing on timescales longer several weeks. confirmed clear positive correlations between dynamic pressure declining phase cycle. conclude timescale cycle control region. In addition, it also south-to-north ratios power altitudes are positively correlated result strongly supports effect activity over cycles discussed comparison terrestrial case.