Statistical distribution of ion cyclotron waves in Saturn’s inner magnetosphere: A survey of Cassini measurements between 2004 and 2016

<p>Based on Cassini observations from 2004 to 2016, we perform a comprehensive analysis of the statistical distribution of the occurrence rate, averaged amplitude, wave normal angle (WNA), ellipticity and power spectral intensity of ion cyclotron waves in Saturn&#8217;s inner magnetosphere. Our results show that ion cyclotron waves mainly occur between the orbits of Enceladus and Dione near the equatorial region (&#955;<20&#176;), with higher occurrence rates in the northern hemisphere than the southern hemisphere. The averaged wave amplitudes vary between 0.1&#8211;2 nT with a strong day-night asymmetry and a pronounced minimum at the equator. Saturnian ion cyclotron waves are predominantly left-handed polarized with small WNAs near the equator, and become linearly polarized with larger WNAs at higher latitudes. The major wave power occurs frequently at frequencies of 0.5-1.2 <em>f</em>_w+, where <em>f</em>_w+is the equatorial gyrofrequency of H₂O⁺ ions, with the strongest intensity (>~10 nT²/Hz) at L~6.5 statistically present in the midnight sector.</p>