Comment on “A new approach to Saturn's periodicities” by J. F. Carbary

摘要: The phenomenon of “planetary period oscillations” in Saturn’s magnetosphere was first observed by the Voyager spacecraft via modulations near planetary rotation intensity radio emissions at kilometer wavelengths [Warwick et al., 1981; Desch and Kaiser, 1981], together with related oscillations particles magnetic fields situ within [Carbary Krimigis, 1982; Espinosa Dougherty, 2000]. Subsequent remote observations Saturn kilometric radiation (SKR) Ulysses showed that can change order ~1% over yearly intervals, such cannot be connected directly to body planet [Galopeau Lecacheux, A more recent Cassini discovery has been two variable are generally present SKR data, periods ~10.6 ~10.8 h during southern summer conditions early themission [Kurth 2008; Gurnett 2009a], though later becoming closer together, variable, intervals only one detectable postequinox [Provan 2014; Fischer Cowley Provan, 2015]. As will indicated below, subsequent discussions these have taken correspond oscillation (PPO) phenomena associated Northern Southern Hemispheres planet. In a paper, however, Carbary [2015] suggested “new approach” findings, pointing out simple fact number elementary demonstrations if single sinusoidal is modulated amplitude, frequency, or phase, its frequency spectrum no longer monochromatic andmay become split into peaks principal period, dual PPO modulations. simplest illustrative example signal S(t) consisting “carrier” ω2 whose amplitude sinusoid ω1, for which it shown trigonometry