A Keogram Analysis of Local Time Variations of Jupiter’s Ultraviolet Aurora using Juno UVS Observations

With 20 successfully completed Perijoves, Juno UVS has collected an enormous amount of data with unprecedented views of the northern and southern auroras spanning all local time geometries. Juno UVS, with its spectral and spatial mapping capabilities allows for the retrieval of both UV brightness as well as color ratio information. Maps of both the brightness and color ratio of the main ovals and polar emissions display strong local time variations, some suggestive of ionospheric local time control while others magnetosphere local time drivers. In an attempt to quantitatively track the evolution of the auroral emission morphology and intensity, we have developed a process to create keograms of Jupiter’s auroral emissions. The keograms display a complicated evolution of northern and southern auroral emissions that depend not only on local time, but also on the overall state of the magnetosphere which varies perijove to perijove. We will present our method of producing the keograms and discuss insights we have drawn from them. Additionally, we present an attempt to trace the origin within the magnetodisk of the observed emissions via magnetic flux mapping using the Vogt et al. 2015 model updated to include the JRM09 magnetic field model.