Vertical Structure and Color of Jovian Latitudinal Cloud Bands during the Juno Era

Abstract

The identity of the coloring agent(s) in Jupiter’s atmosphere and the exact structure of Jupiter’s uppermost cloud deck are yet to be conclusively understood. The Crème Brûlée model of Jupiter’s tropospheric clouds, originally proposed by Baines et al. and expanded upon by Sromovsky et al. and Baines et al., presumes that the chromophore measured by Carlson et al. is the singular coloring agent in Jupiter’s troposphere. In this work, we test the validity of the Crème Brûlée model of Jupiter’s uppermost cloud deck using spectra measured during the Juno spacecraft’s fifth perijove pass in 2017 March. These data were obtained as part of an international ground-based observing campaign in support of the Juno mission using the New Mexico State University Acousto-optic Imaging Camera at the 3.5 m telescope at Apache Point Observatory in Sunspot, NM, USA. We find that the Crème Brûlée model cloud-layering scheme can reproduce Jupiter’s visible spectrum both with the Carlson et al. chromophore and with modifications to its imaginary index of refraction spectrum. While the Crème Brûlée model provides reasonable results for regions of Jupiter’s cloud bands such as the North Equatorial Belt and Equatorial Zone, we find that it is not a safe assumption for unique weather events, such as the 2016–2017 Southern Equatorial Belt outbreak that was captured by our measurements.