Colour and tropospheric cloud structure of Jupiter from MUSE/VLT: Retrieving a universal chromophore

Abstract

Recent work by Sromovsky et al. (2017, Icarus 291, 232-244) suggested that all red colour in Jupiter's atmosphere could be explained by a single colour-carrying compound, a so-called 'universal chromophore'. We tested this hypothesis on ground-based spectroscopic observations in the visible and near-infrared (480-930 nm) from the VLT/MUSE instrument between 2014 and 2018, retrieving a In addition, we retrieved a thick, global cloud layer at 1.4 ± 0.3 bars that was relatively spatially invariant in altitude across Jupiter. We found that this cloud layer was best characterised by a real refractive index close to that of ammonia ice in the belts and the Great Red Spot, and poorly characterised by a real refractive index of 1.6 or greater. This may be the result of ammonia cloud at higher altitude obscuring a deeper cloud layer of unknown composition.

Vertical Distribution of Aerosols and Hazes Over Jupiter's Great Red Spot and Its Surroundings in 2016 From HST/WFC3 Imaging

“…chromophore is in reasonable agreement with our values, although we find slightly lower slopes, contrary to the results of Braude et al. (2020). Our lower m i values could be explained by the mixture of the chromophore with low‐absorbing aerosols in the atmosphere, which increases the scattering and results in a general decrease of the measured absorption.…”

“…We find the upper chromophore to be located near the top of the optically thick tropospheric haze, with its base near the 100 mbar level, higher than the lower 200 mbar bound found by Braude et al. (2020). In addition, Sromovsky et al.…”

Characterizing Temperature and Aerosol Variability During Jupiter's 2006–2007 Equatorial Zone Disturbance

“…The contemporaneous decrease of the 8.6‐μm aerosol opacity and coloration at visible wavelengths suggests that the clearing of tropospheric aerosol opacity is responsible for revealing a red chromophore. However, we note that our observations do not constrain the altitude of the chromophore—the decline in opacity at 600–800 mbar could be revealing chromophores at deeper levels, or condensation nuclei at the ∼600‐ to 800‐mbar altitude of NH 3 condensation (Braude et al, 2020; Simon‐Miller et al, 2001), or possibly even at higher altitudes by increasing the path length through upper tropospheric hazes (Sromovsky et al, 2017), although visually the chromophore appears to be similar to that present in the NEB and SEB under normal conditions. The discrepancy between the results of the aforementioned studies clearly shows that the properties and location of this chromophore are still an open question, and it is likely that there is more than one family of chromophores present on Jupiter—those resulting from photochemical processing of materials lofted from depth (e.g., by storms and vortices), and those that provide the coloration of the belts.…”

A Survey of Small‐Scale Waves and Wave‐Like Phenomena in Jupiter's Atmosphere Detected by JunoCam

“…However, we detected an equal number of waves in the southern component of the EZ, where there was not nearly as great a concentration of ammonia gas, so this particular correlation is imperfect. We note that from studies of cloud properties from reflected sunlight, the full EZ is known as a region in which tropospheric clouds and hazes extend higher than other locations on the planet outside the GRS, as evidenced by the general concentration of upper-atmospheric opacity historically (e.g., West et al, 1986) and in more recent work (see Figures 4 and 12 of Sromovsky et al, 2017, and Figure 13B of Braude et al, 2020) or by the distribution of disequilibrium constituents (see Figure 4 of . This is consistent with the entire EZ being a region of general upwelling.…”