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Colour and Tropospheric Cloud Structure of Jupiter from MUSE/VLT: Retrieving a Universal Chromophore
journal contribution
posted on 2020-03-25, 17:05 authored by Ashwin S. Braude, Patrick G. J. Irwin, Glenn S. Orton, Leigh N. FletcherRecent 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 chromophore absorption spectrum directly from the North Equatorial
Belt, and applying it to model spatial variations in colour, tropospheric cloud
and haze structure on Jupiter. We found that we could model both the belts and
the Great Red Spot of Jupiter using the same chromophore compound, but that
this chromophore must exhibit a steeper blue-absorption gradient than the
proposed chromophore of Carlson et al. (2016, Icarus 274, 106-115). We
retrieved this chromophore to be located no deeper than 0.2+/-0.1 bars in the
Great Red Spot and 0.7+/-0.1 bars elsewhere on Jupiter. However, we also
identified some spectral variability between 510 nm and 540 nm that could not
be accounted for by a universal chromophore. 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.
History
Citation
Icarus 338 (2020) 113589Author affiliation
Department of Physics & AstronomyVersion
- AM (Accepted Manuscript)
Published in
IcarusVolume
338Pagination
113589 - 113589Publisher
Elsevier BVissn
0019-1035Acceptance date
2019-11-29Copyright date
2019Available date
2019-12-02Publisher DOI
Publisher version
http://dx.doi.org/10.1016/j.icarus.2019.113589Notes
14 figures + 4 tables, preprint accepted by Icarus on the 29th of November 2019Language
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