Interpretation of shadows and antishadows on Saturn and the evidence against south polar eyewalls
Lawrence A. Sromovsky, Patrick M. Fry, Kevin H. Baines

TL;DR
This paper challenges the interpretation of Saturn's south polar shadows as hurricane-like eyewalls, proposing instead that they are caused by translucent aerosol layers with optical depth steps, supported by radiative transfer modeling.
Contribution
It provides a new explanation for Saturn's south polar shadows, arguing against the hurricane eyewall analogy and supporting a model involving aerosol layer edges.
Findings
Shadows are caused by aerosol layer edges, not eyewalls.
Optically thick eyewalls would produce different brightness patterns.
Shadow features are consistent with optical depth steps in aerosol layers.
Abstract
Cassini spacecraft observations of Saturn in 2006 revealed south polar cloud shadows, the common interpretation of which was initiated by Dyudina et al. (2008, Science 319, 1801) who suggested they were being cast by concentric cloud walls, analogous to the physically and optically thick eyewalls of a hurricane. Here we use radiative transfer results of Sromovsky et al. (2019, Icarus, doi.org/10.1016/j.icarus.2019.113398), in conjunction with Monte Carlo calculations and physical models, to show that this interpretation is almost certainly wrong because (1) optically thick eyewalls should produce very bright features in the poleward direction that are not seen, while the moderately brighter features that are seen appear in the opposite direction, (2) eyewall shadows should be very dark, but the observed shadows create only 5-10\% I/F variations, (3) radiation transfer modeling of clouds…
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