Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Interpretation of shadows and antishadows on Saturn and the evidence
  against south polar eyewalls   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 in this region have
detected no optically thick wall clouds and no significant variation in
pressures of the model cloud layers, and (4) there is an alternative
explanation that is much more consistent with observations. The most plausible
scenario is that the shadows near 87.9 deg S and 88.9 deg S are both cast by
overlying translucent aerosol layers from edges created by step decreases in
their optical depths, the first in the stratospheric layer at the 50 mbar level
and the second in a putative diphosphine layer near 350 mbar, with optical
depths reduced at the poleward side of each step by 0.15 and 0.12 respectively
at 752 nm. These steps are sufficient to create shadows of roughly the correct
size and shape, falling mainly on the underlying ammonia ice layer near 900
mbar, and to create the bright features we call antishadows.

10
The categories of this paper are: q-bio
2
The categories of this paper are: math
32
The categories of this paper are: atom-ph
31
The categories of this paper are: ao-sci
13
The categories of this paper are: quant-ph
17
The categories of this paper are: q-fin
1
The categories of this paper are: cs
19
The categories of this paper are: eess
25
The categories of this paper are: patt-sol
3
The categories of this paper are: physics
29
The categories of this paper are: funct-an
0
The categories of this paper are: hep-ph
37
The categories of this paper are: supr-con
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The categories of this paper are: acc-phys
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The categories of this paper are: chao-dyn
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The categories of this paper are: nucl-th