Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Altitude of an Infrared Bright Cloud Feature on Neptune from
  Near-Infrared Spectroscopy   We present 2.03-2.30 micron near-infrared spectroscopy of Neptune taken 1999
June 2 (UT) with the W.M. Keck Observatory's near-infrared spectrometer
(NIRSPEC) during the commissioning of the instrument. The spectrum is dominated
by a bright cloud feature, possibly a storm or upwelling, in the southern
hemisphere at approximately 50 degrees S latitude. The spectrum also includes
light from a dimmer northern feature at approximately 30 degrees N latitude. We
compare our spectra (R ~ 2000) of these two features with a simple model of
Neptune's atmosphere. Given our model assumption that the clouds are flat
reflecting layers, we find that the top of the bright southern cloud feature
sat at a pressure level of 0.14 (+0.05, -0.03) bar, and thus this cloud did not
extend into the stratosphere (P < 0.1 bar). A similar analysis of the dimmer
northern feature gives a cloud-top pressure of 0.084 +/- 0.026 bar. This
suggests that the features we observed efficiently transport methane to the
base of the stratosphere, but do not directly transport methane to the upper
stratosphere (P < 0.01-0.001 bar) where photolysis occurs. Our observations do
not constrain how far these clouds penetrate down into the troposphere. We find
that our model fits to the data restrict the fraction of molecular hydrogen in
ortho/para thermodynamic equilibrium to greater than 0.8.

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The categories of this paper are: cond-mat
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The categories of this paper are: nlin
35
The categories of this paper are: mtrl-th
36
The categories of this paper are: cmp-lg
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The categories of this paper are: comp-gas
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The categories of this paper are: bayes-an
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The categories of this paper are: q-alg
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The categories of this paper are: plasm-ph
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The categories of this paper are: q-fin
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The categories of this paper are: funct-an
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The categories of this paper are: hep-th
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The categories of this paper are: chem-ph
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The categories of this paper are: q-bio
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The categories of this paper are: hep-ph
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The categories of this paper are: physics
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The categories of this paper are: gr-qc