Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: 15 years of VLT/UVES OH intensities and temperatures in comparison with
  TIMED/SABER data   The high-resolution echelle spectrograph UVES of the Very Large Telescope at
Cerro Paranal in Chile has been regularly operated since April 2000. Thus, UVES
archival data originally taken for astronomical projects but also including sky
emission can be used to study airglow variations on a time scale longer than a
solar cycle. Focusing on OH emission and observations until March 2015, we
considered about 3,000 high-quality spectra from two instrumental set-ups
centred on 760 and 860 nm, which cover about 380 nm each. These data allowed us
to measure line intensities for several OH bands in order to derive band
intensities and rotational temperatures for different upper vibrational levels
as a function of solar activity and observing date. The results were compared
with those derived from emission and temperature profile data of the radiometer
SABER on the TIMED satellite taken in the Cerro Paranal area between 2002 and
2015. In agreement with the SABER data, the long-term variations in OH
intensity and temperature derived from the UVES data are dominated by the solar
cycle, whereas secular trends appear to be negligible. Combining the UVES and
SABER results, the solar cycle effects for the OH intensity and temperature are
about 12 to 17% and 4 to 5 K per 100 sfu and do not significantly depend on the
selected OH band. The data also reveal that variations of the effective OH
emission layer height and air density can cause significant changes in the OH
rotational temperatures due to a varying ratio of OH thermalising collisions by
air molecules and OH radiation, deactivation, and destruction processes which
impede the rotational relaxation. However, this effect appears to be of minor
importance for the explanation of the rotational temperature variations related
to the solar activity cycle, which causes only small changes in the OH emission
profile.

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The categories of this paper are: stat
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The categories of this paper are: solv-int
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The categories of this paper are: adap-org
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The categories of this paper are: nlin
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The categories of this paper are: patt-sol
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The categories of this paper are: mtrl-th
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The categories of this paper are: hep-ex
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The categories of this paper are: econ
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The categories of this paper are: bayes-an
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The categories of this paper are: eess
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The categories of this paper are: chem-ph
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The categories of this paper are: gr-qc
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The categories of this paper are: cond-mat
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The categories of this paper are: dg-ga
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The categories of this paper are: nucl-th
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The categories of this paper are: math-ph