Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Scanning Lidar Based Atmospheric Monitoring for Fluorescent Detectors of
  Cosmic Showers   Measurements of the cosmic-ray air-shower fluorescence at extreme energies
require precise knowledge of atmospheric conditions. The absolute calibration
of the cosmic-ray energy depends on the absorption of fluorescence light
between its origin and point of its detection. To reconstruct basic atmospheric
parameters we review a novel analysis method based on two- and multi-angle
measurements performed by the scanning backscatter lidar system. Applied
inversion methods, optical depth, absorption and backscatter coefficient, as
well as other parameters that enter the lidar equation are discussed in
connection to the attenuation of the light traveling from shower to
fluorescence detector.

34
The categories of this paper are: chem-ph
19
The categories of this paper are: eess
18
The categories of this paper are: econ
33
The categories of this paper are: plasm-ph
11
The categories of this paper are: hep-lat
36
The categories of this paper are: cmp-lg
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The categories of this paper are: mtrl-th
12
The categories of this paper are: nucl-th
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The categories of this paper are: nucl-ex
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The categories of this paper are: funct-an
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The categories of this paper are: supr-con
20
The categories of this paper are: acc-phys
2
The categories of this paper are: math
9
The categories of this paper are: nlin
32
The categories of this paper are: atom-ph
22
The categories of this paper are: chao-dyn