Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Optical Observations of Meteors Generating Infrasound - I: Acoustic
  Signal Identification and Phenomenology   We analyze infrasound signals from 71 bright meteors simultaneously detected
by video to investigate the phenomenology and characteristics of
meteor-generated near-field infrasound and shock production. A taxonomy for
meteor generated infrasound signal classification has been developed using the
time-pressure signal of the infrasound arrivals. Based on the location along
the meteor trail where the infrasound signal originates, we find most signals
are associated with cylindrical shocks, with about a quarter of events
evidencing spherical shocks associated with fragmentation events and optical
flares. The video data indicate that all events with ray launch angles >117 deg
from the trajectory heading are most likely generated by a spherical shock,
while infrasound produced by the meteors with ray launch angles <117 deg can be
attributed to both a cylindrical line source and a spherical shock. We find
that meteors preferentially produce infrasound toward the end of their trails
with a smaller number showing a preference for mid-trail production. Meteors
producing multiple infrasound arrivals show a strong infrasound source height
skewness to the end of trails and are much more likely to be associated with
optical flares. While a significant fraction of our meteors producing
infrasound (~1/4 of single arrivals) are produced by fragmentation events, we
find no instances where acoustic radiation is detectable more than about 60 deg
beyond the ballistic regime at our meteoroid sizes (grams to tens of kg)
emphasizing the strong anisotropy in acoustic radiation for meteors which are
dominated by cylindrical line source geometry, even in the presence of
fragmentation.

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The categories of this paper are: patt-sol
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The categories of this paper are: supr-con
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The categories of this paper are: bayes-an
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The categories of this paper are: math
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The categories of this paper are: cmp-lg
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The categories of this paper are: alg-geom
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The categories of this paper are: cond-mat
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The categories of this paper are: nlin
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The categories of this paper are: atom-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: stat
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The categories of this paper are: nucl-th
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The categories of this paper are: quant-ph
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The categories of this paper are: econ
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The categories of this paper are: eess
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The categories of this paper are: hep-th