J/A+A/654/A108 Triple-frequency meteor radar reflection coeff. (Stober+, 2021)
Triple-frequency meteor radar full wave scattering.
Measurements and comparison to theory.
Stober G., Brown P., Campbell-Brown M., Weryk R.J.
<Astron. Astrophys. 654, A108 (2021)>
=2021A&A...654A.108S 2021A&A...654A.108S (SIMBAD/NED BibCode)
ADC_Keywords: Solar system ; Meteorites ; Models
Keywords: meteorites, meteors, meteoroids - plasmas -
techniques: radar astronomy - scattering
Abstract:
Radar scattering from meteor trails depends on several poorly
constrained quantities, such as electron line density, q, initial
trail radius, r0, and ambipolar diffusion coefficient, D.
The goal is to apply a numerical model of full wave backscatter to
triple frequency echo measurements to validate theory and constrain
estimates of electron radial distribution, initial trail radius, and
the ambipolar diffusion coefficient.
A selection of 50 transversely polarized and 50 parallel polarized
echoes with complete trajectory information were identified from
simultaneous tri-frequency echoes recorded by the Canadian Meteor
Orbit Radar (CMOR). The amplitude-time profile of each echo was fit to
our model using three different choices for the radial electron
distribution assuming a Gaussian, parabolic exponential, and 1-by-r2
electron line density model. The observations were manually fit by
varying, q, r0, and D per model until all three synthetic
echo-amplitude profiles at each frequency matched observation.
The Gaussian radial electron distribution was the most successful at
fitting echo power profiles, followed by the 1/r2. We were unable to
fit any echoes using a profile where electron density varied from the
trail axis as an exponential-parabolic distribution. While fewer than
5% of all examined echoes had self-consistent fits, the estimates of
r0 and D as a function of height obtained were broadly similar to
earlier studies, though with considerable scatter. Most meteor echoes
are found to not be described well by the idealized full wave
scattering model.
Description:
Tables from full wave scattering model for 6 frequencies at
17.45, 29.85, 32.55, 36.20, 38.15, 53.5 MHz.
The tables have 11 columns consisting of the trail radius r0 (m/s),
the critical radius for the overdense to underdense transition rc
(m/s), the boundary matching radius rb (m/s), the parallel and
perpendicular reflection coefficients gE and gH, the phases of the
parallel and perpendicular reflection coefficients, the polarization
between perpendicular and parallel reflection coefficient, the
electron line density q (e-/m, the order of the Bessel and Hankel
functions included in the solution, and finally an arbitrary scaling
factor for comparisons with previous studies (kr2).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea.dat 44 18 List of tables from full wave scattering model
for 6 frequencies
files/* . 18 Individual files
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Byte-by-byte Description of file: tablea.dat
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Bytes Format Units Label Explanations
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1- 5 F5.2 MHz Freq Frequency
7- 11 A5 --- Model Model (1byr2, Gauss or parab)
13- 44 A32 --- FileName Name of the table in subdirectory files
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Byte-by-byte Description of file: files/*
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Bytes Format Units Label Explanations
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1- 8 F8.5 m/s r0 Trail radius
10- 16 F7.5 m/s rc Critcritical radius for the overdense to
underdense transition
18- 27 F10.5 m/s rb Boundary matching radius
29- 39 E11.6 --- gE Parallel reflection coefficient
41- 51 E11.6 --- gH Perpendicular reflection coefficient
53- 62 F10.5 --- phaseE Phase of the parallel reflection coefficient
64- 73 F10.5 --- phaseH Phase of the perpendicular reflection
coefficient
75- 85 F11.5 --- Pol Polarization between perpendicular and
parallel reflection coefficient
87- 97 E11.6 e-/m q Electron line density
99-101 I3 --- Order Order of the Bessel and Hankel functions
included in the solution
103-110 F8.5 --- kr2 Arbitrary scalscaling factor for comparisons
with previous studies
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Acknowledgements:
Gunter Strober, gunter.stober(at)iap.unibe.ch
(End) Patricia Vannier [CDS] 15-Oct-2021