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Determination of the meteoroid ioniz...

Hunt, Stephen.

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Determination of the meteoroid ionization coefficient using high power large aperture radar.

Record Type:	Language materials, printed : Monograph/item
Title/Author:	Determination of the meteoroid ionization coefficient using high power large aperture radar./
Author:	Hunt, Stephen.
Description:	179 p.
Notes:	Adviser: Peter Brown.
Contained By:	Dissertation Abstracts International67-09B.
Subject:	Engineering, Electronics and Electrical. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3232897
ISBN:	9780542868511

Determination of the meteoroid ionization coefficient using high power large aperture radar.
Hunt, Stephen.

Determination of the meteoroid ionization coefficient using high power large aperture radar. - 179 p.

Adviser: Peter Brown.

Thesis (Ph.D.)--Boston University, 2007.

Most meteoroids have physical cross-sections too small to detect by ground based sensors. To overcome this problem we applied a radar [ARPA Long Range Tracking and Instrumentation Radar (ALTAIR)] with greater capabilities than made available by any other meteor radar to collect measurements from meteor electrons at the leading edge or head of their atmospheric flight path. These ALTAIR head echo data provided the foundation for us to develop new techniques and advance the science of meteoroid-atmosphere interactions. ALTAIR provides high-power, large aperture, high bandwidth, simultaneous UHF and VHF pulsed waveforms, high range resolution, monopulse angle, precise absolute calibration in range and angle and high sensitivity. Leveraging ALTAIR's assets, we collected a greater number of independent calibrated measurements than possible with other radar systems, thereby enhancing our estimates of meteoroid physical parameters (such as position, ionization coefficient, electron line density and mass) because of this reduction in the number of unknown quantities. Typical meteor radars collect fewer independent measurements at lower resolution (e.g. &sim;kilometer to tens of kilometers in range). ALTAIR's periodic sampling at two frequencies also helped characterize and guard our investigation against wavelength dependent biases; the scattering characteristics of meteor electrons are a function of incident wavelength. Using these data we formulated a new approach to estimate a model for the meteor ionization coefficient using dynamical and radar cross section data. The ionization coefficient models the number of electrons produced during collisions between ablated meteoroid atoms and atmospheric constituents; it is central to the estimation of meteoroid parameters such as mass and density. Our approach adds missing information since the last estimate made by Jones (1997) because our value is valid for higher velocity meteors (near 56 km/sec), allows for values greater than unity and requires fewer assumptions. We also provide a comprehensive presentation of ALTAIR characteristics to illustrate the uncertainties in our meteoroid parameter estimates and to serve as a comparative guide for the interpretation of other meteor radar system capabilities.

ISBN: 9780542868511Subjects--Topical Terms:

626636
Engineering, Electronics and Electrical.

Determination of the meteoroid ionization coefficient using high power large aperture radar.
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005 20110929
008 110929s2007 eng d
020 $a 9780542868511
035 $a (UnM)AAI3232897
035 $a AAI3232897
040 $a UnM $c UnM
100 1 $a Hunt, Stephen. $3 1298422
245 1 0 $a Determination of the meteoroid ionization coefficient using high power large aperture radar.
300 $a 179 p.
500 $a Adviser: Peter Brown.
500 $a Source: Dissertation Abstracts International, Volume: 67-09, Section: B, page: 5280.
502 $a Thesis (Ph.D.)--Boston University, 2007.
520 $a Most meteoroids have physical cross-sections too small to detect by ground based sensors. To overcome this problem we applied a radar [ARPA Long Range Tracking and Instrumentation Radar (ALTAIR)] with greater capabilities than made available by any other meteor radar to collect measurements from meteor electrons at the leading edge or head of their atmospheric flight path. These ALTAIR head echo data provided the foundation for us to develop new techniques and advance the science of meteoroid-atmosphere interactions. ALTAIR provides high-power, large aperture, high bandwidth, simultaneous UHF and VHF pulsed waveforms, high range resolution, monopulse angle, precise absolute calibration in range and angle and high sensitivity. Leveraging ALTAIR's assets, we collected a greater number of independent calibrated measurements than possible with other radar systems, thereby enhancing our estimates of meteoroid physical parameters (such as position, ionization coefficient, electron line density and mass) because of this reduction in the number of unknown quantities. Typical meteor radars collect fewer independent measurements at lower resolution (e.g. &sim;kilometer to tens of kilometers in range). ALTAIR's periodic sampling at two frequencies also helped characterize and guard our investigation against wavelength dependent biases; the scattering characteristics of meteor electrons are a function of incident wavelength. Using these data we formulated a new approach to estimate a model for the meteor ionization coefficient using dynamical and radar cross section data. The ionization coefficient models the number of electrons produced during collisions between ablated meteoroid atoms and atmospheric constituents; it is central to the estimation of meteoroid parameters such as mass and density. Our approach adds missing information since the last estimate made by Jones (1997) because our value is valid for higher velocity meteors (near 56 km/sec), allows for values greater than unity and requires fewer assumptions. We also provide a comprehensive presentation of ALTAIR characteristics to illustrate the uncertainties in our meteoroid parameter estimates and to serve as a comparative guide for the interpretation of other meteor radar system capabilities.
590 $a School code: 0017.
650 4 $a Engineering, Electronics and Electrical. $3 626636
650 4 $a Engineering, Environmental. $3 783782
650 4 $a Physics, Astronomy and Astrophysics. $3 1019521
690 $a 0544
690 $a 0606
690 $a 0775
710 2 0 $a Boston University. $3 1017454
773 0 $t Dissertation Abstracts International $g 67-09B.
790 $a 0017
790 1 0 $a Brown, Peter, $e advisor
791 $a Ph.D.
792 $a 2007
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3232897