A technique for calculating meteor plasma density and meteoroid mass from radar head echo scattering

Close, Sigrid; Oppenheim, M. M.; Hunt, Stephen; Coster, A. J.

doi:10.1016/j.icarus.2003.11.018

Cited by 82 publications

(110 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The monopulse data indicate that the maximum SNR of the signal occurs approximately at the center of each beam, with the peak UHF signal occurring 0.08 s and lower in altitude than the VHF signal. This is consistent with the scattering theory described by Close et al [2004]. The head echo, however, shows strong return across multiple range gates at any one instant in time.…”

Section: Frequency Dependence and Meteoroid Masssupporting

confidence: 90%

“…This corresponds to quasi head echo scattering, meaning that the meteoroid is traveling perpendicular to the beam at this point but has not entered the first Fresnel zone. This type of scattering is a combination of higher-order Fresnel scattering and head echo scattering described by Close et al [2004]. These types of echoes, while uncommon, are present in HPLA data sets and have been largely ignored, but may be an indication of fragmentation or a "terminal event" .…”

Section: Characterization Of the Parent Head Echo And Meteoroidmentioning

confidence: 99%

See 1 more Smart Citation

Polarization and scattering of a long-duration meteor trail

Kelley

Vertatschitsch

et al. 2011

J. Geophys. Res.

Self Cite

View full text Add to dashboard Cite

[1] High-power, large-aperture (HPLA) radars have been used over the past two decades to characterize the plasmas formed both around and behind meteoroids as they enter Earth's atmosphere. These plasmas, referred to as heads and trails, respectively, occur with relative frequency (peak head echo detection rate of ∼1/s) but are extremely diverse and have been difficult to define in a general sense. One particular type of plasma, referred to as the nonspecular trail, occurs when the meteoroid travels quasi-parallel to the radar beam with the radar beam lying quasi-perpendicular to the background magnetic field. Reflection is believed to occur from field-aligned irregularities (FAIs) that form after the trail becomes unstable. While FAI scattering pertains to the majority of nonspecular trails that are short in duration, a subset of these trails, referred to as long-duration trails, still remains open to interpretation. In this paper we present a case study analysis of a longduration, nonspecular trail and its associated head echo detected with the Advanced Research Project Agency (ARPA) Long-Range Tracking and Identification Radar (ALTAIR), which is an HPLA radar. These data are unique in that they are high resolution (with monopulse angles), dual frequency, and, most importantly, dual polarized, which allows for unprecedented insight into the scattering process from both heads and trails. First, we determine the velocity and mass of the parent meteoroid, which is a particle weighing more than a milligram and is one of the largest meteoroids ever detected by ALTAIR. Second, we determine the peak plasma density and polarization of the head echo and characterize the unique, yet strong returns in the opposite polarization, which may be due to multiple scattering centers within the range gate. Finally, we examine the polarization properties of the trail and discuss the first conclusive evidence of polarization flipping along the trail striations, which we believe corresponds to sharp gradients at the edges of the trail related to turbulent mixing of a dusty plasma that is elongating along the magnetic field. We look into a new idea, namely, the notion that some nonspecular echoes might correspond to a high Schmidt number, dusty plasma, as is found in and above noctilucent clouds. Our results show how polarized return can aid in scattering diagnostics and that single polarization radars must be used with caution for determining head and trail plasma densities given that some of the return can occur in the "unexpected" channel.

show abstract

Section: Frequency Dependence and Meteoroid Masssupporting

confidence: 90%

Section: Characterization Of the Parent Head Echo And Meteoroidmentioning

confidence: 99%

Polarization and scattering of a long-duration meteor trail

Kelley

Vertatschitsch

et al. 2011

J. Geophys. Res.

Self Cite

View full text Add to dashboard Cite

show abstract

“…Comparisons with atmospheric models show that the cutoff height occurs at a constant atmospheric mean free path value for a given wavelength. Recently Close et al (2004) have confirmed with their theoretical calculations that the VHF distribution should be slightly higher up than the UHF distribution.…”

mentioning

confidence: 72%

The EISCAT meteor-head method – a review and recent observations

Pellinen‐Wannberg

2004

Atmos. Chem. Phys.

View full text Add to dashboard Cite

Abstract. Since the very first meteor observations at EIS-CAT in December 1990, the experimental method has improved significantly. This is due to a better understanding of the phenomenon and a recent major upgrade of the EISCAT signal processing and data storage capabilities. Now the simultaneous spatial-time resolution is under 100 m-ms class. To illuminate the meteor target for as long as possible and simultaneously get as good altitude resolution as possible, various coding techniques have been used, such as Barker codes and random codes with extremely low side lobe effects. This paper presents some background and the current view of the meteor head echo process at EISCAT as well as the observations which support this view, such as altitude distributions, dual-frequency target sizes and vector velocities. It also presents some preliminary results from recent very high resolution tristatic observations.

show abstract

“…Subsequent measurements at ALTAIR, with more dynamic mass estimates as well as scattering masses, are described by Close et al [2002cClose et al [ , 2004Close et al [ , 2005. Dynamic mass measurements together with computer model simulations are described by Bass et al [2008] and Dyrud and Janches [2008].…”

Section: Discussionmentioning

confidence: 99%

“…[55] The electrostatic scattering model is described in detail by Close et al [2004Close et al [ , 2005 [see also Dyrud et al, 2005] and will be discussed only briefly here. It is based on assumptions that (1) the electron cloud surrounding the meteoroid can be approximated as spherically symmetric and (2) the electron distribution within the cloud is a Gaussian in r, given by A theoretical analysis is developed for the scattering of a radar beam from a spherical plasma distribution, through which for each echo along a trace the parameters n max and r max can be determined from a fit to the measured scattering cross section.…”

Section: Appendix C: the Electrostatic Scattering Modelmentioning

confidence: 99%

Analysis of ALTAIR 1998 meteor radar data

Zinn

Colestock

et al. 2011

J. Geophys. Res.

Self Cite

View full text Add to dashboard Cite

[1] We describe a new analysis of a set of 32 UHF meteor radar traces recorded with the 422 MHz Advanced Research Project Agency Long-Range Tracking and Identification Radar facility in November 1998. Emphasis is on the absolute velocity measurements and inferences that can be drawn from them regarding the meteoroid masses and mass densities. We find that the 3-D velocity versus altitude data can be fitted as quadratic functions of the path integrals of the atmospheric densities versus distance, and deceleration rates derived from those fits all show the expected behavior of increasing with decreasing altitude. We also describe a computer model of the coupled processes of collisional heating, radiative cooling, evaporative cooling and ablation, and deceleration for meteoroids composed of defined mixtures of mineral constituents. For each of the cases in the data set, we ran the model starting with the measured initial velocity and trajectory inclination and with various trial values of the quantity mr s 2 (initial mass times mass density squared) and then compared the computed deceleration versus altitude curves versus the measured ones. In this way we arrived at the best fit values of the mr s 2 for each of the measured traces. Then further, assuming various trial values of the density r s , we compared the computed mass versus altitude curves with similar curves for the same set of meteoroids determined previously from the measured radar cross sections and an electrostatic scattering model. In this way we arrived at estimates of the best fit mass densities r s for each of the cases.

show abstract

A technique for calculating meteor plasma density and meteoroid mass from radar head echo scattering

Cited by 82 publications

References 17 publications

Polarization and scattering of a long-duration meteor trail

Polarization and scattering of a long-duration meteor trail

The EISCAT meteor-head method – a review and recent observations

Analysis of ALTAIR 1998 meteor radar data

Contact Info

Product

Resources

About