A Phenomenological Theory of Radar Echoes from Meteors

McKinley, D. W. R.; Millman, Peter M.

doi:10.1109/jrproc.1949.231641

Cited by 61 publications

(19 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Ionization layers during meteor showers have been observed stratified at 5 km intervals between 100 and 125 km (McKinley and Millman, 1949). Gupta (1990) observed from Thumba multiple layers of sporadic-E, with semi thickness of 5 km and separated by 10 km, from the rocket-borne Langmuir probe data on meteor shower days.…”

Section: Discussionmentioning

confidence: 99%

Sporadic-E associated with the Leonid meteor shower event of November 1998 over low and equatorial latitudes

et al. 2001

View full text Add to dashboard Cite

Abstract. Rapid radio soundings were made over Ahmedabad, a low latitude station during the period 16-20 November 1998 to study the sporadic-E layer associated with the Leonid shower activity using the KEL Aerospace digital ionosonde. Hourly ionograms for the period 11 November to 24 November were also examined during the years from 1994 to 1998. A distinct increase in sporadic-E layer occurrence is noticed on 17, 18 and 19 November from 1996 to 1998. The diurnal variations of f 0 E s and f b E s also show significantly enhanced values for the morning hours of 18 and 19 November 1998. The ionograms clearly show strong sporadic-E reflections at times of peak shower activity with multiple traces in the altitude range of 100-140 km in few ionograms. Sporadic-E layers with multiple structures in altitude are also seen in some of the ionograms (quarter hourly) at Thumba, situated near the magnetic equator. Few of ionograms recorded at Kodaikanal, another equatorial station, also show sporadic-E reflections in spite of the transmitter power being significantly lower. These new results highlighting the effect of intense meteor showers in the equatorial and low latitude E-region are presented.

show abstract

Section: Discussionmentioning

confidence: 99%

Sporadic-E associated with the Leonid meteor shower event of November 1998 over low and equatorial latitudes

et al. 2001

View full text Add to dashboard Cite

show abstract

“…5.4 Factors that may affect the determined velocity McKinley and Millman (1949) were the first to suggest that the meteor head echo targets are compact regions of plasma, co-moving with the meteoroids, and virtually independent of aspect. We find no reason to assume otherwise and use the determined target velocities as representative for the meteoroids themselves.…”

Section: Radial Deceleration Due To Finite Beamwidthmentioning

confidence: 99%

Determination of meteoroid physical properties from tristatic radar observations

et al. 2008

View full text Add to dashboard Cite

Abstract. In this work we give a review of the meteor head echo observations carried out with the tristatic 930 MHz EISCAT UHF radar system during four 24 h runs between 2002 and 2005 and compare these with earlier observations. A total number of 410 tristatic meteors were observed. We describe a method to determine the position of a compact radar target in the common volume monitored by the three receivers and demonstrate its applicability for meteor studies. The inferred positions of the meteor targets have been utilized to estimate their velocities, decelerations and directions of arrival as well as their radar cross sections with unprecedented accuracy. The velocity distribution of the meteoroids is bimodal with peaks at 35-40 km/s and 55-60 km/s, and ranges from 19-70 km/s. The estimated masses are between 10 −9 -10 −5.5 kg. There are very few detections below 30 km/s. The observations are clearly biased to high-velocity meteoroids, but not so biased against slow meteoroids as has been presumed from previous tristatic measurements. Finally, we discuss how the radial deceleration observed with a monostatic radar depends on the meteoroid velocity and the angle between the trajectory and the beam. The finite beamwidth leads to underestimated meteoroid masses if radial velocity and deceleration of meteoroids approaching the radar are used as estimates of the true quantities in a momentum equation of motion.

show abstract

“…[4] McKinley and Millman [1949] were the first to observe four spectacular meteor trail echoes of the longduration, nonspecular type. These trails were detected near Ottawa, Canada (45°N), and hence could not be due to FAIs, given the angle of the radar beam with the background magnetic field; that is, they were not due to plasma instabilities.…”

Section: Introductionmentioning

confidence: 99%

Polarization and scattering of a long-duration meteor trail

Kelley

Vertatschitsch

et al. 2011

J. Geophys. Res.

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

A Phenomenological Theory of Radar Echoes from Meteors

Cited by 61 publications

References 12 publications

Sporadic-E associated with the Leonid meteor shower event of November 1998 over low and equatorial latitudes

Sporadic-E associated with the Leonid meteor shower event of November 1998 over low and equatorial latitudes

Determination of meteoroid physical properties from tristatic radar observations

Polarization and scattering of a long-duration meteor trail

Contact Info

Product

Resources

About