Very High Resolution Studies of Micrometeors Using the Arecibo 430 MHz Radar

Mathews, J. D.; Meisel, D. D.; Hunter, K. P.; Getman, V. S.; Zhou, Qin

doi:10.1006/icar.1996.5641

Cited by 102 publications

(123 citation statements)

References 23 publications

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“…Also shown in Fig. 3b is the ablation profile predicted if the velocity distribution is shifted so that the mean velocity increases from 18 to 40 km s −1 , in line with the large aperture radar measurements (Pellinen-Wannberg and Wannberg, 1994;Mathews et al, 1997;Close et al, 2000;Janches et al, 2000). This ablation profile, which will be referred to as the ISR profile, now peaks just above 100 km, and 99% of the material ablates.…”

Section: Meteoroid Ablation Modelsupporting

confidence: 80%

“…the ball of plasma around the ablating particle as it descends through the atmosphere). This enables measurements of the direction of origin, velocity, deceleration and mass to be made (PellinenWannberg and Wannberg, 1994;Mathews et al, 1997;Close et al, 2000;Janches et al, 2000;Mathews et al, 2001). The observed mass distribution is shifted to smaller mass ranges (median mass≈1 µg) compared with the LDEF results, so that the total incoming mass rate is about 10 t d −1 ; that is, 1 order of magnitude lower than the LDEF estimate.…”

Section: Namentioning

confidence: 97%

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A time-resolved model of the mesospheric Na layer: constraints on the meteor input function

2004

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Abstract.A time-resolved model of the Na layer in the mesosphere/lower thermosphere region is described, where the continuity equations for the major sodium species Na, Na + and NaHCO 3 are solved explicity, and the other shortlived species are treated in steady-state. It is shown that the diurnal variation of the Na layer can only be modelled satisfactorily if sodium species are permanently removed below about 85 km, both through the dimerization of NaHCO 3 and the uptake of sodium species on meteoric smoke particles that are assumed to have formed from the recondensation of vaporized meteoroids. When the sensitivity of the Na layer to the meteoroid input function is considered, an inconsistent picture emerges. The ratio of the column abundance of Na + to Na is shown to increase strongly with the average meteoroid velocity, because the Na is injected at higher altitudes. Comparison with a limited set of Na + measurements indicates that the average meteoroid velocity is probably less than about 25 km s −1 , in agreement with velocity estimates from conventional meteor radars, and considerably slower than recent observations made by wide aperture incoherent scatter radars. The Na column abundance is shown to be very sensitive to the meteoroid mass input rate, and to the rate of vertical transport by eddy diffusion. Although the magnitude of the eddy diffusion coefficient in the 80-90 km region is uncertain, there is a consensus between recent models using parameterisations of gravity wave momentum deposition that the average value is less than 3×10 5 cm 2 s −1 . This requires that the global meteoric mass input rate is less than about 20 t d −1 , which is closest to estimates from incoherent scatter radar observations. Finally, the diurnal variation in the meteoroid input rate only slight perturbs the Na layer, because the residence time of Na in the layer is several days, and diurnal effects are effectively averaged out.

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Section: Meteoroid Ablation Modelsupporting

confidence: 80%

Section: Namentioning

confidence: 97%

A time-resolved model of the mesospheric Na layer: constraints on the meteor input function

2004

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“…There are a few contradictions in interpretations from some of the facilities, e.g. interpretation of head echoes from EISCAT and Arecibo Mathews et al, 1997). However, it looks as though an explanation can be found in the size of the instruments.…”

Section: Discussionmentioning

confidence: 99%

“…EISCAT observations on the Geminid and Perseid meteor showers in 1990, 1991 and 1993 started a new era of meteor studies on HPLA radars Wannberg, 1994, 1996;Wannberg et al, 1996;Pellinen-Wannberg et al, 1998;Westman et al, 1997). Almost simultaneously meteor observations were performed at Jicamarca (Chapin and Kudeki, 1994a, b) and at Arecibo (Zhou et al, 1995;Mathews et al, 1997;Zhou and Kelley, 1997). Even other EIS-CAT measurements report possible meteor echoes (Malnes Correspondence to: A. Pellinen-Wannberg (asta.pellinen-wannberg@irf.se) et al, 1996).…”

Section: Introductionmentioning

confidence: 99%

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

Pellinen‐Wannberg

2004

Atmos. Chem. Phys.

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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.

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“…Since the 1990s, head echo observations have been conducted with most HPLA radar facilities around the world (Pellinen- Wannberg and Wannberg, 1994;Mathews et al, 1997;Close et al, 2000;Sato et al, 2000;Chau and Woodman, 2004;Mathews et al, 2008;Malhotra and Mathews, 2011). These radar systems have diverse system characteristics in terms of operating frequency, dish or phased array antenna, aperture size etc.…”

Section: Introductionmentioning

confidence: 99%

A meteor head echo analysis algorithm for the lower VHF band

et al. 2012

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Abstract.We have developed an automated analysis scheme for meteor head echo observations by the 46.5 MHz Middle and Upper atmosphere (MU) radar near Shigaraki, Japan (34.85 • N, 136.10 • E). The analysis procedure computes meteoroid range, velocity and deceleration as functions of time with unprecedented accuracy and precision. This is crucial for estimations of meteoroid mass and orbital parameters as well as investigations of the meteoroid-atmosphere interaction processes. In this paper we present this analysis procedure in detail. The algorithms use a combination of singlepulse-Doppler, time-of-flight and pulse-to-pulse phase correlation measurements to determine the radial velocity to within a few tens of metres per second with 3.12 ms time resolution. Equivalently, the precision improvement is at least a factor of 20 compared to previous single-pulse measurements. Such a precision reveals that the deceleration increases significantly during the intense part of a meteoroid's ablation process in the atmosphere. From each received pulse, the target range is determined to within a few tens of meters, or the order of a few hundredths of the 900 m long range gates. This is achieved by transmitting a 13-bit Barker code oversampled by a factor of two at reception and using a novel range interpolation technique. The meteoroid velocity vector is determined from the estimated radial velocity by carefully taking the location of the meteor target and the angle from its trajectory to the radar beam into account. The latter is determined from target range and bore axis offset. We have identified and solved the signal processing issue giving rise to the peculiar signature in signal to noise ratio plots reported by Galindo et al. (2011), and show how to use the range interpolation technique to differentiate the effect of signal processing from physical processes.

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Very High Resolution Studies of Micrometeors Using the Arecibo 430 MHz Radar

Cited by 102 publications

References 23 publications

A time-resolved model of the mesospheric Na layer: constraints on the meteor input function

A time-resolved model of the mesospheric Na layer: constraints on the meteor input function

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

A meteor head echo analysis algorithm for the lower VHF band

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