First results from the 2009-2010 MU radar head echo observation programme for sporadic and shower meteors: the Orionids 2009

Kero, Johan; Szasz, Csilla; Nakamura, Takuji; Meisel, D. D.; Ueda, Masayoshi; Fujiwara, Yasunori; Terasawa, T.; Miyamoto, H.; Nishimura, Koji

doi:10.1111/j.1365-2966.2011.19146.x

Cited by 46 publications

(81 citation statements)

References 29 publications

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“…In addition, if R ip 2 b is utilized, the probability of detecting particles with V 40 < km s −1 is practically 0 and this radar will only detect particles at these speeds if the masses are almost 1 mg (bottom right panel). This is likely an indication that Revision 2 of ip b presented in Paper I is too extreme since MU's velocity distributions show a significant number, although a minority, of detections of meteors with velocities smaller than 30 km s −1 (Kero et al 2011;Pifko et al 2013). An alternative explanation is that MU detects a significant number of particles with masses greater than a milligram.…”

Section: Modeling the Meteor S/nmentioning

confidence: 87%

“…Looking at the PFISR and MU results in particular, the predicted occurrence rate at the peak when using the revised value of the ionization probability is less than 6 meteors per 20 minutes and 1 meteor in a 5 minutes bin, respectively. Because of the interferometry capabilities of MU, we know that it observes more meteors originating from these sources (Kero et al 2011;Pifko et al 2013), which shows that the revision of ip b is clearly too extreme. Once again, the disagreement at the higher end of the velocity distributions is mostly due to the fact that ZoDy does not include the populations of particles that would produce meteoroids with high geocentric speeds.…”

Section: Discussionmentioning

confidence: 99%

“…One other parameter that may differ between radars and influences the S/N calculation is the sky noise, which can be particularly strong at the lower frequencies. For example, Kero et al (2011) shows that the diurnal cycle of the sky noise background in zenith at Shigaraki varies from its lowest values around 5000 K to almost 15,000 K when Cygnus-A is near the beam. At the AO and PFISR's transmitted higher frequencies, however, the sky noise will decrease dramatically.…”

Section: Discussionmentioning

confidence: 99%

“…In a similar manner than for AO in Paper I, we only considered the first side lobes in this work. Observational evidence shows that detection outside of the region comprised by the main beam and the first side lobe are less than a fraction of a percent (see for example Janches et al 2004;Kero et al 2011). Table 1 provides additional system parameters of each radar that are also required for this calculation.…”

Section: Modeling the Meteor S/nmentioning

confidence: 99%

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Radar Detectability Studies of Slow and Small Zodiacal Dust Cloud Particles. Ii. A Study of Three Radars With Different Sensitivity

Janches

Swarnalingam

Plane

et al. 2015

ApJ

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The sensitivity of radar systems to detect different velocity populations of the incoming micrometeoroid flux is often the first argument considered to explain disagreements between models of the Near-Earth dust environment and observations. Recently, this was argued by Nesvorný et al. to support the main conclusions of a Zodiacal Dust Cloud (ZDC) model which predicts a flux of meteoric material into the Earth's upper atmosphere mostly composed of small and very slow particles. In this paper, we expand on a new methodology developed by Janches et al. to test the ability of powerful radars to detect the meteoroid populations in question. In our previous work, we focused on Arecibo 430 MHz observations since it is the most sensitive radar that has been used for this type of observation to date. In this paper, we apply our methodology to two other systems, the 440 MHz Poker Flat Incoherent Scatter Radar and the 46.5 Middle and Upper Atmosphere radar. We show that even with the less sensitive radars, the current ZDC model over-predicts radar observations. We discuss our results in light of new measurements by the Planck satellite which suggest that the ZDC particle population may be characterized by smaller sizes than previously believed. We conclude that the solution to finding agreement between the ZDC model and sensitive high power and large aperture meteor observations must be a combination of a re-examination not only of our knowledge of radar detection biases, but also the physical assumptions of the ZDC model itself.

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Section: Modeling the Meteor S/nmentioning

confidence: 87%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Modeling the Meteor S/nmentioning

confidence: 99%

See 2 more Smart Citations

Radar Detectability Studies of Slow and Small Zodiacal Dust Cloud Particles. Ii. A Study of Three Radars With Different Sensitivity

Janches

Swarnalingam

Plane

et al. 2015

ApJ

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“…The MU radar antenna gain pattern has relatively strong sidelobes, enabling detections of head echo targets with RCS > 1 m 2 . This detection volume has a horizontal cross-sectional area of the order of 1000 km 2 at 100 km altitude when the beam is pointed vertically (Kero et al, 2011). The observation period dedicated for RCS determination covered 33 h and resulted in ∼10 000 meteors.…”

Section: Radar Cross Sectionmentioning

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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Interferometric meteor head echo observations using the Southern Argentina Agile Meteor Radar

et al. 2014

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A radar meteor echo is the radar scattering signature from the free electrons generated by the entry of extraterrestrial particles into the atmosphere. Three categories of scattering mechanisms exist: specular, nonspecular trails, and head echoes. Generally, there are two types of radars utilized to detect meteors. Traditional VHF all‐sky meteor radars primarily detect the specular trails, while high‐power, large‐aperture (HPLA) radars efficiently detect meteor head echoes and, in some cases, nonspecular trails. The fact that head echo measurements can be performed only with HPLA radars limits these studies in several ways. HPLA radars are sensitive instruments constraining the studies to the lower masses, and these observations cannot be performed continuously because they take place at national observatories with limited allocated observing time. These drawbacks can be addressed by developing head echo observing techniques with modified all‐sky meteor radars. Such systems would also permit simultaneous detection of all different scattering mechanisms using the same instrument, rather than requiring assorted different classes of radars, which can help clarify observed differences between the different methodologies. In this study, we demonstrate that such concurrent observations are now possible, enabled by the enhanced design of the Southern Argentina Agile Meteor Radar (SAAMER). The results presented here are derived from observations performed over a period of 12 days in August 2011 and include meteoroid dynamical parameter distributions, radiants, and estimated masses. Overall, the SAAMER's head echo detections appear to be produced by larger particles than those which have been studied thus far using this technique.

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First results from the 2009-2010 MU radar head echo observation programme for sporadic and shower meteors: the Orionids 2009

Cited by 46 publications

References 29 publications

Radar Detectability Studies of Slow and Small Zodiacal Dust Cloud Particles. Ii. A Study of Three Radars With Different Sensitivity

Radar Detectability Studies of Slow and Small Zodiacal Dust Cloud Particles. Ii. A Study of Three Radars With Different Sensitivity

A meteor head echo analysis algorithm for the lower VHF band

Interferometric meteor head echo observations using the Southern Argentina Agile Meteor Radar

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