Radar meteor rates and atmospheric density changes

Ellyett, C. D.; Kennewell, J. A.

doi:10.1038/287521a0

Cited by 16 publications

(15 citation statements)

References 10 publications

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“…The transition from winter to summer values (and vice versa) is gradual. The changes in the meteor count rate associated with these changes in atmospheric scale height are calculated following Ellyett and Kennewell (1980). The results of these calculations are shown in Fig.…”

Section: The Effect Of Atmospheric Density Perturbationsmentioning

confidence: 99%

“…4a and c show a shift of approximately six months between the height variations in the Northern and Southern Hemispheres. As the Esrange and Rothera radars are identical instruments sited at conjugate latitudes this implies that the variation is likely atmospheric in origin (Ellyett and Kennewell, 1980) rather than a shift in meteor distribution which would produce a simultaneous shift in the height profile of meteor echoes in both hemispheres (McKinley, 1961). This is discussed further in Sect.…”

Section: Observed Meteor Count Ratesmentioning

confidence: 99%

“…This is corrected for following the experimental work of Jones and CampbellBrown (2005) again by assigning an attenuation factor. Ellyett and Kennewell (1980), using the earlier theories of Kaiser and Closs (1952) and Kaiser (1960Kaiser ( , 1961, contend that changes in atmospheric scale height (and hence density and density gradients) can produce significant variations in the observed meteor echo count rate. These not only affect the heights at which meteoriods ablate, but also the area over which a meteoroid will ablate.…”

Section: Data and Analysismentioning

confidence: 99%

“…6e and f). Again, following Ellyett and Kennewell (1980), the associated changes in count rate are calculated. This is displayed in Fig.…”

Section: The Effect Of Atmospheric Density Perturbationsmentioning

confidence: 99%

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The sporadic radiant and distribution of meteors in the atmosphere as observed by VHF radar at Arctic, Antarctic and equatorial latitudes

et al. 2009

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Abstract.Results are presented of a study of the temporal and spatial variability in meteor count rate observations from three VHF meteor radars. These radar are located in the Arctic (at Esrange, 68 • N), in the Antarctic (at Rothera, 68 • S) and near the Equator (on Ascension Island, 8 • S). It is found that for all three locations there is a strong diurnal cycle in observed hourly meteor counts and the time of maxima and minima in these counts depends on the month of the year. In addition, at high latitude there is a strong annual cycle in observed monthly-mean meteor counts, whereas for the radar at low latitude there is a semi-annual cycle. At high latitude there is also an annual cycle in the mean height at which meteors are observed. However, no such annual cycle is found in observed meteor count rates from the low latitude radar. The meteor count data from all the radars are combined to investigate the sporadic radiant distribution (i.e. the distribution of direction of arrival on the celestial sphere of sporadic meteors). This combined radiant distribution shows that there are six main source regions for meteors. The latitudinal and temporal dependence in observed meteor count rates appears to result from a combination of the sporadic radiant distribution, annual fluctuations in atmospheric density, the sensitivity of the radar to meteors from different source directions and the temporal and spatial variability in meteor fluxes.

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Section: The Effect Of Atmospheric Density Perturbationsmentioning

confidence: 99%

Section: Observed Meteor Count Ratesmentioning

confidence: 99%

Section: Data and Analysismentioning

confidence: 99%

“…6e and f). Again, following Ellyett and Kennewell (1980), the associated changes in count rate are calculated. This is displayed in Fig.…”

Section: The Effect Of Atmospheric Density Perturbationsmentioning

confidence: 99%

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The sporadic radiant and distribution of meteors in the atmosphere as observed by VHF radar at Arctic, Antarctic and equatorial latitudes

et al. 2009

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“…Between 2011-2015, solar activity as measured by the 10.7 cm flux increased by only 20% with the most pronounced increase towards the end of 2015 (Stober et al 2014). It is clear that changes in the mass density of the upper atmosphere affect meteor echo counts (Lindblad 1968;Hughes 1976;Ellyett & Kennewell 1980;Elford 1980;Lindblad 2003) and likely also affect the begin and end heights of meteor ablation (Pellinen-Wannberg et al 2010), but the solar cycle impact on mass index measurements by radar is yet to be determined.…”

Section: Multi-year Data Comparisonmentioning

confidence: 99%

A reproducible method to determine the meteoroid mass index

Pokorný

Brown

2016

A&A

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Context. The determination of meteoroid mass indices is central to flux measurements and evolutionary studies of meteoroid populations. However, different authors use different approaches to fit observed data, making results difficult to reproduce and the resulting uncertainties difficult to justify. The real, physical, uncertainties are usually an order of magnitude higher than the reported values. Aims. We aim to develop a fully automated method that will measure meteoroid mass indices and associated uncertainty. We validate our method on large radar and optical datasets and compare results to obtain a best estimate of the true meteoroid mass index. Methods. Using MultiNest, a Bayesian inference tool that calculates the evidence and explores the parameter space, we search for the best fit of cumulative number vs. mass distributions in a four-dimensional space of variables (a, b, X 1 , X 2 ). We explore biases in meteor echo distributions using optical meteor data as a calibration dataset to establish the systematic offset in measured mass index values. Results. Our best estimate for the average de-biased mass index for the sporadic meteoroid complex, as measured by radar appropriate to the mass range 10 −3 > m > 10 −5 g, was s = −2.10 ± 0.08. Optical data in the 10 −1 > m > 10 −3 g range, with the shower meteors removed, produced s = −2.08 ± 0.08. We find the mass index used by Grün et al. (1985) is substantially larger than we measure in the 10 −4 < m < 10 −1 g range.

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Mesospheric temperatures estimated from the meteor radar observations at Mohe, China

Liu

et al. 2017

JGR Space Physics

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In this work, we report the estimation of mesospheric temperatures at 90 km height from the observations of the VHF all‐sky meteor radar operated at Mohe (53.5°N, 122.3°E), China, since August 2011. The kinetic temperature profiles retrieved from the observations of Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) on board the Thermosphere, Ionosphere, Mesosphere, Energetics, and Dynamics satellite are processed to provide the temperature (TSABER) and temperature gradient (dT/dh) at 90 km height. Based on the SABER temperature profile data an empirical dT/dh model is developed for the Mohe latitude. First, we derive the temperatures from the meteor decay times (Tmeteor) and the Mohe dT/dh model gives prior information of temperature gradients. Second, the full width at half maximum (FWHM) of the meteor height profiles is calculated and further used to deduce the temperatures (TFWHM) based on the strong linear relationship between FWHM and TSABER. The temperatures at 90 km deduced from the decay times (Tmeteor) and from the meteor height distributions (TFWHM) at Mohe are validated/calibrated with TSABER. The temperatures present a considerable annual variation, being maximum in winter and minimum in summer. Harmonic analyses reveal that the temperatures have an annual variation consistent with TSABER. Our work suggests that FWHM has a good performance in routine estimation of the temperatures. It should be pointed out that the slope of FWHM as a function of TSABER is 10.1 at Mohe, which is different from that of 15.71 at King Sejong (62.2°S, 58.8°E) station.

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Radar meteor rates and atmospheric density changes

Cited by 16 publications

References 10 publications

The sporadic radiant and distribution of meteors in the atmosphere as observed by VHF radar at Arctic, Antarctic and equatorial latitudes

The sporadic radiant and distribution of meteors in the atmosphere as observed by VHF radar at Arctic, Antarctic and equatorial latitudes

A reproducible method to determine the meteoroid mass index

Mesospheric temperatures estimated from the meteor radar observations at Mohe, China

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