Lidar observations of Ca and K metallic layers from Arecibo and comparison with micrometeor sporadic activity

Raizada, S.; Tepley, C. A.; Janches, Diego; Friedman, J. S.; Zhou, Qihou; Mathews, J. D.

doi:10.1016/j.jastp.2004.01.030

Cited by 44 publications

(50 citation statements)

References 42 publications

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“…6 a Power profile of a meteor event exhibiting a beat pattern after 0.66 s, consistent with a meteoroid undergoing continuous fragmentation. Notice the change in c slope of the unwrapped phase coinciding with the observed beat pattern after 0.66 s intermediate layers (Mathews 1998;Morton et al 1993;Raizada et al 2004;Tong et al 1988).…”

Section: Discussionsupporting

confidence: 55%

Evidence of Meteoroid Fragmentation in Specular Trail Echoes Observed Using Gadanki MST Radar

et al. 2014

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Meteoroids are responsible for deposition of thousands of kilograms of annual mass flux in the Earth's upper atmosphere but the disintegration mechanisms of these bodies, and hence their composition, still remains a subject of debate in the meteor radar community. The role and significance of fragmentation as a meteoroid disintegration mechanism has been of particular interest in the past few years but in contrast to the head echoes, relatively little work has been done to study the effect and extent of fragmentation on trail echoes observed by the high power large aperture radars. Using the 53 MHz Gadanki MST radar, we present examples of radar meteor trails whose evolution cannot be explained with just the aid of classical meteor ablation theory. These examples are analyzed and discussed on a case-by-case basis and it is reported that the evolution of these trails can be explained with the help of fragmentation. This study will form the basis for future modeling efforts of fragmenting meteor trails and has important implications on the form in which the meteoroid mass is deposited in the upper atmosphere.

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Section: Discussionsupporting

confidence: 55%

Evidence of Meteoroid Fragmentation in Specular Trail Echoes Observed Using Gadanki MST Radar

et al. 2014

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“…In that way the summer topside extensions described by H&F may reflect a seasonal change in the average mass flux as observed by Singer et al (2004). Raizada et al (2004) considered the effect of sporadic micrometeor activity versus chemistry on the Ca and K metal layers above Arecibo, particularly with regard to the behaviour of the column abundance in pre-dawn hours and the appearance of sporadic layers. They found that above 100 km ionic chemistry is dominant over neutral chemistry, while the reverse is true below.…”

Section: Introductionmentioning

confidence: 98%

“…Throughout the literature, many discussions have focused either on these permanent metal layers or on infrequent events, such as sporadic layers or single meteor trails, and their influences on the average metal layers (Hacke et al, 1972;Me´gie and Blamont, 1977;Uchiumi et al, 1993;Gerding et al, 1999; Chu et al, 2000;Raizada et al, 2004). Even though it has been known for a long time that free metal atoms are occasionally observable for short periods of time at altitudes above 110 km, the presence of a permanent metal layer at those altitudes has not received attention.…”

Section: Introductionmentioning

confidence: 99%

The mesospheric metal layer topside: Examples of simultaneous metal observations

Höffner

Friedman

2005

Journal of Atmospheric and Solar-Terrestrial Physics

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“…EMI 9863-350B and Hamamatsu R943-02 photomultiplier tubes were used to collect the light at 372 and 589 nm, respectively. Other instrumental details can be found in the earlier work (Raizada and Tepley, 2002;2003;Raizada et al, 2004;Tepley et al, 2003;Raizada et al, 2011;.…”

Section: Methodsmentioning

confidence: 99%

Dependence of mesospheric Na and Fe distributions on electron density at Arecibo

et al. 2015

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We present case studies of the mesospheric alkali and non-alkali metals, Na and Fe, along with electron concentrations [N e , respectively, within the sporadic-E layer. In order to investigate ion-neutral coupling, a correlative analysis was performed in two altitude regions. Similar features are seen between neutrals and electrons in the 96-100-km altitude range, while within the altitude range of 80-90 km, an opposite behavior is seen. A comparative study between neutral layers below 90 km often referred to as the main or permanent layer and sporadic activity above 90 km reveals different characteristics for alkali and non-alkali metal. Fe concentrations in the main layer are higher than in Fe s resulting in a density ratio of less than 1 determined from two layers of 3 km thickness centered at 97 and 87 km. For the case of Na, the ratio exceeds 1 during E s activity on both the nights. The case studies discussed in this work facilitate our understanding of different factors that can influence the sporadic activity in alkali and non-alkali metals. In a region dominated by ion-molecule chemistry, temperature fluctuations that can be induced by wave activity will have more impact on Na than for Fe within their layers depending on altitude.

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Lidar observations of Ca and K metallic layers from Arecibo and comparison with micrometeor sporadic activity

Cited by 44 publications

References 42 publications

Evidence of Meteoroid Fragmentation in Specular Trail Echoes Observed Using Gadanki MST Radar

Evidence of Meteoroid Fragmentation in Specular Trail Echoes Observed Using Gadanki MST Radar

The mesospheric metal layer topside: Examples of simultaneous metal observations

Dependence of mesospheric Na and Fe distributions on electron density at Arecibo

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