Summer to winter variability in mesospheric calcium ion distribution and its dependence on Sporadic E at Arecibo

Raizada, S.; Tepley, C. A.; Williams, B. P.; García, R.

doi:10.1029/2011ja016953

Cited by 16 publications

(29 citation statements)

References 26 publications

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“…The ratio of Ca + /N e concentrations and abundances inferred using in situ data obtained from Wallops Island rocket measurements is~1-2 % and~4.27 × 10 −3 , respectively (Kopp 1997). This agrees well with ground-based airglow and lidar measurements from Arecibo (Tepley et al, 1981Raizada et al, 2012). Assuming that the fraction of Fe and Na ions in the E layer do not change drastically at Arecibo and Wallops, the fraction of these ions and abundances can be inferred using electron density information from ISR data.…”

Section: Discussionsupporting

confidence: 74%

“…The occurrence of both sporadic-E and neutral layers has been linked to several processes that include neutralization, the presence of wind shears, and advection Tepley et al, 2003;Plane, 2004;Raizada et al, 2011Raizada et al, ,2012. Recently, Yuan et al (2014) related the seasonal variations of Na s and E s layers to the convergence of metal ions in summer, while ion diffusion appeared to dominate in wintertime.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Discussionsupporting

confidence: 74%

Section: Introductionmentioning

confidence: 99%

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

et al. 2015

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“…In any case, with the absence of any ionosonde observations close to the lidar location during these observations, it is difficult to comment further on the occurrence/influence of E S layer over Gadanki region. Sporadic-E layers are related to the neutral enhancements via ion-neutral coupling (Raizada et al 2011(Raizada et al , 2012, any structure-like appearance of billow-like features are usually linked to dynamical instabilities (Sarkhel et al 2012b). In order to address this aspect comprehensively, further investigations involving instrument clusters are needed (Mathews 1996).…”

Section: Role Of Sporadic-e Activitymentioning

confidence: 99%

A case study on occurrence of an unusual structure in the sodium layer over Gadanki, India

et al. 2015

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The height-time-concentration map of neutral sodium (Na) atoms measured by a Na lidar during the night of 18 to 19 March 2007 over Gadanki, India (13.5°N, 79.2°E) reveals an unusual structure in the Na layer for around 30 min in the altitude range of 92 to 98 km which is similar to the usual 'C' type structures observed at other locations. In order to understand the physical mechanism behind the generation of this unusual event, an investigation is carried out combining the data from multiple instruments that include the meteor wind radar over Thiruvananthapuram, India (8.5°N, 77°E) and the SABER instrument onboard the TIMED satellite. The temperature and wind profiles from the data set provided by these instruments allow us to infer the Richardson number which is found to be noticeably less than the canonical threshold of 0.25 above 92 km over Thiruvananthapuram suggesting the plausible generation of Kelvin-Helmholtz (KH) billows over southwestern part of the Indian subcontinent. Based on the average wind speed and direction over Thiruvananthapuram, it is proposed that the KH-billow structure was modified due to the background wind and was advected with it in nearly 'frozen-in' condition (without significant decay) in the northeastward direction reaching the Na lidar location (Gadanki). This case study, therefore, presents a scenario wherein the initially deformed KH-billow structure survived for a few hours (instead of a few minutes or tens of minutes as reported in earlier works) in an apparently 'frozen-in' condition under favorable background conditions. In this communication, we suggest a hypothesis where this deformed KH-billow structure plays crucial role in creating the abovementioned unusual structure observed in the Na layer over Gadanki.

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“…The lidar system at the Arecibo Observatory (18 o N) employed for measurements of neutral Ca at 423 nm has been described 15 previously (Raizada et al, 2011;Raizada et al, 2012). Nd:YAG-pumped dye laser output at 701 nm is mixed with the YAG fundamental at 1064 nm to produce 423 nm light by sum frequency.…”

Section: Observational Datamentioning

confidence: 99%

“…the resonance lidar technique, and shown to peak around 90 km (Granier et al, 1985). Since then, a relatively small number of lidar studies of Ca and Ca + (which uniquely among the meteoric metal ions can be observed by ground-based lidar) have been performed (Alpers et al, 1996;Gerding et al, 2000;Granier et al, 1989;Qian and Gardner, 1995;Raizada et al, 2011;Raizada et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

A new model of meteoric calcium in the mesosphere and lower thermosphere

Plane¹,

Feng²,

Martı́n³

et al. 2018

Preprint

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Abstract. Meteoric ablation produces layers of metal atoms in the mesosphere and lower thermosphere (MLT). It has been known for more than 30 years that the Ca atom layer is depleted by over 2 orders of magnitude compared with Na, despite these elements having essentially the same elemental abundance in chondritic meteorites. In contrast, the Ca + ion abundance 15 is depleted by less than a factor of 10. To explain these observations, a large data-base of neutral and ion-molecule reaction kinetics of Ca species, measured over the past decade, was incorporated into the Whole Atmosphere Community Climate Model (WACCM). A new meteoric input function for Ca and Na, derived using a chemical ablation model that has been tested experimentally with a Meteoric Ablation Simulator, shows that Ca experiences significant differential ablation, by almost 1 order of magnitude, with respect to Na. WACCM-Ca simulates the seasonal Ca layer satisfactorily when compared with lidar 20 observations, but tends to overestimate Ca + measurements made by rocket mass spectrometry and lidar. A key finding is that CaOH and CaCO3 are very stable reservoir species because they are involved in essentially closed reaction cycles with O2 andO. This has been demonstrated experimentally for CaOH, and in this study for CaCO3 using electronic structure and statistical rate theory. Most of the neutral Ca is therefore locked in these reservoirs, enabling rapid loss through polymerization into meteoric smoke particles and explaining the extreme depletion of Ca. 25

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Summer to winter variability in mesospheric calcium ion distribution and its dependence on Sporadic E at Arecibo

Cited by 16 publications

References 26 publications

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

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

A case study on occurrence of an unusual structure in the sodium layer over Gadanki, India

A new model of meteoric calcium in the mesosphere and lower thermosphere

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