Double sodium layers observation over Beijing, China

Wang, Jihong; Yang, Ye; Cheng, Xuewu; Yang, Guotao; Song, Shalei; Gong, Shunsheng

doi:10.1029/2012gl052134

Cited by 49 publications

(54 citation statements)

References 25 publications

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“…Wang et al . [] presented descending Na layers with high densities in the lower thermosphere below 130 km over Beijing (40.2°N, 116.2°E), and Xue et al . [] reported two enhanced Na layers below 130 km for Lijiang (26.7°N, 100.0°E).…”

Section: Introductionmentioning

confidence: 99%

Lidar observations of thermospheric Na layers up to 170 km with a descending tidal phase at Lijiang (26.7°N, 100.0°E), China

et al. 2015

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We report the first lidar observations of thermospheric Na layers up to 170 km at Lijiang (geomagnetic 21.6°N, 171.8°E), China, in March, April, and December 2012. The Na densities inside the layers are low, ranging from ~1 to ~6 cm−3 at altitudes of 130–170 km, about 3 orders of magnitude lower than the Na peak density in the mesopause region. All of these layers exhibit an apparent downward phase progression with a descending rate of 11–12 km/h or ~3 m/s, consistent with the vertical phase speed of semidiurnal tides around 140 km. We have identified at least 12 events from the total 37 nights of lidar observations with four shown in this report, giving an occurrence frequency of ~33% over Lijiang. These thermospheric layer events correspond to strong to moderate equatorial fountain effects, bolstering our hypothesis that the deposit of metallic ions from the equatorial region to low latitudes via the fountain effect provides the Na+ ions in the thermosphere over Lijiang. Adopting the theory by Chu et al. (2011) and the hypothesis by Tsuda et al. (2015), we further hypothesize that the thermospheric Na layers are formed through the neutralization of the tidal‐wind‐shear‐converged Na+ layers via direct electron‐Na+ recombination Na+ + e− → Na + hν. An envelope calculation using reasonable ion and electron densities shows good consistency with the observations.

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Section: Introductionmentioning

confidence: 99%

Lidar observations of thermospheric Na layers up to 170 km with a descending tidal phase at Lijiang (26.7°N, 100.0°E), China

et al. 2015

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“…Wang et al . [] reported Na events occurring between 105 and 130 km altitudes with peak concentrations up to 64% of the maximum density within the main layer over Beijing, China. They occurred mainly in spring/summer, and their formation mechanisms are still unknown.…”

Section: Introductionmentioning

confidence: 99%

First simultaneous measurements of Na and K thermospheric layers along with TILs from Arecibo

Raizada

Brum

Tepley

et al. 2015

Geophysical Research Letters

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This work presents the first simultaneous observations of Na and K between 120 and 150 km altitudes along with ionospheric tidal ion layers (TILs) obtained on 30 January 2006 data from Arecibo. The latter displays an average downward phase velocity of ~14.7 ms−1. However, the neutral layers descend together at a much slower velocity of about ~0.69 ms−1. This indicates that thermospheric atomic metal layers are not necessarily associated with TILs. The ratio of the average Na/K abundances in thermosphere is ~35.5 as compared to 150 in the main layer (80–105 km). The long lifetimes of ions at ~140 km implies that neutral layers cannot result from direct neutralization of metal ions in the TILs. We investigate different mechanisms that can deposit neutral atoms at thermospheric altitudes.

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“…A large aperture telescope (1-m diameter) and high sensitivity photomultipliers (PMTs) are used to detect the weak backscattered signal. The time resolution of the Na lidar is 3 min, with a vertical resolution of 96 m. A more detailed description of the lidar system is given by Wang et al (2012).…”

Section: Observationsmentioning

confidence: 99%

Investigation of a mesospheric bore event over northern China

Yue

et al. 2013

Ann. Geophys.

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Abstract. A mesospheric bore event was observed using an OH all-sky airglow imager (ASAI) at Xinglong (40.2° N, 117.4° E), in northern China, on the night of 8–9 January 2011. Simultaneous observations by a Doppler meteor radar, a broadband sodium lidar, and TIMED/SABER OH intensity and temperature measurements are used to investigate the characteristics and environment of the bore propagation and the possible relations with the Na density perturbations. The bore propagated from northeast to southwest and divided the sky into bright and dark halves. The calculations show that the bore has an average phase velocity of 68 m s−1. The crests following the bore have a horizontal wavelength of ~ 22 km. These parameters are consistent with the hydraulic jump theory proposed by Dewan and Picard, as well as the previous bore reports. Simultaneous wind measurements from the Doppler meteor radar at Shisanling (40.3° N, 116.2° E) and temperature data from SABER on board the TIMED satellite are used to characterize the propagating environment of the bore. The result shows that a thermal-Doppler duct exists near the OH layer that supports the horizontal propagation of the bore. Simultaneous Na lidar observations at Yanqing (40.4° N, 116.0° E) suggest that there is a downward displacement of Na density during the passage of the mesospheric bore event.

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Double sodium layers observation over Beijing, China

Cited by 49 publications

References 25 publications

Lidar observations of thermospheric Na layers up to 170 km with a descending tidal phase at Lijiang (26.7°N, 100.0°E), China

Lidar observations of thermospheric Na layers up to 170 km with a descending tidal phase at Lijiang (26.7°N, 100.0°E), China

First simultaneous measurements of Na and K thermospheric layers along with TILs from Arecibo

Investigation of a mesospheric bore event over northern China

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