Joint observations of sporadic sodium and sporadic E layers at middle and low latitudes in China

Jiao, Jiaguo; Yang, Guotao; Xu, Zhigang; Gong, Shunsheng; Wang, Jihong; Tian, Dai-Ke; Zhang, Wenzhen; Zhang, Tiemin; Xianchang, Yang; Fu, Jun; Cheng, Xuewu

doi:10.1007/s11434-014-0441-0

Cited by 8 publications

(9 citation statements)

References 32 publications

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“…This varying pattern is similar to those reported in the previous works about the SSLs and Es [21,30,35]. Comparing the statistical parameters of the LTSLs with the statistical parameters of the SSLs observed at Yanqing [11,32], three differences become clear. The altitude of the LTSLs (ranging from 105 to 120 km with an average altitude of 109.5 km) are higher than those of the SSLs (ranging from 90 to 100 km with an average of 95.7 km); the densities of the LTSLs (which are much lower than that of the main sodium layer) are less than those of the SSLs (which are much greater than that of the main sodium layer); and the FWHMs of the LTSLs (distributed from 1 to 12 km with an average width of approximately 4.7 km) are broader than those of the SSLs (approximately 0.2-3.0 km with an average value of 1.7 km).…”

Section: The Parameters Of the Ltslssupporting

confidence: 89%

“…Most SSLs appeared to occur around midnight local time and were located above 90 km. The full width at half maximum (FWHM) of the SSL was less than 5 km, and the peak value of the SSL was generally several times larger than that of the background sodium layer [11]. Furthermore, the occurrence rates, central heights and densities variations of the LTSLs, and the relationships among the LTSLs, Es and tidal wave.…”

Section: Introductionmentioning

confidence: 95%

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The Comprehensive Study of Low Thermospheric Sodium Layers during the 24th Solar Cycle

et al. 2020

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The low thermospheric sodium layer (LTSL) is the separate sodium atom layer above 105 km. Based on 11,607 h of lidar observations from Yanqing (40.5° N, 116.0° E) from 2010 to 2016, we found 38 LTSLs wherein the peak densities were more than five percent above those of the main sodium layers. This work presents the peak altitudes, peak local times and peak densities of the LTSLs as well as the long-term characteristics of the seasonal and inter-annual variations of LTSLs. We analyzed the correlation between the LTSL and sporadic E layer (Es). The seasonal variation trends of the occurrences of LTSL and Es are similar, and the results showed that 95% of the LTSLs were accompanied by Es. We also found that 69% of the LTSL cases exhibited apparent downward phase progressions, while the descending rates of the LTSLs are consistent with the phase speeds of the tide.

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Section: The Parameters Of the Ltslssupporting

confidence: 89%

Section: Introductionmentioning

confidence: 95%

The Comprehensive Study of Low Thermospheric Sodium Layers during the 24th Solar Cycle

et al. 2020

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“…Many previous studies reported the correlation between Nas and sporadic E layer (E s ) [Friedman et al, 2000;Kane et al, 1993;Williams et al, 2007]. However, in some middle-latitude locations, Nas events were well related with E s only in summer, and many of them occurred in the absence of E s during other season [Dou et al, 2009;Jiao et al, 2014]. One possible reason might be found in the ablation of meteoroids Journal of Geophysical Research: Space Physics 10.1002/2014JA020955 [Dou et al, 2010].…”

Section: Discussionmentioning

confidence: 99%

First report of sporadic K layers and comparison with sporadic Na layers at Beijing, China (40.6°N, 116.2°E)

et al. 2015

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A double-laser beam lidar was successfully developed to simultaneously measure K and Na layers at Beijing (40.6°N, 116.2°E) in 2010. Statistical analysis of the parameters of sporadic K (K s ) and sporadic Na (Nas) layers was performed over 2 years of lidar data, and different characteristics of them were found. The average K s occurrence (2.9%) was lower than that of Nas (5.9%); the Nas occurrence had a maximum (19.3%) in May-June months and a minimum (1.6%) in January-February months, while the K s occurrence had a maximum (4.9%) in January-February months and a minimum (1.0%) in September-October months; most K s peaks tended to occur around 93 km, which was~2 km lower than that of Nas (~95 km); the K s peak density was often at least 1 order of magnitude lower than that of Nas; notably, two K s with high peak densities (>1000 cm À3 ) were observed, which were much higher than K density (15-300 cm À3 ) reported before. The ascending time of K s was often longer than its descending time, but an opposite trend occurred for Nas. During the 152 cases of joint observation for the K and Na layers, 21% (32/152) were cases in which K s and Nas events simultaneously occurred, while 79% (120/152) were cases in which only one layer (K or Na) exhibited a strong K s or Nas.

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“…The Urbana, Illinois lidar operated for 350 hours in 53 single nights throughout the whole year of 1988, but only two convincing SSL occasions with periods less than 2 hours in total were observed on the night of Oct 30 (Senft et al, 1989). However, recent observations by sodium lidar at Beijing (40.5˚N, 116.0˚E) revealed that although not frequently, SSLs could also have some occurrence at this mid latitude station (Jiao et al, 2015;Jiao et al, 2014;Yuan et al, 2014).…”

Section: Possible Reasons For the Rarity Of Ssls Near 40˚nmentioning

confidence: 95%

A review of latitudinal characteristics of sporadic sodium layers, including new results from the Chinese Meridian Project

Qiu

Tang

Jia

et al. 2016

Earth-Science Reviews

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Characteristics of the sporadic sodium layers (SSLs or NaS) in different latitudes and altitudes are summarized in this paper and the possible mechanisms are discussed. The SSLs in high latitude have a maximum frequency near midnight with significant seasonal differences of height and intensity being reported in previous studies. The average height of summer SSLs was much lower than that of winter SSLs and the average density enhancement factor for summer SSLs was much larger than that for winter SSLs. The simultaneous observations of the SSLs and sporadic E layers (ES) suggested that the ES probably contribute significantly to the formation of high latitude SSLs. In contrast, the temperature mechanism seemed to contribute little to the high latitude SSLs, especially since plenty or frequent high latitude SSLs were observed under minimum temperature conditions. The SSLs in the subtropical area from 20˚N to 35˚N show similar characteristics between different stations. The onset of SSLs in Hefei (31.8˚N, 117.3˚E) maintains (?) high occurrence from 20 to 03 LT and the peak height distribution is distinctly different between summer and winter. The winter sporadic sodium events are largely confined to altitudes below 96 km, while summer SSLs occurred frequently above 96 km. The simultaneous observations of SSLs, ES and high temperature suggested that the SSLs in subtropical area have a closer link with high temperature conditions than with the formation of ES. The high temperature are most likely caused by gravity wave breaking, together with a newly proposed icy dust sodium reservoir, both processes probably contribute importantly for the formation of subtropical SSLs. In contrast, the ES are not essential for most SSLs in the subtropical area, and they seem to influence only a few SSLs above 96 km, especially in the summer months from May to August. The observations from the Haikou station (19.5˚N, 109.1˚E) suggested that the SSLs in low latitude have some similar characteristics with that of the subtropical area. SSLs in Haikou also have stable occurrence frequency between 20-03 LT and the average altitude of the winter SSLs is lower than that of the summer SSLs. However, the occurrence frequency of SSLs above 96 km does not show any obvious seasonal difference for this station. The abundance of data and observations from low-latitude stations indicate that both the temperature control mechanism and ES theory are likely responsible for the formation of SSLs in the low latitudes and each mechanism can generate distinct types of SSLs. Temperature control mechanism is more likely to account for the large SSLs below 96 km, while ES theory probably contributes more directly to some SSLs above 96 km. Our results highlighted both the single-mechanism and combined actions of the temperature mechanism and ES theory on the formation of the SSLs in different latitudes and altitudes. The high latitude SSLs have a closer link with the ES theory and the subtropical SSLs correlate more strongly to high temperature, while both the...

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Joint observations of sporadic sodium and sporadic E layers at middle and low latitudes in China

Cited by 8 publications

References 32 publications

The Comprehensive Study of Low Thermospheric Sodium Layers during the 24th Solar Cycle

The Comprehensive Study of Low Thermospheric Sodium Layers during the 24th Solar Cycle

First report of sporadic K layers and comparison with sporadic Na layers at Beijing, China (40.6°N, 116.2°E)

A review of latitudinal characteristics of sporadic sodium layers, including new results from the Chinese Meridian Project

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