Lidar, radar and airglow observations of a prominent sporadic Na/sporadic E layer event at Arecibo during AIDA-89

Kane, Timothy J.; Gardner, Chester S.; Znou, Q; Mathews, J. D.; Tepley, C. A.

doi:10.1016/0021-9169(93)90084-c

Cited by 90 publications

(76 citation statements)

References 26 publications

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“…Nas has been studied for almost 2 decades and is now known to be common at low and high latitudes but rare at midlatitudes , 1996]. Lidar and radar observations at Arecibo showed that many low-latitude Nas are associated with regions containing high concentrations of ions and electrons [Kane et al, 1993]. The first observations of Nas in Hawaii were made by Kwon et al [1988] at Mauna Kea.…”

Section: Introductionmentioning

confidence: 99%

Characteristics of the sporadic Na layers observed during the Airborne Lidar and Observations of Hawaiian Airglow/Airborne Noctilucent Cloud (ALOHA/ANLC‐93) campaigns

Qian¹,

Gu²,

Gardner³

1998

J. Geophys. Res.

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Abstract. We summarize the characteristics of the 43 sporadic Na (Na0 layers observed by the airborne Na density and the Haleakala Na wind/temperature lidars during the Airborne Lidar and Observations of Hawaiian Airglow/Airborne Noctilucent Cloud (ALOHA/ANLC-93) campaigns. Na• layers are clearly not a local phenomenon since the horizontal extents varied from approximately 25 to almost 1600 km with a mean of 440 km. For the majority of the Na• layers observed above Haleakala, the temperatures were significantly warmer than the mean. The average enhancement was 12.9øK or about 6%. The temperature variations typically led the Na• density variations in time and on average reached their maximum values approximately 0.7 km below and 23 min before the Na• maxima. However, the maximum temperatures and Na• densities were only weakly correlated. Strong vertical shears in the horizontal winds were observed during the majority of the Na• events. The average maximum total shear was approximately equal to the shear instability limit of 42 rn s -• km -•. The maximum shears were located on average about 0.5 km below the Na• layer. In most cases the meridional shears were significantly stronger than the zonal shears. The maximum total shears were generally directed to the N-NE and to the south. The strong temperature and wind perturbations observed during the majority of the events suggest that gravity waves play an important role in Na• formation, although the exact nature of that role remains unclear.

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Section: Introductionmentioning

confidence: 99%

Characteristics of the sporadic Na layers observed during the Airborne Lidar and Observations of Hawaiian Airglow/Airborne Noctilucent Cloud (ALOHA/ANLC‐93) campaigns

Qian¹,

Gu²,

Gardner³

1998

J. Geophys. Res.

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“…Supply of sodium atoms from an Es layer has been considered the most possible generation mechanism. Kane et al (1993) argued that an Es layer triggered the release of sodium atoms, but the Es layer was not the major source of the SSL observed at Arecibo. This is because the number of sodium ions contained in the Es layer was not enough for the generation of the SSL compared to IS radar and lidar observations.…”

Section: Discussionmentioning

confidence: 99%

“…Possible proposed candidates are the supply of sodium atoms from an Es layer, an effect of the electric field (downward ion motion), chemical reactions due to local temperature enhancements, meteor absorption, and auroral particle sputtering (cf. Kane et al, 1993;Heinselman, 2000;Kirkwood and von Zahn, 1991;Gardner et al, 1993;Clemesha et al, 1988;von Zahn and Hansen, 1988). The key requirements for any mechanism to fulfill are how to supply enhanced sodium atoms and how to make a thin layer structure with a large horizontal extent.…”

Section: Discussionmentioning

confidence: 99%

“…When we assume that the Es layer contained sodium ions numbering 10 % of the total (cf. Hansen and von Zahn, 1990;Kane et al, 1993;Heinselman, 2000), the amount of the sodium ions was 3.0 × 10 9 m −3 , which corresponds to about 21 % for the 0.5 km resolution data and to about 37 % for the 2.2 km resolution data of the averaged maximum sodium density of the SSL. Furthermore, even if we assume the abundance of sodium ions to be 20 % in the Es layer, the amount of sodium ions corresponds to less than 74 %.…”

Section: Production From the Es Layermentioning

confidence: 99%

“…Some in situ measurements suggest that sodium ion abundance is several percent of the total abundance. Kane et al (1993) estimated that the sodium ion abundance in an Es layer was 10 % at most. Figure 4b shows variations in sodium and electron densities.…”

Section: Production From the Es Layermentioning

confidence: 99%

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A case study on generation mechanisms of a sporadic sodium layer above Tromsø (69.6° N) during a night of high auroral activity

et al. 2015

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Abstract.We have quantitatively evaluated generation mechanisms of a sporadic sodium layer (SSL) based on observational data obtained by multiple instruments at a highlatitude station: Ramfjordmoen, Tromsø, Norway (69.6 • N, 19.2 • E). The sodium lidar observed an SSL at 21:18 UT on 22 January 2012. The SSL was observed for 18 min, with a maximum sodium density of about 1.9 × 10 10 m −3 at 93 km with a 1.1 km thickness. The European Incoherent Scatter (EISCAT) UHF radar observed a sporadic E layer (Es layer) above 90 km from 20:00 to 23:00 UT. After 20:00 UT, the Es layer gradually descended and reached 94 km at 21:18 UT when the SSL appeared at the same altitude. In this event, considering the abundance of sodium ions (10 % or less), the Es layer could provide only about 37 % or less of the sodium atoms to the SSL. We have investigated a temporal development of the normal sodium ion layer with a consideration of chemical reactions and the effect of the (southwestward) electric field using observational values of the neutral temperature, electron density, horizontal neutral wind, and electric field. This calculation has shown that those processes, including contributions of the Es layer, would provide about 88 % of sodium atoms of the SSL. The effects of meteor absorption and auroral particle sputtering appear to be less important. Therefore, we have concluded that the major source of the SSL was sodium ions in a normal sodium ion layer. Two processes -namely the downward transportation of sodium ions from a normal sodium ion layer due to the electric field and the additional supply of sodium ions from the Es layer under relatively high electron density conditions (i.e., in the Es layer) -played a major role in generating the SSL in this event. Furthermore, we have found that the SSL was located in a lower-temperature region and that the temperature inside the SSL did not show any remarkable temperature enhancements.

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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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Lidar, radar and airglow observations of a prominent sporadic Na/sporadic E layer event at Arecibo during AIDA-89

Cited by 90 publications

References 26 publications

Characteristics of the sporadic Na layers observed during the Airborne Lidar and Observations of Hawaiian Airglow/Airborne Noctilucent Cloud (ALOHA/ANLC‐93) campaigns

Characteristics of the sporadic Na layers observed during the Airborne Lidar and Observations of Hawaiian Airglow/Airborne Noctilucent Cloud (ALOHA/ANLC‐93) campaigns

A case study on generation mechanisms of a sporadic sodium layer above Tromsø (69.6° N) during a night of high auroral activity

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

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