Atmospheric Ca and Ca+ layers: Midlatitude observations and modeling

Gerding, M.; Alpers, M.; Zahn, U. von; Rollason, R. J.; Plane, J. M. C.

doi:10.1029/2000ja900088

Cited by 79 publications

(166 citation statements)

References 41 publications

(11 reference statements)

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“…7) to maximize in altitude about 3-4 km higher (with 5 km bin-width) than the density of the regular Ca layer (Gerding et al, 2000). This is similar to the behavior of sodium: Hansen and von Zahn (1990) reported the mean altitude of 75 Na s observed above Andenes, Norway (69 • N, 16 • E) to be 95 km, while the density peak of the regular Na layer was found to be at 90 km altitude.…”

Section: Discussion Of the Observationssupporting

confidence: 64%

“…3), we observed between 84 and 91 km altitude a typical narrow regular summer Ca layer, similar to the ones reported by Granier et al (1989), Alpers et al (1996), and Gerding et al (2000). Throughout the observation, its lower ledge ascended wavelike from 83 to 86 km.…”

Section: Observations Of Neutral and Ionized Sporadic Metal Layers: Fsupporting

confidence: 73%

“…Neutral Ca s without Ca + s have been observed only twice above 100 km. This reflects the low concentration of Ca at these altitudes (Gerding et al, 2000).…”

Section: Altitude Distribution Of Neutral and Ionized Sporadic Ca Layersmentioning

confidence: 99%

“…Recently, Gerding et al (2000) have presented a detailed ion chemistry scheme for Ca and Ca (Plane and Helmer, 1994;Gerding et al, 2000). CaX + can dissociate and recombine with e − , giving back the Ca atom.…”

Section: Interpretation Of Variations and Implications For The Formatmentioning

confidence: 99%

“…In addition, 54 nights of Ca-only observations improve the statistics on the regular and sporadic Ca layers. Gerding et al (2000) have presented a description of the lidars in use and of their results concerning the regular Ca and Ca + layers. Here we report on the almost 200 sporadic layers observed during the same observation period.…”

Section: Introductionmentioning

confidence: 99%

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Sporadic Ca and Ca+ layers at mid-latitudes: Simultaneous observations and implications for their formation

et al. 2001

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Abstract. We report on the observations of 188 sporadic layers of either Ca atoms and/or Ca ions that we have observed during 112 nights of lidar soundings of Ca, and 58 nights of Ca + soundings, at Kühlungsborn, Germany (54 • N, 12 • E). The Ca + soundings have been performed simultaneously and in a common volume with the Ca soundings by two separate lidars. Correlations between sporadic neutral and ionized metal layers are demonstrated through four case studies. A systematic study of the variations of occurrence of sporadic Ca and Ca + layers reveals that neutral and ionized Ca layers are not as closely correlated as expected earlier: (a) The altitude distribution shows the simultaneous occurrence of both sporadic Ca and Ca + layers to be most likely only in the narrow altitude range between 90 and 95 km. Above that region, in the lower thermosphere, the sporadic ion layers are much more frequent than atom layers. Below 90 km only very few sporadic layers have been observed; (b) The seasonal variation of sporadic Ca layers exhibits a minimum of occurrence in summer, while sporadic Ca + layers do not show a significant seasonal variation (only the dense Ca + layers appear to have a maximum in summer). At midlatitudes sporadic Ca layers are more frequent than sporadic layers of other atmospheric metals like Na or K. For the explanation of our observations new formation mechanisms are discussed.

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Section: Discussion Of the Observationssupporting

confidence: 64%

Section: Observations Of Neutral and Ionized Sporadic Metal Layers: Fsupporting

confidence: 73%

“…Neutral Ca s without Ca + s have been observed only twice above 100 km. This reflects the low concentration of Ca at these altitudes (Gerding et al, 2000).…”

Section: Altitude Distribution Of Neutral and Ionized Sporadic Ca Layersmentioning

confidence: 99%

Section: Interpretation Of Variations and Implications For The Formatmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Sporadic Ca and Ca+ layers at mid-latitudes: Simultaneous observations and implications for their formation

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

Raizada

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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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Atmospheric Ca and Ca⁺ layers: Midlatitude observations and modeling

Cited by 79 publications

References 41 publications

Sporadic Ca and Ca<sup>+</sup> layers at mid-latitudes: Simultaneous observations and implications for their formation

Sporadic Ca and Ca<sup>+</sup> layers at mid-latitudes: Simultaneous observations and implications for their formation

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

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

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Atmospheric Ca and Ca+ layers: Midlatitude observations and modeling

Cited by 79 publications

References 41 publications

Sporadic Ca and Ca&lt;sup&gt;+&lt;/sup&gt; layers at mid-latitudes: Simultaneous observations and implications for their formation

Sporadic Ca and Ca&lt;sup&gt;+&lt;/sup&gt; layers at mid-latitudes: Simultaneous observations and implications for their formation

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

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

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Atmospheric Ca and Ca⁺ layers: Midlatitude observations and modeling

Sporadic Ca and Ca<sup>+</sup> layers at mid-latitudes: Simultaneous observations and implications for their formation

Sporadic Ca and Ca<sup>+</sup> layers at mid-latitudes: Simultaneous observations and implications for their formation