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

Abstract. We have quantitatively evaluated generation mechanisms of a sporadic sodium layer (SSL) based on observational data obtained by multiple instruments at a high-latitude 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 × 1010 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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The sporadic sodium layer: a possible tracer for the conjunction between the upper and lower atmospheres

Atmospheric Chemistry and Physics ◽

10.5194/acp-21-11927-2021 ◽

2021 ◽

Vol 21 (15) ◽

pp. 11927-11940

Author(s):

Shican Qiu ◽

Ning Wang ◽

Willie Soon ◽

Gaopeng Lu ◽

Mingjiao Jia ◽

...

Keyword(s):

Electric Field ◽

World Wide ◽

Fluxgate Magnetometer ◽

Ionospheric Disturbances ◽

Sodium Layer ◽

The World ◽

Sporadic E Layer ◽

Sporadic E

Abstract. In this research, we reveal the inter-connection between lightning strokes, reversal of the electric field, ionospheric disturbances, and a sodium layer (NaS), based on the joint observations by a temperature/wind (T/W, where the slash means “and”) lidar, an ionosonde, an atmospheric electric mill, a fluxgate magnetometer, and the World Wide Lightning Location Network (WWLLN). Our results suggest that lightning strokes could trigger or amplify the formation of an NaS layer in a descending sporadic E layer (ES), through a mechanism that involves the overturning of the electric field. A conjunction between the lower and upper atmospheres could be established as follows by these inter-connected phenomena, and the key processes could be suggested to be: lightning strokes → overturning of the electric field → ES generating NaS.

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Chemistry of sprite discharges through ion-neutral reactions

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-8-2311-2008 ◽

2008 ◽

Vol 8 (1) ◽

pp. 2311-2336 ◽

Cited By ~ 4

Author(s):

Y. Hiraki ◽

Y. Kasai ◽

H. Fukunishi

Keyword(s):

Electric Field ◽

Electron Density ◽

Middle Atmosphere ◽

Time Behavior ◽

High Electron ◽

One Dimensional ◽

Long Time ◽

Concentration Changes ◽

Source Sink ◽

Odd Nitrogen

Abstract. We estimate the concentration changes, caused by a single streamer in sprites, of ozone and related minor species as odd nitrogen (NOx) and hydrogen (HOx) families in the upper stratosphere and mesosphere. The streamer has an intense electric field and high electron density at its head where a large number of chemically-radical ions and atoms are produced through electron impact on neutral molecules. After propagation of the streamer, the densities of minor species can be perturbed through ion-neutral chemical reactions initiated by the relaxation of these radical products. We evaluate the production rates of ions and atoms using electron kinetics model and assuming the electric field and electron density in the streamer head. We calculate the density variations mainly for NOx, Ox, and HOx species using a one-dimensional model of the neutral and ion composition of the middle atmosphere, including the effect of the sprite streamer. Results at the nighttime condition show that the densities of NO, O3, H, and OH increase suddenly through reactions triggered by firstly produced atomic nitrogen and oxygen, and electrons just after streamer initiation. It is shown that NO and NO2 still remain for 1 h by a certain order of increase with their source-sink balance predominantly around 60 km; for other species, increases in O3, OH, HO2, and H2O2 still remain in the range of 40–70 km. From this affirmative result of long time behavior previously not presented, we emphasize that sprites would have a power to impact on local chemistry at night. We also discuss comparison with previous studies and suggestion for satellite observations.

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Sporadic sodium layer: A possible tracer for the conjunction between the upper and lower atmospheres

10.5194/acp-2020-1079 ◽

2020 ◽

Author(s):

Shican Qiu ◽

Ning Wang ◽

Willie Soon ◽

Gaopeng Lu ◽

Mingjiao Jia ◽

...

Keyword(s):

Electric Field ◽

World Wide ◽

Atmospheric Electric Field ◽

Fluxgate Magnetometer ◽

Ionospheric Disturbances ◽

Sodium Layer ◽

Sporadic E Layers ◽

Sporadic E ◽

Statistical Results

Abstract. In this research, we reveal the inter-connection between lightning strokes, reversal of the electric field, ionospheric disturbances, and a trigger of sporadic sodium layer event (NaS), based on the joint observations by three lidars, an ionosonde, an atmospheric electric mill, a fluxgate magnetometer, and World Wide Lightning Location Network (WWLLN). Our results suggest that lightning strokes would probably have an influence on the ionosphere and thus give rise to the occurrence of NaS, with the overturning of electric field playing an important role. Statistical results reveal that the sporadic E layers (ES) could hardly be formed or maintained when the atmospheric electric field turns upward. A conjunction between the lower and upper atmospheres could be established by these inter-connected phenomena, and the key processes could be suggested as follows: lightning strokes→overturning of electric field→different collisional frequencies for ions and electrons→depletion of ES/generation of NaS.

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A sporadic sodium layer event detected with five-directional lidar and simultaneous wind, electron density, and electric field observation at Tromsø, Norway

Geophysical Research Letters ◽

10.1002/2015gl066411 ◽

2015 ◽

Vol 42 (21) ◽

pp. 9190-9196 ◽

Cited By ~ 9

Author(s):

T. T. Tsuda ◽

S. Nozawa ◽

T. D. Kawahara ◽

T. Kawabata ◽

N. Saito ◽

...

Keyword(s):

Electric Field ◽

Electron Density ◽

Field Observation ◽

Sodium Layer

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Chemistry of sprite discharges through ion-neutral reactions

Atmospheric Chemistry and Physics ◽

10.5194/acp-8-3919-2008 ◽

2008 ◽

Vol 8 (14) ◽

pp. 3919-3928 ◽

Cited By ~ 22

Author(s):

Y. Hiraki ◽

Y. Kasai ◽

H. Fukunishi

Keyword(s):

Electric Field ◽

Electron Density ◽

Middle Atmosphere ◽

Time Behavior ◽

High Electron ◽

Streamer Discharge ◽

Head Region ◽

Long Time ◽

Concentration Changes ◽

Odd Nitrogen

Abstract. We estimate the concentration changes, caused by streamer discharge in sprites, of ozone and related minor species as odd nitrogen (NOx) and hydrogen (HOx) families in the upper stratosphere and mesosphere. The streamer has an intense electric field and high electron density at its head, where a large number of chemically-radical ions and atoms are produced through electron impact on neutral molecules. After its propagation, densities of minor species can be perturbed through ion-neutral chemical reactions initiated by the relaxation of these radical products. We evaluate the production rates of ions and atoms using an electron kinetics model and by assuming that the electric field and electron density are in the head region. We calculate the density variations mainly for NOx, Ox, and HOx species using a one-dimensional model of the neutral and ion composition of the middle atmosphere, including the effect of the sprite streamer. Results at the nighttime condition show that the densities of NO, O3, H, and OH increase suddenly through reactions triggered by the first atomic nitrogen and oxygen product, and electrons just after streamer initiation. It is shown that NO and NO2 still remain for 1 h by a certain order of increase with their source-sink balance, predominantly around 60 km; for other species, increases in O3, OH, HO2, and H2O2 still remain in the range of 40–70 km. From this affirmative result of long-time behavior previously not presented, we emphasize that sprites would have the power to impact local chemistry at night. We also discuss the consistency with previous theoretical and observational studies, along with future suggestions.

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Electron microscope study of the secretory activity of epithelial cells in embryonic thymus

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010015945x ◽

1990 ◽

Vol 48 (3) ◽

pp. 382-383

Author(s):

H. Alasam

Keyword(s):

Cell Differentiation ◽

T Cell ◽

Epithelial Cells ◽

Electron Density ◽

Secretory Activity ◽

T Cell Differentiation ◽

High Electron ◽

Transmission Electron ◽

Medullary Epithelial Cells ◽

Thymic Factor

The possibility that intrathymic T-cell differentiation involves stem cell-lymphoid interactions in embryos led us to study the ultrastructure of epithelial cell in normal embryonic thymus. Studies in adult thymus showed that it produces several peptides that induce T-cell differentiation. Several of them have been chemically characterized, such as thymosin α 1, thymopoietin, thymic humoral factor or the serum thymic factor. It was suggested that most of these factors are secreted by populations of A and B-epithelial cells.Embryonic materials were obtained from inbred matings of Swiss Albino mice. Thymuses were disected from embryos 17 days old and prepared for transmission electron microscopy. Our studies showed that embryonic thymus at this stage contains undifferentiated and differentiated epithelial cells, large lymphoblasts, medium and few small lymphocytes (Fig. 5). No differences were found between cortical and medullary epithelial cells, in contrast to the findings of Van Vliet et al,. Epithelial cells were mostly of the A-type with low electron density in both cytoplasm and nucleus. However few B-type with high electron density were also found (Fig. 7).

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Effective Dielectric Function of Porous Silicon: the Transverse Component

MRS Proceedings ◽

10.1557/proc-358-49 ◽

1994 ◽

Vol 358 ◽

Author(s):

G. Gumbs

Keyword(s):

Absorption Spectrum ◽

Absorption Coefficient ◽

Electron Density ◽

Quantum Wires ◽

Interband Transition ◽

Incident Light ◽

Transverse Component ◽

Effect Of Temperature ◽

High Electron ◽

Confining Potential

ABSTRACTA self-consistent many-body theory is developed to study the effect of temperature and electron density on the interband absorption coefficient and the frequency-dependent refractive index for an array of isolated quantum wires. The peaks in the absorption coefficient correspond to interband transitions resulting in the resonant absorption of light. The oscillations in the derivative spectrum are due to the quantization of the energy levels related to the in-plane confining potential for such reduced dimensional systems. There are appreciable changes in the absorption spectrum when the electron density or temperature is increased. One interband transition peak is suppressed in the high electron density limit and the thermal depopulation effect on the electron subbands can be easily seen when the temperature is high. We also find that the exciton coupling weakens the shoulder features in the absorption spectrum. This study is relevant to optical characterization of the confining potential and the areal density of electrons using photoreflectance. By using incident light with tunable frequencies in the interband excitation regime, contactless photoreflectance measurements may be carried out and the data compared with our calculations. By fitting the numerical results to the peak positions of the photoreflectance spectrum, the number of electrons in each wire may be extracted.

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