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

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.

scholarly journals The sporadic sodium layer: a possible tracer for the conjunction between the upper and lower atmospheres

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.

scholarly journals Coincident extremely large sporadic sodium and sporadic E layers observed in the lower thermosphere over Colorado and Utah

2007 ◽  
Vol 25 (1) ◽  
pp. 3-8 ◽  
Author(s):  
B. P. Williams ◽  
F. T. Berkey ◽  
J. Sherman ◽  
C. Y. She
Keyword(s):  
North America ◽  
Layer Structure ◽  
Lower Thermosphere ◽  
Ion Density ◽  
Bear Lake ◽  
Sodium Layer ◽  
Sporadic E Layers ◽  
Fort Collins ◽  
Sporadic E ◽  
Wind Shears

Abstract. On the night of 2 June 2002, the sodium lidar in Fort Collins, CO (40.6 N, 105 W) measured an extremely strong sporadic sodium layer lasting from 03:30 to 05:00 UT with several weaker layers later in the night at 06:00 and 09:00 UT. There is a double layer structure with peaks at 101 and 104 km. The peak sodium density was 21 000 atoms/cm3 with a column abundance of up to twice that of the normal sodium layer. The peak density was 500 times greater than the typical density at that altitude. The sporadic layer abundance and strength factor were higher than any reported in the literature. The two lidar beams, separated by 70 km at this altitude, both measured 0.6 h periodicities in the abundance, but out of phase with each other by 0.3 h. There is also evidence for strong wave activity in the lidar temperatures and winds. The NOAA ionosonde in Boulder, CO (40.0 N, 105 W) measured a critical frequency (foEs) of 14.3 MHz at 03:00 UT on this night, the highest value anytime during 2002. The high values of total ion density inferred means that Na+ fraction must have been only a few percent to explain the neutral Na layer abundances. The Bear Lake, Utah (41.9 N, 111.4 W) dynasonde also measured intense Es between 02:00 and 05:00 UT and again from 06:00 to 08:00 UT about 700 km west of the lidar, with most of the ionograms during these intervals measuring Es up to 12 MHz, the limit of the ionosonde sweep. Other ionosondes around North America on the NGDC database measured normal foEs values that night, so it was a localized event within North America. The peak of Es activity observed in Europe during the summer of 2002 occurred on 4 June. The observations are consistent with the current theories where a combination of wind shears and long period waves form and push downward a concentrated layer of ions, which then chemically react and form a narrow layer of sodium atoms.

scholarly journals Anomalous radon emanation linked to preseismic electromagnetic phenomena

2007 ◽  
Vol 7 (5) ◽  
pp. 629-635 ◽  
Author(s):  
Y. Omori ◽  
Y. Yasuoka ◽  
H. Nagahama ◽  
Y. Kawada ◽  
T. Ishikawa ◽  
...  
Keyword(s):  
Electric Field ◽  
Power Law ◽  
Radon Concentration ◽  
Damage Evolution ◽  
Atmospheric Electric Field ◽  
Ionospheric Disturbances ◽  
Radon Emanation ◽  
Radon Anomaly ◽  
Large Earthquakes ◽  
Atmospheric Radon

Abstract. Anomalous emanation of radon (222Rn) was observed preceding large earthquakes and is considered to be linked to preseismic electromagnetic phenomena (e.g. great changes of atmospheric electric field and ionospheric disturbances). Here we analyze atmospheric radon concentration and estimate changes of electrical conditions in atmosphere due to preseismic radon anomaly. The increase of radon emanation obeys crustal damage evolution, following a power-law of time-to-earthquake. Moreover, the radon emanation decreases the atmospheric electric field by 40%, besides influencing the maximum strength of atmospheric electric field by 104–105 V/m enough to trigger ionospheric disturbances. These changes are within the ranges observed or explaining electromagnetic phenomena associated with large earthquakes.

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

2015 ◽  
Vol 33 (8) ◽  
pp. 941-953 ◽  
Author(s):  
T. Takahashi ◽  
S. Nozawa ◽  
T. T. Tsuda ◽  
Y. Ogawa ◽  
N. Saito ◽  
...  
Keyword(s):  
Electric Field ◽  
Electron Density ◽  
Sodium Ion ◽  
High Electron ◽  
Sodium Ions ◽  
Sodium Layer ◽  
Sodium Atoms ◽  
Sporadic E ◽  
Lower Temperature ◽  
Generation Mechanisms

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.

scholarly journals High resolution observations of sporadic-E layers within the polar cap ionosphere using a new incoherent scatter radar experiment

2002 ◽  
Vol 20 (9) ◽  
pp. 1429-1438 ◽  
Author(s):  
B. Damtie ◽  
T. Nygrén ◽  
M. S. Lehtinen ◽  
A. Huuskonen
Keyword(s):  
High Resolution ◽  
Electric Field ◽  
Single Layer ◽  
Meridional Wind ◽  
Two Phase ◽  
Range Resolution ◽  
Incoherent Scatter ◽  
Sporadic E Layers ◽  
Sporadic E ◽  
Ionospheric Electric Field

Abstract. High resolution observations of sporadic-E layers using a new experiment with the EISCAT (European Incoherent SCATter) Svalbard radar (ESR) are presented. The observations were made by means of a new type of hardware, which was connected in parallel with the standard receiver. The radar beam was aligned with the geomagnetic field. The experiment applies a new modulation principle. Two phase codes, one with 22 bits and the other with 5 bits, were transmitted at separate frequencies. Each bit was further modulated by a 5-bit Barker code. The basic bit length of both transmissions was 6 µs. Instead of storing the lagged products of the ionospheric echoes in the traditional way, samples of both the transmitted pulses and the ionospheric echoes were taken at intervals of 1 µs and stored on hard disk. The lagged products were calculated later in an off-line analysis. In the analysis a sidelobe-free Barker decoding technique was used. The experiment produces range ambiguities, which were removed by mathematical inversion. Sporadic-E layers were observed at 105–115 km altitudes, and they are displayed with a 150-m range resolution and a 10-s time resolution. The layers show sometimes complex shapes, including triple peaked structures. The thickness of these sublayers is of the order of 1–2 km and they may be separated by 5 km in range. While drifting downwards, the sublayers merge together to form a single layer. The plasma inside a layer is found to have a longer correlation length than that of the surrounding plasma. This may be an indication of heavy ions inside the layer. The field-aligned ion velocity is also calculated. It reveals shears in the meridional wind, which suggests that shears probably also exist in the zonal wind. Hence the wind shear mechanism is a possible generation mechanism of the layer. However, observations from the coherent SuperDARN radar indicate the presence of an ionospheric electric field pointing in the sector between west and north. Thus, the layer could also be produced by the electric field mechanism. This means that both mechanisms may be active simultaneously. Their relative importance could not be determined in this study.Key words. Ionosphere; polar ionosphere, instruments and techniques

scholarly journals A case study of a sporadic sodium layer observed by the ALOMAR Weber Na lidar

2008 ◽  
Vol 26 (5) ◽  
pp. 1071-1081 ◽  
Author(s):  
H. Nesse ◽  
D. Heinrich ◽  
B. Williams ◽  
U.-P. Hoppe ◽  
J. Stadsnes ◽  
...  
Keyword(s):  
Energetic Electron ◽  
Electron Bombardment ◽  
Meteor Radar ◽  
Temperature Dependent ◽  
Sodium Layer ◽  
Sporadic E Layers ◽  
Meteoric Smoke ◽  
Sporadic E ◽  
Dependent Mechanism

Abstract. Several possible mechanisms for the production of sporadic sodium layers have been discussed in the literature, but none of them seem to explain all the accumulated observations. The hypotheses range from direct meteoric input, to energetic electron bombardment on meteoric smoke particles, to ion neutralization, to temperature dependent chemistry. The varied instrumentation located on Andøya and near Tromsø in Norway gives us an opportunity to test the different theories applied to high latitude sporadic sodium layers. We use the ALOMAR Weber sodium lidar to monitor the appearance and characteristics of a sporadic sodium layer that was observed on 5 November 2005. We also monitor the temperature to test the hypotheses regarding a temperature dependent mechanism. The EISCAT Tromsø Dynasonde, the ALOMAR/UiO All-sky camera and the SKiYMET meteor radar on Andøya are used to test the suggested relationships of sporadic sodium layers and sporadic E-layers, electron precipitation, and meteor deposition during this event. We find that more than one candidate is eligible to explain our observation of the sporadic sodium layer.

scholarly journals Comparison of sporadic sodium layer characteristics observed at different time resolutions

2013 ◽  
Vol 31 (11) ◽  
pp. 1899-1912 ◽  
Author(s):  
Y. J. Liu ◽  
B. R. Clemesha ◽  
J. H. Wang ◽  
X. W. Cheng
Keyword(s):  
Time Resolution ◽  
Apparent Movement ◽  
Peak Height ◽  
Thin Layers ◽  
Height Range ◽  
Sodium Layer ◽  
Sporadic E Layers ◽  
Excellent Work ◽  
Sporadic E ◽  
Meteor Trails

Abstract. Sporadic sodium (Nas) layers, occurring in roughly the same height range as ionospheric sporadic-E layers, were first detected by lidar some 30 yr ago. Nas layers have a typical thickness of a few hundred meters to a few km, with peak atom concentrations several times that of the background layer. Despite a great deal of excellent work over the past decades, the source of Nas layers is still not altogether clear, partly as a result of our incomplete knowledge of Nas layer characteristics. In this paper we concentrate on some typical case studies chosen from the ~127 h of sporadic sodium layer observations made at a time resolution of 1.5 s at Yanqing (115.97° E, 40.47° N), Beijing, China. This is a much better time resolution than what has been employed in most earlier measurements. The results show that the Nas layer peak heights are dispersed at slightly different although adjacent heights. When averaged over several minutes, as has been the case with most earlier measurements, the height scatter results in an apparent layer thickness of a few km. We conclude, therefore, that these dispersed peaks at different but adjacent heights constitute the 5 min Nas layer. Similar to the observations of sporadic-E-ion (Es) layers and meteor rate, we observe quasi-periodic fluctuations on a timescale on the order of several minutes in the peak height and the peak density of sporadic layers, which is a universal feature but concealed by the lower temporal resolution previously adopted. Spatially localized multiple scatterers and multiple thin layers with similar apparent movement in Nas layers are also found. We discuss the possible formation mechanism by the direct deposition of large swarms of micrometeoroids and demonstrate a typical example of meteor trails evolving into a Nas layer, which suggests that this mechanism might indeed occur.

scholarly journals The role of electric field and neutral wind in the generation of polar cap sporadic E

2008 ◽  
Vol 26 (12) ◽  
pp. 3757-3763 ◽  
Author(s):  
T. Nygrén ◽  
M. Voiculescu ◽  
A. T. Aikio
Keyword(s):  
Electric Field ◽  
Driving Forces ◽  
Neutral Wind ◽  
Polar Cap ◽  
Sporadic E Layers ◽  
Sporadic E ◽  
In The Beginning ◽  
Model Formation ◽  
Good Agreement

Abstract. This paper investigates the roles of electric field and neutral wind in the generation of sporadic-E layers within the polar cap. Two Es layers above Svalbard, observed by the EISCAT Svalbard Radar (ESR), were chosen for investigation. The radar experiment contains four beam directions, and this was used for determining the electric field. The neutral wind was obtained from the HWM93 model. Formation of Es layers was calculated by integrating the continuity equation under the action of driving forces due to neutral wind and electric field. A flat height profile of metal ions was assumed in the beginning. The calculation gives the time variation of the layer, which can be compared with observations. In one case the electric field was shown to be the main driving agent in layer generation. In the other case the electric field was weak and the layer was produced mainly by the neutral wind, but the electric field had influence on the height of the layer. A fairly good agreement between the variations of the observed and calculated layer altitudes was obtained and some agreement between the intensity variations was also found.

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