scholarly journals Characteristics of double sodium layer over Haikou, China (20.0° N, 110.1° E)

2019 ◽  
Vol 5 (2) ◽  
pp. 30-34
Author(s):  
Ян Дали ◽  
Yang Dali ◽  
Чжан Теминь ◽  
Zhang Tiemin ◽  
Ван Цзихун ◽  
...  
Keyword(s):  
Lower Thermosphere ◽  
Dye Laser ◽  
Low Latitude ◽  
Middle Latitudes ◽  
Sodium Layer ◽  
Layer Structures ◽  
Low Latitudes ◽  
Sporadic E Layer ◽  
Mesosphere And Lower Thermosphere ◽  
Sporadic E

We study the property of double sodium layer structures (DSLs) in the mesosphere and lower thermosphere (MLT) by a lidar at the low-latitude location of Haikou (20.0° N, 110.1° E), China. From April 2010 to December 2013, 21 DSLs were observed within a total of 377 observation days. DSLs were recorded at middle latitudes of Beijing and Wuhan, China, but were rarely observed at low latitudes. We analyze and discuss characteristics of DSLs such as time of occurrence, peak altitude, FWHM, duration time, etc. At the same time, the critical frequency foEs and the virtual height h'Es of the sporadic E layer Es were observed by an ionosonde over Danzhou (19.0° N, 109.3° E). We discuss such their characteristics as differences of time, differences of altitude compared to DSLs. We used an Nd:YAG laser pumped dye laser to generate the probing beam. The wavelength of the dye laser was set to 589 nm by a sodium fluorescence cell. The backscattered fluorescence photons from the sodium layer were collected by a telescope with the Φ1000 mm primary mirror.

scholarly journals Characteristics of double sodium layer over Haikou, China (20.0° N, 110.1° E)

2019 ◽  
Vol 5 (2) ◽  
pp. 28-32
Author(s):  
Ян Дали ◽  
Yang Dali ◽  
Чжан Теминь ◽  
Zhang Tiemin ◽  
Ван Цзихун ◽  
...  
Keyword(s):  
Lower Thermosphere ◽  
Dye Laser ◽  
Low Latitude ◽  
Middle Latitudes ◽  
Sodium Layer ◽  
Layer Structures ◽  
Low Latitudes ◽  
Sporadic E Layer ◽  
Mesosphere And Lower Thermosphere ◽  
Sporadic E

We study the property of double sodium layer structures (DSLs) in the mesosphere and lower thermosphere (MLT) by a lidar at the low-latitude location of Haikou (20.0° N, 110.1° E), China. From April 2010 to December 2013, 21 DSLs were observed within a total of 377 observation days. DSLs were recorded at middle latitudes of Beijing and Wuhan, China, but were rarely observed at low latitudes. We analyze and discuss characteristics of DSLs such as time of occurrence, peak altitude, FWHM, duration time, etc. At the same time, the critical frequency foEs and the virtual height h'Es of the sporadic E layer Es were observed by an ionosonde over Danzhou (19.0° N, 109.3° E). We discuss such their characteristics as differences of time, differences of altitude compared to DSLs. We used an Nd:YAG laser pumped dye laser to generate the probing beam. The wavelength of the dye laser was set to 589 nm by a sodium fluorescence cell. The backscattered fluorescence photons from the sodium layer were collected by a telescope with the Φ1000 mm primary mirror.

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 Seasonal variability and descent of mid-latitude sporadic E layers at Arecibo

2009 ◽  
Vol 27 (3) ◽  
pp. 923-931 ◽  
Author(s):  
N. Christakis ◽  
C. Haldoupis ◽  
Q. Zhou ◽  
C. Meek
Keyword(s):  
Lower Thermosphere ◽  
Time Base ◽  
Large Set ◽  
Seasonal Behavior ◽  
Incoherent Scatter ◽  
Electron Density Gradient ◽  
Sporadic E Layers ◽  
Sporadic E Layer ◽  
Sporadic E ◽  
Wind Shears

Abstract. Sporadic E layers (Es) follow regular daily patterns in variability and altitude descent, which are determined primarily by the vertical tidal wind shears in the lower thermosphere. In the present study a large set of sporadic E layer incoherent scatter radar (ISR) measurements are analyzed. These were made at Arecibo (Geog. Lat. ~18° N; Magnetic Dip ~50°) over many years with ISR runs lasting from several hours to several days, covering evenly all seasons. A new methodology is applied, in which both weak and strong layers are clearly traced by using the vertical electron density gradient as a function of altitude and time. Taking a time base equal to the 24-h local day, statistics were obtained on the seasonal behavior of the diurnal and semidiurnal tidal variability and altitude descent patterns of sporadic E at Arecibo. The diurnal tide, most likely the S(1,1) tide with a vertical wavelength around 25 km, controls fully the formation and descent of the metallic Es layers at low altitudes below 110 km. At higher altitudes, there are two prevailing layers formed presumably by vertical wind shears associated mainly with semidiurnal tides. These include: 1) a daytime layer starting at ~130 km around midday and descending down to 105 km by local midnight, and 2) a less frequent and weaker nighttime layer which starts prior to midnight at ~130 km, descending downwards at somewhat faster rate to reach 110 km by sunrise. The diurnal and semidiurnal-like pattern prevails, with some differences, in all seasons. The differences in occurrence, strength and descending speeds between the daytime and nighttime upper layers are not well understood from the present data alone and require further study.

scholarly journals Sporadic-E associated with the Leonid meteor shower event of November 1998 over low and equatorial latitudes

2001 ◽  
Vol 19 (1) ◽  
pp. 59-69 ◽  
Author(s):  
H. Chandra ◽  
S. Sharma ◽  
C. V. Devasia ◽  
K. S. V. Subbarao ◽  
R. Sridharan ◽  
...  
Keyword(s):  
Meteor Shower ◽  
Low Latitude ◽  
Equatorial Station ◽  
Radio Science ◽  
Ionospheric Physics ◽  
Transmitter Power ◽  
Multiple Structures ◽  
E Region ◽  
Sporadic E Layer ◽  
Sporadic E

Abstract. Rapid radio soundings were made over Ahmedabad, a low latitude station during the period 16–20 November 1998 to study the sporadic-E layer associated with the Leonid shower activity using the KEL Aerospace digital ionosonde. Hourly ionograms for the period 11 November to 24 November were also examined during the years from 1994 to 1998. A distinct increase in sporadic-E layer occurrence is noticed on 17, 18 and 19 November from 1996 to 1998. The diurnal variations  of  f0Es and fbEs also show significantly enhanced values for the morning hours of 18 and 19 November 1998. The ionograms clearly show strong sporadic-E reflections at times of peak shower activity with multiple traces in the altitude range of 100–140 km in few ionograms. Sporadic-E layers with multiple structures in altitude are also seen in some of the ionograms (quarter hourly) at Thumba, situated near the magnetic equator. Few of ionograms recorded at Kodaikanal, another equatorial station, also show sporadic- E reflections in spite of the transmitter power being significantly lower. These new results highlighting the effect of intense meteor showers in the equatorial and low latitude E-region are presented.Key words. Ionosphere (equatorial ionosphere) – Radio science (ionospheric physics)

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 Tidal wind shear observed by meteor radar and comparison with sporadic E occurrence rates based on GPS radio occultation observations

2019 ◽  
Vol 17 ◽  
pp. 213-224
Author(s):  
Christoph Jacobi ◽  
Christina Arras
Keyword(s):  
Wind Shear ◽  
Radio Occultation ◽  
Signal To Noise Ratio ◽  
Lower Thermosphere ◽  
Horizontal Component ◽  
Meteor Radar ◽  
Good Correspondence ◽  
Gps Radio Occultation ◽  
Middle Latitudes ◽  
Sporadic E

Abstract. We analyze tidal (diurnal, semidiurnal, terdiurnal, quarterdiurnal) phases and related wind shear in the mesosphere/lower thermosphere as observed by meteor radar over Collm (51.3∘ N, 13.0∘ E). The wind shear phases are compared with those of sporadic E (Es) occurrence rates, which were derived from GPS radio occultation signal-to-noise ratio (SNR) profiles measured by the COSMIC/FORMOSAT-3 satellites. At middle latitudes Es are mainly produced by wind shear, which, in the presence of a horizontal component of the Earth's magnetic field, leads to ion convergence in the region where the wind shear is negative. Consequently, we find good correspondence between radar derived wind shear and Es phases for the semidiurnal, terdiurnal, and quarterdiurnal tidal components. The diurnal tidal wind shear, however, does not correspond to the Es diurnal signal.

scholarly journals Special Structures of Sodium Layer Observed in the Daytime Over Beijing, China

2020 ◽  
Vol 237 ◽  
pp. 04005
Author(s):  
Yuan Xia ◽  
Guotao Yang ◽  
Jihong Wang ◽  
Xuewu Cheng ◽  
Faquan Li
Keyword(s):  
Signal To Noise Ratio ◽  
Lower Thermosphere ◽  
Meteor Radar ◽  
Diurnal Cycles ◽  
Dual Channel ◽  
Sodium Layer ◽  
Mesosphere And Lower Thermosphere ◽  
Beijing China ◽  
Observation Results ◽  
Mlt Region

In this paper the observation of sodium (Na) layer in mesosphere and lower thermosphere (MLT) region over complete diurnal cycles based on broadband Na lidar at Yanqing Station, Beijing, China (40.5°N,116°E ) was reported. Faraday filters with dual-channel design were used in the lidar receiving unit to suppress the strong background light in the daytime, which allow observation of Na layer with an acceptable signal-to-noise ratio (SNR) under sunlit condition. Several special structures of Na layer observed in the daytime was discussed. The simultaneous continuous observation of zonal wind by meteor radar was presented for comparison. These observation results can provide direct and reliable supports for the study of mesopause dynamics and solar effect on Na layer.

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