The Possible Role of Turbopause on Sporadic‐E Layer Formation at Middle and Low Latitudes

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.

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Longitudinal Structure in the Altitude of the Sporadic E Observed by COSMIC in Low-Latitudes

Remote Sensing ◽

10.3390/rs13224714 ◽

2021 ◽

Vol 13 (22) ◽

pp. 4714

Author(s):

Zhendi Liu ◽

Qingfeng Li ◽

Hanxian Fang ◽

Ze Gao

Keyword(s):

Dominant Role ◽

Longitudinal Structure ◽

Zonal Wavenumber ◽

Low Latitudes ◽

June Solstice ◽

Sporadic E ◽

First Time ◽

De3 Tide ◽

Northern And Southern Hemispheres

The longitudinal structure in the altitude of the Sporadic E (Es) was investigated for the first time based on the S4 index provided by the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) in low latitudes. The longitudinal structure is identified as a symmetrically located wavenumber-4 (WN4) pattern within 30°S–30°N. The WN4 occurs primarily during the daytime at the June solstice and equinoxes, with the largest amplitude at the September equinox and the smallest one at the March equinox. It moves eastward with a speed of ~90°/day. The strongest WN4 appears within 10–20°N and 5–15°S in the Northern and Southern hemispheres, respectively. At the June solstice and the September equinox, the WN4 is stronger in the Northern hemisphere than in the Southern hemisphere, while the situation is reversed at the March equinox. The altitude distribution of the convergence null in the diurnal eastward non-migrating tide with zonal wavenumber-3 (DE3) for the zonal wind is similar to that of the WN4. This and other similar features, such as the seasonal variation, eastward speed, and the symmetrical locations, support the dominant role of the DE3 tide for the formation of the WN4 structure.

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

Solar-Terrestrial Physics ◽

10.12737/stp-52201904 ◽

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.

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Sporadic E layer at mid-latitudes: average properties and influence of atmospheric tides

Annales Geophysicae ◽

10.5194/angeo-32-1427-2014 ◽

2014 ◽

Vol 32 (11) ◽

pp. 1427-1440 ◽

Cited By ~ 17

Author(s):

A. Pignalberi ◽

M. Pezzopane ◽

E. Zuccheretti

Keyword(s):

Diurnal Variation ◽

Atmospheric Tides ◽

Fast Fourier Transform Analysis ◽

June July August ◽

Solar Cycle 24 ◽

Sporadic E Layer ◽

Sporadic E ◽

Cycle 24 ◽

June July

Abstract. This paper describes a study of the daily variability shown by the main characteristics of the sporadic E (Es) layer, that is the top frequency (ftEs) and the lowest virtual height (h'Es). The study is based on ionograms recorded by the Advanced Ionospheric Sounder by the Istituto Nazionale di Geofisica e Vulcanologia (AIS-INGV) ionosondes installed in the ionospheric stations at Rome (41.8° N, 12.5° E) and Gibilmanna (37.9° N, 14.0° E), Italy, during the summer (June, July, August and September) of 2013, a year falling in the ascending phase of solar cycle 24. The ftEs presents a diurnal variation characterized by two maxima, the first around noon is very well defined and the second in the evening/night is much less defined; the amplitude of both maxima decreases from June to September accompanied by a general decrease of the ftEs values which is more pronounced in the daytime than in the nighttime. h'Es also presents a diurnal variation characterized by two maxima but, unlike ftEs, these present the same amplitude which is independent from the considered month. Assuming that both ftEs and h'Es trends are influenced by the atmospheric tides, the height–time–intensity (HTI) technique was applied to deeply investigate how these waves control the Es dynamics. The HTI study, along with a fast Fourier transform analysis, show that a well-defined semidiurnal periodicity characterizes the Es layer dynamics most accurately in June and July, while in August and September the daytime semidiurnal periodicity becomes weaker and the role of the diurnal periodicity is consequently highlighted.

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