Modelling the horizontal structure of mid-latitude Es from its refraction effects on F-region echoes

Barnes R.I. (1991) Modelling the horizontal structure of mid-latitude Es from its refraction effects on F-region echoes. Journal of Atmospheric and Terrestrial Physics, 53 1-2: 105-114. doi:10.1016/0021-9169(91)90025-3

Author Barnes R.I.
Title Modelling the horizontal structure of mid-latitude Es from its refraction effects on F-region echoes
Journal name Journal of Atmospheric and Terrestrial Physics
ISSN 0021-9169
Publication date 1991-01-01
Sub-type Article (original research)
DOI 10.1016/0021-9169(91)90025-3
Open Access Status Not yet assessed
Volume 53
Issue 1-2
Start page 105
End page 114
Total pages 10
Language eng
Subject 1902 Film, Television and Digital Media
1908 Geophysics
Abstract The Bribie Island HF radar (situated at 27 S, 153 E) synthesizes a narrow beam, 2.5 wide at an operating frequency of 5.8 MHz, which is used to measure angle of arrival of echoes reflected from the ionosphere. At times underlying sporadic-E (Es) ionization appears to disturb the F-region angle of arrival. This effect on the narrow beam is evidently due to refraction and diffraction effects caused by Es having significant horizontal structure. Examples are presented along with theoretical models, using wind-shear theory and parameters of the Es event recorded on a phase ionosonde. To model the horizontal structure either the wind-shear compression or the metallic-ion content is allowed to vary horizontally. The resulting cloud is moved across the sky and synthetic measurements of angle or arrival, amplitude and Doppler shift are produced, allowing a comparison between the two models and experimental data. Neither model fits the data in all cases. Variation in the wind shear best models small irregularities in larger background clouds, while variations in metallic-ion content best fits the structure of blanketing Es (foEs ≈ fbEs). However, severe quantitative problems arise when fitting either model as a travelling cloud to blanketing Es While blanketing Es structure appears to move at about the same velocity as the small irregularities (∼ 35 ms 1). it seems that variations in foEs are primarily due to the electron concentration changing uniformly over a very large region including the region over the radar. This leads to little horizontal gradient and hence little refraction is seen with the radar. Another interesting point is that the cloud size is much smaller than would be deduced from using geometry and the time and strength of occultation. This is due to the small irregularities acting as powerful diverging lenses. Irregularity sizes of the order of 1 km are detected.
Q-Index Code C1
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article (original research)
Collection: Scopus Import - Archived
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Citation counts: TR Web of Science Citation Count  Cited 3 times in Thomson Reuters Web of Science Article | Citations
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