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Journal of Atmospheric and Terrestrial Physics, 1963
An explanation of the position of the spread-F equator under sunspot maximum and sunspot minimum conditions is put forward. This explanation is based on the theory of spread-F irregularity production by Martyn amplification of irregularities initiated by hydromagnetic waves.
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An explanation of the position of the spread-F equator under sunspot maximum and sunspot minimum conditions is put forward. This explanation is based on the theory of spread-F irregularity production by Martyn amplification of irregularities initiated by hydromagnetic waves.
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Duration of equatorial spread F
Nature, 1975IT is well established1–3 that the spread-F phenomenon, which is observed as diffuse echoes on the ionograms is a common feature during night time between the dip latitudes 20°N and 20°S. Based on the study of ionograms and published monthly f0F2 bulletins, morphological features of spread F have been reported for several equatorial stations1,4–10 ...
V. V. SOMAYAJULU +2 more
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A study of equatorial spread-F
Journal of Atmospheric and Terrestrial Physics, 1963Data from seven stations ranging in magnetic dip from 0° to 44°N have been analysed to study night time and seasonal variations of spread-F through nearly half a solar cycle. It is observed that the inhibition of spread-F due to geomagnetic activity is maximum in the equinoxes.
S. Rangaswamy, K.B. Kapasi
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AIP Conference Proceedings, 1992
Because of its complex nature, the knowledge of spread F is not commensurate with the long period of its study. Rockets, satellites and radar systems have greatley advanced observational information on spread F. We have outlined some of these observations and presented information on certain morphology and characteristics of both the equatorial and ...
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Because of its complex nature, the knowledge of spread F is not commensurate with the long period of its study. Rockets, satellites and radar systems have greatley advanced observational information on spread F. We have outlined some of these observations and presented information on certain morphology and characteristics of both the equatorial and ...
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Journal of Atmospheric and Terrestrial Physics, 1981
Our understanding of equatorial spread-F (ESF) phenomena has progressed significantly in the past several years. ESF phenomena involves ionospheric irregularities spanning some 5–6 orders of magnitude in scale size. The largest scale sizes, on the order of many kilometers, are thought to be caused by a plasma fluid type Rayleigh-Taylor instability ...
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Our understanding of equatorial spread-F (ESF) phenomena has progressed significantly in the past several years. ESF phenomena involves ionospheric irregularities spanning some 5–6 orders of magnitude in scale size. The largest scale sizes, on the order of many kilometers, are thought to be caused by a plasma fluid type Rayleigh-Taylor instability ...
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Mid-latitude spread-F structure
Journal of Atmospheric and Terrestrial Physics, 1988Spread-F has been observed at frequencies of 1.98, 3.84 and 5.80 MHz and multiple angles of arrival have been resolved using an HF radar near Brisbane (27°S, 153°E). The spreading of the ionogram trace has been shown to be due to a spread in angles of arrival of echoes, rather than any 'vertical' spreading.
From W.R., Meehan D.H.
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A study of midlatitude spread-F
Journal of Atmospheric and Terrestrial Physics, 1977Abstract Results of a study of the occurrence of spread-F at Christchurch (43.6°S, 172.8°E; invariant latitude Λ = 49.0°S) over the period June 1965-December 1974 are presented. There is a significant positive correlation between the occurrence of spread-F in the post-midnight period and Kp, the occurrence of spread-F lagging behind Kp by 1 to 2 days.
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Artificial control of equatorial spread-F
Journal of Atmospheric and Terrestrial Physics, 1978Abstract We have studied the influence of a large amplitude electric field oscillating near the upper hybrid frequency on the dispersion characteristics of low frequency Rayleigh-Taylor modes and collisional drift modes. Since these modes have been proposed as principal constituents of spread- F , we investigate the conditions for the parametric ...
S Bujarbarua, A Sen
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Spread-F and the Latitude Variation of Occurrence of Whistlers
Nature, 1961RECENT work of whistling atmospherics has suggested that the incidence of the phenomenon is dependent on latitude. Crouchley1, using data from Australian and Japanese stations, demonstrated that whistler activity reaches a maximum at about 45°geomagnetic latitude, while the Stanford group 2 report a maximum of occurrence at 50°geomagnetic latitude.
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On spread-F in the ionosphere before earthquakes
Journal of Atmospheric and Solar-Terrestrial Physics, 2006Occurrence probability of the ionospheric spread-F in connection with earthquakes is analyzed. The F-layer is not close to the Earth (∼400 km), but in situ data could be obtained either by ionospheric sounders or by satellites. Data from the two Japanese ionospheric stations Kokubunji and Akita have been analyzed to find out long-term (a few weeks ...
Liperovskaya, E. V. +3 more
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