Results 251 to 260 of about 87,973 (293)

Equatorial Spread-F and Magnetic Activity

Nature, 1958
IT is well known that the ionospheric spread-F condition is extremely common at night in equatorial regions. At Ibadan, Nigeria (latitude 7½°N.), this has been especially so during the past 2½ years of high sunspot activity. It is believed that the same irregularities which produce the wide spread of scattered echoes from the F-region are also ...
A. J. LYON, N. J. SKINNER, R. W. WRIGHT
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Equatorial spread-F (ESF) and vertical winds

Journal of Atmospheric and Solar-Terrestrial Physics, 1999
Abstract The Equatorial Spread-F (ESF) phenomenon is recorded in ionograms as a hierarchy of plasma instabilities in the F-layer of the equatorial ionosphere. The ESF is characterized by irregularities in the plasma (electron and ion) density and electric field distributions perpendicular to the Earth’s magnetic field.
R. Raghavarao, R. Suhasini, H.G. Mayr, W.R. Hoegy, L.E. Wharton   +4 more
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Equatorial spread-F and solar activity

Journal of Atmospheric and Terrestrial Physics, 1964
Abstract The effect of solar activity on equatorial spread- F has been studied using the published tables of f 0 F 2 from six Afro-Asian stations. The strong negative correlation between equatorial spread- F and magnetic activity observed during sunspot maximum is no longer significant during low sunspot years.
S. Rangaswamy, K.B. Kapasi
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Equatorial Spread-F and Tropospheric Tropical Disturbances

Journal of the Atmospheric Sciences, 1966
Equatorial spread-F and tropical disturbances, supplying data on typhoon, geomagnetic activity and atmospheric pressure ...
Kaichi Maeda, Victor L. Badillo
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A study of equatorial spread-F

Journal of Atmospheric and Terrestrial Physics, 1963
Data 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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Radio wave heating and equatorial spread-F

Journal of Atmospheric and Terrestrial Physics, 1987
Abstract High frequency radio waves passing through the F -region of the ionosphere can modify the spectrum of spread- F irregularities via a four wave parametric interaction. Non-linear coupling arises through the thermal gradient force. The growth rate is a sensitive function of the angle θ between the wave vectors of the incident wave and the ...
V.N. Laxmi, V.K. Tripathi
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Geomorphology of spread F and characteristics of equatorial spread F

Journal of Geophysical Research, 1959
Between magnetic latitudes 20°N and 20°S there is a well defined region where spread F is a normal occurrence on magnetically quiet days. Equatorial spread F is a night-time phenomenon that begins between 1900 and 2200 by a characteristic doubling of the layer and an increase in virtual height, indicating a vertical velocity.
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Joule dissipation in F-region and equatorial spread-F events

Nature, 1978
The dissipation of turbulent electric fields varying with time, which are associated with spread-F in equatorial regions, has been thought to cause significant heating of the neutral atmospheric gases at F-region altitudes and higher1. The time-varying electric fields have been shown to exist during spread-F at Jicamarca2, and the two phenomena are ...
T. N. RAJARAMAN, J. N. DESAI, S. S. DEGAONKAR, K. D. COLE   +3 more
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Linear theory of equatorial spreadF

Journal of Geophysical Research, 1975
A fluid dispersion relation for the drift and interchange (Rayleigh-Taylor) modes in a collisional plasma forms the basis for a linear theory of equatorial spread F. The collisional-drift-mode growth rate will exceed the growth rate of the Rayleigh-Taylor mode at short perpendicular wavelengths and density-gradient scale lengths.
Mary K. Hudson, Charles F. Kennel
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Nocturnal and seasonal variations of equatorial spread-F

Journal of Atmospheric and Terrestrial Physics, 1961
A new classification of spread-F echo patterns based on the relative amplitudes of the echoes is described and discussed. The results of nocturnal and seasonal variations in spread-F at Waltair are presented and a comparison is made with data of other equatorial stations with particular reference to that of Kodaikanal.
M.S.V.Gopal Rao, B.Ramachandra Rao
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