Results 251 to 260 of about 3,568,047 (295)

Classification of spread-F ionograms

Journal of Atmospheric and Terrestrial Physics, 1962
Abstract Scaling of original ionograms obtained in the polar regions has lead to a classification scheme for spread-F ionograms. Defined are three types of frequency spreading (spreadish-F, furcated-F and spurred-F) and one type of range spreading. Each type is subdivided into species.
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Spread F modeling over Brazil

Journal of Atmospheric and Solar-Terrestrial Physics, 2017
Abstract Based on a numerical model developed by Carrasco et al. (2014), the dynamics and morphology of ionospheric plasma bubbles for both magnetic hemispheres over Brazil are examined. Observational results show that the post sunset maximum velocity of the pre-reversal vertical drift velocity, V P , has different values at the conjugate ...
A.J. Carrasco, I.S. Batista, J.H.A. Sobral, M.A. Abdu   +3 more
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Control of equatorial spread-F by the F-layer height

Journal of Atmospheric and Terrestrial Physics, 1966
Abstract The dependence of equatorial spread-F occurrence on the height of the layer is examined in detail in the case of two equatorial stations viz. Kodaikanal and Huancayo, lying close to the magnetic equator. The percentage of occurrence associated with different heights is found to vary with time, season and longitude.
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The nocturnal and seasonal variations of spread-F

Journal of Atmospheric and Terrestrial Physics, 1963
Abstract The nocturnal variations of spread- F at Waltair using data over a period of 22 months (March, 1960–December, 1961) are studied and discussed in comparison with the variations at other equatorial stations. The seasonal characteristics of spread- F are studied separately for magnetically quiet and disturbed days, using data at four ...
B.V. Krishnamurthy, B.Ramachandra Rao
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Spread-F and the parameters of the F-layer of the ionosphere-II. Spread-F and F-layer height

1962
An analysis has been made of spread-F data obtained from I.G.Y. f{hook}-plots for several ionosonde stations grouped about longitude 75°W to establish whether there is any connexion between the incidence of the frequency-spreading component of spread-F and the height of the F2-layer.
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Spread-F at Temperate and High Latitudes

IETE Journal of Research, 1966
ABSTRACTSpread-F at temperate and high latitudes has been analysed to study its variation with season, geomagnetic activity, sunspot activity and h'F. It is observed that at low temperate latitudes there is no correlation with geomagnetic activity. At high temperate latitudes spread-F is positively correlated with geomagnetic activity in winter and ...
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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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Quantifying spread F by digital ionosondes

Advances in Space Research, 2003
The width of frequency-spreading (Δff) on ionograms was shown (Wright, et al., 1977, by comparison with OGO-6 Satellite observations) to be proportional to ΔNN near and above the F-region peak. Thus, even classical analog ionograms using logarithmic frequency scales were direct reading for this important parameter, although little use has been made of ...
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Plasma density discontinuity and spread F

Journal of Atmospheric and Terrestrial Physics, 1984
It is shown that the generation of the equatorial spread F irregularity in the post-sunset period need not he always at the base of the F region. The irregularities are generated at the E region, provided there existed a retardation type E2 layer or a uniform blanketing sporadic E layer before the sunset.
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The aspect sensitivity of spread-F irregularities

Journal of Atmospheric and Terrestrial Physics, 1971
Abstract A high latitude oblique incidence echo, previously shown to be produced by irregularities strongly aligned along the magnetic field, is found to occur whenever vertical incidence spread- F is recorded from the same volume of the F -layer.
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