Variations in critical frequency of the F2-layer of the ionosphere associated with geomagnetic storms at equatorial stations

Kotadia, K. M.

doi:10.1016/0021-9169(65)90148-0

Cited by 9 publications

(4 citation statements)

References 7 publications

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“…Using ionosonde data, Kotadia [1965] showed that the transequatorial F layer responds very differently over small latitude spans, depending on the times when the storm begins and intensifies. An example of this is shown in Figure 17a.…”

Section: Multisite Tec Studies During Geomagnetic Stormsmentioning

confidence: 99%

“…Early in a storm (but after MPO), there is a “mirror image” transition from an enhanced to a suppressed EIA in the two top plots, in contrast to the standard midlatitude results during the same years shown in the bottom two plots. Reprinted from Kotadia [1965] with permission from Elsevier. (b) A case study using topside sounder data during the storm of 21–22 September 1963 ( Ap = 44–126, Kp = 7°–7 + ).…”

Section: Multisite Tec Studies During Geomagnetic Stormsmentioning

confidence: 99%

“…Electric field penetration scenarios are short‐lived, and thus past statistical studies [e.g., Kotadia , 1965; Somayajulu , 1963; Kane , 1975] tended to emphasize the fact that the dominant effect at low latitudes is that the EIA is reduced in scale during storms. For TEC this was shown clearly by Basu and Das Gupta [1968] using low‐orbit TEC data (see Figure 17c).…”

Section: Multisite Tec Studies During Geomagnetic Stormsmentioning

confidence: 99%

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Storms in the ionosphere: Patterns and processes for total electron content

Mendillo

2006

Reviews of Geophysics

469

440

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[1] The ionosphere's total electron content (TEC) is a parameter widely used in studies of the near-Earth plasma environment. The scientific use of TEC appeared early in the artificial satellite era, and among its many contributions were fundamental insights into how the ionosphere responds to geomagnetic storms. While many excellent reviews of solar-terrestrial disturbances exist in the literature, none have concentrated on the TEC parameter per se. With new TEC data sets increasingly available from the Global Positioning System (GPS), a comprehensive summary of pre-GPS storm studies is needed to set the base for progress in the GPS era. This review summarizes past case studies, describes statistical occurrence pattern, and identifies responsible mechanisms validated via modeling. It presents a new set of results of TEC disturbance patterns during 180 geomagnetic storms to describe seasonal and solar cycle effects. It concludes with a set of open questions that require additional study.Citation: Mendillo, M. (2006), Storms in the ionosphere: Patterns and processes for total electron content, Rev. Geophys., 44, RG4001,

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Section: Multisite Tec Studies During Geomagnetic Stormsmentioning

confidence: 99%

Section: Multisite Tec Studies During Geomagnetic Stormsmentioning

confidence: 99%

Section: Multisite Tec Studies During Geomagnetic Stormsmentioning

confidence: 99%

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Storms in the ionosphere: Patterns and processes for total electron content

Mendillo

2006

Reviews of Geophysics

469

440

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“…Figure 9, which gives similar plots for Cp < 0.2 and Cp > 0.8, clearly shows that, on average, the equatorial anomaly vanishes on disturbed days and the total electron content becomes substantially less at latitudes more than 10øS from the dip equator. It would appear that the equatorial anomaly in the topside electron content is reduced by magnetic disturbance and that the equatorial arch is higher and wider on magnetically quiet days than on disturbed days [Kotadia, 1965;King et al, 1967a;King et al, 1967b].…”

Section: Introductionmentioning

confidence: 99%

Total Electron Content Studies in Equatorial Regions

Hunter¹

1970

Radio Science

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This paper reviews current knowledge of the diurnal variation and spatial distribution of total electron content in the equatorial ionosphere. The problems of data reduction peculiar to stations near the equator are considered. There is a large diurnal variation up to 40:1 that is greatest at the equinoxes and least in local winter. An 'equatorial anomaly' in total electron content similar to the anomaly observed in [oF, exists and is largely associated with the topside. Considerable differences in detail, particularly with regard to the time of disappearance of the anomaly, occur at different longitudes. Peaks of ionization have been observed around 2300 LT at about 26 ø of magnetic dip. Although little correlation has been found with magnetic activity on individual days, collective data indicate a reduction in the depth of the equatorial trough with magnetic disturbances, with the maxima occurring closer to the dip equator. More detailed work is indicated on the effects of longitude and magnetic activity, on the nighttime content, and on large-scale irregularities. lites, using the Faraday rotation, the corresponding Doppler shift of a radio wave passing through the ionosphere, or some combination of these two techniques [Garriott, 1960; Golton, 1962; Garriott and de Mendonca, 1963; Golton, 1963; Papet-Lepine, 1965; Houminer, 1966]. Indeed, the provision of satellite beacons has been an important stimulus to such measurements, especially in equatorial regions, because of the simplicity and cheapness of the equipment required. This review is mainly devoted to such measurements. For the purpose of this review, the equatorial region has been taken as lying roughly between + 30 ø and -30 ø of magnetic dip, although some data have been included from stations (such as Hawaii) lying just outside this region. Hunter et al., 1969; Jayendran and O'Brien, 1969]. Such measurements are most suited to the determination of the spatial variations in total electron content, since with satellite orbits of high inclination the slow precession rate relative to the rotation of the earth can yield a mean diurnal variation only over a long period of time. A satellite in equatorial orbit could give more detailed diurnal information, but the only satellite beacon of this kind, the San Marco B, was designed for propagation experiments and was too low for total content studies [Checcacci and Pellegrini , 1966]. This is particularly the case for equatorial stations where the longitude difference between successive transits is at its greatest and only two transits a day are normafly available for recording. Geostationary satellites carrying continuously radiating beacons enable a continuous recording of total electron content to be made. Unfortunately, 869 870 A.N. HUNTER such satellites have been in convenient positions

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Solar flare effects on F2-ionization in low latitudes

Kotadia

1966

Journal of Atmospheric and Terrestrial Physics

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Variations in critical frequency of the F2-layer of the ionosphere associated with geomagnetic storms at equatorial stations

Cited by 9 publications

References 7 publications

Storms in the ionosphere: Patterns and processes for total electron content

Storms in the ionosphere: Patterns and processes for total electron content

Total Electron Content Studies in Equatorial Regions

Solar flare effects on F2-ionization in low latitudes

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