The equatorial F-region of the ionosphere

Duncan, R. A.

doi:10.1016/0021-9169(60)90081-7

Cited by 170 publications

(91 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Each of these effects has different weight depending on the geomagnetic/geographic location, solar and geomagnetic activity, season and local time. While production is mainly controlled by solar EUV radiation, transport at the low latitude region is dominated by the equatorial fountain effect (Appleton 1946;Martyn 1955;Duncan 1959;Ross 1966;Das Gupta & Basu 1973;Richmond et al 1976;Balan et al 1993;Doherty et al 2000). The electron production by photo-ionization of neutral atoms and molecules is proportional to the intensity of solar radiation, governed by the Beer Lambert law.…”

Section: Model Developmentmentioning

confidence: 99%

“…It may be mentioned that TEC is a height-integrated parameter and is weighted mostly by the electrons in the F-regions, with 2/3rd of the contribution coming from regions above the altitude of the F-region peak. The vertical E · B drift of plasma driven by the orthogonal configuration of the geomagnetic field (B) and zonal electric field (E) over the magnetic equator, and subsequent diffusion along the geomagnetic field lines due to gravitational and pressure gradient forces lead to the development of the EIA (Martyn 1955;Duncan 1959). The EIA is a double humped structure in the latitudinal distribution of the ionization at low magnetic latitudes.…”

Section: Model Developmentmentioning

confidence: 99%

See 1 more Smart Citation

An empirical model of ionospheric total electron content (TEC) near the crest of the equatorial ionization anomaly (EIA)

Hajra

Chakraborty²,

Tsurutani

et al. 2016

J. Space Weather Space Clim.

View full text Add to dashboard Cite

We present a geomagnetic quiet time (Dst > À50 nT) empirical model of ionospheric total electron content (TEC) for the northern equatorial ionization anomaly (EIA) crest over Calcutta, India. The model is based on the 1980-1990 TEC measurements from the geostationary Engineering Test Satellite-2 (ETS-2) at the Haringhata (University of Calcutta, India: 22.58°N, 88.38°E geographic; 12.09°N, 160.46°E geomagnetic) ionospheric field station using the technique of Faraday rotation of plane polarized VHF (136.11 MHz) signals. The ground station is situated virtually underneath the northern EIA crest. The monthly mean TEC increases linearly with F 10.7 solar ionizing flux, with a significantly high correlation coefficient (r = 0.89-0.99) between the two. For the same solar flux level, the TEC values are found to be significantly different between the descending and ascending phases of the solar cycle. This ionospheric hysteresis effect depends on the local time as well as on the solar flux level. On an annual scale, TEC exhibits semiannual variations with maximum TEC values occurring during the two equinoxes and minimum at summer solstice. The semiannual variation is strongest during local noon with a summer-to-equinox variability of 50-100 TEC units. The diurnal pattern of TEC is characterized by a pre-sunrise (0400-0500 LT) minimum and near-noon (1300-1400 LT) maximum. Equatorial electrodynamics is dominated by the equatorial electrojet which in turn controls the daytime TEC variation and its maximum. We combine these long-term analyses to develop an empirical model of monthly mean TEC. The model is validated using both ETS-2 measurements and recent GNSS measurements. It is found that the present model efficiently estimates the TEC values within a 1-r range from the observed mean values.

show abstract

Section: Model Developmentmentioning

confidence: 99%

Section: Model Developmentmentioning

confidence: 99%

An empirical model of ionospheric total electron content (TEC) near the crest of the equatorial ionization anomaly (EIA)

Hajra

Chakraborty²,

Tsurutani

et al. 2016

J. Space Weather Space Clim.

View full text Add to dashboard Cite

show abstract

“…Since the geomagnetic ®eld lines passing through the F-layer crests (at about 15°±20°magnetic latitude) cross the equator at about 800±1000 km height, where the production rate q is small, some other source of plasma seems necessary. Martyn (1947) and Duncan (1960) envisaged that the plasma comes from lower levels in the F2-layer; it is lifted to great heights by the eastward electric ®elds that exist in low latitudes by day, and then diuses downward along ®eld lines, as Mitra (1946) suggested. As Kendall and Pickering (1967) say,``The electron-ion pairs may be thought of as sliding down the magnetic ®eld lines with a diusive motion, while at the same time the whole ®eld line drifts at right angles to itself.''…”

Section: The Equatorial Fountainmentioning

confidence: 99%

The equatorial F-layer: progress and puzzles

Rishbeth

2000

Ann. Geophys.

185

View full text Add to dashboard Cite

Abstract. This work reviews some aspects of the ionospheric F-layer in the vicinity of the geomagnetic equator. Starting with a historical introduction, brief summaries are given of the physics that makes the equatorial ionosphere so interesting, concentrating on the large-scale structure rather than the smaller-scale instability phenomena. Several individual topics are then discussed, including eclipse eects, the asymmetries of the`equatorial trough', variations with longitude, the semiannual variation, the eects of the global thermospheric circulation, and ®nally the equatorial neutral thermosphere, including`superrotation' and possible topographic in¯uences.

show abstract

“…This is popularly known as the "Fountain Effect." The various aspects of equatorial anomaly have been studied quite extensively both experimentally and theoretically (RASTOGI, 1959(RASTOGI, , 1966RASTOGI and RAJARAM, 1971;DUNCAN, 1960;LYON, 1963;MOFFETT and HANSON, 1965;BRAMLEY and PEART, 1965;HANSON and MOFFETT, 1966;ANDERSON, 1971;RAJARAM and RASTOGI, 1974; Rotation measurements, which give ionospheric Total Electron Content (TEC), are being widely used for ionospheric studies. Latitudinal variation of TEC has been studied by various workers (BASU and DAS GUPTA, 1968;TITHERIDGE and SMITH, 1969;MENDONCA et al, 1969;GOLTON and WALKER, 1971;RASTOGI et al, 1973RASTOGI et al, , 1975IYER et al, 1976).…”

mentioning

confidence: 99%

Equatorial electrojet control of the low latitude ionosphere.

Sethia

Rastogi

Deshpande

et al. 1980

J. geomagn. geoelec

View full text Add to dashboard Cite

The role of the equatorial electrojet on the distribution of ionization at low latitudes has been discussed using mult-location Total Electron Content (TEC) data obtained through the radio beacon signals from the geostationary satellite ATS-6 and from ground-based ionosonde data. It has been found that the electrojet has a pronounced influence on TEC at latitudes extending from equator to as high as 25N dip latitude. It is suggested that ionosphere-to-plasmasphere ionization flow plays an important role in understanding the behaviour of the equatorial TEC.

show abstract

The equatorial F-region of the ionosphere

Cited by 170 publications

References 13 publications

An empirical model of ionospheric total electron content (TEC) near the crest of the equatorial ionization anomaly (EIA)

An empirical model of ionospheric total electron content (TEC) near the crest of the equatorial ionization anomaly (EIA)

The equatorial F-layer: progress and puzzles

Equatorial electrojet control of the low latitude ionosphere.

Contact Info

Product

Resources

About