The day-to-day variability of the equatorial electrojet in Peru

Burrows, K.

doi:10.1029/ja075i007p01319

Cited by 18 publications

(8 citation statements)

References 13 publications

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“…She concludes that taking 0.75 of 4Ho will give a better estimate of the width of the jet. BURROWS (1970) who has studied the day-to-day variability of the jet width in the Peruvian region agrees with HUTTON's conclusions. Considering these results and the results of correlation of 4H observed at different stations in the Indian region, the half width of the electrojet is taken here as the distance from the dip equator to the point where the ground 4H becomes 0.7 of that at the dip equator.…”

Section: Determination Of Widthsupporting

confidence: 77%

Depth of non-conducting layer in the Indian Ocean region around Thumba, derived from in situ investigations of equatorial electrojet. II.

Sampath¹,

Sastry²

1979

J. geomagn. geoelec

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The height integrated current density in the electrojet over Thumba has been measured between the years 1966 and 1976 on nine different occasions by rocketborne magnetometers. Using this data and the H variation data from a spread of ground magnetic stations in the region of the electrojet, the depth of the non-conducting layer has been evaluated. The results are compared with the results obtained from POGO and Kosmos 321 satellite experiments. It is shown that the depth of non-conducting layer in the region around Thumba is 230±20 km. Using the above data, the internal and the external contributions to the diurnal variation of geomagnetic field observed at the ground have been evaluated.

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Section: Determination Of Widthsupporting

confidence: 77%

Depth of non-conducting layer in the Indian Ocean region around Thumba, derived from in situ investigations of equatorial electrojet. II.

Sampath¹,

Sastry²

1979

J. geomagn. geoelec

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“…No direct observations on the latitude structure of JT are available, while extensive ground-based observations on the latitude structure of (AH)T are available [Hutton, 1967a, b;Onwumechilli, 1967;Burrows, 1970;Fambitakoye and Mayaud, 1976a, b, c]. In addition to the systematic and extensive analyses of a large amount of data by Fambitakoye and Mayaud [1976a, b, c], a model calculation of the wind-generated currents and a comparison of the theoretical model structures with the observed latitudinal structures of the ground-level (AH)T were carded out by Fambitakoye et al [1976].…”

Section: Comparison With Observationsmentioning

confidence: 99%

“…Single-station magnetometer recordings clearly demonstrate the large day-to-day variability of the current intensity in the equatorial electrojet (EEJ) [Chapman and Bartels, 1940;Onwumechilli, 1967;Kane, 1976; and references therein]. The observations on the latitude structure of EEJ show that the latitudinal extent as well as the latitudinal structure of EEJ vary significantly from day to day [Hutton, 1967a, b;Burrows, 1970;Fambitakoye and Mayaud, 1976a, b, c;Fambitakoye et al 1976]. The extreme manifestation of this variability is the 'counter electrojet' phenomenon, wherein the normal daytime eastward current flow gets reversed in direction for a limited period of time [Gouin, 1962;Gouin and Mayaud, 1967;Hutton and Oyinloye, 1970;Krishna Murthy and Sen Gupta, 1972;Onwumechilli and Akasofu, 1972;Rastogi, 1974].…”

Section: Introductionmentioning

confidence: 99%

Height and latitude structure of electric fields and currents due to local east‐west winds in the equatorial electrojet

Reddy¹,

Devasia²

1981

J. Geophys. Res.

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Using the equivalent electrical circuit method for the theoretical treatment of the local wind effects on the equatorial electrojet, the height structures of electric fields and currents that are generated by height‐varying east‐west winds in the electrojet region have been calculated for theoretical model wind sturctures and for a variety of experimentally observed wind structures. The results bring out clearly the nature and extent of the local wind effects on the height and latitude structures of the equatorial electrojet. The more important conclusions of the present study are: (a) The vertical wind shears associated with tidal winds and gravity waves can generate significantly large electric fields and east‐west currents in the equatorial electrojet (EEJ). (b) The wind‐generated electric fields and currents are characterized by large height gradients, latitudinal gradients, and reversals of direction. (c) At the magnetic equator, wind‐generated electric fields and currents are often small (10%–30%) in comparison with the eastward electric‐field‐generated polarization field and east‐west currents around noon hours. (d) At geomagnetic latitudes of 3° and beyond the wind‐generated currents and electric fields often exceed those caused by the eastward electric field. (e) Beyond 2° the neutral winds can drastically alter the intensity and latitudinal structure of the EEJ, depending upon the magnitude and height location of the wind shear. (f) The observed variabilities in the ‘width’ and latitude structure of the EEJ can arise from the effects of such east‐west winds that have been observed experimentally.

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“…Similarly, the studies of day‐to‐day variabilities of the Sq daily ranges and associated ionospheric parameters in the equatorial zone included those of Forbush & Casaverde (1961), Osborne (1962, 1963, 1964, 1966, 1968), Ogbuehi & Onwumechili (1964), Onwumechili & Ogbuehi (1965, 1967), Onwumechili (1967), Ogbuehi et al . (1967), Hutton (1867a,b), MacDougall (1969, 1979a,b), Burrows (1970), Kane (1971) and Mann & Schlapp (1988).…”

Section: Introductionmentioning

confidence: 99%

“…(1996). There have also been studies of the variability of the equatorial electrojet (EEJ) current centre and focus, including those of Osborne (1962, 1964, 1966, 1968), Ogbuehi & Onwumechili (1964), Onwumechili (1967), Onwumechili & Ogbuehi (1967), Burrows (1970), Cain & Sweeney (1972, 1973), Fambitakoye & Mayaud (1976a), Oko et al . (1996) and Ratanova et al .…”

Section: Introductionmentioning

confidence: 99%

Day-to-day variability of geomagnetic hourly amplitudes at low latitudes

Okeke

Onwumechili

Rabiu

1998

Geophysical Journal International

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A study of the variability of the amplitude of Sq at a fixed hour from one day to the next at nine stations from the dip equator to about 22° north of it has produced interesting results. The amplitude and sign of the variability change virtually randomly, making the mean practically zero. The variability occurs at all hours of the day. Its magnitudes in the components D, H and Z have the same diurnal variation, which peaks in the noon period like Sq(H) in low latitudes, and a weak seasonal variation that peaks at the June solstice (local summer). It is demonstrated that changes in the current intensities of the equatorial electrojet (EEJ) and the worldwide part of the Sq (W Sq) current layers have contrasting phases and can sometimes be in antiphase. Indeed, the changes are mostly independent. Inclusion of the magnetic element D revealed that the EEJ current system has not only an east–west but also a north–south component. The study shows that the meridional component of the EEJ current intensity evidenced at the Kodaikanal and Annamalainagar stations is an integral part of the zonal component at Trivandrum. This confirms the results of Rastogi (1996) and validates those of Onwumechili (1997). The results suggest that ionospheric conductivity mainly controls the magnitude, while the electric field and ultimately winds mainly control the phase and randomness of the day‐to‐day variability of the hourly amplitudes of Sq. The random component is attributed to local and/or regional atmospheric winds, probably of gravity wave origin.

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The day-to-day variability of the equatorial electrojet in Peru

Cited by 18 publications

References 13 publications

Depth of non-conducting layer in the Indian Ocean region around Thumba, derived from in situ investigations of equatorial electrojet. II.

Depth of non-conducting layer in the Indian Ocean region around Thumba, derived from in situ investigations of equatorial electrojet. II.

Height and latitude structure of electric fields and currents due to local east‐west winds in the equatorial electrojet

Day-to-day variability of geomagnetic hourly amplitudes at low latitudes

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