Counter-electrojet and Esq disappearance

Fambitakoye, O.; Rastogi, R. G.; Tabbagh, Jeanne; Vila, P.

doi:10.1016/0021-9169(73)90009-3

Cited by 42 publications

(16 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The irregularities' disapearance between 0800 and 0950 UT during the same period of decreasing H and reversed Z (Fig. 1b, d) indicates that a belt of current¯ows in the reverse direction with respect to the normal west-east electrojet ow (Fambitakoye et al, 1973). These E-region irregularities at equatorial latitude giving the appearance of Es-q layer during daytime ionograms have been suggested to be due to cross-®eld instabilities (Rastogi, 1973b).…”

Section: Ionospheric Electrodynamics Datamentioning

confidence: 87%

Equatorial electrojet as part of the global circuit: a case-study from the IEEY

Kobea

Amory‐Mazaudier²,

M.³

et al. 1998

Ann. Geophys.

View full text Add to dashboard Cite

Abstract. Geomagnetic storm-time variations often occur coherently at high latitude and the day-side dip equator where they a ect the normal eastward Sq ®eld. This paper presents an analysis of ground magnetic ®eld and ionospheric electrodynamic data related to the geomagnetic storm which occured on 27 May 1993 during the International Equatorial Electrojet Year (IEEY) experiment. This storm-signature analysis on the auroral, mid-latitude and equatorial ground ®eld and ionospheric electrodynamic data leads to the identi®cat-ion of a sensitive response of the equatorial electrojet (EEJ) to large-scale auroral return current: this response consists in a change of the eastward electric ®eld during the pre-sunrise hours (0400±0600 UT) coherently to the high-, mid-, and equatorial-latitude H decrease and the disappearance of the EEJ irregularities between the timeinterval 0800±0950 UT. Subsequent to the change in h'F during pre-sunrise hours, the observed foF2 increase revealed an enhancement of the equatorial ionization anomaly (EIA) caused by the high-latitude penetrating electric ®eld. The strengthening of these irregularities attested by the Doppler frequency increase tracks the H component at the equator which undergoes a rapid increase around 0800 UT. The DH variations observed at the equator are the sum of the following components: S R , DP, DR, DCF and DT.

show abstract

Section: Ionospheric Electrodynamics Datamentioning

confidence: 87%

Equatorial electrojet as part of the global circuit: a case-study from the IEEY

Kobea

Amory‐Mazaudier²,

M.³

et al. 1998

Ann. Geophys.

View full text Add to dashboard Cite

show abstract

“…Rastogi et al (1971) showed, for the ®rst time, that the counter electrojet events observed in geomagnetic r ®eld, the absence of i s -q re¯ections in the ionograms and the reversal of the ionospheric drift direction during the daytime hours at an equatorial station were concurrent phenomena. Fambitakoye et al (1973) showed that the reversal of the latitudinal pro®les of Dr and D are the main criterions for the disappearance of i s -q rather than the decrease Dr below its night time level at the equatorial station. Comparing the high resolution modi®ed range time intensity (MRTI) records of VHF backscatter radar echoes at Jicamarca and the magnetograms at Huancayo and Fuquene, Rastogi et al (1977) showed that the E region irregularities disappear precisely (with an accuracy of less than 2 min) when Dr at Huancayo minus Dr at Fuquene decreases below the corresponding night time value.…”

Section: Introductionmentioning

confidence: 99%

Midday reversal of equatorial ionospheric electric field

Rastogi

1997

Ann Geophysicae

View full text Add to dashboard Cite

Abstract. A comparative study of the geomagnetic and ionospheric data at equatorial and low-latitude stations in India over the 20 year period 1956±1975 is described. The reversal of the electric ®eld in the ionosphere over the magnetic equator during the midday hours indicated by the disappearance of the equatorial sporadic E region echoes on the ionograms is a rare phenomenon occurring on about 1% of time. Most of these events are associated with geomagnetically active periods. By comparing the simultaneous geomagnetic r ®eld at Kodaikanal and at Alibag during the geomagnetic storms it is shown that ring current decreases are observed at both stations. However, an additional westward electric ®eld is superimposed in the ionosphere during the main phase of the storm which can be strong enough to temporarily reverse the normally eastward electric ®eld in the dayside ionosphere. It is suggested that these electric ®elds associated with the Â fz electric ®elds originate at the magnetopause due to the interaction of the solar wind and the interplanetary magnetic ®eld.

show abstract

“…Instead of the parameter d Sdi defined above we also tried out the simpler parameter 4(HTRI-HALI) considering deviations from pre-dawn level (FAMBITAKOYE et al, 1973). Results were similar to those for d Sdi and hence are not shown here.…”

Section: -2400 Ltmentioning

confidence: 97%

Equatorial enhancement of SSC magnitudes.

Kane

1978

J. geomagn. geoelec

View full text Add to dashboard Cite

Storm sudden commencement (SSC) magnitudes are known to be generally larger in the equatorial electrojet region. This aspect is studied in detail and it is shown that the equatorial enhancement ratio fluctuates over a very wide range and is not always commensurate with the equatorial electrojet strength. Large ratios during weak or reverse (counter) electrojets are not uncommon. During nights when electrojet is very small, ratios greater than, lesser than or equal to unity are observed. During daytime too, ratios as low as unity (no equatorial enhancement) are sometimes observed even when the electroject is strong.

show abstract

Counter-electrojet and Esq disappearance

Cited by 42 publications

References 8 publications

Equatorial electrojet as part of the global circuit: a case-study from the IEEY

Equatorial electrojet as part of the global circuit: a case-study from the IEEY

Midday reversal of equatorial ionospheric electric field

Equatorial enhancement of SSC magnitudes.

Contact Info

Product

Resources

About