Neutral Wind Profiles During Periods of Eastward and Westward Equatorial Electrojet

Abstract. In November 2004, a large and variable interplanetary electric field (IEF) was felt in the reference frame of the Earth. This electric field penetrated to the magnetic equator and, when the Jicamarca Radio Observatory (JRO) was in the dusk sector, resulted in a reversal of the normal zonal component of the field. In turn, this caused a counter-electrojet (CEJ), a westward current rather than the usual eastward current. At the time of the normal pre-reversal enhancement (PRE) of the eastward field, the Jicamarca incoherent scatter radar (ISR) observed that the westward component became even more westward. Two of the three current explanations for the PRE depend on the neutral wind patterns. However, this unique event was such that the neutral wind-driven dynamos could not have changed. The implication is that the Haerendel-Eccles mechanism, which involves partial closure of the equatorial electrojet (EEJ) after sunset, must be the dominant mechanism for the PRE.

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Observations of neutral wind profiles between 115- and 175-km altitude in the dayside auroral oval

Journal of Geophysical Research Atmospheres ◽

10.1029/ja085ia06p02935 ◽

1980 ◽

Vol 85 (A6) ◽

pp. 2935 ◽

Cited By ~ 24

Author(s):

E. Pereira ◽

M.C. Kelley ◽

D. Rees ◽

I.S. Mikkelsen ◽

T.S. Jørgensen ◽

...

Keyword(s):

Auroral Oval ◽

Neutral Wind ◽

Wind Profiles

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The interpretation of ionospheric radio drift measurements—I. Some results of experimental comparisons with neutral wind profiles

Journal of Atmospheric and Terrestrial Physics ◽

10.1016/s0021-9169(68)80044-3 ◽

1968 ◽

Vol 30 (5) ◽

pp. 919-930 ◽

Cited By ~ 31

Author(s):

J.W. Wright

Keyword(s):

Neutral Wind ◽

Wind Profiles ◽

Experimental Comparisons

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Equivalent circuit analysis of neutral wind effects on equatorial electrojet

Nature ◽

10.1038/273195a0 ◽

1978 ◽

Vol 273 (5659) ◽

pp. 195-199 ◽

Cited By ~ 9

Author(s):

C. A. Reddy ◽

C. V. Devasia

Keyword(s):

Equivalent Circuit ◽

Equatorial Electrojet ◽

Circuit Analysis ◽

Neutral Wind ◽

Wind Effects ◽

Equivalent Circuit Analysis

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Meteor radar measurements of MLT winds near the equatorial electro jet region over Thumba (8.5° N, 77° E): comparison with TIDI observations

Annales Geophysicae ◽

10.5194/angeo-29-1209-2011 ◽

2011 ◽

Vol 29 (7) ◽

pp. 1209-1214 ◽

Cited By ~ 7

Author(s):

S. R. John ◽

K. V. Subrahmanyam ◽

G. Manju ◽

Q. Wu ◽

Keyword(s):

Lower Thermosphere ◽

Equatorial Electrojet ◽

Hf Radar ◽

Meteor Radar ◽

Radar Observations ◽

Diurnal Cycles ◽

Four Seasons ◽

E Region ◽

Radar Measurements ◽

Wind Profiles

Abstract. The All-Sky interferometric meteor (SKYiMET) radar (MR) derived winds in the vicinity of the equatorial electrojet (EEJ) are discussed. As Thumba (8.5° N, 77° E; dip lat. 0.5° N) is under the EEJ belt, there has been some debate on the reliability of the meteor radar derived winds near the EEJ height region. In this regard, the composite diurnal variations of zonal wind profiles in the mesosphere-lower thermosphere (MLT) region derived from TIMED Doppler Interferometer (TIDI) and ground based meteor radar at Thumba are compared. In this study, emphasis is given to verify the meteor radar observations at 98 km height region, especially during the EEJ peaking time (11:00 to 14:00 LT). The composite diurnal cycles of zonal winds over Thumba are constructed during four seasons of the year 2006 using TIDI and meteor radar observations, which showed good agreement especially during the peak EEJ hours, thus assuring the reliability of meteor radar measurements of neutral winds close to the EEJ height region. It is evident from the present study that on seasonal scales, the radar measurements are not biased by the EEJ. The day-time variations of HF radar measured E-region drifts at the EEJ region are also compared with MR measurements to show there are large differences between ionospheric drifts and MR measurements. The significance of the present study lies in validating the meteor radar technique over Thumba located at magnetic equator by comparing with other than the radio technique for the first time.

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