A. B. Rabiu1 and Nandini Nagarajan2
1Department of Physics, Federal University of Technology, Akure,
Nigeria
2National Geophysical Research Institute, Uppal road, Hyderabad 500
007, India
Abstract. The temporal variations of the thickness, width and current intensity of equatorial electro jet over Indian sector have been evaluated from a thick current shell format of continuous current distribution model of equatorial electro jet on quiet condition. The thick current shell model takes into account the vertical ionospheric currents; permits both the width and the thickness of the jet to be determined simultaneously. The EEJ intensity increases from dawn reaches the peak at about local noon and thereafter decays towards sunset. The thickness and width of equatorial electro jet EEJ exhibit consistent diurnal variations. The thickness decreases from about 0.06642o at dawn to the minimum at about 1100 hr LT and then begins to increase towards the dusk. The width increases with the sunrise, reaches maximum at about 1100 hr LT and then begins to decrease towards the dusk. The mean annual half-thickness and half-width for the solar minimum year 1986 (Sunspot number R = 13.4) is 0.0625 ±0.0037o and 2.68 ±0.23 orespectively. The dynamics of the variation of electro jet intensity and thickness shows that electro jet shrinks as its inten- sity increases. The thick current shell model is shown to give better hourly representation of jet behaviour than thin shell format hitherto being used. The thin current shell model best fits only the near local noon jet observation. The transient variation of the jet thickness is explained in terms of the wind shears in consistency with the electrodynamics of the dynamo region.
Keywords: Earth - solar-terrestial interactions - magnetic field