Asymmetries in the equatorial electrojet around N-E Brazil sector

Abstract. The paper examines the data of geographic northward (X), eastward (Y) and vertical (Z) components of the magnetic field from a dense array of 26 vector magnetometers operated in N-NE Brazil from November 1990 to March 1991. As expected, the daily variation of X showed a minor maximum around 03:00–04:00 LT and a major maximum around 12:00 LT. The daily range of ΔY showed a strong minimum around noon at all stations. The combined ΔY and ΔX indicated the direction of the equatorial electrojet currents to be flowing along 25° north of east at the centre and 20° north of east at the edges of the equatorial electrojet (EEJ) belt. The centre of the EEJ as defined by the zero intercept of the Z versus latitude was found to be near 1.0° S dip latitude. The electrojet current was stronger in the northern half than in the southern half of the electrojet belt. These anomalies are suggested to be due to the abnormal distribution of the mean magnetic field in this region.