Equatorial electrojet in east Brazil longitudes

This paper describes the morphology of the equatorial electrojet (EEJ) along 45 degrees W longitude in east Brazil, where the ground magnetic (dip) equator is associated with the largest declination in the world. Daily range of the horizontal field (Delta H), as expected, was largest at the station in the chain closest to the dip equator, Sao Luiz (inclination -0.25 degrees S). Delta Z was largest positive at Eusebio (inclination 9.34 degrees S) and largest negative at Belem (inclination 7.06 degrees N); both near the fringe of EEJ belt. Delta Z at Sao Luiz during the daytime was unexpectedly large negative in-spite of a small dip and also located south of the dip equator where Delta Z should be positive. Center of EEJ was found to be shifted southward of the dip equator by about 1 degrees in latitude. During southern summer, Delta Y started decreasing from 00 h and reached a minimum value in the afternoon, an abnormal feature not discussed for any station so far. The mid-day value of the direction of Delta H vector was 22 degrees-24 degrees W compared to the declination of 19 degrees-21 degrees W in the region.