Variabilities of the equatorial electrojet in Brazil and Perú

Abstract

This report presents seasonal and longitudinal variabilities of the equatorial electrojet in the east (Brazil, Sao Luís: 2.3° S; 315.8° E; 0.5° S dip latitude) and west (Jicamarca, Perú: 11.95° S; 283.13° E; 0.6° N dip latitude) coasts of the continent of South America. Ground-based magnetic field perturbation measurements ΔH for solar maximum (2001/2002) and solar minimum (2006/2007) conditions from the two equatorial stations (Sao Luís and Jicamarca) have been used for the study. The ΔH signal which is a measure of the strength of the equatorial electrojet is spectrally analyzed using wavelet analysis. The results of our analysis show that (1) the equatorial electrojet has maxima around equinoxes in Jicamarca, Perú but it has a prominent maximum during Southern Hemisphere summer (centered about December/January) in Sao Luís, Brazil. The observed seasonal behavior of the equatorial electrojet in Sao Luís is highly likely due to the large magnetic declination angle (about 20° west) there. (2) The equatorial electrojet is stronger in the west coast (Jicamarca) compared to the east coast (Sao Luís), irrespective of solar activity condition. (3) The magnitude of the equatorial electrojet is more variable with season and solar cycle over Sao Luís than over Jicamarca. Copyright © 2010 by the American Geophysical Union.