Magnetic declination control of the equatorial F region dynamo electric field development and spread F

Abstract

We have carried out a comparative study of the evening prereversal enhancements in the equatorial F region vertical ionization drift velocities (V Z ) over Fortaleza (4°S, 38°W), Brazil, and Jicamarca (12°S, 77°W), Peru, two magnetic equatorial stations in the American zone. The results show profound dissimilarities in the seasonal trends in the times and widths of the V Z prereversal peak, which reflect in the spread F characteristics as well, at the two stations. The dissimilarities are shown to be arising mainly from the difference in the magnetic field declination angles that causes differences in the conjugate E region sunset durations and, hence, in the F region polarization electric field development rates at the two stations.