Showing papers by "Inez S. Batista published in 1981"
TL;DR: In this paper, the authors carried out a comparative study of the evening prereversal enhancements in the equatorial F region vertical ionization drift velocities (VZ) over Fortaleza (4°S, 38°W), Brazil, and Jicamarca (12°S and 77°W) in Peru, two magnetic equatorial stations in the American zone.
Abstract: We have carried out a comparative study of the evening prereversal enhancements in the equatorial F region vertical ionization drift velocities (VZ) 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 VZ 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.
285 citations
TL;DR: In this article, the authors studied the spread F in ionograms of both the range and frequency spread types for the magnetic equatorial station Fortaleza (geographic coordinates 38°W, 4°S; dip latitude −1.7°) for a 1-year period during 1978-1979).
Abstract: Spread F in ionograms of both the range and frequency spread types is studied for the magnetic equatorial station Fortaleza (geographic coordinates 38°W, 4°S; dip latitude −1.7°) for a 1-year period during 1978–1979). Satellite traces suggesting ionization structures with scale sizes of 100–200 km are found to be necessary precursors to the formation of the irregularities that give rise to range type spread F, whereas frequency type spread F was observed under different circumstances. Striking differences are noted in the spread F characteristics and related parameters over Fortaleza as compared with Huancayo (geographic coordinates 75.3°W, 12.05°S; dip latitude 0.6°) and Jicamarca (geographic coordinates 76.8°W, 11.95°S; dip latitude 0.9°), situated within only ∼38° in longitude west of Fortaleza. The postsunset maximum in h′F, in winter, is delayed by about 1½ hr with respect to other seasons over Fortaleza, as compared with Huancayo, where it occurs earlier in winter than in other seasons. Similar differences also exist in the prereversal peak near sunset in the vertical drift velocity (Vz) between Fortaleza and Jicamarca. The differences are attributed possibly to the large difference in the magnetic field declination and to other factors such as the difference in the magnetic field intensity and the relative separation between geographic and magnetic equators that exist between Fortaleza and the other stations.
136 citations