On the nature of equatorial spreadF

摘要: Ionospheric propagation via scattering from the F region was sought at 50 Mc/s over a transequatorial path (with midpoint near Huancayo, Peru) employing 2580-km transmitter-receiver separation. Propagation scatter present this about 10 per cent of time, though only night. A condition closely related to occurrence presence equatorial spread-F configurations on Huancayo ionograms. The height medium supporting usually identifiable with lowest associated spread On basis an interpretation experimental results, is shown arise by relatively thin sheets irregularities in electron density which occur bottom layer or as much 100 km lower. thickness these patches estimated order km. comprising are found be elongated along earth's magnetic lines force. Electron scale meters smaller measured least one dimension transverse field lines, and 1000 longer exist high 450 nocturnal during conditions. Equatorial echoes observed demonstrated arriving all elevation angles east-west plane. geographical extension given sheet direction times great An observational procedure suggested for distinguishing two fundamental varieties appearing necessary condition, that contours mean parallel force, proposed controlling factor ionosphere.