An olden but golden EISCAT observation of a quiet‐time ionospheric trough

摘要: [1] Incoherent scatter measurements were carried out on 9 November 1987, showing the presence of an ionospheric trough in F region. The experiment was made using EISCAT UHF radar, and it consisted azimuthal scan with constant beam elevation a meridional scan. Since radar rotates Earth, beams different directions from subsequent scans meet same MLT- CGMLat pixel nonrotating frame. If ionosphere is not too variable, these can be combined to give average value electron density ion/electron temperature each pixel. Furthermore, since passing through ion velocity components, also possible obtain vector. geomagnetic conditions during observations quiet enough for assuming quasi-stationary ionosphere. It found that both temperatures have minima within region increase at poleward wall. Ion measurements, together convection model, suggest depletion due recombination plasma convecting long time dusk cell beyond terminator. northern edge associated soft particle precipitation. southern steeper than edge, built by sunlit brought corotation. thus result combination transport precipitation processes rather stagnation.