Variations in the altitude of the F2 peak associated with trough-formation processes

摘要: A novel approach is described which can help to determine, from ground-based data, of the possible production mechanisms for mid-latitude F-region ionospheric trough dominant during a particular event. This involves numerically modelling causal see how each will affect altitude F2-layer electron-concentration peak (hmF2), and then comparing these predictions with observed variation hmF2 formation. The work predicts that, if neutral-wind velocity does not vary, remain almost constant formed via stagnation, but rise it as result high ion velocities or neutral upwelling. Observations made at Halley (76°S, 27°W, L=4.2), Antarctica, show that most frequently only changes in formation are those expected due variations wind, suggests stagnation common mechanism. During geomagnetically active night studied, on Ap varied between 18 32, there was cannot be explained by wind. On this plasma also decayed faster, poleward edge seen earlier than other nights. These differences, together fact remained relatively low, suggest caused change composition, possibly advected into observing area.