The observation of related F-region height and electron content changes at mid-latitudes during magnetic storms and their comparison with a numerical model.

An effort is made to distinguish between the downward diffusion of plasma from the protonosphere and lifting by neutral air winds as the major cause of magnetic storm associated increases in Flayer electron concentration at a low-midlatitude station. A theoretical model is used to predict that increases in ƒoF2 and total electron content (TEC) lag in time behind increases in hmF2 if neutral wind lifting is responsible, while for diffusion from the protonosphere the changes in ƒoF2 and TEC occur together. Observations of hmF2 variations during several storm increases of TEC show phase lags of TEC with respect to hmF2 which support neutral wind lifting as a major cause of the increases in TEC.