Behavior of the scale height at the F2 layer peak derived from Digisonde measurements at two European stations

A new technique is presented to estimate the electron density topside profile from information derived from ground-based ionograms. The electron density above the F2 peak is approximated by an a-Chapman function with constant scale height (Hm). The scale height is derived from the shape of the bottomside profile near the F2 peak. Digisonde data obtained at two European stations: Ebro (40.4 N, 0.3 E) and El Arenosillo (37.1 N; 353.2 E) for different times of day, seasons, and periods of the solar cycle to study the variations of Hm. The results of the analysis are in good agreement with those reported by other authors. A table of values is presented for typical hours of the day and different seasons and solar activity conditions. This study, once extended to a larger database, will support modeling Hm as a function of time, season, latitude, solar activity and magnetic activity, and contribute to the formulation of the topside electron density in the IRI model.