Day-to-day changes in experimental electron density profiles and their implications to IRI model

The electron density variability at fixed heights is studied for use in the International Reference Ionosphere IRI model. Monthly median, upper and lower quartile values were obtained for foF2, hmF2, B0 and B1 as deduced from ionograms. The IRI electron density profiles established with these values were then compared with the median and quartiles at fixed heights. Results are shown for the three ionospheric stations E1 Arenosillo (37.1 N, 353.3 E), Tucuman (26.9 S, 294.6 E) and San Juan (31.5 S, 290.4 E) as a function of solar activity, season and local time. As found by other authors the height of maximum variability, hvmax, is located below the peak electron density height (hmF2) in all the cases. Values of differences between hmF2 and hvmax are analized. Variability defined as the interquartile difference and hvmax results are calculated from experimental electron density profiles measured at the three stations.