Comparison of measured and predicted F2 peak altitude

Different models for the F2 peak altitude hmF2 are compared with mean values determined from incoherent scatter measurements of the radar stations Jicamarca/Peru and Arecibo/Puerto Rico at all local times. Our investigation shows that the daytime hmF2 is fairly well represented by the most recent models, whereas at nighttime, higher peak altitudes are measured than predicted by either model. The observed diurnal structure is slightly misinterpreted by the models above Jicamarca and is strongly disagreeing above Arecibo.