International Reference Ionosphere - Performance during the cycle 23/24 minimum

Cycle 23 was exceptional in that it lasted almost two years longer than its predecessors and in that it ended in an extended minimum period that proofed all predictions wrong. We will discuss the effect that these uncertainties in the solar indices prediction had on the IRI representation of ionospheric conditions during the minimum. We will review some of the recent studies that have compared IRI with measurements and that have found agreement as well as significant discrepancies. Results will be present from our comparisons of ionosonde and C/NOFS data with the values predicted by IRI. We find that IRI describes the peak densities and TEC quite well both before and during the solar minimum. Discrepancies are found with satellite insitu measurements in the 400 km altitude range. We will discuss the possible causes for these discrepancies and investigate ways of improving IRI in this altitude range for solar minimum conditions.