Comparison of the IRI 2001 model with electron density profiles observed from topside sounder on-board the Ohzora (EXOS-C) and the Akebono (EXOS-D) satellites

For the purpose of evaluation of the IRI 2001 model, the topside sounder data obtained from the Ohzora (EXOS-C) and the Akebono (EXOS-D) satellites in the magnetic latitude range from −50° to 50° were compared with the profiles calculated from the IRI model. Based on the electron density profiles obtained from the Ohzora satellite, the difference between the IRI model and observations is within a factor of 0.2-2.0. However, within the magnetic latitude range from 10° to 30° for the local time sector from 19 LT to 21 LT, the calculated peak height and density of the F2 layer (hmF2 and foF2) were higher and lower than the observational profiles. The IRI 2001 model was able to reproduce well density profiles in the mid-latitude region, on the other hand, it tended to overestimate in the equatorial region. As a result of the comparison with the Akebono satellite sounder data, it was confirmed that the IRI model generally tended to reproduce observed profiles well in lower altitude region (<1000 km) and overestimate in higher altitude region (>1000 km). However, even below 1000 km, the IRI model also overestimated in the magnetic latitude range from −50° to 20° for the local time sector from 00 LT to 09 LT.