摘要：The diurnal, seasonal, and solar activity variations of the bottomside ionospheric profile parameters B 0 and B 1 are studied using electron density profiles measured over Wuhan (30.4°N, 114.4°E) of China with a DGS- 256 Digisonde during 1999–2004. Comparisons are made with the International Reference Ionosphere model (IRI-2001) using both the standard option ( B 0-Tab and B 1-Tab) and the Gulyaeva’s option ( B 0-Gul and B 1- Gul). The results show that: (1) observed B 0 has distinct diurnal and seasonal variations, while observed B 1 changes little with season. The value of B 0 is larger in summer than that in equinox and winter, especially for daytime. In winter and equinox, B 0 also presents morning and afternoon collapses as reported by Lei et al. (2004). (2) B 0 increases about 18.6 km from low solar activity (LSA) to high solar activity (HSA). B 1 in HSA is smaller than that in LSA before 10:00 LT and with an opposite tendency during the rest time. (3) Observed B 0 is in better agreement with B 0-Gul than with B 0-Tab, though the B 0-Gul overestimates during 09:00 to 17:00 LT in equinox and summer. B 0-Tab is 12–20 km larger than the observations over Wuhan almost all the time. Meanwhile, B 1-Tab is in good agreement with the observations.
关键词：Low latitude ionosphere ;DGS-256 Digisonde ;IRI model ;modeling and forecasting
