Abstract:

A long run of EISCAT Svalbard Radar and DPS-4 in Zhongshan Station, between December 2006 and December 2007, have been analyzed with respect to diurnal variability in the F2 region critical frequency（f0F2） and peak altitude（hmF2）. Comparison with the international reference ionosphere model (IRI-2007) clearly demonstrates that the observations in both stations were consistent with the IRI prediction in summer, but with great deviations in winter. It suggested that though the photoionization factor had been well considered in the model, the electron precipitation should be taken into account, especially in winter.

Key words: IRI