COMPARISON OF TOTAL ELECTRON-CONTENT CALCULATED USING THE IRI WITH OBSERVATIONS IN CHINA

Values of total electron content (TEC) calculated using the International Reference Ionosphere (IRI-86 and IRI-90) are compared with the observations at Xinxiang based on the Faraday rotation measurement. It is found that the IRI gives acceptable values with respect to the observations during low solar activity. Generally the IRI-90 is better than the IRI-86 and the URSI coefficients are better than the CCIR coefficients in the calculation of TEC. Making use of the foF2 and M(3000)F-2 calculated using the Asia Oceania Region F-2-layer mapping (AOR) instead of using the CCIR or the URSI coefficients, the IRT gives more accurate TEC values. In October-April during high solar activity, however, the IRI obviously underestimates TEC in the daytime, which could be due to an improper topside electron density profile.