Objectives Using IonPrf of COSMIC (constellation observation system for meteorology ionosphere and climate) measurements during 2006—2020, the temporal-spatial variation characteristics of ionosphere is analyzed over China region.
Methods First, the quality of new generation COSMIC-2 data is introduced over China and global regions. Then, the method of extracting the ionospheric characteristic parameters and controlling the quality of IonPrf products data is illustrated. Finally, the temporal-spatial variation characteristic of ionospheric parameters is analyzed over China region for 15 years during a complete solar cycle by different time scale.
Results Experimental results show that the ionospheric variation of China region has the characteristic of annual, seasonal, and diurnal variation related to solar activity. In annual variation, NmF2, HmF2 and total electron content（TEC） in southern China being generally higher than those in northern China, has obvious spatial distribution characteristic. In seasonal variation, NmF2 and TEC have maximum in March and October, and minimum in June and July.
Conclusions The winter anomaly only appears in parts of southern China and the average of HmF2 in spring and autumn is higher than one in summer and winter. In diurnal variation, NmF2 and TEC have maximum during local time 12:00-16:00 and the local time corresponding to the peak value moves forward with increasing of latitude. The NmF2 and TEC are still high relatively after sunset during year of solar high activity. HmF2 of southern China has maximum during local time 12:00-16:00 and minimum during local time 05:00—07:00. And HmF2 of northern China in daytime is generally lower than one in night.
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