Comparisons Of Ionospheric F2 Region Critical Frequency And Peak Height(foF2 And HmF2)between Measurements And IRI Predictions Over China

The F2 region critical frequency(foF2)and the F2 region peak height(hmF2)are very important parameters in the relevant characteristic parameters of the ionosphere F2 layer.The foF2 and hmF2 play an important role in ionospheric research and communication.The International Reference Ionosphere(IRI)model is the most widely used empirical model for low geomagnetic activity in ionospheric research.The latest version is IRI-2016.Since the IRI model does not use ionospheric parameter data in China,it is necessary to evaluate and study the applicability of the IRI model in China.This paper uses the Sanya(18.3°N,109.6°E)ionosonde observation data from 2013 to 2016 and the 2014(high solar activity)and 2016(low solar activity)Wuhan(30.54°N,114.34°E),Beijing(39.98°N,116.37°E),Mohe(53.49°N,122.34°E)observation data of the ionosonde,and analyzed the measured values of foF2 and hmF2 during the geomagnetic calm period(Kp?3)day(day and night)changes,seasonal changes and annual changes,and the ionospheric ionosonde observations were compared with the predicted values of the corresponding IRI-2016 model,and the characteristics of the regional ionospheric changes and the IRI model were obtained.The detailed information of the comparison results provides a reference for improving the prediction accuracy of the IRI model in China.This paper has carried out the following research work.First,a comparative analysis program of ionosonde observation data(i.e.foF2 and hmF2)processing program and ionosonde observation data and IRI-2016 prediction results was developed to verify the correctness of the program.The daily(day and night)changes,seasonal changes and annual changes of the foF2 and hmF2 observations of the Sanya,Wuhan,Beijing and Mohe ionosonde were analyzed using the ionosonde observation data processing program.The analysis results are as follows.1.Comparing the Sanya foF2 observations in 2013,2014 and 2015,it was found that foF2 changed most with the seasons in the high solar activity in 2014,and bimodal and nighttime enhancement occurred in spring and autumn.In 2014,the foF2 observations in Wuhan,Beijing,and Mohe did not show double peaks and nighttime enhancement.In 2014,the foF2 observations in Sanya,Wuhan,Beijing,and Mohe all showed the minimum of daytime throughout the year,which occurred in the summer and nighttime normal half-year anomalies and winter anomalies.2.In 2014,the maximum values of foF2 observations in Sanya,Wuhan,Beijing,and Mohe were 18.2 MHz,16.1 MHz,14.3 MHz,and 13.5 MHz,respectively.That is,as the latitude of the station increased,the foF2 observation decreased,and the foF2 observation was the largest.The value appears from 8 UT to 4 UT.In 2014,there was no significant change in the minimum value of the foF2 observations at the four stations,but the time to maintain the minimum was extended with increasing latitude.3.In 2016,the hmF2 observations showed significant bimodal phenomena in Sanya and Wuhan.The 2016 Sanya hmF2 observations showed two distinct peaks at 6 UT and 16 UT,and increased significantly at 14-20 UT(local night).In 2016,with the increase of latitude,the observations of hmF2 in Sanya,Wuhan,Beijing and Mohe continued to decrease,and the maximum values of observations of Wuhan,Beijing and Mohe hmF2 appeared at 16-18 UT(i.e.0-2 LT).Second,using the comparative analysis program of ionosonde observation data and IRI-2016 prediction results,the foF2 observations of Sanya,Wuhan,Beijing,Mohe ionosonde and the corresponding IRI-2016 model foF2 prediction values were compared and found.The following results were obtained.The predicted value of foF2 in IRI-2016 model can predict the trend of foF2 with solar activity well,but it can not predict the anomaly in low latitude area.The measured value of Sanya is generally underestimated,especially at night.However,the forecast results during the day are better.In 2014,the IRI-2016 model with coefficients of CCIR and URSI predicted that foF2 predictions were more accurate during the 0-12 UT period.In 2014,the predicted value of foF2 predicted by IRI-2016 was highly accurate in Sanya and Wuhan in the mid-low latitudes of Beijing and Mohe in the mid-latitude region.When the IRI-2016 model coefficient was URSI,the predicted foF2 was more severe at 12-22 UT(i.e.,local nighttime)than the CCIR underestimation observation.Therefore,the analysis results of this paper show that it is more accurate to choose the CCIR coefficient in China to predict the true value of foF2.Third,the hmF2 observations of the Sanya,Wuhan,Beijing,and Mohe stations were compared with the AMTB2013 model of the IRI-2016 model,the BSE-1979 model,and the SHU using the comparative analysis program of the ionosonde observation data and the IRI-2016 prediction results.The predicted values of hmF2 given in the-2015 model were compared and the results obtained are as follows.In 2016,the predicted values obtained by the IRI-2016 model using the models AMTB2013,BSE-1979 and SHU-2015 were basically the same as the hmF2 observations of Sanya,Wuhan,Beijing and Mohe stations.The accuracy of the IRI-2016 model for predicting hmF2 was significantly higher than that of the forecast foF2.In 2016,when the IRI-2016 model predicted the hmF2 of four stations,the overestimation was the most serious when the mode AMTB2013 was selected,the mode BSE-1979 was followed,and the mode SHU-2015 was underestimated.In 2016,the IHU-2016 model SHU-2015 was selected to predict hmF2 to be the most accurate.The analysis results in this paper show that the SHU-2015 model that selects the IRI-2016 model in China predicts the true value of hmF2.