Research On Empirical Modeling Of Mid-latitude Ionosphere Based On Multi-source Observational Dat

The Ionosphere is a partially ionized region of the Earth’s atmosphere within a height range of 60-1000 km.Charged particles within the ionosphere affect the propagation of radio waves and significantly impact navigation,communication,and human space activities.Conducting research on the characteristics of ionospheric variations is of great significance.Due to the complex nature of ionospheric variations in mid-latitudes and the relatively limited observational data available,the characteristics and physical mechanisms of ionospheric variations in mid-latitudes have not been systematically studied.In recent years,with the continuous advancement of detection technology,the construction of empirical models based on detection data has become an important means of researching the ionosphere,providing new ideas and opportunities for exploring the characteristics of ionospheric variations in midlatitudes.This paper focuses on the variations of the ionosphere in mid-latitudes,and carries out research on empirical modeling of ionospheric longitude variations,precision evaluation of IGS data products in China,and modeling of regional ionospheric nowcasting,based on satellite-acquired electron density data,IGS-GIM data products,and the total electron content of the China Crustal Movement Monitoring Network.The specific work of this paper is as follows:(1)Based on the electron density obtained by the CHAMP satellite from 2002 to 2008,the principal component analysis method was used to conduct empirical modeling and study the longitudinal structure variations of the ionosphere in mid-latitudes.The research results show that the longitudinal structure of the ionosphere in mid-latitudes exhibits significant local time dependence,seasonal variations,and hemispheric differences.Through analysis,it was found that the interaction between neutral winds,including meridional and zonal winds,and the geomagnetic field is the main cause of the longitudinal structure variations of the ionosphere in mid-latitudes.(2)To address the applicability issue of IGS-GIM products in China,this paper evaluated the accuracy of IGS-GIM data products from 2013 to 2014 based on TEC data provided by the China Crustal Motion Monitoring Network.The statistical results indicate that there are significant errors in the IGS-GIM products in the China region during 2013-2014,and the errors are significantly dependent on local time variations and latitude differences.In addition,the difference between IGS-GIM and TEC data from the China Crustal Motion Monitoring Network is larger in spring and autumn,and smallest in summer.Preliminary analysis suggests that the errors of IGS-GIM in China during 2013-2014 are related to the geomagnetic environment in China and the number and distribution of IGS observation stations in the China region.(3)This article employs the Total Electron Content(TEC)data obtained from the China Crustal Movement Monitoring Network during 2013-2014.A Principal Component Analysis(PCA)method is utilized to construct an empirical model for the TEC of the ionosphere in China.The newly constructed model is evaluated and validated by IGS-GIM data products and measured data.The results demonstrate that the empirical model exhibits high consistency with the measured data and is capable of effectively reproducing the diurnal variation characteristics of the ionosphere.Additionally,the precision of the empirical model(RMSE=2.36)surpasses that of the IGS-GIM data product(RMSE=4.64).Therefore,the newly constructed TEC model for the China region presents an advantage for research and applications related to ionospheric studies within the region.