Research On TEC Distribution And Inversion Of Ionospheric Electron Density Based On Satellite Beacon

Computerized ionospheric tomography(CIT)plays an important role in the study of ionospheric sounding because of its own advantages such as low cost and implementation simplicity.And the total electron content(TEC)measured by the low-earth orbit(LEO)is one of the important data sources of the ionospheric tomography.The successful launch of the weather,ionosphere and climate satellite observing system(COSMIC)by the United States and Taiwan has increased the source of the satellite signal and the TEC data in the middle and low latitude area.The tri-band beacon carried by the COSMIC also lays the foundation for high precision ionospheric tomography.Compared with the traditional dual-band beacon technique,the tri-band beacon greatly improves TEC phase ambiguity and reduces the calculation error of phase integral constant by using the differential phase between each pair of frequencies.Based on this,the paper reconstructs the high precision electron density in the middle and low latitude area and the influence of the geomagnetic storm event on the TEC is analyzed.The main research content is as follows:1.The influence of the average ionospheric height on the accuracy of absolute TEC is calculatedBecause the orbit of COSMIC-? is a little low,a large calculation error will be caused by the average altitude.In this paper,the Ne Quick model is used to calculate the absolute TEC error at different altitudes and the average ionospheric altitude with minimum error is obtained.The error is not more than 1 TECu.The vertical TEC obtained from the measured data also verifies its accuracy.2.The high precision two-dimensional distribution of electron density is reconstructed by using the measured data.In this paper,the electron density from IRI model is considered as the initial value to reconstruct the distribution of electron density in the middle and low latitude area.The computational efficiency and accuracy of the algebraic reconstruction technique and the multiplicative algebraic reconstruction technique in the reconstruction of the electron density are compared.The error of the reconstructed TEC value is about 0.2TECu.Based on the reconstruction results,the variation of electron density with latitude and altitude at different time,and the different forms of equatorial anomaly in the day and night is analyzed.3.The influence of geomagnetic storm on the two-dimensional distribution of TEC is analyzed.A large number of vertical TEC data can be obtained by using the hundreds of GPS stations which are distributed around the world.In this paper,a reconstruction method of high precision TEC is proposed.The Kriging interpolation method is used to interpolate the vertical TEC data in order to obtain the high resolution two-dimensional distribution of TEC.The accuracy and effectiveness of the proposed method are compared with the measured data.Based on the two-dimensional distribution,the change of regional TEC value with time and latitude is analyzed,particularly in the influence of geomagnetic storms on the TEC value.And the differences and explanations of TEC changes in different latitudes are given.The related research results can provide the method support for the establishment of regional high resolution ionospheric monitoring system.