Modeling And Accuracy Evaluation Of GNSS Regional Ionosphere

With the continuous development of the times,the progress of science and technology has brought many changes with each passing day.The rapid development and improvement of the surveying and mapping industry can be well applied to many aspects of scientific research,such as the Global Navigation Satellite System(GNSS),which provides a good platform for ionospheric research.This paper mainly studies the ionosphere,which is one of the main components of the Earth’s atmosphere.Because it will cause delay errors for GNSS observation data and affect the positioning accuracy of GNSS,it reduces or eliminates the delay errors caused by the ionosphere by studying the structure and change characteristics of the ionosphere and extracting the Total Electron Contentin(TEC)the ionosphere with high accuracy.The regional model construction of the ionosphere is actually related to the construction of a highprecision TEC model,which can promote the development of each other.The construction of the model can improve the positioning accuracy of GNSS observation,and can also bring us a lot of available experimental reference for the study of the ionosphere and the monitoring of its abnormal changes,and promote people’s understanding of the ionosphere and its unnecessary impact.Ionosphere has complex structure and variation characteristics,so this paper will study the regional ionosphere modeling of the ionosphere,introduce its relevant structure and variation characteristics,and the principle and method of modeling,and complete the construction of the ionosphere regional model by using a functional model,and analyze the results and applications of the model.The main research contents are summarized as follows:1.This paper briefly introduces the research background and significance of ionospheric modeling,as well as the research progress of ionospheric modeling at home and abroad.Then,the structure and change characteristics of the ionosphere itself and the influence on GNSS signal propagation(including the impact of hardware delay)and its anomalies and related indices will be analyzed,and the extraction of TEC from the ionosphere will be introduced,and the determination of GNSS observation information and the observation of carrier phase smoothing pseudorange will be briefly introduced.Through these introductions,the theoretical framework of ionospheric region modeling is constructed,which is the basis for the completion of model construction.2.This paper introduces the methods and basic principles of ionospheric model construction,the projection function of STEC converted to VTEC and the common models of ionospheric modeling,such as the empirical model,mathematical model and ionospheric stochastic model.3.Based on the spherical harmonic function in the mathematical function model commonly used in ionospheric modeling,the ionospheric regional model is constructed.Through downloading and solving the data,the regional ionospheric model in low latitude regions(30 ° S-30 ° N,180 ° W-180 ° E)is established by using the spherical harmonic function model.The conclusion is that if the TEC model based on a single data source(COSMIC2 TEC)is only able to show the overall change trend compared with the ionospheric model based on the fusion data source(COSMIC2 TEC and CODE TEC),the COSGIM model based on the fusion data source is not as good as the detailed changes of TEC and equatorial anomalies.The model can better describe the change characteristics of the ionospheric TEC.4.The empirical model of ionospheric single station TEC is constructed based on harmonic function.This paper introduces the ionospheric TEC empirical models used in two different situations,then selects three single stations to download data in 2016 and 2020,constructs their TEC empirical models at the four time points of equinox and solstice,and analyzes the results.It is concluded that the TEC empirical model of two single station mkea stations and brst stations outside the MSNA area has a good fitting effect and can reflect the daily variation characteristics of the ionosphere.The ohi3 station located in MSNA area reflects the ionospheric anomaly.Figure[thirty] Table [five] Reference [90]...