Establishment Of Regional Ionospheric Model Based On SDCORS Data And Application In Earthquakes Monitoring

Ionospheric delay error is one of the main error sources of global navigation satellite system(GNSS).How to eliminate ionospheric delay error to improve GNSS positioning accuracy and reliability has become an important research topic.The vertical total electron content(VTEC)is an important parameter to characterize the ionospheric morphology and structure in navigation and positioning.The research and prediction of its variation characteristics can not only provide important data for the research of ionospheric morphology,but also have important significance for the research of GNSS high-precision measurement,real-time navigation and positioning and network RTK.Earthquake is not only a threat to the safety of human life and property,but also a key and difficult area for scientific research and development of science and technology,such as geodesy,geophysics and seismology.At present,with the development of world economy and society and the acceleration of urbanization,the loss of earthquake disaster shows the trend of non-linear and accelerated growth.In recent years,the rapid development of GNSS provides a lot of data and technical support for the research of geodesy,geophysics and seismology.At present,GNSS plays an important role in the military field and national economy.With the development of technology and social economy,it is an urgent problem to be solved in earthquake prediction.The Beidou navigation satellite system(BDS),which is independently developed in China,is about to be formally networked,which lays a foundation for the research.Because the GNSS observation data is affected by the regional/spatial environment factors,it can not be directly applied to the earthquake prediction.Therefore,based on the GNSS data to obtain high-precision ionospheric background value,it is the focus of earthquake prediction research to explore the correlation between earthquake and ionospheric disturbance.Based on global ionospheric data Map(GIM),analyzes the temporal and spatial characteristics of the ionosphere in Shandong Province,studies the correlation among solar activity,geomagnetic activity and ionosphere,builds the ionosphere model in Shandong Province with the help of spherical harmonic function model and analyzes the model accuracy,and studies the reliability of the relationship between earthquake and ionosphere disturbance by using the method of singular spectrum principal component analysis and sliding quartile distance The contents and achievements are as follows:1.The total electron content of ionosphere retrieved by GPS is summarized the theory and method of content(TEC),are introduced.The common ionospheric model and its detection method of seismic ionospheric disturbance are summarized.It provides the theoretical basis for the following analysis of the spatial-temporal characteristics of the regional ionosphere in Shandong Province,the establishment of the regional ionospheric model with the help of sdcors data,and the correlation research of seismic ionospheric disturbance.2.Based on GIM data,the spatial-temporal characteristics of ionosphere in Shandong and its surrounding areas are analyzed.The ionospheric VTEC values in Shandong and its surrounding areas have obvious annual and half year cycle characteristics;VTEC will appear "winter anomaly";with the increase of latitude,VTEC values will decrease significantly,and the temporal and spatial characteristics of longitude will not change significantly;solar activity and geomagnetic activity are important factors affecting the VTEC values in Shandong and its surrounding areas.3.Based on spherical harmonic function model and sdcors data,the ionosphere model of Shandong Province is established.In the regional ionosphere model,the accuracy of DCB solution is stable at 0.4ns,and the deviation between satellite DCB and code is generally stable at 0.5ns.The ionosphere products' time resolution is increased from 2H to 1H,and the spatial resolution is increased from 2.5 ° × 5 ° to 1°× 1°.At the same time,the correction effect of Shandong single frequency PPP in all directions is better than that of global ionosphere model products.4.Taking the ms8.2 earthquake near the Gulf of Alaska(55.87°n,149.35°w)on January 23,2018 as an example,the correlation between earthquakes and ionospheric disturbances is studied.The results show that the principal component of Tec extracted based on singular spectrum analysis is basically the same as that detected by the sliding quartile method.After excluding the influence of the space environment on the ionosphere,the ionospheric disturbance anomaly occurs three days before and two days after the earthquake it can provide reference value for earthquake monitoring and prediction.