GNSS Seismic Deformation Inversion And Its Relationship With Troposphere And Ionosphere

Earthquake is one of the most common and natural disaster affecting human life and property.Although natural disaster such as earthquake is uncontrollable and unavoidable,people are seeking ways actively to deal with them.With the development of high-rate GNSS technology,it has been able to capture surface displacements including statics offsets and dynamic motions in the near field.Since GNSS is not affected by recording limitation like strong seismographs,it can acquire seismic displacement better in the near field even in large earthquakes.Therefore,GNSS has been widely used in related research in the region of earthquake research.The earth is a huge ecosystem composed of multiple layers.There are complex energy transportation and material exchanges between the layers.The ionosphere and troposphere,as the important parts of the near-Earth space,must be closely related to the atmosphere and the lithosphere.As the production of the intense movement of the lithospheric plates,the earthquake will inevitably have an impact on the state of atmosphere.Based on the GNSS single-frequency precise point positioning method and relative positioning method,this paper studies the correlation between the earthquake and the troposphere and the ionosphere with the Tohoku-Oki Earthquake and Ya'an Earthquake as examples,and draws some conclusions.The specific work is as follows:(1)The original GNSS observation equations and the main error factors affecting the accuracy and the correction methods of various errors are introduced.The principle of GNSS single-frequency PPP positioning and relative positioning are given.(2)The dynamic calculation theory of single-frequency PPP and the dynamic solution principle of GAMIT/GLOBK software-TRACK kinematics analysis module are studied in detail.The noise source of high frequency GNSS coordinate time series is analyzed,which is common mode error,and the PCA spatial filtering method for effectively removing common mode error is studied.In order to illustrate the filtering effect,the power spectral density and the root mean square value are calculated for the residual time series.(3)Correlation coefficients are calculated for the time series of coseismic displacement and the corresponding tropospheric zenith wet delay,and the correlation between the two segments and the relationship with the spatial distribution of the observatory are analyzed.For the ionospheric TEC data,the spatial interpolation was performed by the method of distance inverse weighting,and the distribution of ionospheric TEC before and after the earthquake was analyzed.The experimental results show that single-frequency PPP has the ability to capture transient deformation signals and has the advantage of low cost.It can be used in the field of seismic research after continuous improvement.PCA spatial filtering method can effectively remove the effect of common mode error on the displacement sequence.The correlation between seismic and tropospheric zenith wet delay and ionospheric TEC is existed,but may not reflected in the earthquake time.