The Technique Of The GNSS Ionosphere Observation And Its Research On Application

The seismic fault zones are quite common in China continent because of the long time continuous compression between the Pacific plate,the India plate and the Philippine plate.Frequently occurring earthquakes in China,especially in the south China,have brought a huge disaster and loss not only to people's lives but to public property safety of our country.A number of the researches illustrate that the ionosphere disturbance was observed before the earthquake or during the earthquake,Recently,a stereo earthquake monitoring system has been paid more and more attention.Thus,the Seismo-Electromagnetic Satellite in China will be launched in 2016.The ionosphere is in the environment of solar-terrestrial space,not only coupling with the lithosphere,but also the upper atmosphere.Therefore,before extracting the ionosphere anomaly information about earthquake,and the normal background variation of the ionosphere must be researched.The spherical harmonic function is used in this paper to obtain China area ionosphere information.Firstly,the accuracy of this model is evaluated,furthermore,the normal variation of the equator ionosphere anomaly(EIA)and the ionosphere disturbance about the earthquake before or during the earthquake are examined.The CMONOC(Crustal Movement Observation Network Of China)and the IGS(International GNSS System)GPS observation data from 2008 to 2012 year was used in this paper,the spherical harmonic function is used to attain China area ionosphere TEC(Total Electron Content),respectively,the IES results(the CMONOC GPS observation data not included)and the ENIES results(the CMONOC GPS observation data included).The three components of the EIA(TEC,Location,Time)was made,finally,the study about of seismic precursor and the coseismic ionosphere disturbance(CID)was investigated combining with some earthquakes which recently occurred in China.The main results are listed as follows:(1)The TEC value increase with the ascend year of the solar activity,showing that the range of the grid value residual and the RMS of the TEC.Finally,the ENIES results is superior to the IES and CODE in VTEC of the single station at China mid-low latitude area.Increasing by 2TECU during different solar activity.(2)The occurrence time and occurrence location of EIA(Equator Ionosphere Anomaly)also vary with the solar activity presenting the long term 11 years variation,namely,the location of the EIA is higher and the the time is more late in high solar activity.The TEC,one of the EIA parameters,has a maximum value at spring equinox and autumn equinox each year,and has a minimum value at summer solstice and the winter solstice.Last,the relationship of the TEC value and the index of the solar activity and the geomagnetism was made finding that TEC presents the strong positive correlation with the F10.7cm about 0.99 and the significant negative correlation with the Dst.(3)The research about the seismic precursor demonstrates that before the earthquake,some EIA crest moves equatorward tendency proving there maybe exists the lower eastward electric field,meanwhile,some EIA crest also moves polarward tendency proving there maybe exists the stronger eastward electric field.Furthermore,the study of Wenchuan earthquake coseismic ionospheric disturbance was conducted.Through the process of the GPS data,the horizontal speed is 1.1km/s as the acoustic speed in the ionosphere was acquired,meanwhile,the secondary CID speed closed to 0.7km/s also was obtained it may belong to the gravity wave.After,using the ray-tracing technique,when the CID speed is equal to the 1000m/s,the RMS of the earthquake insert time can reach the minimum value 19.551s,and the origin of the CID is 30.8°N,103.15°E,apart from the epicenter 33.6 km.