Study Of The Computerized Ionosphere Tomography Over The Yangtze River Delta Area Using The Ground-based Gps

The ionosphere has the close relation with the human activities. The various disturbances of the Earth's space environment and irregular structures with widely different spatial scales induced by solar activities existing in the ionosphere influence seriously shortwave communication, satellite communication, navigation and positioning precision of GPS and so on. How to monitor and study the various phenomena of the ionosphere in order to promulgates the physical mechanism attract the attention of the people. With the development of the GPS net, the computerized tomography technology became a main method in the study of the ionosphere. The computerized ionosphere tomography technology is suitable to monitor the distribution of the ionosphere's electron density and the disturbance. The thesis used the computerized ionosphere tomography technic to study and inverse the ionosphere's electron density combined with the GPS observations of the Yangtze River delta area mainly. We can provide the three dimensional distribution of the ionosphere density which can help to study the rule of the ionosphere action and the spatial environment. The main contents is:1. The thesis mainly introduced the principles and methods to compute the (Total Electron Content) of the ionosphere using the GPS. We wrote the program to process the GPS data and solve the differential code bias and discussed the reflection of the different time interval and station number for the parameter's solution. I compared the results with the values provided by the IGS and found the differences lies in the 1ns through the 19 day's data. And i used the TEC which calibrated using the differential code bias to study the response of the ionosphere during the magnetic storm.2. The thesis mainly introduced the principles and methods of the computerized ionosphere tomography technology. I wrote the three-dimensional tomography programs using the MART algorithm. Using the IRI model to produce the original distribution of the electron density and then make the simulation. Compared with the original distribution the tomography results consist with the original values and the results proved the reliability and the stability of the program.3. Using the observation data of the Shanghai's GPS net i inversed the ionosphere over the Yangtze River delta area using the computerized ionosphere tomography technic. The results obtained on the quiet day prove that the tomography results consist with the IRI model basically and reflect the change of the electron density during a day. During the especially big magnetic storm happened in 11.8, the main change of the electron density happens in the F layer of the ionosphere and the electron density has a rapid increase during the magnetic storm. It increase 150% than quiet day's and reflect the intense positive phase.The duration of the positive is about 36 hours. The time of the appearance of the largest value of the electron density consist with the main phase of the magnetic storm and reflect the Comparing with IRI model we can find the results of the tomography using the GPS reflect the change of ionosphere better than IRI model.