Based On Ground-based Gps Monitoring Of Ionospheric Delay Correction Study

Usually, there are two ways to correct the ionospheric delay in GPS signals while we use GPS for navigation. One is using the broadcasted Klobuchar ionosphere model by GPS satellites. Another is using the established ionospheric grid or function model based on the ground GPS continuous tracking network. These two ways can achieve 50% and 80% separately. On the other hand, in the precise GPS data post-processing and its corresponding applications, more accurate and multi-parameters models are adopted to describe the time-spatial variations of the ionospheric delays, reflect and study the ionospheric modal characteristics. This kind of post-processing ionosphere models have many types aiming at different application fields, but they usually can achieve an effect of 90%. Currently, the main ionosphere researches using GPS in China and worldwide step forward in two directions: One is to establish high precision and time-spatial ionospheric delay models using GPS data, which is used to correct the delays caused by the ionosphere in radio signals. Another is to inverse the two-dimensional, or three-dimensional distribution and variations of the electronic content in the ionosphere, describing, explaining and revealing the characteristics and rules of the ionosphere using GPS.For the purpose of the application of GPS/TEC, this thesis has designed a set of data processing methods used to model and monitor the ionospheric VTEC variations. Several years' GPS data of more than 40 continuously tracking stations over China has been processed to present a high time spatial resolution monitoring of VTEC variations and characteristics in the ionosphere. Especially, to meet the requirements and developments of Chinese GNSS progress, the daily variations of VTEC and its unique characteristics have been deeply discussed based on the time series of the characteristic parameters of VTEC daily variations derived from post-processing. According to the rules reflected by the time series, an improved Klobuchar model is suggested to be the predicting model for GNSS. On the other hand, viewing the importance of the disturbance monitoring of the ionosphere in the research, here some methods are involved in the discussion using the ground-based densely distributed GPS network. As an example, an irregularity is successfully monitored and analyzed using Shanghai GPS Comprehensively application network. The variations of TEC reflected by VTEC maps as time goes indicate that an ionospheric irregularity, whose scale is about 50 km and existence time 5 minutes, complete its whole process of...