Study Of Ionosphere Prediction Models And Discussion Of Pre-seism Ionosphere Anomalous

As one of the important approaches about space environment, the ionosphere, affect human's manufacture, live, scientific research and engineering application. Research of ionosphere has important significance on communication, radar, spaceflight, GNSS, high pressure electrical wire and other domains. This text analyzed and discussed the contents about methods of computing TEC with GPS data, building the ionosphere forecast model, reconstruction of TEC maps and ionosphere TEC anomalous of Pre-seism. The main contents as follows:1. Introduced the method of calculating ionosphere TEC through the phase smoothing pseudorange based on dual-frequency GPS data. At the same time, the method of hardware delay calculating is analyzed.2. Aiming at the problem of accuracy of traditional ionosphere model not high, build up a globe ionosphere forecast model with CODE GIM data in time sequence method. Analysis some key problem about the chosen of upper limit order and order-determining rule. Then, predict the TEC by using linearity least variance prediction method and correcting prediction method. Results show that the correcting prediction method has a better precision than linearity least variance prediction method in a day.3. Considered the problem that both methods, linearity least variance prediction method and correcting prediction method, have large predicting errors at the extreme. Improved correcting prediction method is proposed, which using last period error to modify result of correcting prediction method. The results suggest that accuracy of Improved correcting prediction method is obviously higher and stable than the former two.4. On account of the issue that the temporal resolution and space resolution of ionosphere grid data released by IGS processing center are not high, even the precision in China is not ideality. With data of the Crustal Observation Network of China (COMNOC), TEC maps of Chinese Mainland are reconstruct by distance weighted interpolation. Whereas, this method doesn't consider the space distributing of sample points, and because of lack of IPP information in the edge, part points can not be caculated. Therefore, ionosphere distance variable was introduced. Ionosphere TEC maps of Chinese Mainland are reconstructed in Kriging method. Results shows that, at 30s and 5min temporal resolution, the precision of Kriging is better than distance weighted method, also the maps of Kriging are smoother.5. The ionosphere anomalous before Wen Chuan, Yu Shu and Japan earthquakes by CODE GIM data is analyzed, the result indicates that, considered the sun and geomagnetism activity, anomalous have been observed before all earthquakes. Both positive and negative anomalous have benn detected before Wen Chuan earthquake while only positive anomalous before Yushu and Japan earthquakes. The same character is that before all earthquakes, anomalous can be found at the Southern Hemisphere geomagnetic conjugate area.