Ionospheric Profile Reconstruction Based On The Ground-based Detection Of Radio And Anomalous Distribution Research.

This thesis reviews the process of ionosphere probe, data processing and model establishing, based on which the structural changes in the ionosphere is analyzed. Principle of vertical and oblique ionospheric detection is discussed, and then the ramp-probe ionograms is obtained with the ray tracing method. The SAO code is applied to obtain some important physical parameters of ionosphere, such as foF2, NmF2, etc. Also, the POLAN program is used to get ionospheric profiles, and the vertical profile of the ionosphere is inversed with Kriging difference method. Then artificial neural network is used for the reconstruction of the Quasi-parabolic model of ionosphere. Several typical structural changes of ionosphere were discussed and the influence of the ionosphere structure on the ray path is analyzed. Origin of sun and geomagnetic is excluded for the ionosphere anomalies before Wenchuan earthquake based on the knowledge of Dst and Ap. Ionospheric anomaly before the earthquake is then analyzed from the viewpoint of local anomaly of the largest electron density, foF2 and―equivalent sunspot‖, respectively. Finally, ionospheric anomalies before the earthquake is analyzed and compared with that individually caused by geomagnetic activity.The results shows that the region of ionospheric anomaly before earthquake is smaller than that caused by geomagnetic activity.