Some Applications Of GPS Beacon On The Investigation Of Ionospheric Properties

The Global Positioning System (GPS) has been widely applied in the ionospheric research during the last decade. The present thesis shows various ionospheric studies concerned with the GPS derived parameters such as the Total Electron Content (TEC), the Signal to Noise Rate (S/N), the Carrier to Noise Rate (C/N), the amplitude scintillation index (S4), as well as the Rate of TEC Index (ROTI). Our works is focused on the properties of S/N, C/N, S₄ and ROTI, as well as the relationships among them. The main results are as follows.(1) We derived the daily variation of the radio attenuation in the ionosphere from S/N of GPS beacon. At the middle and low latitude station of MANA (273.75°E, 12.15°N; magnetic latitude 22.50°N), the S/N attenuation of GPS beacon is mainly caused by ionosphere absorption when the radio penetrates through the ionosphere. The attenuation value is larger in daytime than at night. The maximum value appears at noon or 1～3 hours later. Comparing with the attenuation value calculated by IRI, we find that our result fits well with that from the model.(2) We analyzed the daily and seasonal variations of the ionospheric scintillation. The ionospheric scintillations measured in Sanya(109.62°E, 18.34°N; magnetic latitude 7.61°N) appear mainly between 18:00 LT and 4:00 LT. The occurrence ratio is higher in spring and autumn than in summer and winter. The yearly variation of the scintillation strength has a pronounced semiannual component, in which the maximum scintillation appears in spring and autumn.(3) We also analyzed the correlation between S₄ and C/N over Sanya. The S₄ index and C/N observed at the same station (Sanya) are negatively correlated. The correlation coefficient of the two parameters can reach -0.80424 on a yearly average. The correlation is higher in summer and winter than in spring and autumn, and is higher in daytime than at night.(4) We investigated the relationship among ROTI and S₄. The parameters ROTI and S₄ are also correlated each other. As the result, ROTI can be used as an indicator of scintillation.The results in this thesis indicate that the observation of GPS beacon is of essential significance in the investigation of ionospheric structure and irregularities. This may be also important for the application of radio propagation in the ionosphere.