Studies On Space-based Ionospheric Monitoring Architecture And Forecasting Model Of Ionospheric Scintillation

With the development of application and construction of satellite communication, radar, BEIDOU satellite navigation system and so on, there are more urgent requirements for the monitoring of global ionosphere and the capabilities of forcasting and alert of ionospheric scintillation events over Chinese region, but there is few model of ionospheric scintillation occurrence probability prediction for engineering operation over wide area in our country. Therefore it's important to investigate and implement a model of ionospheric scintillation occurrence probability prediction over the low-latitude region of China. Based on those considerations, our studies are mainly engaged in three aspects:(1) Architecture study of space-based ionospheric monitoring. (2) Validation and Verification of space-based ionospheric payloads and data processing techniques of these payloads. (3) Application and investigation of the model of ionospheric scintillation occurrence probability prediction over the low-latitude region of China.In chapter 2, we attempt to explore the method of argumentation and design for space-based ionospheric monitoring architecture. Firstly, we analyzed the requirements of space-based ionospheric monitoring; secondly, we explored and analyzed the method of argumentation and design for space-based ionospheric monitoring tasks, and putted forward the preliminary process of argumentation and design for space-based ionospheric monitoring tasks, which may be helpful for our national investigation and construction of space-based ionospheric monitoring system.In chapter 3, we studied the Validation and Verification (V&V) techniques of space-based tri-band beacon payload, and data processing techniques of several space-based ionospheric payloads. The V&V of performance of ionospheric payloads relating to Earth-satellite radiowave links is an difficult problem to be resolved. In this thesis, the Semi-physical and semi-emulational method is put forward to validate and verify the performance of tri-band beacon. In addition, an algorithm is presented for deriving latitudinal TEC variations along the satellite track based on DORIS observations. Preliminary processing results show that the DORIS system is an effective means to derive the large scale variations of TEC. However, if we make some improvements on DORIS system, this system has potential to become a more useful ionospheric scintillation monitoring and ionospheric electron density 3-D tomography technique, due to its capabilities of global monitoring and shorter revisiting time to the same area.The chapter 4 is the most important part in this thesis. We investigated and developed a model of ionospheric scintillation occurrence probability prediction over the low-latitude region of China, which is one of the key kernel techniques of ionospheric scintillation forcasting and application, and presented several new findings.(1) The power spectra and their spectral indices of ionospheric irregularities over the low-latitude region of China are analyzed. It's found that there is a rule in the variations of annual mean spectral index P with time, which presents a structure of double peaks. The first peak locates in postsunset period (22:00LT-23:00LT), and there is a valley around 1:00LT in postmidnight; another peak occurs around 2:00LT. We also analyzed the feature of the mean spectral index in vernal season, which could be described by a gauss function, while the feature of the mean spectral index in autumn season is different, which presents a structure of double peaks and the postmidnight peak of the mean spectral index is more obvious. For the first time, we use a rational function to model the variations of annual mean spectral index P. In addition, the distribution of all spectral indices is more like to probability density distribution function of Nakagami-m type.(2) It is concluded that the maximum percentage occurrence of UHF-band scintillations in and around the northern EIA crest occurs in vernal equinox and least in winter months based on the observations recorded at Haikou, Guangzhou and Kunming in 2013, and an equinoctial asymmetry in the percentage occurrence of scintillations exists over the low-latitude region of China that the occurrence of scintillations is greater in the vernal equinox than in the autumn equinox. Some of the possible sources for the equinoctial asymmetry have been investigated and the results suggest that background electron density may be playing an important role in the equinoctial asymmetry, and the ratio between the maximum foF2 at 20:00LT in the autumn equinox months (September and October) and the mean foF2 at 20:00LT in the vernal equinox months (March and April) could act as a proxy of the equinoctial asymmetry in the occurrence of scintillations over the low-latitude region of China, which is used to model the equinoctial asymmetry in an empirical climatological model of scintillation occurrence probability (CMSOP).Finally, The CMSOP has been developed to predict the scintillation occurrences over the low-latitude region of China of recent years. As an empirical climatological model, a collection of empirically derived models are used to provide the variations of the full probability distribution function of the irregularity strength parameter over the low-latitude region of China. The S4 index of amplitude scintillations for a user-defined system and application scenarios is calculated using a power law phase screen propagation model. The CMSOP takes into account the temporal, seasonal, equinoctial asymmetric, latitudinal and longitudinal variations of the occurrences of scintillation as well as the effects of the solar activity and geomagnetic activity. We validated the CMSOP using the observations recorded during 2013...