【作者】 刘军；

【导师】 柴洪洲；

【作者基本信息】 解放军信息工程大学 ， 大地测量学与测量工程， 2011， 硕士

【摘要】 电离层作为空间环境影响人类生产、生活、科学研究和工程应用的重要途径之一,电离层相关方面的研究对通信、雷达、航天、卫星导航定位系统以及高压输电网等领域都有重要意义。本文对GPS数据计算TEC的方法、电离层预报模型的建立、TEC地图的重构以及震前电离层TEC异常等内容进行了分析和讨论,主要内容如下:1.介绍了利用GPS双频观测数据,采用相位平滑伪距计算电离层TEC的方法。同时对硬件延迟解算方法进行了分析。2.针对传统电离层模型精度不高的问题,利用CODE GIM数据,建立了基于时间序列的全球电离层预报模型。对建立模型过程中阶数上限的确定及定阶准则的选取等关键问题进行了分析,分别采用线性最小方差预测法和修正预测法进行了预报。结果表明,修正预测法在一天内的精度比线性最小方差预测法好。3.针对线性最小方差预测法和修正预测法在极值点处预报误差较大的问题,提出了改进的修正预测法,用上一周期的预报误差对修正预测法结果进行修正,预报结果显示,改进的修正预测法精度明显比前两种方法高且稳定。4.针对IGS各数据处理中心发布的电离层格网数据在时间分辨率和空间分辨率上都不高,且在中国范围内精度不理想的问题,利用中国地壳运动观测网络的数据,采用距离加权方法,重构了中国大陆区域的电离层TEC地图。针对距离加权方法没有考虑样本点空间分布的不足以及在边缘区域由于没有穿刺点信息无法计算的问题,引入电离层距离变量,用Kriging方法对中国大陆区域电离层TEC地图进行了重构,结果表明,30s和5min时间分辨率下Kriging方法的精度要略微优于距离加权,且Kriging方法的结果明显要比距离加权方法的平滑。5.利用CODE GIM数据,分析了汶川地震、玉树地震以及日本地震震前电离层TEC异常情况,结果表明,考虑太阳和地磁活动情况下,三次地震震前都有异常出现,汶川地震电离层正负异常都有出现,玉树和日本地震只观测到了正异常,且三次地震在南半球磁共轭区也发现了异常。更多还原

【Abstract】 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.更多还原