Study of Ionosphere Using GPS Data and its Application to Analysis About Earthquake
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摘要: 利用地基GPS数据计算了电离层单球壳模型穿刺点上的垂向总电子含量(VTEC), 根据VTEC和卫星及测站接收机的差分码间偏差DCB的不同时变特性采用了复弧法, 将VTEC作为局部变量(每30 min 一组, 可调), DCB作为一天的全局量进行解算. 在解算的过程中, 充分考虑VTEC的空间分布特性, 利用变异函数通过Kriging插值法建立电离层VTEC的二维格网模型, 并给出了卫星和接收机的差分码间偏差DCB. 通过与IGS结果的比较, 发现其结果可靠, 且时空分辨率和稳定性都有较大提高. 同时, 基于简化的三元样条插值基函数对电离层电子密度进行三维展开, 利用乘型代数重建技术MART算法构建了同批数据的四维层析成像结果, 获得了电离层电子密 度的四维分布. 其结果与CHAMP无线电掩星结果非常一致. 利用上面两种算法又分别对2008年5月长江三角洲地区地基GPS数据进行处理, 简要分析了该时段该地区上空电离层总电子含量和电子密度的变化情况及其对汶川地震的响应.Abstract: To obtain VTEC as well as DCB, a method is developed by using ground-based GPS data with multiple-arc method and Kriging interpolation. Assisted by multiple-arc method, VTEC was calculated every 30 minutes as local variables, and DCB was calculated every day as global variables. Kriging method, taking the spatial information of VTEC into account, helps us to establish a 2D model and get DCB of both satellites and receivers. The result shows itself reliably in comparison with IGS result, but more stable and precise in resolution. Meanwhile, grounded on 3-variable spline basis function, we unfold electron density into a linear combination of a set of grid point. With its contribution, CT result of ionospheric electron density was made by MART. This result is consistent with CHAMP result get by occultation method. These two ways are applied to the data of Yangtze River triangle region in May, 2008 when the shocking earthquake happened in Wenchuan. A simple statistic analysis reveals the response of ionosphere to the signal associated with earthquake but occurred before it.
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Key words:
- GPS /
- Ionosphere /
- TEC (Total Electron Content) /
- Kriging /
- MART
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