中国东部沿海区域天顶对流层延迟模型精化

Refinement of Zenith Tropospheric Delay Model for the Eastern Coastal Region of China

  • 摘要: 天顶对流层延迟(Zenith Tropospheric Delay, ZTD)的精确建模对提高全球卫星导航系统(Global Navigation Satellite System, GNSS)定位精度与气象应用至关重要。我国东部沿海区域南北跨度大,ZTD的时空变化复杂,现有全球气压气温3(Global Pressure and Temperature 3, GPT3)模型难以准确模拟ZTD在不同时空尺度上复杂的非线性变化。本研究基于GPT3模型,采用具有强大非线性拟合能力的反向传播神经网络(Back Propagation Neural Network, BPNN)和径向基函数神经网络(Radial Basis Function, RBF)算法,并针对2种算法分别采用分季节(BPNN)和逐日(RBF)建模策略,建立了中国东部沿海区域改进ZTD模型。选取中国大陆构造环境监测网(Crustal Movement Observation Network of China, CMONOC)2016—2019年连续4年中国东部沿海区域GNSS ZTD数据中的92个站点数据作为训练数据集,构建模型,其余24个站点数据进行模型测试,结果表明:①改进ZTD模型具有良好的内符合精度,基于BPNN和RBF算法的改进模型ZTD估值的均方根误差(RMSE)分别为2.70和1.94 cm,与原有GPT3模型相比,精度分别提高了46.9%和61.8%;②利用不参与建模的测试集站点数据对改进模型进行检验,2种算法的改进模型ZTD估值的RMSE分别为2.78和2.28cm,与原有GPT3模型相比,精度分别提高了46.5%和56.2%。

     

    Abstract: Accurate modeling of the Zenith Tropospheric Delay (ZTD) is crucial for enhancing the accuracy of Global Navigation Satellite System (GNSS) positioning and for meteorological applications. Due to the extensive geographical range from north to south along the east coast of China, the spatio-temporal variation of ZTD is intricate. However, the existing GPT3 model struggles to accurately describe the complex nonlinear changes of ZTD on different space-time scales. In this study, two advanced deep learning algorithms, namely, back-propagation neural network (BPNN) and radial-basis-function neural network (RBF), were employed to establish a highly accurate tropospheric delay model for the eastern coast of China using their excellent nonlinear fitting capabilities.The model made full use of the ZTD calculated from regional GNSS data and the corresponding ZTD estimated from the Global Pressure and Temperature 3 (GPT3) model, and adopted the strategy of seasonal and daily modeling. We used data from 92 stations (80%) for the eastern coast of China provided by the Crustal Movement Observation Network of China from 2016 to 2019 for model construction, and the remaining 24 stations (20%) for model testing. Results showed that (1) the proposed model had a good internal coincidence accuracy. The root mean square error (RMSE) of the BPNN_GPT3 and RBF_GPT3 models were 2.70 cm and 1.94 cm, which had an improvement of 46.9% and 61.8% over the GPT3 model. (2) The external validations in non-modeling stations demonstrated the superiority of the proposed approach. The RMSE values were 2.78 cm and 2.28 cm, which had an improvement of 46.5% and 56.2% over the GPT3 model.

     

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