Short-term Prediction of Ionospheric TEC Based on the WNN-LSTM-Attention Combined Model
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摘要: 针对电离层总电子含量(TEC)短期预测中非线性、非平稳特征提取不足及在空间天气扰动下模型鲁棒性弱的问题,本文提出了一种融合小波神经网络(WNN)、长短期记忆网络(LSTM)与复合注意力机制的组合预测模型(WNN-LSTM-Attention)。该模型利用WNN提取TEC序列的局部多尺度特征,利用LSTM捕获其长期时序依赖,并通过复合注意力机制(时间、特征、小波注意力)自适应加权关键信息,实现特征互补与优化。基于中国区域7个GNSS观测站2016-2018年的TEC数据及Dst、Kp指数进行实验。结果表明:组合模型的整体均方根误差(RMSE)为1.19 TECu,较单一LSTM和WNN模型分别降低48.7%和36.3%;在弱、中、强三种磁暴条件下,其平均绝对误差(MAE)相比LSTM平均下降21.1%,相比WNN平均下降12.0%;在季节性预测中亦表现出最优的稳定性和精度。本文模型为提升极端空间天气下电离层TEC的预测精度与鲁棒性提供了有效方法。Abstract: To address the issues of insufficient extraction of nonlinear and non-stationary features in short-term forecasting of ionospheric total electron content (TEC) and weak model robustness under space weather disturbances, this paper proposes a combined prediction model integrating Wavelet Neural Network (WNN), Long Short-Term Memory network (LSTM), and a composite attention mechanism (WNN-LSTM-Attention). The model uses WNN to extract local multi-scale features of TEC sequences, LSTM to capture long-term temporal dependencies, and a composite attention mechanism (temporal, feature, wavelet attention) to adaptively weight key information, achieving feature complementarity and optimization. Experiments were conducted based on TEC data from seven GNSS observation stations in China from 2016 to 2018, along with Dst and Kp indices. The results show that the overall root mean square error (RMSE) of the combined model is 1.19 TECu, reducing by 48.7% and 36.3% compared with single LSTM and WNN models, respectively; under weak, moderate, and strong geomagnetic storm conditions, its mean absolute error (MAE) decreased by an average of 21.1% compared to LSTM and 12.0% compared to WNN; it also demonstrates the best stability and accuracy in seasonal forecasting. The proposed model provides an effective method to improve the prediction accuracy and robustness of ionospheric TEC under extreme space weather conditions.
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