基于物理意义引导的双天线GNSS-R集成学习积雪深度反演方法研究

Physically guided dual-antenna GNSS-R snow depth inversion based on ensemble learning

  • 摘要: 全球导航卫星系统反射测量(Global Navigation Satellite System Reflectometry, GNSS-R)技术在积雪监测方面有重要意义. 针对传统单天线GNSS-R积雪反演中反射信号弱、特征提取不准确,精度不足的问题,本文提出了一种基于物理意义引导的双天线GNSS-R集成分类积雪深度反演方法. 利用双天线分别接收直射信号与反射信号,使用变分模态分解(variational mode decomposition, VMD)与Lomb-Scargle周期图(Lomb-Scargle periodogram, LSP)处理信号,提取具有物理意义的主、副频特征,进而构建集成分类器,建立特征与雪深的非线性映射模型. 为验证该方法的有效性,本文基于2025年新疆阿勒泰站的数据开展了相关实验,并分析了多个卫星组合的反演性能. 实验结果表明,VMD算法展现出对非平稳GNSS信号优异的分解与重构能力,有效剔除了环境噪声干扰;基于沙普利加性解释(Shapley additive explanations, SHAP)值的特征权重分析阐明了物理与统计特征的协同互补机理,确立了模型在不同观测条件下自适应重分配权重的物理基础;同时,基于投票机制的集成学习策略通过多模型加权融合,有效克服了单一模型的过拟合风险,显著增强了系统鲁棒性,得到了平均绝对误差(mean absolute error, MAE)为0.364 cm、最大绝对误差为2 cm的反演精度,相比单一随机森林(random forest, RF)模型精度提升约50%. 总体而言,本文方法在多星观测组合下均保持了良好的一致性,验证了其在复杂环境下进行积雪监测的工程应用潜力.

     

    Abstract: Global Navigation Satellite System Reflectometry (GNSS-R) is significant for snow cover monitoring. To address the issues of weak reflected signals, inaccurate feature extraction, and insufficient precision in traditional single-antenna GNSS-R snow depth inversion, a physically guided dual-antenna ensemble learning inversion method is proposed. Dual antennas are utilized to receive direct and reflected signals. variational mode decomposition (VMD) and Lomb-Scargle periodogram (LSP) are employed to process signals and extract physically meaningful primary and secondary frequency features. Subsequently, an ensemble classifier is constructed to establish a non-linear mapping model between features and snow depth. To verify the effectiveness of the method, experiments were conducted based on data from the Altay station in Xinjiang in 2025, and the inversion performance of multiple satellite combinations was analyzed. Experimental results demonstrate that the VMD algorithm exhibits superior decomposition and reconstruction capabilities for non-stationary GNSS signals, effectively mitigating environmental noise interference. Feature weight analysis based on Shapley additive explanations (SHAP) values clarifies the synergistic mechanism between physical and statistical features, establishing a physical basis for adaptive weight redistribution under varying observation conditions. Meanwhile, the voting-based ensemble learning strategy, through multi-model weighted fusion, effectively overcomes the overfitting risks associated with single models and significantly enhances system robustness, obtaining an inversion precision with a mean absolute error (MAE) of 0.364 cm and a maximum absolute error of 2 cm, which improves the accuracy by about 50% compared to the single random forest model. Overall, the proposed method maintains consistent performance across multiple satellite combinations, verifying its potential for engineering applications in snow monitoring within complex environments.

     

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