GNSS-IR multisatellite combination for soil moisture retrieval based on wavelet analysis considering detection and repair of abnormal phases
GNSS-IR multisatellite combination for soil moisture retrieval based on wavelet analysis considering detection and repair of abnormal phases
复制标题
考虑异常相位检测与修复的基于小波分析的GNSS-IR多星组合土壤水分反演
DOI：
10.1016/j.measurement.2022.111881
复制
发表时间：
2022-09-22
期刊：
影响因子：
5.6
通讯作者：
Hu, Xinmiao
中科院分区：
文献类型：
--
作者：
Liang, Yueji;Lai, Jianmin;Hu, Xinmiao
利用标准大地测量仪器接收的信噪比（SNR）数据可以反演近地表土壤湿度（SM）。然而，在非线性最小二乘（LLS）算法的拟合中，低信噪比数据通常会导致异常相位。这不利于有效利用多卫星相位。本文提出了一种基于多星组合并考虑异常相位检测和修复的同步信号反演方法。该方法首先利用小波变换分离信噪比数据中的趋势项和调制项，然后对所有卫星进行异常相位检测和修复，最后建立多卫星线性回归（MSLR）模型进行SM反演，并分析了模型精度随模型检验天数的变化。结果表明，与传统的低阶多项式相比，coif5小波能更好地分离信噪比的趋势项和调制项。通过四分位距和滑动平均滤波相结合，可以有效地检测和修复异常相位，并进一步提高每颗卫星的相位质量。MSLR可以充分联合收割机组合多星相位信息，提高SM反演精度，适用于不同时段的SM反演。
Signal-to-noise ratio (SNR) data received with standard geodetic instrumentation can be used to retrieve near -surface soil moisture (SM). However, low-quality SNR data usually cause abnormal phases in the fitting of nonlinear least squares (LLS) algorithms. This is not conducive to the effective use of multisatellite phases. In this paper, an SM retrieval method based on multisatellite combinations considering the detection and repair of abnormal phases is proposed. This method is aimed at using wavelet transform to separate the trend and modulation terms in SNR data, followed by detecting and repairing the abnormal phase for all satellites, finally constructing the multisatellite linear regression (MSLR) model for SM retrieval, and analysing the variation of accuracy with the increase of model testing days. The results indicate that with the coif5 wavelet, the trend and modulation terms of the SNR (compared to the traditional low-order polynomial) can be better separated. The abnormal phases can effectively be detected and repaired by combining the interquartile range and moving average filter, and further, the quality of the phases for each satellite can be improved. Furthermore, MSLR can fully combine the multisatellite phases to improve the accuracy of SM retrieval, and it is suitable for SM retrieval over different time periods.