A combined denoising method of empirical mode decomposition and singular spectrum analysis applied to Jason altimeter waveforms: A case of the Caspian Sea
A combined denoising method of empirical mode decomposition and singular spectrum analysis applied to Jason altimeter waveforms: A case of the Caspian Sea
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DOI：
10.1016/j.geog.2021.11.004
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发表时间：
2022-04
影响因子：
2.4
通讯作者：
Wenguang Jiang;Wei You
中科院分区：
文献类型：
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作者：
Wenguang Jiang;Wei You
在卫星脉冲的传播和接收过程中，高度计波形不可避免地会受到噪声的影响。为了降低Jason高度计波形中的噪声水平，我们采用奇异谱分析(SSA)、经验模式分解(EMD)以及奇异谱分析和经验模式分解相结合的方法得到去噪后的波形。验证了组合方法的优越性，提高了平均海面高度模型的精度。比较了三种去噪方法的去噪效果，结果表明，SSA和EMD相结合有效地改善了信噪比、相关系数和均方根误差。用50%阈值去噪波形回溯器重新测量海面高度，由Jason-1/2/3的海面高度恢复建立了网格为1‘×1’的里海MSSH模型。以4个模型的平均值为对照，联合去噪方法计算的模型精度最高。这表明使用联合去噪方法降低噪声水平有利于提高MSSH模型的精度。
During the satellite pulse propagation and reception, the altimeter waveform is inevitably affected by noise. To reduce the noise level in Jason altimeter waveforms, we used singular spectrum analysis (SSA), empirical mode decomposition (EMD), and the combination of SSA and EMD to obtain the denoised waveforms. The advantages of the combined method were verified and the accuracy of the mean sea surface height (MSSH) model was improved. Comparing the denoising effect of the three methods, the results show that the signal-to-noise ratio (SNR), correlation coefficient and root-mean-square error are effectively improved by the combination of SSA and EMD. The sea surface heights (SSHs) were remeasured with a 50% threshold retracker of denoised waveforms, and the MSSH model of the Caspian Sea with a grid of 1′× 1′ was established from the retracked SSHs of Jason-1/2/3. Taking the mean value of the four models as a control, it is found that the model calculated by the combined denoising method has the highest accuracy. This indicates that using the combined denoising method to reduce the noise level is beneficial to improve the accuracy of the MSSH model.