中国科学院上海天文台陈俊平及其团队成员的一项最新研究取得了新进展，他们对云南GPS的时变季节信号进行了奇异谱分析。2024年5月25日出版的《大地测量与地球动力学》发表了这项成果。

据研究人员介绍，研究GPS时间序列中的季节变形对于解释地球物理成因，和识别未建模和错误建模的季节信号具有重要意义。传统的季节信号提取使用最小二乘法，该方法将季节变形建模为恒定的季节振幅和相位。然而，每年的季节变化并不是恒定的，季节的振幅和相位是时变的。为了获得GPS站坐标时间序列中的时变季节信号，本文采用奇异谱分析(SSA)方法。

研究人员首先对不同频率每年1.00个周期(cpy)、每年1.04个周期和时变振幅的模拟季节信号进行SSA叠加。结果表明，SSA可以很好地得到不同频率和时变振幅叠加的季节变化。然后，研究人员对云南省的GPS观测数据进行了SSA分析。结果表明，时变振幅季节信号在云南省普遍存在，研究提取了该地区2019年的时变振幅变化，并进一步用土壤水分质量负荷和大气压力负荷解释了这一变化。

去除这两种载荷效应后，SSA得到的调制季节信号具有明显的季节变化，其中包含频率为1.046cpy的明显季节变化，这与GPS交点年的频率1.040cpy相接近。研究结果强调，利用云南的SSA可以较好地判别该地区2019年的时变振幅变化和季节性GPS的交点年。

附：英文原文

Title: Singular spectrum analysis for the time-variable seasonal signals from GPS in Yunnan Province

Author: JunPing Chen a b c

Issue&Volume: 2024/05/25

Abstract: Studying the seasonal deformation in GPS time series is important to interpreting geophysical contributors and identifying unmodeled and mismodeled seasonal signals. Traditional seasonal signal extraction used the least squares method, which models seasonal deformation as a constant seasonal amplitude and phase. However, the seasonal variations are not constant from year to year, and the seasonal amplitude and phase are time-variable. In order to obtain the time-variable seasonal signal in the GPS station coordinate time series, singular spectrum analysis (SSA) is conducted in this study. We firstly applied the SSA on simulated seasonal signals with different frequencies 1.00 cycle per year (cpy), 1.04 cpy and with time-variable amplitude are superimposed. It was found that SSA can successfully obtain the seasonal variations with different frequencies and with time-variable amplitude superimposed. Then, SSA is carried out on the GPS observations in Yunnan Province. The results show that the time-variable amplitude seasonal signals are ubiquitous in Yunnan Province, and the time-variable amplitude change in 2019 in the region is extracted, which is further explained by the soil moisture mass loading and atmospheric pressure loading. After removing the two loading effects, the SSA obtained modulated seasonal signals which contain the obvious seasonal variations at frequency of 1.046 cpy, it is close with the GPS draconitic year, 1.040 cpy. Hence, the time-variable amplitude changes in 2019 and the seasonal GPS draconitic year in the region could be discriminated successfully by SSA in Yunnan Province.

DOI: 10.1016/j.geog.2024.05.002

Source: https://www.sciencedirect.com/science/article/pii/S1674984724000442