Periodicity Analysis of VMD in GNSS Elevation Time Series
Due to various geophysical effects,the time series of most IGS stations exhibit significant nonlinear changes,with more pronounced coordinate changes in the elevation direction and more complex periodicity.From this,the VMD method to decompose the elevation time series of four IGS stations was introduced in order to obtain IMF of different scales.Then,fourier transform was used to process each component to obtain the spectrum of each station,and it was found that the period terms of each station were 2,4,and 6 days,with some stations containing annual and monthly periods.The period term obtained by EMD included quarterly,monthly,bimonthly,annual,two-year,and four-year periods for each station.The experimental results have showed that VMD can effectively avoid modal aliasing,noise interference,and suppress endpoint effects by setting appropriate convergence conditions and iterative optimization,and more adaptively and accurately extract periodic terms from GNSS elevation time series,compared with EMD.
万方数据
维普
