Comparison of very long baseline interferometry, GPS, and satellite laser ranging height residuals from ITRF2005 using spectral and correlation methods

Abstract

[1] For the first time, the ITRF2005 input data are in the form of time series of station positions and Earth orientation parameters, together with full variance-covariance information. The first step of the ITRF2005 analysis consists of rigorously stacking each time series to yield a long-term solution per technique. As a by-product, time series of position residuals contain the nonlinear motion of points over the Earth's surface. In this paper, the height residual time series of very long baseline interferometry (VLBI), Global Positioning System (GPS), and satellite laser ranging (SLR) solutions submitted to ITRF2005 are compared. We note that the interpretation of the ITRF2005 position residual time series as observed physical motions at the various stations is delicate due to the inhomogeneous site distribution. We estimate that the network effect may introduce an averaged scatter of 3 and 2 mm in the VLBI and SLR height residuals, respectively. Although noise levels are different among these three techniques, a common 1.0 cycles per year (cpy) frequency is clearly detected. The GPS height annual signal exhibits significant regional correlations that are confirmed by VLBI and SLR measurements in some colocated sites. Significant power near frequencies 2.00, 3.12, and 4.16 cpy is also detected in the individual GPS height residuals time series as mentioned by Ray et al. (2007). However, neither VLBI nor SLR show any significant signals at these frequencies for colocated sites. The agreement between detrended height time series at colocated sites is quantified using a novel method based on Kalman filtering and on maximum likelihood estimation. The GPS and VLBI measurements are shown to agree fairly well for most of the colocated sites. However, agreement is not generally observed in the GPS and SLR comparisons. A study of the interannual signal at colocated sites indicates that the good correlation cannot be completely attributed to the annual harmonic.Citation: Collilieux, X., Z. Altamimi, D. Coulot, J. Ray, and P. Sillard (2007), Comparison of very long baseline interferometry, GPS, and satellite laser ranging height residuals from ITRF2005 using spectral and correlation methods,

Combination of GNSS and SLR observations using satellite co-locations

“…Our approach is equivalent to a combination on the observation level, because GNSS and SLR observations are independent, all common parameters are contained in the NEQ (and are combined later on), and the same partial derivatives are used for the orbit integration. A proof for this statement can be found in, e.g., Brockmann (1997).…”

On the combined effect of periodic signals and colored noise on velocity uncertainties

“…In these cases, a number of seasonals being fitted into position time series play a crucial role in the GDP estimates. As was shown by Collilieux et al (2007) that the VLBI and SLR position time series are characterized by a number of significant oscillations, which have to be taken into account when a realistic model is to be employed. Riddell et al (2017) found that the uncertainties of X, Y, and Z translations increase of 0.10 mm/year at a minimum, when a power-law noise is employed to describe them.…”

Stochastic models in the DORIS position time series: estimates for IDS contribution to ITRF2014

“…The time series produced via processing of observations derived from space techniques always contain seasonal signatures (Collilieux et al 2007). The amplitudes of seasonal signals in the DORIS data have already been described by Le Bail (2006), Williams and Willis (2006) and Khelifa et al (2013).…”