The Global SLR Network and the Origin and Scale of the TRF in the GGOS Era [article]

E.C. Pavlis, Maryland Shared Open Access Repository
2020
Satellite Laser Ranging (SLR) data contribute to the realization of the Terrestrial Reference Frame (TRF), defining primarily its origin—geocenter, and in combination with VLBI, its scale. Both entities are fundamental in monitoring vital global change parameters, such as mean sea level, Earth rotation and orientation, etc. The Global Geodetic Observing System (GGOS), places the utmost importance on the development, maintenance and wide distribution of a TRF with very stringent attributes, an
more » ... igin definition at 1 mm or better at epoch and a temporal stability of 1 mm/y, with similar numbers for the scale and orientation components. The stability, integrity and applicability of the TRF are directly related to the accuracy and fidelity with which mass redistribution can be observed or modeled during its development. Variations in the very low degree and order harmonics, produce geometric effects that are manifested as changes in the origin and orientation relationship between the instantaneous and the mean reference frame. The unambiguous nature of SLR measurements and absence of significant biases, results in a very precise height determination, and thus the scale of the TRF. SLR has demonstrated millimeter level accuracy for weekly averages. Nevertheless, weather- or failure-induced changes in the network, and the small number and poor spatial distribution of the sites comprising the SLR network, generate additional signals aliased in the results. "Secular trends" seen in the recovered geocenter time series for example cannot be explained by any geophysical phenomena, and are primarily the result of these deficiencies of the present SLR network (poor geometry, lack of redundancy, N-S hemisphere unbalanced distribution, etc.). We investigate here through a number of alternate solutions the robustness of our results, using our SLR analyses spanning the past thirteen years.
doi:10.13016/m22gfk-wxbv fatcat:gmk5w4csnbfark5exkpmp2mxbi