Very long baseline interferometry determination of neglected tidal terms in high‐frequency Earth orientation variation
John Gipson
Abstract
John Gipson
Abstract
I present a model of high‐frequency earth orientation parameter (HF‐EOP) variation derived from 15 years of very long baseline interferometry (VLBI) data. This model uses twice as much data as previously published VLBI models. I estimate the coefficients of HF‐EOP at all tides with a magnitude greater than 5 mm in the tidal potential. This includes sidebands of the larger tides K1, O1, M2, and N2. I compare this model with other empirical models derived from VLBI and satellite laser ranging (SLR) data and also with predictions for HF‐EOP variation derived from models of the ocean. This model has the best agreement of any VLBI model with the independent SLR results: The RMS level of agreement of the coefficients is 1.2 μs in UT1 and 9 microseconds of arc (μas) in polar motion (PM). This model also has the best agreement of any VLBI or SLR model with the predictions of the best ocean model: The RMS level of agreement of the coefficients are 1.1 μs in UT1 and 6.5 μas in PM. I also compare the predictions of this model with the hourly measurements of EOP from the CONT94 VLBI campaign. The residuals are 8.9 μs in UT1 and 222 μas in PM, which are consistent with the formal errors of the measurements.
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I present a model of high‐frequency earth orientation parameter (HF‐EOP) variation derived from 15 years of very long baseline interferometry (VLBI) data. This model uses twice as much data as previously published VLBI models. I estimate the coefficients of HF‐EOP at all tides with a magnitude greater than 5 mm in the tidal potential. This includes sidebands of the larger tides K1, O1, M2, and N2. I compare this model with other empirical models derived from VLBI and satellite laser ranging (SLR) data and also with predictions for HF‐EOP variation derived from models of the ocean. This model has the best agreement of any VLBI model with the independent SLR results: The RMS level of agreement of the coefficients is 1.2 μs in UT1 and 9 microseconds of arc (μas) in polar motion (PM). This model also has the best agreement of any VLBI or SLR model with the predictions of the best ocean model: The RMS level of agreement of the coefficients are 1.1 μs in UT1 and 6.5 μas in PM. I also compare the predictions of this model with the hourly measurements of EOP from the CONT94 VLBI campaign. The residuals are 8.9 μs in UT1 and 222 μas in PM, which are consistent with the formal errors of the measurements.
Key concepts: Very-long-baseline interferometry, Polar motion, Universal Time, Geodesy, Satellite laser ranging, Earth's rotation, Tidal Model, Interferometry