VERY LONG-BASE-LINE INTERFEROMETRY DETERMINATION OF NEGLECTED TIDAL TERMS IN HIGH-FREQUENCY EARTH ORIENTATION VARIATION

I present a model of high-frequency earth orientation parameter (HF-EO P) variation derived from 15 years of very long baseline interferometr y (VLBI) data. This model uses twice as much data as previously publis hed VLBI models. I estimate the coefficients of HF-EOP at all tides wi th 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 mode l with other empirical models derived from VLBI and satellite laser ra nging (SLR) data and also with predictions for HF-EOP variation derive d from models of the ocean. This model has the best agreement of any V LBI model with the independent SLR results: The RMS level of agreement of the coefficients is 1.2 mu s in UT1 and 9 microseconds of arc (mu as) in polar motion (PM). This model also has the best agreement of an y VLBI or SLR model with the predictions of the best ocean model: The RMS level of agreement of the coefficients are 1.1 mu s in UT1 and 6.5 mu as in PM. I also compare the predictions df this model with the ho urly measurements of EOP from the CONT94 VLBI campaign. The residuals are 8.9 mu s in UT1 and 222 mu as in PM, which are consistent with the formal errors of the measurements.