DETERMINATION OF TIDAL H LOVE NUMBER PARAMETERS IN THE DIURNAL BAND USING AN EXTENSIVE VLBI DATA SET

We use over a decade of geodetic VLBI data to estimate parameters in a resonance expansion of the frequency dependence of the tidal h2 Love number within the diurnal band. The resonance is associated with the r etrograde free core nutation (RFCN). We obtain a value for the real pa rt of the resonance strength of (-0.27 +/- 0.03) X 10(-3); a value of -0.19 X 10(-3) is predicted theoretically. Uncertainties in the VLBI e stimates of the body tide radial displacement amplitudes are approxima tely 0.5 mm (1.1 mm for the Kl frequency), but they do not yield suffi ciently small Love number uncertainties for placing useful constraints on the frequency of the RFCN, given the much smaller uncertainties ob tained from independent analyses using nutation or gravimetric data. W e also consider the imaginary part or the tidal h2 Love number. The es timated imaginary part of the resonance strength is (0.00 +/- 0.02) X 10(-3). The estimated imaginary part of the nonresonant component of t he Love number implies a phase angle in the diurnal tidal response of the Earth of 0.7-degrees +/- 0.5-degrees (lag).