SUBDAILY EARTH ROTATION DETERMINED FROM GBS

摘要

A UT1-TAI series was determined with triple-differenced GPS data for January 15-28, 1995. A priori UTI-TAI values at 30-minute intervals were taken from the IERS Bulletin B prediction and constrained to 6.5 x 10(-3) s; increments to the initial UT1-TAI were estimated. The tidal correction according to IERS Standards, and the atmospheric effects were removed. The remaining signal was smoothed with a Vondrak smoother and compared with UT1 tidal model empirically determined from VLBI [Herring and Dong, 1994]. In a second test, normalized length of day variations and the pole coordinates, with once-per-day resolution (at 12 h UT), were estimated. Bulletin B a priori values were introduced only at the beginning of a four-week period. Since UT1-TAI is related to lod variations in the following way: delta(lod)/lod = -d(UT1-TAI)/dt, [Lambeck, 1980, p. 63], the variation in UT1-TAI can be obtained by integrating normalized variation in led. The a priori standard deviation for delta(lod)/lod was 6.5 x 10(-3) s/day. [References: 15]