A Study Of The High Frequency Variations Of Earth Rotation Parameters Based On VLBI Observation

The Earth Orientation Parameters (EOP) are the linkage parameters between the Celestial and Terrestrial Reference Frames. In this dissertation my effort is delivered to the determination method, real data reduction and ocean tidal terms analysis of the high frequency (HF) variation of EOP from astrometric and geodetic observations of Very Long Baseline Interferometry (VLBI). My analysis is summarized as follows.(1) The current research status of the HF variation of EOP is reviewed including the determination of the HF variation of EOP based on VLBI and GPS observations and the excitation explanation. It is shown that though there exists impressive progress in the studies of the diurnal and semidiurnal variations of EOP, there exist questions still need to be answered. For instance, what is the reason for the difference between the estimations of the oceanic tidal terms of EOP from real data reduction? How could the reliable time series of high frequency variation of EOP be solved from observation? What will be the effect of the modeling deficiency of precession and nutation on the solving of HF variation of EOP? Studies are still required in the solving of HF variation of EOP and in the excitation explanation.(2) There are four aspects concerning the analysis and improvement of the CALC/SOLVE system as follows.(a) Some ordinary forms of sparse matrix and the application of sparse matrix technology in astrometric and geodetic VLBI data analysis are introduced. The algorithm of parameter solution and the covariance matrix calculation in the astrometric and geodetic VLBI data reduction are deduced. Based on the estimation and comparison of the number of operations in solving the observation equations by using the sparse matrix technology and by a straightforward least square adjustment (LSQ), it was shown that the number of operations is approximately proportional to the cube of the total number of parameters for the straightforward LSQ solution, while it is about linearly proportional to the total number of parameters for the sparse matrix technology which remarkably decrease the requirement of the computer time and resources in the reduction of the modern space geodetic observations characterized by huge amount.(b) We checked the dependence of the estimation of parameters on the choice of piecewise interval in the continuous piecewise linear modeling of the residual clock and atmosphere effects by single analysis of 27 VLBI experiments involving Shanghai station (Seshan25). The following are tentatively shown. Different choices of the piecewise interval lead to differences in the estimation of station coordinates and in the weighted root mean squares (wrms) of the delay residuals, which can be centimeters or dozens of picoseconds large respectively. So the choice of piecewise interval should not be arbitrary. The piecewise interval should not be too long, otherwise the short-term variations in the residual clock and atmospheric effects can not be properly modeled. While in order to maintain enough degrees of freedom in...