Researches On The Prediction Theories And Algorithms Of Polar Motion Of Earth Orientation Paramters

The Earth Orientation Parameters(EOPs) include four items which are Polar Motion(PM)、 Length of Day(LOD、 Precessiona and Nutation. Precise transformations between the international celestial and terrestrial reference frames are needed for many advanced geodetic and astronomical tasks including positioning and navigation. To perform this transformation, highly accurate EOPs are necessary. However, the precise measurements of EOPs by space-geodetic techniques have to be pre-processed before the EOPs are available. This causes a delay of15to20hours in case of GPS and of a few days in case of very-long-baseline interferometry (VLBI) and satellite laser ranging (SLR).Thus it’s necessary to predict the EOPs over at least a few days. In addition, it might be interesting to look further into the future to estimate the Earth’s rotation in the next few months. As a result, the prediction of polar motion, which is involved in EOPs, is essential.The prediction precision of polar motion has improved greatly as that of observed polar motion values have improved and the forecasting methods have been optimized. However, in general, there are still several issues to be resolved in prediction of polar motion. These issues involve:1improvement in the prediction precision of polar motion;2) time-variant characteristics of Chandler Wobble and Annual Wobble are neglected in the present prediction methods which are commonly based least square method;3) Most forecast approaches are based on the mathematical and statistical properties of PM series, to build physical model and introduce the physical excitation to predict PM also has large space to study.In order to resolve these problems, the Joint Model of Least-squares and ARIMA, Joint Model of Weighted Least-squares and AR, Joint Model of Corrected Least-squares and AR Based on Correction of Time-varying Parameters of the Chandler Wobble and the approach to predict PM by introducing Atmospheric Angular Momentum are put forward. Through comparison and analysis of the prediction values, the effectiveness and the superiority of these models are proved.