Estimation of Earth Rotation Parameters and ΔLOD with Combining VLBI and GPS Observations

The Earth rotation parameters (ERP) and the variation of length of day (ΔLOD) are estimated by processing the seventeen IGS stations' data collected in September 2005, January and February 2006 with GAMIT, the estimated results of which are compared with the IGS solutions. Secondly, the ERP and the ΔLOD are estimated by processing VLBI data during the same period with OCCAM 6.2, the results of which are compared with the IVS solutions. Thirdly, the results of GPS and VLBI are combined in a weighted way, based on their internal accord accuracy and IERS 08C04 respectively. Finally, the conclusion not only shows that the interpolation methods have a significant impact on the VLBI results, but also shows that the combining of VLBI and GPS in the second way can improve the stability and reliability of ERP and ΔLOD, which can make up for the shortcoming of the single technique as VLBI or GPS.