Method of Building High Precision Velocity Model in China and Its Application in Frame Transformation

Objectives : High precision GNSS positioning results are generally expressed under the International Terrestrial Reference Frame, but China's surveying and mapping results require the use of the China Geodetic Coordinate System 2000. High precision velocity field model is the key to achieve the conversion between the ITRF2014 and CGCS2000. At present, most studies use a single method to build the velocity field model, without in-depth study of the impact of different parameter settings on the construction of the velocity field, and without discussion of the performance of different methods in different speed directions. Methods : For this reason, based on the data of 260 continuously operating reference stations of the CMONOC and 90 IGS stations within and around China, and based on the tension spline function method and the Kriging method. This paper uses different parameter settings to build a 1-mm high-precision velocity field model covering the country, establishes three methods with the highest accuracy in three directions of ENU, and uses these three methods to build a combined velocity field field. The model is applied to the coordinate transformation of ITRF2014 and CGCS2000 of CORS stations nationwide. Results : The research results indicate that the overall conversion accuracy of the combined velocity field established in this article is about 2.3cm, and the conversion accuracy of a single directional component is maintained at around 1.3cm, which can achieve benchmark conversion of centimeter level accuracy for large-scale surveying and mapping results in China. Conclusions : Based on experiments, this article concludes that constructing the optimal component velocity field and forming a combined velocity field through different methods can effectively improve the accuracy of the overall velocity field model and be further applied in practice.