基于地球重力场模型的GNSS高程转换与精度分析

GNSS Elevation Conversion and Accuracy Analysis Based on Earth Gravity Field Model

为了解决纯数学模型在进行高程转换时,只能反映测区高程异常的大致趋势,影响高程转换精度的问题,采用地球重力场模型与数学函数相结合的"移去-恢复"法来反映高程异常的细节变化,以达到提高转换精度的目的。以安徽省某输电线路工程部分走向线实验区为例,分别采用数学模型的二次曲面、Kriging插值、多面函数以及与EGM2008、EIGEN-6C4、GOCO05S地球重力场模型结合的"移去-恢复"法等13种方案实现了测区的高程转换。结果表明,多面函数的精度优于Kriging插值法和二次曲面法,地球重力场模型与数学函数相结合的"移去-恢复"法精度较纯数学模型有了大幅提升,GOCO05S、EIGEN-6C4与多面曲面相结合的方案精度最佳,内外符合精度优于10.0 mm,RMS、STD均优于9.2 mm。

In order to solve the problems that the pure mathematical model for the elevation conversion can only reflect the general trend of elevation anomaly in the survey area and affect the accuracy of the elevation conversion, we used the "Remove-Restore" method combining the earth gravity field model with mathematical functions to reflect the details of elevation anomalies, which could achieve the goal of improving conversion accuracy. Taking the partial strike line of a DC transmission line project in Anhui Province for example, we realized the elevation conversion of the measured area by 13 schemes, such as quadratic surfaces, Kriging interpolation, polyhedral function, and the "Remove-Restore" method combined with EGM2008, EIGEN-6 C4 and GOCO05 S earth gravity field models respectively. The experimental results show that the accuracy of polyhedral function is better than Kriging interpolation and quadratic surfaces. Comparing with the pure mathematical model, the accuracy of the "RemoveRestore" method combined the earth gravity field model with the mathematical function has been greatly improved. The schemes that combined GOCO05 S, EIGEN-6 C4 with the polyhedral surface have the best accuracy. The conformance accuracy is better than 10.0 mm, RMS and STD are better than 9.2 mm.