国际高程参考系统在珠峰地区的实现

Realization of the international height reference system in the region of Mount Qomolangma

2020珠峰高程测量,首次确定并发布了基于国际高程参考系统(IHRS)的珠峰正高。在珠峰地区实现国际高程参考系统,采用的方案是建立珠峰区域高精度重力大地水准面。利用地球重力场谱组合理论和基于数据驱动的谱权确定方法,测试优选参考重力场模型及其截断阶数和球冠积分半径等关键参数,联合航空和地面重力等数据建立了珠峰区域重力似大地水准面模型,61点高精度GNSS水准高程异常检核表明,模型精度达3.8 cm,加入航空重力数据后模型精度提升幅度达51.3%。提出顾及高差改正的峰顶高程异常内插方法,采用顾及地形质量影响的高程异常——大地水准面差距转换改正严密公式,使用峰顶实测地面重力数据,基于国际高程参考系统定义的重力位值W_(0)和GRS80参考椭球,最终确定了国际高程参考系统中的高精度珠峰峰顶大地水准面差距。

For the first time,the orthometric height of Mount Qomolangma based on the international height reference system(IHRS)is determined and released in the 2020 height measurement campaign of Mount Qomolangma.In order to realize the IHRS in the region of Mount Qomolangma,the scheme of establishing high precision gravimetric geoid model in this area is adopted.Based on the spectral combination approach and data-driven spectral determination method,the gravimetric quasigeoid model in the area of Mount Qomolangma is computed from the combination of airborne and terrestrial gravity data.Optimal reference gravity model,its truncation degree and spherical cap integration radius are chosen through comprehensive test.The validation against highly accurate GNSS leveling measured height anomalies at 61 benchmarks indicates that the accuracy of the gravimetric quasigeoid model reaches 3.8 cm and the addition of airborne gravity data improves the model accuracy by 51.3%.The interpolation method considering height difference correction is proposed for interpolating the height anomaly at the summit from the quasigeoid model.The rigorous formula for geoid-quasigeoid separation considering topographic masses is used for converting the height anomaly to the geoid undulation at the summit.Based on the IHRS defined gravity potential value W_(0) and the GRS80 reference ellipsoid,and using the newly observed ground gravity at the summit,the high precision geoid undulation of Mount Qomolangma in the IHRS is determined.