华北稳定参考框架NChina20的建立及应用

Establishment and Application of Stable North China Reference Frame: NChina20

摘要:

选用中国大陆地壳运动观测台网（CMONOC）在华北地区约8年（2011年10月～2019年9月）的连续观测数据，建立了华北稳定参考框架——NChina20。NChina20与全球参考框架（IGS14）保持坐标系缩放比例一致，两坐标系统在历元2020.0对齐。本文详细介绍了将相对于IGS14的位置时间序列转换到NChina20的方法，并列举了NChina20在城市地面升降长期观测领域的应用。NChina20的稳定性（精度）在水平方向约为0.5mm/a，在垂直方向约为0.6mm/a。参考框架的稳定性随时间的推移而退化，建议NChina20的使用范围在时间上限于2006～2025年的时间窗口内，在空间上限于华北活动地块区域内。选用华北地区5个基岩站20年（2000～2019年）的连续观测数据，建立了华北地区季节性地面升降预测模型。华北稳定参考框架将每隔几年更新一次，以缓解框架稳定性随时间的退化，并与IGS参考框架同步更新。

Abstract:

We have established a stable North China reference frame,designated as NChina20,by using eight-year continuous observation data from 30 GNSS stations fixed on the North China active crustal block. NChina20 is aligned in scale with IGS14. The two coordinate systems are tied at epoch 2020.0. In this article we introduce the method of converting the positional time series with respect to IGS14 to NChina20. Applications of NChina20 in precise land subsidence and rebound monitoring are illustrated. The stability(accuracy)of NChina20 is 0.5mm/a in the horizontal directions and 0.6mm/a in the vertical direction. The stability of the reference frame degrades with the expansion of the coverage area and the time window. We recommend that the use of NChina20 is limited to the North China tectonic block within a time window of 20 years from 2006 to 2025. We have also developed a seasonal vertical ground motion model in North China using 20 years(2000～2019)of continuous observation data from 5 GNSS stations mounted on bedrock. The regional reference frame will be updated every few years to mitigate degradation with time and synchronize with the update of IGS reference frames.