利用GNSS水准成果融合构建中国大陆垂直运动模型

Establishment of Vertical Movement Model of Chinese Mainland by Fusion Result of Leveling and GNSS

  • 摘要: 水准和全球导航卫星系统(global navigation satellite system, GNSS)成果是研究中国大陆垂直运动的重要数据,充分发挥水准点高精度和GNSS点分布均匀的优势,有利于提升垂直运动模型的可靠性。在融合过程中,针对水准和GNSS成果缺少重合点导致速度融合失效的问题,提出一种基于模型结果融合的方法,分别利用水准和GNSS成果建立垂直运动模型,并基于模型格网点精度及控制点与模型格网点的最近距离联合确定两类模型点权值,逐点加权平均,实现两类模型的融合;针对利用反距离加权方法建模过程中观测点速度精度和空间距离均影响定权结果的问题,提出了权因子相乘的方法,合理确定各因素影响程度。综合利用国家一等水准网、国家GNSS大地控制网等成果,基于双因子相乘的方式定权建立单源垂直运动模型,并按照基于结果融合的方法建立了中国大陆垂直运动模型。结果表明,华北、苏沪一带沉降严重,极个别区域沉降速度达100 mm/a;东北、西藏一带呈现隆升趋势,局部隆升速度达5 mm/a;其余地区垂直运动相对稳定。

     

    Abstract:
      Objectives  The leveling and GNSS (global navigation satellite system) results are provided important data for studying the vertical movement in Chinese Mainland. Give full play to the advantages of high precision leveling points and uniform distribution of GNSS points and help improve the reliability of the vertical movement model. In the process of fusion, the lack of coincidence points between leveling and GNSS causes joint adjustment of velocity fusion to fail, a fusion method based on final model is proposed.
      Methods  First, we establish respective vertical movement model by leveling and GNSS with the method of inverse distance to a power. Second, we fuse two types of models by weighted average according to the grid point precision and nearest point principle depending on the distance between grid point and measured point. Aiming at the problem that the weight associated with the distance and the velocity precision affects the final model when inverse distance weighted is applied, a method of multiplying the weight is proposed to determine reasonable weight value for each factor.The vertical movement model of Chinese Mainland is established by using the national first order leveling result, national GNSS geodetic control network and so on. In order to measure the improvement of GNSS results on the vertical movement model, we utilize 20% of the modeling points selected from leveling and GNSS points uniformly to statistics the precision of leveling and fused vertical movement model.
      Results  The results show that the fused vertical movement model has increased by 35.3% in Qinghai Tibet region, 53.6% in other regions of Chinese Mainland and 50.8% in Chinese Mainland. The subsidence of North China Plain and Jiangsu-Shanghai areas are severe, where the velocity of individual areas is up to 100 mm/a, the North-East of China and Tibet areas show a rising trend, and the velocity exceeds 5 mm/a in local area, the vertical movement in other areas is relatively stable.
      Conclusions  Therefore, GNSS results can improve the precision and accuracy of the leveling vertical movement model, which is especially obvious inside the leveling loop. The single-source data vertical movement model is established based on the method of multiplication of two factors, and the fused vertical movement model of Chinese Mainland is established by the method of the result fusion.

     

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