利用残差地形模型空域法精化局部地球重力场

Refining Local Earth’s Gravity in Spatial Domain with Residual Terrain Modelling Technique

陆地高分辨率重力数据是超高阶重力场模型及其应用研究的基础,但现有的观测技术和手段限制了陆地重力测量的覆盖区域,全球仍有大量的重力测量空白地区。采用残差地形模型空域法,利用高通滤波技术提取航天飞机雷达地形测绘任务(shuttle radar topography mission,SRTM)分辨率3″×3″的V4.1数据短波信号,结合EGM2008重力场模型,反演精化1’×1’分辨率的局部地球重力场参量。利用美国地面实测重力观测数据NGS99共57387个点检验基于该方法恢复的1’×1’分辨率的美国局部重力场,相比于EGM2008模型,其误差均方根(root mean square,RMS)由15.470 mGal降低到12.999 mGal,表明该方法可以在保证精度的同时有效地提高陆地重力场的分辨率。将该方法应用于中国华北平原(114°E~117°E,32°N~35°N),计算了该地区1’×1’分辨率的重力扰动和垂线偏差,重力扰动的RMS为25.311 mGal,垂线偏差南北分量和东西分量的RMS分别为2.215″和8.452″,填补了该地区1’×1’分辨率重力测量的空白。

Objectives:The land high-resolution gravity data is the basis of the research on ultra-high-degree gravity field model and its application.But the existing observation technology and means limit the coverage area of land gravity measurement,and there are still a lot of areas without gravity measurement.Methods:Based on the residual terrain modelling method,short-wave signal of 3″×3″resolution shuttle radar topography mission(SRTM)V4.1 data is extracted using high-pass filtering technology,combined with the EGM2008 gravity field model,to inverse and refine local gravity field parameters with 1’×1’resolution.57387 points of NGS99 are used to test the local gravity field of America with 1’×1’resolution restored by this method.Then this method is applied to the North China Plain(114°E—117°E,32°N—35°N),and gravity disturbance and vertical deflection of 1’×1’resolution in this area are calculated.Results:Compared with EGM2008 model,the root mean square(RMS)of error is reduced from 15.470 mGal to 12.999 mGal.In the North China Plain,the RMS of gravity disturbance is 25.311 mGal,and the RMS of South-North and East-West vertical deflections are 2.215″and 8.452″,respectively.Conclusions:This method can effectively improve the resolution of the land gravity field while ensuring the accuracy,and fill in the blank of 1’×1’resolution ground gravity measurement.