零漂改正对中国地壳运动观测网络重力数据处理的影响
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摘要
基于中国地壳运动观测网络2000年流动重力观测数据,分析18台LCR-G型相对重力仪的零漂特性。结果显示,重力仪零漂率在某些时段变化较大,最大达10μGal/h以上。根据重力仪零漂改正的不同处理方法,利用传统平差模型与改进模型对观测数据进行平差计算,并对结果进行比较。在相同先验中误差的情况下,传统平差模型的后验中误差为39μGal,重力值平均精度为26.5μGal,而改进模型的后验中误差为16.5μGal,重力值平均精度为11.2μGal,远高于传统平差模型。在数据预处理阶段按闭合观测分段进行零漂改正,可以有效消除重力仪零漂剧烈变化的影响,明显优于将仪器零漂率当作固定参数的计算方法。
Based on CMONOC mobile gravity data from 2000,zero drift characteristics of 18LCR-G relative gravimeters are studied.The results show that zero drift rate of gravimeter may sometime shave a significant change,up to 10μGal/h.Based on different processing methods of zero drift correction,the results of traditional and improved adjustment models are compared.Given the same priori error,the posterior error of the traditional adjustment model is 39μGal,and its average accuracy of gravity value is 26.5μGal;however,for the improved adjustment model,its posterior error is 16.5μGal and the average accuracy of gravity value is 11.2μGal.The accuracy of the improved model is much higher than that of the traditional adjustment model.The comparison shows that computing the zero drift correction by circuit in the data preprocessing can effectively eliminate the error of significant change of zero drift.The improved model is superior to traditional adjustment model that assumes the zero drift as a constant.
Based on CMONOC mobile gravity data from 2000,zero drift characteristics of 18LCR-G relative gravimeters are studied.The results show that zero drift rate of gravimeter may sometime shave a significant change,up to 10μGal/h.Based on different processing methods of zero drift correction,the results of traditional and improved adjustment models are compared.Given the same priori error,the posterior error of the traditional adjustment model is 39μGal,and its average accuracy of gravity value is 26.5μGal;however,for the improved adjustment model,its posterior error is 16.5μGal and the average accuracy of gravity value is 11.2μGal.The accuracy of the improved model is much higher than that of the traditional adjustment model.The comparison shows that computing the zero drift correction by circuit in the data preprocessing can effectively eliminate the error of significant change of zero drift.The improved model is superior to traditional adjustment model that assumes the zero drift as a constant.
引文
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[2]许厚泽.重力观测在中国地壳运动观测网络中的作用[J].大地测量与地球动力学,2003,23(3):1-3(Xu Houze.Function of Gravimetry in CMONOC[J].Journal of Geodesy and Geodynamics,2003,23(3):1-3)
[3]张为民,王勇,詹金刚.中国地壳运动观测网络基准站绝对重力的测定[J].地壳形变与地震,2001,21(4):114-116(Zhang Weimin,Wang Yong,Zhan Jingang.Absolute Gravity Observation on Benchmark Station of CMONOC[J].Crustal Deformation and Earthquake,2001,21(4):114-116)
[4]郝洪涛.基于地表重力观测的地壳垂直运动和同震位错研究[D].北京:中国科学院大学,2015(Hao Hongtao.Research on Vertical Displacement of Crust and Coceismic Gravity Change Based on Land Gravimetry[D].Beijing:University of Chinese Academy of Sciences,2015)
[5]王宝仁.重力仪重复观测数据处理方法[J].物探化探计算技术,1992(2):96-105(Wang Baoren.Data Processing Methods for Repeating Observation by Gravimeter[J].Computing Techniques for Geophysical and Geochemical Exploration,1992(2):96-105)
[6]Pagiatakis S D,Salib P.Historical Relative Gravity Observations and the Time Rate of Change of Gravity Due to Postglacial Rebound and Other Tectonic Movements in Canada[J].Journal of Geophysical Research,2003,108(B9)
[7]Hwang C,Wang C G,Lee L H.Adjustment of Relative Gravity Measurements Using Weighted and Datum-free Constraints[J].Computers&Geosciences,2002,28(9):1 005-1 015
[8]李辉,刘冬至,刘绍府.地震重力监测网统一平差模型的建立[J].地壳形变与地震,1991,11(增1):68-74(Li Hui,Liu Dongzhi,Liu Shaofu.Integrated Adjustment Models for the Seismic-Gravity Network[J].Crustal Deformation and Earthquake,1991,11(Supp1):68-74)
[9]Torge W.Gravimetry[M].Berlin:Springer,1989