CG-5重力仪格值系数修正与应用研究

Research on Correction and Application of Scale Parameter of CG-5 Gravimeter

在地表重力观测过程中,CG-5重力仪的格值系数会随着时间推移而发生变化。选用河北测区内2015-2017年相对重力观测数据,基于重力差法对两台编号为C859、C873的CG-5相对重力仪进行格值系数的误差计算及修正,研究其变化特征,并对修正前后不同时间尺度的重力场变化进行对比分析。结果表明:两台CG-5相对重力仪的格值系数在3年内存在不同程度的变化,均呈现整体上升的趋势,累计变化量分别为0.028%,0.034%;采用修正后的格值系数可得到点值精度更高的平差结果;不同时间尺度上的重力场变化相比修正前也出现明显差异,2017年河北大城ML3.6级地震发生在格值系数修正后0.5 a期重力变化零值线附近,这些结果表明了对CG-5重力仪进行格值系数修正的正确性和必要性。

In the process of gravity observation,the scale parameter of CG-5 gravimeter will change with time.Based on the relative gravity data from 2015 to 2017 in Hebei gravity survey network and the gravity difference method,the scale parameter error of CG-5 gravimeter numbered C859,C873 was calculated and corrected.The variation characteristics were studied,and the gravity variation of different time scale before and after the correction were compared and analyzed.The results show that:the scale parameters of the two CG-5 gravimeters have different degrees of change in three years,showing an overall upward trend with cumulative changes of 0.028% and 0.034%respectively;the results with higher accuracy can be obtained by using the modified scale parameter.The gravity field variation at different time scale is also significantly different from those before the correction.The Dacheng M_(L)3.6 earthquake in 2017 occurred near the zero line of gravity change in period 0.5 a after the correction of the scale coefficient,indicating the correctness and necessity of the scale parameter correction for CG-5 gravimeter.