FG5绝对重力仪观测数据的实测重力潮汐改正

Correction of Measured Gravity Tides with FG5 Absolute Gravimeter Observations

  • 摘要: 基于中国计量科学研究院北京昌平院区的超导重力仪iGrav-012实测重力潮汐数据,以FG5绝对重力仪为例研究了绝对重力观测中的实测潮汐改正问题,分析了用高精度超导重力仪获得的实测合成重力潮汐与理论合成重力潮汐间的差异。并采用iGrav-012超导重力仪和FG5X-249绝对重力仪两种实测数据对实测潮汐改正效果进行了验证。结果表明,FG5绝对重力仪中用的理论合成重力潮汐在考虑海潮重力影响后的结果与实测合成重力潮汐之差在1 μGal之内,因此理论合成重力潮汐经过海潮重力影响改正后的结果可满足绝对重力观测精度要求,从观测精度来讲,无需对绝对重力的实测数据实施潮汐改正即可满足绝对重力观测的精度要求。但是FG5X-249绝对重力观测数据的潮汐改正结果表明,不同的潮汐改正方法对绝对重力观测值的影响不同,但这种影响较小,在0.1 μGal的量级,因此建议只在高精度绝对重力观测中考虑实测重力潮汐改正。

     

    Abstract: The tidal correction on data recorded with FG5 absolute gravimeter is investigated in the study using gravity tides observed with a superconducting gravimeter iGrav-012 installed at Beijing Changping station, National Institute of Metrology, China. The difference between measured synthetic gravity tidal and theoretical synthetic gravity tidal obtained by high precision superconducting gravimeter is analyzed. Two kinds of measured data obtained by iGrav-012 superconducting gravimeter and FG5X-249 absolute gravimeter were used to verify the correction effect of measured tides.Numerical results show that the difference between the observed gravity tides and the theoretical gravity tides considering ocean loading effect is less than 1 μGal, which is lower than the observed accuracy of FG5 gravimeter. As a conclusion, it is not necessary to consider the tidal correction with observed tides from the view of the observed accuracy. However, the results from the FG5X-249 absolute gravimeter indicate that different methods of tidal correction can change the absolute gravity value itself. Although this change is very small and at the order of 0.1 μGal, tidal correction using observed tide is still recommended in precise absolute gravimetry.

     

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