为研究重力场的时变特性,考虑到我国全国重力网布设和观测的现状,引入一种分段线性动态平差模型,用于流动重力网的平差处理。与传统静态平差模型相比,该模型可以得到更可靠的重力场变化特征。为验证模型的有效性,对我国全国重力网数据和模拟数据分别进行了动态平差和静态平差处理。结果显示,对于全国重力网数据,两种平差方法得到的重力变化率的平均差值为13.4×10-8 m·s-2/a,最大差值达50×10-8 m·s-2/a,且动态平差精度明显优于传统静态平差。对于模拟数据,动态平差结果中80%以上的平差值与理论值差值在1×10-8 m·s-2/a以内,只有两个差值超过2×10-8 m·s-2/a,而静态平差结果中只有44.4%的平差值与理论值差值在1×10-8 m·s-2/a以内,差值超过2×10-8 m·s-2/a的占21%。因此,本文提出的分段线性动态平差模型与传统静态平差模型相比能更有效地反映真实重力场的变化信息。
Based on the status of the distribution and measurements in the national gravity network, a piece-wise linear dynamic adjustment model is introduced and applied to the analysis of the relative gravity observations in order to study the temporal gravity variations in mainland China. Compared with the traditional static adjustment model, more reliable temporal gravity variation characteristics can be given by the new model. To verify the validity of the model, it is processed that the gravity data from the national network and simulated data using the two methods, respectively. For the national gravity network, the mean difference of the rates of gravity changes obtained by the two adjustment methods is 13.4×10-8 m·s-2/a, with a maximum of 50×10-8 m·s-2/a. The precision of the dynamic adjustment is obviously better than the traditional static adjustment. For the simulated data, the rates of gravity change are compared with the theoretical ones at the same points. It is found that over 80% of the differences are less than 1×10-8 m·s-2/a from dynamic adjustment, and only two differences are larger than 2×10-8 m·s-2/a. In contrary, there are only 44.4% of the differences are less than 1×10-8 m·s-2/a from static adjustment, and 21% of the differences are larger than 2×10-8 m·s-2/a. Therefore, the piece-wise linear dynamic adjustment model can provide more reliable information of the temporal gravity changes compared with the traditional static adjustment model.
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