Abstract: 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.

Key words: mobile gravity observation, national gravity network, dynamic adjustment, piece-wise linear model