Loading effect of a selfconsistent equilibrium ocean pole tide on the gravimetric parameters of the gravity pole tides at superconducting gravimeter stations
Chen, X.D.; Ducarme, B.; Sun, H.P.; Xu, J.Q. (2008). Loading effect of a selfconsistent equilibrium ocean pole tide on the gravimetric parameters of the gravity pole tides at superconducting gravimeter stations. J. Geodyn. 45(45): 201207. dx.doi.org/10.1016/j.jog.2007.11.003
In: Journal of Geodynamics. Elsevier Science: Amsterdam. ISSN 02643707; eISSN 18791670, meer
 
Trefwoord 

Author keywords 
selfconsistent equilibrium ocean pole tide; gravimetric parameter of 
Auteurs   Top 
 Chen, X.D.
 Ducarme, B.
 Sun, H.P.
 Xu, J.Q.



Abstract 
The gravimetric parameters of the gravity pole tide are the amplitude factor delta, which is the ratio of gravity variations induced by polar motion for a real Earth to variations computed for a rigid one, and the phase difference K between the observed and the rigid gravity pole tide. They can be estimated from the records of superconducting gravimeters (SGs). However, they are affected by the loading effect of the ocean pole tide. Recent results from TOPEX/Poseidon (TP) altimeter confirm that the ocean pole tide has a selfconsistent equilibrium response. Accordingly, we calculate the gravity loading effects as well as their influence on the gravimetric parameters of gravity pole tide at all the 26 SG stations in the world on the assumption of a selfconsistent equilibrium ocean pole tide model. The gravity loading effect is evaluated between I January 1997 and 31 December 2006. Numerical results show that the amplitude of the gravity loading effect reaches 10^{9} ms^{2}, which is larger than the accuracy (10^{10} ms^{2}) of a SG. The gravimetric factor delta is 1% larger at all SG stations. Then, the contribution of a selfconsistent ocean pole fide to the pole tide gravimetric parameters cannot be ignored as it exceeds the current accuracy of the estimation of the pole tide gravity factors. For the nine stations studied in Ducarme et al. [Ducanne, B., Venedikov, A.P., Arnoso, J., et al., 2006. Global analysis of the GGP superconducting gravimeters network for the estimation of the pole tide gravimetric amplitude factor. J. Geodyn. 41, 334344.], the mean of the modeled tidal factors d_{m} = 1. 1813 agrees very well with the result of a global analysis d_{CH} = 1. 1816 +/ 0.0047 in that paper. On the other hand, the modeled phase difference K_{m} varies from 0.273° to 0.351°. Comparing to the two main periods of the gravity pole tide, annual period and Chandler period, K_{m} is too small to be considered. Therefore, The computed time difference K_{L} induced by a selfconsistent ocean pole tide produces a negligible effect on K_{L}. It confirms the results of Ducarme et al., 2006, where no convincing time difference was found in the SG records. 
