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OCEAN TIDE LOADING CORRECTION ON LONG PERIOD EARTH TIDAL GRAVITY OBSERVATION AT WUHAN STATION

Applying the long term tidal parameters gravity obtained with the VAV and Etema softwares,the gravity observations with superconducting gravimeter at Wuhan station and on the ocean tide models:TPXO5,TPXO6,TPXO7,NAO99 and FES04.We have made the ocean tide loading correction to these observations.The numerical results show that the residuals of constituents of Mm and Mf are mainly caused by ocean tide loading.The corrected amplitude factors are closer to the theoretical ones of which the differences decrease from 3.4% and 2.5% to 0.16% and 0.12% respectively.Due to the low signal noise ratio of the long-period constituents with relatively small amplitudes,the tidal parameters of these constituents are difficult to be measured accurately at present.This is also proved by the results of ocean tide loading correction.