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Non-tidal variation on sea level generates immediate changes in gravity field and deformation of the Earth's crust, thus influencing the stability of geodetic datums. To achieve higher accuracy of geodetic datums in coastal and island areas, sea-level changes should be adequately considered when conducting the maintenance of datums. Based on the data of sea-level anomalies from 2014 to 2017 and the theory of load-deformation of elastic spherical earth, this paper demonstrates that impacts of non-tidal ocean load can be quantitatively calculated on geodetic datums along the east coast of China, by using remove-restore technique and combining spherical harmonic analysis of gravity field and Green's functions to calculate loads. Temporal and spatial analyses on the impacts are conducted with Continuously Operating Reference Stations (CORS) sites along the coast and on the islands. This paper has drawn some conclusions as follows: (1) The impact of non-tidal ocean loads on the east coastal geoid ranges from −4.16 to 4.17 mm, that on ground gravity ranges from −15.44 to 17.02 some conclusions as follows: (1) The impact oranges from −7.55 to 6.69 mm. (2) The impacts are dominated by annual and semi-annual cycles. (3) The impacts appear to be more prominent in coastal areas and on islands than in inland areas. [ABSTRACT FROM AUTHOR]

Different types of gravity observations are available over coastal areas. The main challenge for coastal geoid determination is the proper fusion of heterogeneous gravity data including land, shipborne, airborne, and altimetry-derived gravity data. This paper describes the gravity data fusion and the computation of the gravimetric quasigeoid in the coastal area of mainland China. An iterative procedure of the weighted least-squares prediction based on rectangular harmonic functions is used for merging the land, altimetric, shipborne, and airborne gravity data. Applying the analytical continuation method in Molodensky's theoretic frame, the merged gravity data are then used to determine the gravimetric quasigeoid model by using the generalized Stokes' integral in a remove-compute-restore fashion. The gravimetric quasigeoid model is compared with the height anomalies determined at 662 GPS leveling points over the coastal region of mainland China, where both the geodetic height and the normal height are known. The standard deviations of the differences in the coastal provinces range from 1.8 to 4.4 cm. For the entire computation area, the mean and standard deviation of the differences are 27.9 and 3.9 cm, respectively. [ABSTRACT FROM AUTHOR]

The characteristics of shipborne gravimetric data from offshore China were analysed, and a method to eliminate systematic deviation in the gravity for different survey lines located in different regions is also proposed. A criteria for determining shipborne gravimetric survey lines for base lines is presented, and the residual disturbance gravity at the cross point between two different survey lines on the base line was used to rectify the other values for different shipborne gravimetric survey lines. These experiemental results show that, in accordance with the criteria presented, when correcting the gravity of the survey line in the proposed method the gravity value difference on different lines does not include a systematic bias, the intersections of discrepancies significantly improved, and the survey lines to correct the gravity disturbance were significantly better than those without pre-corrected gravity disturbance. [ABSTRACT FROM AUTHOR]