Free-air anomaly from a consistent preprocessing of land gravity data in South Korea

To determine the precise geoid, the quality land gravity data as well as the accurate position information of the observation points are required. Here, the land gravity data should be processed in a consistent way from the raw data level producing the quality free-air anomaly being used in the geoid determination. In this study, we processed land gravity data of KIGAM(Korea Institute of Geoscience and Mineral Resources) and Pusan national university which has precise position information acquired from GPS and raw gravity data. The conversion from readings of gravimeter to the gravity value, corrections of instrumental height and tide were carried out from the raw gravity data for each surveying session. Then, a cross-over adjustment was applied to generate a free-air anomaly for whole data with precision of 0.48 mGal. It is expected that the data processed through this study shall be a foundation on the determination of the precise geoid model in Korea.