COMPARISON OF COMPLETE BOUGUER ANOMALIES FROM SATELLITE MARINE GRAVITY MODELS WITH SHIPBORNE GRAVITY DATA IN EAST SEA, KOREA

This paper describes the results of complete bouguer anomalies (B.A) computed from the free-air anomalies (F.A) of Sandwell and DTU13 marine gravity models that derived from satellite altimetry observations in the area of East Sea, South Korea. In order to confirm the usefulness of satellite-derived gravity anomalies to analyze the geophysical, geological and geographical characteristics in East Sea, the results of marine gravity models have been compared with shipbome gravity anomalies obtained from KHOA (Korea Hydrographic and Oceanographic Agency). To calculate the complete B.A, we applied complete bouguer correction which consists of three steps: the bouguer slab correction (Bullard A), the curvature correction (Bullard B) and the terrain correction (Bullard C). All these corrections have been computed over the East Sea with the 1' x 1' bathymetric data derived from ETOPO1 global relief model. In addition, a constant topographic and sea-water density, 2,670 kg/m(3) and 1,030 kg/m3, has been used for all correction terms according to the location of gravity points respectively. The distribution of complete B.A computed from Sandwell and DTU13 are very similar to each other with similar statistics i.e., mean of around 101.9 +/- 42 mGal. But, the differences with the complete B.A. calculated from shipbome gravities are slightly different over the whole study area, especially around Dok-do and Ulleung-do island, and also in the south-eastern part of Ulleung basin. As the final result, both models shows similar difference and variation, but Sandwell model shows little closer precision towards the shipborne observation data than DTU13 model in the study area. Hence, Sandwell model with the proper complete bouguer correction can be used as an alternative in effective application of gravity data to analyze the geophysical, geological and geographical characteristics in those areas which are not covered by shipborne gravity observations in large area of East Sea. But both combined or separately can also be used in case island or abyssal hill structures with higher slope can be avoided.