###### Abstract  
Precise geoid heights are not as important for understanding Earth's gravity field, but they are important to geodesy itself, since the vertical datum is defined as geoid in a cm-level accuracy. Several high-degree geopotential models have been derived lately by using satellite tracking data such as those from Gravity Recovery and Climate Experiment (GRACE) and Gravity Field and Steady-State Ocean Circulation Explorer (GOCE), satellite altimeter data, and terrestrial and airborne gravity data. The Korean national geoid (KNGeoid) models of the National Geographic Information Institute (NGII) were developed using the latest global geopotential models (GGMs), which are combinations of gravity data from satellites and land gravity data. In this study, geoid heights calculated from the latest high-degree GGMs were used to evaluate the accuracy of the three GGMs (European Improved Gravity model of Earth by New techniques (EIGEN)-6C4, Earth Gravitational Model 2008 (EGM2008), and GOCE-EGM2008 combined model (GECO)) by comparing them with the geoid heights derived from the Global Navigation Satellite System (GNSS)/leveling of the 1182 unified control points (UCPs) that have been installed by NGII in South Korea since 2008. In addition, the geoid heights derived from the KNGeoid models were compared with the geoid heights derived from the GNSS/leveling of the 1182 UCPs to assess the accuracy of the KNGeoid models in terms of relative geoid heights for further gravimetric geoid determination studies in South Korea. As a result, the EGM2008 model could be selected as the suitable GGM from among the three GGMs for determining a gravimetric geoid model for South Korea. Keywords:Korean national geoid; GNSS/leveling-derived geoid height; unified control points; global geopotential model +
Footnote †: journal: Applied  
geoid height accuracy is necessary for determining the high-degree GGMs that have the best fit to GNSS/leveling data in national control points over South Korea. The recently released GGMs were based on gravity data obtained from the Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) gravitational exploration satellite launched in 2009. Several GGMs have been calculated using satellite tracking data from the GRACE and GOCE gravity missions [10; 11]. High-degree geopotential models of spherical harmonic coefficients are used for modeling the Earth's exterior gravity field. Such coefficients are derived from satellite tracking data, altimeter data, and terrestrial and airborne gravity data. Hundreds of thousands of coefficients and standard deviation values for these coefficients are estimated through millions of measurements. The number and distribution of measurements, as well as the type of measurement, affect the accuracy of a geopotential model. Since the 1960s, satellite gravity field missions have provided accurate data for forming geopotential models and these models have been evaluated based on the data provided by the satellite gravity field missions. The National Geographic Information Institute (NGII) has developed three Korean national geoid (KNGeoid) models--KNGeoid13, KNGeoid14, and KNGeoid18--using the Earth's gravity field model, satellite-altimetry-derived gravity data, land and ocean gravity data, airborne gravity data, and digital elevation model (DEM) data. The KNGeoid models are hybrid geoid models developed by NGII to improve the height measurement accuracy based on GNSS surveying. First, the KNGeoid13 model, developed by NGII for the land part, was based on gravity data obtained from several national control points (unified control point (UCP), benchmark (BM), triangulation point), airborne gravity data obtained since 2008, DTU10 satellite altimeter data [12], EGM2008 data, and 5 m gridded topographic data. The standard deviation of residuals of the KNGeoid13 model are 3.41 cm [13].