Impact of SRTM and ASTER Terrain Models on Geoid Determination: A Case Study in the High‐Mountainous Region

Abstract An accurate geoid has important consequences for many fields such as engineering applications, underground resource exploration, geophysical surveys, etc. Its precise determination relies on two key data sets: gravity measurements and high‐resolution elevation data, both of which are critical for achieving reliable results. In particular, accurate elevation data is indispensable for geoid modeling, as it is required for various computational steps, including the prediction of the free‐air gravity anomalies, terrain corrections, and the calculation of complete Bouguer gravity anomalies. In the absence of accurate regional elevation data, the digital elevation model (DEM) generated by the Shuttle Radar Topography Mission (SRTM) is commonly used as a reliable alternative. Additionally, researchers from Japan and the United States have released a new DEM generated from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), which provides an alternative to the widely used SRTM DEM. This study explores the consequence of the ASTER DEM on estimating mean free‐air gravity anomalies in geoid determination, focusing on the Colorado experiment area, which is characterized by mountainous and rugged terrain. Numerical results indicate that the ASTER DEM yields less favorable statistics compared to the SRTM DEM in terms of height accuracy. The use of ASTER DEM introduces discrepancies (compared to SRTM DEM) ranging from −2 to 4 mGal in the interpolation of free‐air gravity anomalies. Furthermore, it is demonstrated that the geoid differences resulting from the use of ASTER DEM are within a few centimeters, remaining below the accuracy level of external GNSS‐leveling data.