Development and evaluation of the xGEOID20 Digital Elevation Model at NGS

Abstract

<p>The U.S. National Geodetic Survey (NGS), an office of the National Oceanic and Atmospheric Administration (NOAA), will release a new vertical datum in 2022, the North American-Pacific Geopotential Datum of 2022 (NAPGD2022). This new datum will be based on a high degree spherical harmonic model of the Earth’s gravitational potential, and will yield a geoid undulation model (GEOID2022) to calculate orthometric heights from GNSS-derived ellipsoid heights.</p><p>In preparation for the new vertical datum, NGS has computed annual experimental geoid models (xGEOID) since 2014. This year’s xGEOID model (xGEOID20) will use an updated digital elevation model (DEM) composed of TanDEM-X, 3DEP, MERIT, and other DEMs. The DEMs are merged together to create a seamless elevation model across the extent of the xGEOID20 model. The accuracy of the merged DEM is tested using independent datasets such as GPS on benchmarks and Icesat-2. The effect of the updated DEM on the geoid model is also determined by comparing geoid models computed with previous DEMs to the new xGEOID20 model, and with comparisons to the NGS Geoid Slope Validation Survey lines.</p>