Assessment of NAPGD2022's Performance in Oregon's Willamette Valley Using Astronomical Leveling and GNSS/Leveling

Abstract The North American‐Pacific Geopotential Datum of 2022 (NAPGD2022) is anticipated to become the official height system of the United States in 2027. This new datum is realized through a suite of models, including GEOID2022 (geoid) and DEFLEC2022 (deflection of the vertical). GEOID2022 targets 1–2 cm height accuracy in the contiguous United States, but its performance in areas containing terrestrial gravity data gaps and varying geology has not been well studied. In this study, we evaluate the 2025 beta versions of the GEOID2022 and DEFLEC2022 models using an established GNSS network to assess their performance in Oregon's Willamette Valley, a populated region with relatively sparse terrestrial gravity data coverage. A total of 23 selected marks in the GNSS network were occupied with the QDaedalus astrogeodetic system to measure geoid slopes with sub‐microradian accuracy. Geodetic coordinates were derived from long‐duration static GNSS observations. Eleven of the selected marks also have leveled orthometric heights. These three observation types enable validation of GEOID2022 using both GNSS/leveling and astronomical leveling. Thin‐plate splines were used to fit residual geoid undulation grids to observed astronomical geoid slopes. Despite limited terrestrial gravity data coverage, the astrogeodetic and GNSS/leveling observations are broadly consistent with both GEOID2022 and DEFLEC2022, within 2 cm and 0.7 arcseconds RMS. However, higher‐elevation sites exhibit pronounced multi‐centimeter and multi‐arcsecond systematic errors, particularly near Oregon's geologic surface density contrast boundaries. These results highlight the robustness of NAPGD2022 in regions with sparse gravity data, while underscoring the need for more complete and consistent terrestrial gravity coverage.