Abstract's details
The DTU25GRA SWOT derived global gravity field and evaluation with airborne gravity in the Norwegian coastal zone
Event: 2025 SWOT Science Team Meeting
Session: Deltas, Estuaries and Coasts
Presentation type: Poster
The observations from the Surface Water and Ocean Topography (SWOT) satellite have shown to be revolutionary in spatial resolution and precision. With the introduction of wide-swath altimetry sampled at a spacing of 250 m by 250 m, we are able to get reliable and accurate observations in more complex coastal zones than ever before. Traditional gravity fields have always relied on conventional nadir-looking satellite altimetry. Even with the introduction of Synthetic Aperture Radar (SAR) altimeters, the altimetric gravity field was always degraded in the coastal zone due to smoothing and/or extrapolation.
To utilize the high spatial resolution of SWOT, the new DTU25 GRA utilizes the ocean SWOT product (2 km spacing) in the open ocean, but uses the high-sampling of 250 m spacing in the coastal zones globally within the closest 10km.
The airborne gravity data were used for comparison with satellite altimetry-derived gravity models from several sources, including the most recent model DTU25GRA, which includes new high-resolution data from SWOT. We present the results of evaluating the SWOT derived gravity with gravity measured by a strapdown gravimetry campaign using an iMAR iCORUS-01 temperature-stabilized IMU along the south-western coast of Norway conducted in the fall of 2024.
The obtained results are assessed with respect to distance from the coast to quantify the accuracy of satellite altimetry, which has been a challenge for conventional altimetry. We demonstrate how the Inclusion of SWOT data sampled at high resolution (250 meters) results in higher consistency closer to the coast. The findings will be used to determine a distance-based threshold for relative weighting of the different datasets to be used in geoid computations, especially relevant for the computation of the new Scandinavian NKG geoid planned to be released in 2026.
Back to the list of abstractTo utilize the high spatial resolution of SWOT, the new DTU25 GRA utilizes the ocean SWOT product (2 km spacing) in the open ocean, but uses the high-sampling of 250 m spacing in the coastal zones globally within the closest 10km.
The airborne gravity data were used for comparison with satellite altimetry-derived gravity models from several sources, including the most recent model DTU25GRA, which includes new high-resolution data from SWOT. We present the results of evaluating the SWOT derived gravity with gravity measured by a strapdown gravimetry campaign using an iMAR iCORUS-01 temperature-stabilized IMU along the south-western coast of Norway conducted in the fall of 2024.
The obtained results are assessed with respect to distance from the coast to quantify the accuracy of satellite altimetry, which has been a challenge for conventional altimetry. We demonstrate how the Inclusion of SWOT data sampled at high resolution (250 meters) results in higher consistency closer to the coast. The findings will be used to determine a distance-based threshold for relative weighting of the different datasets to be used in geoid computations, especially relevant for the computation of the new Scandinavian NKG geoid planned to be released in 2026.