High-Resolution Quasi-Geoid Recovery Over Coastal Zone by Using Airborne Gravity Gradient Data

The potential of using airborne gravity gradient tensor (GGT) for coastal quasi-geoid (QG) refinement is explored, and the contributions introduced from individual GGT components and their combinations are quantified and evaluated. High-resolution QGs, with a spatial resolution of ~0.5 km, are computed over St. George’s Bay in southwestern Newfoundland, Canada. The findings indicate that fully focused synthetic aperture radar (FFSAR) and surface water and ocean topography (SWOT) altimetry data are effective in differentiating the performance of various QGs in coastal areas. The application of the vertical gravity gradient (VGG) obtains the highest quality QG when utilizing individual GGT components. The combination of two or more components results in improved QGs compared to the results derived from individual components. The integration of full GGT yields the best QG, with a standard deviation (SD) of misfits against Sentinel-3A FFSAR (SWOT) altimetry data being 1.13 (2.49) cm, representing reductions of 28.48%–53.50% (5.32%–15.02%) compared to results derived from individual GGT components. Comparisons of the QG computed by fusing full GGT with the Canadian gravimetric QG CGG2013 and high-degree global geopotential models (GGMs) further underscore the advantages of using GGT in QG modeling, revealing SD reductions of 55.16%–65.02% (7.55%–33.95%) against FFSAR (SWOT) altimetry data. These findings underscore the effectiveness of using airborne GGT in coastal QG modeling, particularly in recovering short-wavelength signals and addressing challenges in satellite altimetry over coastal environments. In addition, this study highlights the superiority of using full GGT over individual components in QG modeling.