Evaluating Ocean Tide Models Using Absolute Gravity Measurements at Aboa, Dronning Maud Land, Antarctica

Abstract Accurate modeling of ocean tidal loading (OTL) is essential for geodetic data analysis, allowing isolation of other geophysical signals such as ice mass changes and glacial isostatic adjustment (GIA). Modeling OTL in the Antarctic region is challenging due to sparse observations, poorly constrained sub-ice topography, and complex grounding line dynamics. We use absolute gravity (AG) measurements from the Finnish Antarctic station Aboa (Dronning Maud Land) to evaluate several global and regional ocean tide models. Two AG campaigns in January–February 2024 (each ~6 days) reveal OTL amplitudes of up to 20 μGal (2 × 10 −7 m/s 2 ) peak-to-peak, providing the first comparison of absolute gravity measurements and OTL models in the Western Dronning Maud Land. Synthetic OTL time series were computed for global models FES2004, FES2022b, DTU23, EOT20, TPXO10-atlas-v2, and the regional CATS2008v2023 model, and compared directly with AG measurements. The modelled loadings were subtracted from the AG measurements to quantify model misfit and identify which model minimizes the residual gravity variability. Because of the limited observation duration, the analysis focuses on diurnal and semidiurnal tidal constituents. Comparisons show that differences between models in predicted loading primarily originate within a ~200 km radius around Aboa. All models provide adequate correction to the AG time series, with inter-model differences below the AG measurement uncertainty. These results suggest that, while current global models already perform well for OTL corrections at Aboa, the inclusion of regional Antarctic model CATS2008v2023 helps to constrain local tidal dynamics and improves confidence in gravimetric studies in coastal Antarctica.