HUST-Grace2026s: a high-resolution static gravity field product from GRACE and GRACE-FO observations (2002–2025)

Abstract. HUST-Grace2026s is a GRACE-only static gravity field determined by HUST (Huazhong University of Science and Technology). It’s determined based on more than 20 years’ observation data from GRACE (Gravity Recovery and Climate Experiment) and its successor GRACE-FO. The model provides high spatial resolution (up to degree/order 180) for mass distribution monitoring, complementing temporal series like HUST-Grace2024. This study presents the motivation and key outcomes behind our new static gravity field model, HUST-Grace2026s: (1) Merely adding current GRACE-FO observations offers limited improvement to existing GRACE-only models, due to GRACE-FO’s current orbital altitude. (2) The application of stochastic model based on postfit residual significantly enhances accuracy, reducing cumulative geoid error by up to 66 % at degree 180 compared to the nominal strategy. (3) The benefit of LRI data on static gravity field determination is strongly tied to the strategy for estimating rate terms. (4) Comprehensive internal and external validation confirms that HUST-Grace2026s achieves higher spatial resolution than unregularized solutions and improves accuracy by over 50 % compared to its predecessor, HUST-Grace2016s. This product serves as a benchmark for long-term mass change studies. The primary model data consisting of potential coefficients representing Earth’s static gravity field, together with secular and annual variations. This data set is identified with the following DOI: https://doi.org/10.5880/icgem.2026.001 (Zhou et al, 2026).