HUST-Grace2016s: A new GRACE static gravity field model derived from a modified dynamic approach over a 13-year observation period

The modified dynamic approach, where the observation vector and design matrix of observation equation are simultaneously filtered by empirical parameters, is implemented in this study. Using approximately 13 years (spanning from January 2003 to April 2015) of Gravity Recovery and Climate Experiment (GRACE) Level 1B data published by JPL and kinematic orbits published by ITSG, we developed a new GRACE static gravity field model called HUST-Grace2016s complete to degree and order 160. To evaluate the quality of our model, other GRACE-only gravity field models including AIUB-GRACE03S, GGM05S, ITG-Grace2010s, ITSG-Grace2014s and Tongji-GRACE01, are introduced for comparison. The difference degree amplitudes in terms of geoid height of our HUST-Grace2016s relative to GOCO05c are smaller than 1 mm and 1 cm before degree 100 and degree 138, respectively. In terms of global gravity anomalies and geoid heights relative to GOCO05c, the RMS values of our model up to degree 140 are 4.31 cm and 0.87 mGal respectively, which are smaller compared to AIUB-GRACE03S, GGM05S and Tongji-GRACE01. In addition, validated with GPS-leveling data in North America and the Netherlands, the standard deviation values of our HUST-Grace2016s model are 46.56 cm and 24.80 cm respectively, which also performs better than AIUB-GRACE03S, GGM05S and Tongji-GRACE01.