GRACE Estimated Terrestrial and Aquifer Storage Change Using An Improved Energy Balance And Regional Gravity Modeling Approach

Energy Balance Approach (EBA) has been demonstrated to be an efficient method to estimate the regional terrestrial water storage changes from GRACE via in situ geopotential difference observations directly computed using the GRACE Level 1B data. The primary purpose of this study is to overcome several limitations in previous EBA by demonstrating an improved EBA to obtain a more precise estimation of in situ geopotential difference, which would be able to preserve both the low- and high-frequency gravity signals and also improve the temporal resolutions. Consequently, this method would yield a full scale, i.e., both regional and global water storage change, including world’s aquifers. To achieve this goal, we developed an innovative approach to incorporate GRACE inter-satellite range-rate observations into energy conservation equation, which is realized by a so-called alignment equation, together with a technique to estimate the reference orbits for the GRACE twin-satellites. We will present our results for both global and regional GRACE solutions using the improved EBA for water storage change estimates with enhanced spatial and temporal resolutions over selected terrestrial hydrologic basins and large aquifers.