Evaluation of GRACE mascon solutions for small spatial scales and localized mass sources

Abstract

Mascon solutions, one of the recent advances in Gravity Recovery and Climate Experiment (GRACE) products, are being widely used due to their significant improvement in spatial accuracy and their ability to be directly employed without post-processing. However, few studies have verified the performance of mascon solutions at different regional scales, especially those smaller than GRACE's native resolution. We investigated the consistency between mascon and spherical harmonic solutions (hereafter named mascon and SH solutions) as release-05 products from the Center for Space Research and determined whether mascon solutions had a higher resolution than SH solutions (approximately 300 km). In addition, we used ICESat, LEGOS and DAHITI observations of water levels as independent supplementary data to validate the comparison results. We considered three cases of mass signals with varying spatial scales to examine the performance of mascon solutions in specific regions: (1) the abrupt water-level change in Longyang Reservoir (an area smaller than 1° × 1°) driven by heavy rainfall, (2) mass increase in the middle and lower Yangtze River basin and (3) mass loss of Tianshan Mountain glaciers and their subregions, including Bosten Lake at the foot of the glaciers. We concluded that mascon solutions have the potential to reveal gravity signals in areas larger than 3° × 3° from mass sources of Terrestrial Water Storage Anomalies, whereas they perform poorer than gridded SH products or SH solutions with a decorrelation filter in some specific regions smaller than 3° × 3°. The results of the three different cases provide references to non-geodetic users to select suitable GRACE solutions for different applications.