Improved Earth Oblateness Rate Reveals Increased Ice Sheet Losses and Mass‐Driven Sea Level Rise

Abstract

Abstract Satellite laser ranging (SLR) observations are routinely applied toward the estimation of dynamic oblateness, C 20 , which is the largest globally integrated component of Earth's time‐variable gravity field. Since 2002, GRACE and GRACE Follow‐On have revolutionized the recovery of higher spatial resolution features of global time‐variable gravity, with SLR continuing to provide the most reliable estimates of C 20 . We quantify the effect of various SLR processing strategies on estimating C 20 and demonstrate better signal recovery with the inclusion of GRACE‐derived low‐degree gravity information in the forward model. This improved SLR product modifies the Antarctic and Greenland Ice Sheet mass trends by −15.4 and −3.5 Gt/year, respectively, as compared to CSR TN11, and improves global mean sea level budget closure by modifying sea level rise by +0.08 mm/year. We recommend that this new C 20 product be applied to RL06 GRACE data products for enhanced accuracy and scientific interpretation.