Improved Estimates of Geocenter Variability from Time-Variable Gravity and Ocean Model Outputs

• Main Authors: Tyler C. Sutterley, Isabella Velicogna
• Format: Article
• Language: English
• Published: MDPI AG 2019-09-01
• Series: Remote Sensing
• Subjects: GRACE; GRACE-FO; time-variable gravity; geocenter; reference frames; self-attraction and loading
• Online Access: https://www.mdpi.com/2072-4292/11/18/2108

Geocenter variations relate the motion of the Earth&#8217;s center of mass with respect to its center of figure, and represent global-scale redistributions of the Earth&#8217;s mass. We investigate different techniques for estimating of geocenter motion from combinations of time-variable gravity measurements from the Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-On missions, and bottom pressure outputs from ocean models. Here, we provide self-consistent estimates of geocenter variability incorporating the effects of self-attraction and loading, and investigate the effect of uncertainties in atmospheric and oceanic variation. The effects of self-attraction and loading from changes in land water storage and ice mass change affect both the seasonality and long-term trend in geocenter position. Omitting the redistribution of sea level affects the average annual amplitudes of the <i>x</i>, <i>y</i>, and <i>z</i> components by 0.2, 0.1, and 0.3 mm, respectively, and affects geocenter trend estimates by 0.02, 0.04 and 0.05 mm/yr for the the <i>x</i>, <i>y</i>, and <i>z</i> components, respectively. Geocenter estimates from the GRACE Follow-On mission are consistent with estimates from the original GRACE mission.