Work

Oscillations in the Earth's figure axis from 50-yr SLR data and polar motion

Year: 2026

Type: article

Abstract: SUMMARY The Earth’s figure axis is the axis of maximum inertia for the deformed (oblate) Earth, as described by the degree-two, order-one geopotential coefficients C21 and S21. An extended mean-pole model is presented for evaluating solid-Earth and ocean-pole tides. 50-yr Satellite Laser Ranging (SLR) data and 24-yr GRACE/GRACE-FO (Gravity Recovery and Climate Experiment and followon) data were analysed to determine variations in Earth’s figure axis, as reflected in changes in the C21 and S21 coefficients. This study reveals that a significant atmosphere-ocean motion induced a variation in C21 that is captured by SLR data but does not appear in the GRACE solution. The current glacial isostatic adjustment ICE-6 G model requires improvement to account for the observed linear rates of C21 and S21. A significant 30- and 60-yr signal with an amplitude of ∼3 × 10−11 in the Earth’s figure axis is observed using SLR and an amplitude of ∼10 mas in the polar-motion, which could be predominantly driven by a 0.05-deg tilt of the inner-core figure axis relative to the figure axis of the entire core and is linked to partial electromagnetic core–mantle coupling.

Source: Geophysical Journal International

DOI: 10.1093/gji/ggag206

Author: Minkang Cheng

Institution: The University of Texas at Austin

Language: English

Topic: Geophysics and Gravity Measurements

Subfield: Oceanography

Field: Earth and Planetary Sciences

Domain: Physical Sciences

SDG: Climate action

Open Access status: gold

Estimated APC paid: $3,416