Gravity Gradiometry With GRACE Space Missions: New Opportunities for the Geosciences

Abstract

A new paradigm views the recently launched Gravity Recovery and Climate Experiment (GRACE) follow‐on mission as a gradiometer system, outside the mission's design concept, promising potentially major implications in geosciences. We develop an innovative and straightforward concept, the “GRACE gradiometer mode,” to process future GRACE follow‐on measurements to derive three‐dimensional gravitational gradients. Using positions, accelerations, and attitude measurements from the identical predecessor mission GRACE, we generate common and differential accelerations. We validate GRACE differential accelerations using Gravity field and steady‐state Ocean Circulation Explorer (GOCE) mission gradiometer measurements and we demonstrate an important and promising agreement between GRACE and GOCE. Consequently, we estimate gravitational gradients in full and we confirm their ability to detect geophysical signals over three example regions, namely, the Himalayas, Indonesia, and Canada. Coherence analysis between GOCE and GRACE gradients reveals a strong match that reaches up to 80%. GRACE gradiometer mode gradients are also compared with GRACE level 2‐ derived gradients, and results show that the new method captures smaller spatial‐scale signals than GOCE with the trade‐off being at higher noise level. We argue that future enhancements of the proposed proof‐of‐concept method will expand and enhance the GRACE follow‐on objectives that will lead to new insights, discoveries, and applications in the Earth system and the geosciences.

Analysis of GRACE Satellite Data in Terms of Geomonitoring of Strong Underwater Earthquakes

“…At present, a large amount of data has been accumulated from the space systems GRACE (2002-2017) and GRACE-FO (from 2018 to the present) [6]. On the basis of this information, the space-time variations of the Earth's gravity field with a period of 30 days are studied [7,8]. The GRACE CS implements the Satellite-to-Satellite Tracking (SST) method [8].…”

“…On the basis of this information, the space-time variations of the Earth's gravity field with a period of 30 days are studied [7,8]. The GRACE CS implements the Satellite-to-Satellite Tracking (SST) method [8]. High-precision positioning of Grace 1 and Grace 2 is provided by linking to the GPS navigation system.…”

A method for extracting the pre-seismic gravity anomalies over the Tibetan Plateau based on the maximum shear strain using GRACE data

“…Before and after the 1964 Alaska earthquake, the 1965-1967 Songdai earthquake swarm in Japan, the 1974 Izu earthquake in Japan, the 1976 Gazley earthquake swarm in the Soviet Union, and the 2013 M s 7.0 Lushan earthquake and gravity drop after the mainshock (Barnes, 1966;Wang LH et al, 2023Zhu YQ et al, 2023, the time-varying information on gravity before earthquakes was observed with time series of absolute and relative gravity data. The gravity data obtained by the Gravity Recovery And Climate Experiment (GRACE), which is representative of gravity satellite technology, contains information on the crustal density distribution and can be used to study the interaction mechanism between and within plates before earthquakes (Wahr et al, 1998;Peidou and Pagiatakis, 2019;Zotin et al, 2019;Gido et al, 2020;Velicogna et al, 2020;Liu C and Sun WK, 2023). Sun W and Okubo (2004) studied whether the GRACE satellites could detect coseismic gravity changes based on dislocation theory and concluded that GRACE is capable of detecting coseismic deformation signals from earthquakes with a magnitude greater than 7.5.…”