Abstract

The global gravitational gradient field has not been observed since the decommission of GOCE in 2013. Based on the foundational work of Peidou and Pagiatakis (2019), we advance the concept of GRACE gradiometer mode (GM) for the purpose of using GRACE, GRACE-FO and future gravity space missions as ‘gradiometer missions’. Certainly, the GRACE missions have never carried a gradiometer, it is only the concept of GM that creates a fictitious gradiometer system very similar to GOCE, only the GRACE ‘gradiometers’ have long and variable baselines, an unprecedented paradigm for space-based gravitational gradiometry that extends the bandwidth of the gradient solution. In this contribution, we develop a new configuration for GM that views an individual satellite as the ‘gradiometer’, in order to directly use Level 1A accelerometer measurements in a 10 Hz sampling interval. We apply the new method in geodynamically active regions around the globe, and we demonstrate that using GRACE-C as a ‘gradiometer’ in the single-satellite gradiometer mode (SS-GM) produces higher-fidelity gravitational gradient estimates, clearly delineating tectonic plate boundaries and subduction zones in the Himalayas and North Africa regions, the Aleutian trench, the Java trench, and the Peru-Chile trench. Over Canada, we see the delineation of the Canadian shield, and the effect of glacial isostatic adjustment (GIA) is apparent. We also observe well-known signals resembling terrestrial water storage (TWS) changes in Africa, among others, demonstrating the usefulness of the GM for a wide variety of geoscience applications.