Sea-level fingerprints emergent from GRACE mission data

摘要

The Gravity Recovery and Climate Experiment (GRACE) mission data have animportant, if not revolutionary, impact on how scientists quantify the watertransport on the Earth's surface. The transport phenomena include landhydrology, physical oceanography, atmospheric moisture flux, and globalcryospheric mass balance. The mass transport observed by the satellite systemalso includes solid Earth motions caused by, for example, great subductionzone earthquakes and glacial isostatic adjustment (GIA) processes. Whencoupled with altimetry, these space gravimetry data provide a powerfulframework for studying climate-related changes on decadal timescales, such asice mass loss and sea-level rise. As the changes in the latter aresignificant over the past two decades, there is a concomitant self-attractionand loading phenomenon generating ancillary changes in gravity, sea surface,and solid Earth deformation. These generate a finite signal in GRACE andocean altimetry, and it may often be desirable to isolate and remove them forthe purpose of understanding, for example, ocean circulation changes andpost-seismic viscoelastic mantle flow, or GIA, occurring beneath theseafloor. Here we perform a systematic calculation of sea-level fingerprintsof on-land water mass changes using monthly Release-06 GRACE Level-2 Stokescoefficients for the span April 2002 to August 2016, which result in a set ofsolutions for the time-varying geoid, sea-surface height, and verticalbedrock motion. We provide both spherical harmonic coefficients and spatialmaps of these global field variables and uncertainties therein(https://doi.org/10.7910/DVN/8UC8IR; Adhikari et al.,?2019). Solutions are providedfor three official GRACE data processing centers, namely the University ofTexas Austin's Center for Space Research (CSR), GeoForschungsZentrum Potsdam(GFZ), and Jet Propulsion Laboratory (JPL), with and without rotationalfeedback included and in both the center-of-mass and center-of-figurereference frames. These data may be applied for either study of the fieldsthemselves or as fundamental filter components for the analysis ofocean-circulation- and earthquake-related fields or for improving ocean tidemodels.