Abstract
Abstract. The Gravity Recovery and Climate Experiment (GRACE) mission data have an important, if not revolutionary, impact on how scientists quantify the water transport on the Earth's surface. The transport phenomena include land hydrology, physical oceanography, atmospheric moisture flux, and global cryospheric mass balance. The mass transport observed by the satellite system also includes solid Earth motions caused by, for example, great subduction zone earthquakes and glacial isostatic adjustment (GIA) processes. When coupled with altimetry, these space gravimetry data provide a powerful framework for studying climate-related changes on decadal timescales, such as ice mass loss and sea-level rise. As the changes in the latter are significant over the past two decades, there is a concomitant self-attraction and loading phenomenon generating ancillary changes in gravity, sea surface, and solid Earth deformation. These generate a finite signal in GRACE and ocean altimetry, and it may often be desirable to isolate and remove them for the purpose of understanding, for example, ocean circulation changes and post-seismic viscoelastic mantle flow, or GIA, occurring beneath the seafloor. Here we perform a systematic calculation of sea-level fingerprints of on-land water mass changes using monthly Release-06 GRACE Level-2 Stokes coefficients for the span April 2002 to August 2016, which result in a set of solutions for the time-varying geoid, sea-surface height, and vertical bedrock motion. We provide both spherical harmonic coefficients and spatial maps of these global field variables and uncertainties therein (https://doi.org/10.7910/DVN/8UC8IR; Adhikari et al., 2019). Solutions are provided for three official GRACE data processing centers, namely the University of Texas Austin's Center for Space Research (CSR), GeoForschungsZentrum Potsdam (GFZ), and Jet Propulsion Laboratory (JPL), with and without rotational feedback included and in both the center-of-mass and center-of-figure reference frames. These data may be applied for either study of the fields themselves or as fundamental filter components for the analysis of ocean-circulation- and earthquake-related fields or for improving ocean tide models.
Highlights
Geodesists have long understood that the ocean mean sea surface follows the shape of the Earth’s geoid (Rapp, 1983) and that changes in on-land water storage are a source of time-varying gravity (Lambert and Beaumont, 1977)
The utility of the data we provide is that they may be used to rigorously remove those patterns that are attributable to geoid height change and bedrock motions caused by on-land mass changes from ocean altimetry, bottom-pressure, and tide gauge studies
In this paper we describe a data product that emerges from the Release-06 Gravity Recovery and Climate Experiment (GRACE) Level-2 Stokes coefficients, provided by Center for Space Research (CSR), GeoForschungsZentrum Potsdam (GFZ), and Jet Propulsion Laboratory (JPL), which contain the basic information necessary to create monthly sea-level fingerprints, and these are general enough that they may be employed in reconstructions of vertical bedrock motion, perturbed relative sea surface, and geoid height change
Summary
Geodesists have long understood that the ocean mean sea surface follows the shape of the Earth’s geoid (Rapp, 1983) and that changes in on-land water storage are a source of time-varying gravity (Lambert and Beaumont, 1977). Sea-level fingerprints are a consequence of the fact that the water elements being transported laterally between land and oceans carry mass, gravitational attraction, and the ability to change the radial stress at the solid Earth surface. These are characterized, for example, as changes in relative sea level encircling areas of intense ice mass loss such as Patagonia, coastal Alaska, the Amundsen Sea sector of West Antarctica, and the Greenland Ice Sheet (e.g., Mitrovica et al, 2001; Tamisiea et al, 2014; Riva et al, 2010; Adhikari and Ivins, 2016)
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