Estimating geoid height change in North America: past, present and future

Abstract

The forthcoming GRAV-D gravimetric geoid model over the United States is to be updated regularly to account for changes in geoid height. Its baseline precision is to be at the 10-20 mm level over non-mountainous regions. The aim of this study is to provide an estimate of the magnitude, time scale, and spatial footprint of geoid height change over North America, from mass redistribution processes of hydrologic, cryospheric and solid Earth nature. Geoid height changes from continental water storage changes over the past 50 years and predicted over the next century are evaluated and are highly dependent on the used model. Groundwater depletion from anthropogenic pumping in regional scale aquifers may lead to geoid changes of 10 mm magnitude every 50-100 years. The GRACE time varying gravity fields are used to (i) assess the errors in a glacial isostatic adjustment model, which, if used to correct the GRAV-D model, may induce errors at the 10 mm geoid height level after ∼20 years, (ii), evaluate geoid height change over ice mass loss regions of North America, which, if they remain unchanged in the future, may lead to geoid height changes at the 10 mm level in under a decade and (iii), compute sea level rise and its effect on the geoid, which is found to be negligible. Coseismic gravitational changes from past North American earthquakes are evaluated, and lead to geoid change at the 10-mm level for only the largest thrust earthquakes. Finally, geoid change from volcanic processes are assessed and found to be significant with respect to the GRAV-D geoid model baseline precision for cataclysmic events, such as that of the 1980 Mt. St. Helens eruption. Recommendations on how to best monitor geoid change in the future are given.

Reprint of: Requirements of 3D cadastres for height systems

“…Natural changes to the geoid have been evaluated by Jacob et al (2012) and his team in the study ''Estimating geoid height change in North America: past, present and future''.…”

Automated Dynamic Mascon Generation for GRACE and GRACE-FO Harmonic Processing

“…Global mascon solutions from the Level-1 data are provided to the scientific community by the JPL [11], CSR [12], and the Goddard Space Flight Center (GSFC) [13,14]. For end users, customized regional mascon solutions can also be created using the Level-2 spherical harmonic solutions [15][16][17][18][19]. Reference [10] used a filtering and smoothing approach to calculate the mass balance of Indian water basins from Level-2 harmonics.…”

“…Reference [10] used a filtering and smoothing approach to calculate the mass balance of Indian water basins from Level-2 harmonics. Later studies by Jacob and colleagues used a least-squares mascon approach to calculate the mass balance of regionally defined non-uniform regions in North America [16] and the world's glaciated regions [20]. This approach was further improved by [15,21] by using regional uniform spherical caps that minimize the leakage of the mascon solutions.…”