Abstract
The vertical motion of the Earth’s surface is dominated by the hydrologic cycle on a seasonal scale. Accurate land deformation measurements can provide constructive insight into the regional geophysical process. Although the Global Positioning System (GPS) delivers relatively accurate measurements, GPS networks are not uniformly distributed across the globe, posing a challenge to obtaining accurate deformation information in data-sparse regions, e.g., Central South-East Asia (CSEA). Model simulations and gravity data (from the Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-On (GRACE-FO)) have been successfully used to improve the spatial coverage. While combining model estimates and GRACE/GRACE-FO data via the GRACE/GRACE-FO data assimilation (DA) framework can potentially improve the accuracy and resolution of deformation estimates, the approach has rarely been considered or investigated thus far. This study assesses the performance of vertical displacement estimates from GRACE/GRACE-FO, the PCRaster Global Water Balance (PCR-GLOBWB) hydrology model, and the GRACE/GRACE-FO DA approach (assimilating GRACE/GRACE-FO into PCR-GLOBWB) in CSEA, where measurements from six GPS sites are available for validation. The results show that GRACE/GRACE-FO, PCR-GLOBWB, and GRACE/GRACE-FO DA accurately capture regional-scale hydrologic- and flood-induced vertical displacements, with the correlation value and RMS reduction relative to GPS measurements up to 0.89 and 53%, respectively. The analyses also confirm the GRACE/GRACE-FO DA’s effectiveness in providing vertical displacement estimates consistent with GRACE/GRACE-FO data while maintaining high-spatial details of the PCR-GLOBWB model, highlighting the benefits of GRACE/GRACE-FO DA in data-sparse regions.
Highlights
Land deformation is a response of (1) geophysical processes governed by, e.g., hydrology, atmosphere, ocean mass transports associated with the earth system, and (2)anthropogenic impact associated with the human intervention [1,2]
The results show that GRACE/GRACE-FO, PCRGLOBWB, and GRACE/GRACE-FO data assimilation (DA) accurately capture regional-scale hydrologic- and floodinduced vertical displacements, with the correlation value and RMS reduction relative to Global Positioning System (GPS)
It was found that the ∆r estimate in Central SouthEast Asia (CSEA) is primarily governed by hydrologic variations and extreme events, which can be detected by the GRACE/GRAE-FO satellites, hydrology model, and ground measurements
Summary
Land deformation is a response of (1) geophysical processes governed by, e.g., hydrology, atmosphere, ocean mass transports associated with the earth system, and (2). Anthropogenic impact associated with the human intervention [1,2]. Such processes cause the Earth’s surface to subside or uplift, severely affecting the scientific and industrial sectors [3,4]. Despite being affected by different Earth system drivers, land deformation is dominated by the hydrology cycle at annual and interannual scales [1,5,6,7]. Significant terrestrial water storage variation (∆TWS), influenced by exceptional annual precipitation
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