Global-scale validation of model-based load deformation of the Earth's crust from continental watermass and atmospheric pressure variations using GPS |
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| Institution: | 1. Institut für Planetare Geodäsie, Technische Universität Dresden, 01069 Dresden, Germany;2. Institut für Physische Geographie, Johann Wolfgang Goethe-Universität, 60054 Frankfurt am Main, Germany;1. College of Surveying and Geo-Informatics, Tongji University, Shanghai 200092, China;2. State Key Laboratory of Marine Geology, Tongji University, Shanghai 200092, China;1. Department of Mechanical Engineering, École de Technologie Supérieure (ÉTS), Montréal, QC, Canada H3C 1K3;2. IRSST, Montréal, QC, Canada H3A 3C2;3. Department of Mechanical Engineering, Université de Sherbrooke, Sherbrooke, QC, Canada J1K 2R1;1. College of Physics and Optoelectronics, Taiyuan University of Technology, Taiyuan 030024, China;2. Key Laboratory of Advanced Transducers and Intelligent Control Systems (Ministry of Education and Shanxi Province), Taiyuan University of Technology, Taiyuan 030024, China;3. State Key Laboratory of Coal and CBM Co-mining, Jincheng 048000, China;1. Department of Mechanical Engineering, École de Technologie Supérieure (ÉTS), Montréal, (Qc) H3C 1K3, Canada;2. School of Mechanical and Manufacturing Engineering, UNSW Sydney, NSW 2052, Australia;1. College of Earth Science and Engineering, Hohai University, Nanjing 211100, China;2. North China University of Water Resources and Electric Power, Zhengzhou 450045, China |
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| Abstract: | Temporal mass variations in the continental hydrosphere and in the atmosphere lead to changes in the gravitational potential field that are associated with load-induced deformation of the Earth’s crust. Therefore, models that compute continental water storage and atmospheric pressure can be validated by measured load deformation time series. In this study, water mass variations as computed by the WaterGAP Global Hydrology Model (WGHM) and surface pressure as provided by the reanalysis product of the National Centers for Environmental Prediction describe the hydrological and atmospheric pressure loading, respectively. GPS observations from 14 years at 208 stations world-wide were reprocessed to estimate admittance factors for the associated load deformation time series in order to determine how well the model-based deformation fits to real data. We found that such site-specific scaling factors can be identified separately for water mass and air pressure loading. Regarding water storage variation as computed by WGHM, weighted global mean admittances are 0.74 ± 0.09, 0.66 ± 0.10, 0.90 ± 0.06 for the north, east and vertical component, respectively. For the dominant vertical component, there is a rather good fit to the observed displacements, and, averaged over all sites, WGHM is found to slightly overestimate temporal variations of water storage. For Europe and North America, with a dense GPS network, site-specific admittances show a good spatial coherence. Regarding regional over- or underestimation of WGHM water storage variations, they agree well with GRACE gravity field data. Globally averaged admittance estimates of pre-computed atmospheric loading displacements provided by the Goddard Geodetic VLBI Group were determined to be 0.88 ± 0.04, 0.97 ± 0.08, 1.13 ± 0.01 for the north, east and vertical, respectively. Here, a relatively large discrepancy for the dominant vertical component indicates an underestimation of corresponding loading predictions. |
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