Annual vertical crustal motions predicted from surface mass redistribution and observed by space geodesy

Temporal variations of surface mass redistribution among atmosphere, oceans, and continental water reservoirs deform the Earth's crust, in particular in the vertical direction. These displacements can now be measured by space geodesy and predicted from climatic loading data. In this study we first compute globally theoretical vertical displacements of the Earth's crust caused by the main annual surface mass redistributions (atmosphere and ocean mass, soil moisture, and snow load). For that purpose we consider atmospheric pressure data from the National Centers for Environment Prediction (NCEP), soil moisture data from Huang et al, [1996] and from the Global Soil Wetness Project (GSWP), snow data from the International Satellite and Surface Climatology Project (ISLSCP) and GSWP, and ocean mass data from the Parallel Ocean Climate Model (POCM) and from TOPEX-Poseidon satellite altimetry after correcting for steric effects. Annual vertical displacements are computed for each load individually as well as for the total climatic contribution on global 2.5 degrees x2.5 degrees grids. We then present space geodesy-derived annual variations of vertical coordinates of 16 Doppler orbitography and radiopositioning integrated by satellite (DORIS) stations globally distributed around the globe. A comparison is then performed for each station between observed (by DORIS) and predicted (from climatology) results.