Annual vertical crustal motions predicted from surface mass redistributionand 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 c ompute globally theoretical vertical displacements of the Earth's crust cau sed by the main annual surface mass redistributions (atmosphere and ocean m ass, soil moisture, and snow load). For that purpose we consider atmospheri c pressure data from the National Centers for Environment Prediction (NCEP) , soil moisture data from Huang et al, [1996] and from the Global Soil Wetn ess Project (GSWP), snow data from the International Satellite and Surface Climatology Project (ISLSCP) and GSWP, and ocean mass data from the Paralle l Ocean Climate Model (POCM) and from TOPEX-Poseidon satellite altimetry af ter correcting for steric effects. Annual vertical displacements are comput ed for each load individually as well as for the total climatic contributio n on global 2.5 degrees x2.5 degrees grids. We then present space geodesy-d erived annual variations of vertical coordinates of 16 Doppler orbitography and radiopositioning integrated by satellite (DORIS) stations globally dis tributed around the globe. A comparison is then performed for each station between observed (by DORIS) and predicted (from climatology) results.