Retrieval of surface loading and geocenter motion from a new combination of GRACE, modeled OBP andreprocessed GPS data

Variations in continental water storage, ocean and atmosphere cause changes in the gravitational potential of the Earth. Additionally, the solid Earth deforms noticeably under its load, which can be detected by a network of permanent GPS stations. The conservation of linear momentum implies that a shift of the center of gravity of the surface load is accompanied by a shift of the solid part of the Earth. Here, we combine GRACE gravimetry, homogeneously processed GPS site displacements, and modeled Ocean Bottom Pressure (OBP) in a least squares inversion. This approach yields weekly estimates of global surface loading, including a consistent treatment of the geocenter motion. Furthermore, we describe the updated spatially varying OBP error, used in the inversion. The inversion results are compared against a globally distributed set of in-situ bottom pressure recorders. Additionally, we propagate the weekly solutions back to the GPS site displacements and asses to what extent the measured GPS site displacements can be explained by surface loading.