Models for Variations in the Global Geophysical Fluids and Their Impact on Space-Geodetic Solutions

Abstract:

Mass redistributions in the atmosphere, the oceans and the continental hydrology (i.e., the global geophysical fluids) cause loading deformations of the Earth’s crust. Special data sets to model the non-tidal loading deformations are available at the Global Geophysical Fluids Centre (GGFC) of the IERS. Different groups are generating loading models, thus, a comparison is needed in order to assess the difference between the models and set these differences in relation to the size of the loading deformation itself.

When analyzing space-geodetic data, the loading deformation has a direct impact on the station positions estimated as they cause non-linear station variations. Additionally, there is an indirect impact on other parameters of global space-geodetic solutions, e.g., Earth orientation parameters, geocenter coordinates, satellite orbits or troposphere parameters.

We show that the loading deformation as well as the differences between the models depend on the region. As a consequence, the impact on the space-geodetic solutions heavily depends on the network chosen for the analysis. This makes it special for the VLBI and SLR analysis as their networks are not as dense as the GNSS network used for global analysis.

We show the impact of atmospheric, oceanic and hydrological loading on the parameters of space-geodetic solutions when correcting for the global geophysical fluid models at the observation level. The agreement between GNSS, SLR and VLBI solutions is addressed, too.