Surface loading effects for precise geodetic observations: models and error estimates

Abstract:

The precision reached by modern geodetic techniques requires an accurate modeling of surface loading processes in order to reach the millimeter-level for displacements, the nanogal-level for surface gravity observations. Over the past decade, many operational loading services have been established, allowing researchers to access atmospheric, tidal and non-tidal oceanic, hydrological loading models and correct geodetic observations.

We present here an overview of the EOST loading service (http://loading.u-strasbg.fr) providing different products of atmospheric, non-tidal oceanic and hydrological loading effects on displacements and surface gravity.

We also investigate and assess the different sources of errors in loading computations:

1. The choice of the reference frame for displacement computations (Center-of-Figure versus Center-of-Mass).
2. The differences between different atmospheric (reanalysis versus operational models), non-tidal oceanic (low resolution versus eddy-resolving models) and hydrological models.
3. The model of ocean response to pressure forcing (inverted barometer versus a dynamic model).
4. The resolution of the land/sea mask used for the loading computations.
5. The choice of an Earth model to compute Green’s functions.
6. The differences between interpolated loading grids and station computations.