About this service

The global circulation of surface geophysical fluids (atmosphere, oceans, continental hydrology) induces global Earth deformation and gravity field changes, which can be detected by precise modern geodetic techniques. This service provides models of 3-D surface displacements (global maps and site displacements), surface gravity and tilt variations at various sites, computed using atmospheric, oceanic and hydrological general circulation models.

Version 1.0 (APLO, AGRA, HGRA)

• 3-D displacements due to atmospheric loading, assuming an Inverted Barometer ocean response, for SLR (102), VLBI (203), DORIS (157) and IGS (424) sites.
• Time-variable gravity field (& geocenter motions) due to atmospheric loading, assuming an Inverted Barometer ocean response, up to degree 72.
• Time-variable gravity field (& geocenter motions) due to continental hydrology (soil-moisture and snow), up to degree 72.

computed from 6-hourly surface pressure and continental hydrology from ECMWF operational and reanalysis (ERA40 and ERA-interim) products.

Global maps of 3-D displacements

3-D displacement maps are currently provided on 3-hourly and 0.5-degree grids, in both the Center-of-Mass and Center-of-Figure reference frames:

• Atmospheric loading using ECMWF surface pressure fields (operational model), assuming an inverted barometer oceanic response.
• Atmospheric loading, assuming a barotropic oceanic response to pressure and winds using TUGO-m model (Carrere and Lyard, 2003).
• Continental hydrology using GLDAS/Noah (Rodell et al., 2004) model

3-D displacements at ITRF sites

We provide 3-D displacements due to atmospheric, induced oceanic (inverted barometer or dynamic response) and hydrological loading for ITRF 2014 sites at high sampling rate (less than 1-day), computed in both Center-of-Mass and Center-of-Figure reference frames.

Time-variable gravity field

We provide Stokes coefficients due to atmospheric, oceanic and hydrological loading, fully compatible with the 3-D global displacement maps.

Surface gravity

We also release surface gravity variations due to atmospheric, induced oceanic and hydrological loading effects computed at IGETS (International Geodynamics and Earth Tide Service) sites.

Tilts for selected sites

Tilt variations due to atmospheric, induced oceanic and hydrological loading effects are provided for a selection of sites.

This service has been developped thanks to funding from CNES through its TOSCA program.