Introduction to GRACE and SLR solutions from CNES/GRGS


This site contains time series of gravity field models as well as mean gravity field models, expressed in normalized spherical harmonic coefficients.

These fields are recovered from GRACE GPS and K-band range-rate data and from the SLR data from 5 satellites: LAGEOS-1/2, Starlette, Stella and Ajisai (SLR data provide over 90% of the information on the coefficient C(2,0) of the gravity field, whereas GRACE data provide nearly 100% of the information on all the other harmonic coefficients).

To this day, five series of variable fields have been released. The first release (standards 2005) consists of 30-day models based on the running average of three 10-day data periods with weights 0.5/1.0/0.5. The second release (standards 2009) consists of strictly 10-day models. In both cases, fields are given every 10 days and are complete up to spherical harmonic degree 50. The third release (standards 2013), based on the reprocessed level-1B data « L1B-v2 », features monthly and 10-day solutions up to spherical harmonic degree 80. The fourth release (standards 2018) features monthly solutions up to spherical harmonic degree 90. The fifth release (standards 2019) features GRACE & GRACE-FO monthly and 10-day solutions up to spherical harmonic degree 90.

In parallel with gravity field time series, mean models containing time variable gravity coefficients are also produced. They can be found here.

The models are tide free.

Gravitational variations such as Earth tides, ocean tides, 3D-atmospheric pressure fields and barotropic ocean response model have been taken into account in the processing of the data. The time-variable gravity field models therefore only depart from the static gravity field by the unmodelled effects: hydrology, snow cover, baroclinic oceanic signals and post-glacial rebound. The uncertainties of those fields include errors in the measurement data, in the processing, lack of coverage in some instances, and possible remaining errors in the FES, MOG2D/TUGO and ECMWF models.

 RL01 and RL02RL03RL04RL05
IERS Conventions200320102010 (with 2018 update for the linear mean pole model)2010 (with 2018 update for the linear mean pole model)
Ocean tide modelFES2004 (LEGOS)FES2012 (LEGOS)FES2014 (LEGOS)FES2014b (LEGOS)
Atmospheric pressure dealiasing


ECMWF operational, every 6 h
(processed by P Gégout, CNRS/GET)
ECMWF ERA-Interim, every 3 h
(processed by P Gégout, CNRS/GET)
ECMWF ERA-Interim, every 3 h
(processed by P Gégout, CNRS/GET)
Ocean barotropic response modelMOG2D (LEGOS), every 6hTUGO (LEGOS), every 3 hTUGO (LEGOS), every 3 hAOD1B RL06

The grids and maps of geoid variations and equivalent water height (EWH) variations at 10-day or monthly intervals (mean 1°×1° values), as well as movies (in animated-gif format), are also provided.

Important notice

It is reminded to the users of the GRGS products that NO SMOOTHING OR FILTERING is necessary when using them, since they have already been stabilized during their generation process.

Release 05

Our latest release is now available.

Latest models

See RL05 page for recent information about latest available models.

THE GRACE PLOTTER : a new website for plotting and comparing GRACE solutions

We propose to the community of GRACE users a new website for plotting and comparing GRACE solutions.

On this website you will be able to plot time series of GRACE solutions in terms of equivalent water height (EWH), either for point locations, spherical rectangles or polygons (up to 10 summits), or hydrological basins (approx. 30 are available, ordered by surface area from the Amazon to the Brahmaputra).

Not only the CNES/GRGS releases are present there, but also the three RL05 releases from CSR, GFZ and JPL, filtered using the DDK5 filter. The series of CSR, GFZ and JPL were obtained from the ICGEM data base.

We hope this website can be a useful tool for most GRACE users whether they want to conduct scientific research, solutions comparisons or evaluation. It is still in a development phase and all suggestions for improvement are welcome.

The location of this new site is: