Updated Release 3 of the GRACE Gravity Solutions from CNES/GRGS

Wednesday, 17 December 2014
Sean Bruinsma1, Jean-Michel Lemoine1, Pascal Gegout2, Richard Biancale1 and Stephane Bourgogne3, (1)CNES, Toulouse, France, (2)OMP/CNRS/GS/GRGS, Toulouse, France, (3)Geode&Cie, Toulouse, France
The GRACE satellites, launched in 2002, have provided data for more than 130 monthly gravity models in its 11 years of operation. Comparison of the models mainly shows the changes in continental water and snow storage.

CNES/GRGS has recomputed its solutions providing now updated Release 3 (RL03-v1) gravity solutions in terms of spherical harmonics up to degree/order 80. They are based on GRACE GPS and KBR data, as well as on LAGEOS-1/2 SLR data mainly to solve degrees 1 and 2 more accurately. Compared to the previous Release 2, it is now based on reprocessed Level-1B.v2 data, and it includes several improvements regarding dealiasing a priori models such as the FES2012 ocean tide model, ECMWF ERA-interim (atmosphere) and TUGO (non IB-ocean) models every 3 hours. The orbit parameterization with respect to KBR and accelerometer data has been modified with the goal to better constrain the dynamics. Finally, the inversion procedure is now done by Eigen values decomposition, which allows - by truncation of negligible Eigen values - a direct interpretation of the gravity solutions without the need for additional filtering.

This RL03, completed to Summer 2014, can be easily compared to project groups RL05 solutions thanks to the newly developed “Grace Plotter” tool (www.thegraceplotter.com).