GRACE > GRGS Time Variable Models from GRACE / LAGEOS > GRACE solutions release 02

Groupe de Recherche de Géodésie Spatiale Centre national d’études spatiales

The second release of CNES/GRGS gravity field models (10-day models)

Latest models

2012/12/05: 17 new gravity field models are available, covering January 28th to August 24th 2012!
4 fields are missing (from April 17th to May 26th) due to accelerometer gaps.

2012/04/24: 15 new gravity field models are available, covering August 31st 2011 to January 27th 2012!
3 fields are missing (from November 19th to December 18th) due to accelerometer gaps.

2011/12/23: 12 new gravity field models are available, covering April 3rd to August 30th 2011.
2 fields are missing (from June 12th to July 1st), due to accelerometer gaps.

2011/07/22: 7 new gravity fields models are available, covering February 2nd to April 12th 2011.
4 fields are missing (from December 24th to February 1st), due to accelerometer gaps.

2011/04/07: 12 new gravity fields models are available, covering August 26th to December 23rd 2010.
 We now also provide grids in GRACE format (3 columns file), and images in polar projection.
 We have corrected two bugs in our files:

  • the grids in GRGS format had a small amplitude problem, the amplitudes were exagerated by a factor between 0 % at low latitudes up to 10 % at high latitudes ;
  • the dealiasing products were not corrected for the Love load numbers and therefore didn't take into account the loading effect.

These two bugs are now corrected. SH models (coefficients) were not affected by these problems.

Spherical harmonic coefficients of 10-day gravity field models

These are 10-day gravity field models from SH degree 2 up to SH degree and order 50, given every 10 days, using GRACE and LAGEOS data (in ITRF2000).

Models are provided every 10 days and are based solely on the 10 days (maximum) of data that are in this time interval (whereas "version 1" models were provided every 10 days but were based on three consecutive 10-day periods with the weighting 0.5/1./0.5).

10-day models are stabilized towards EIGEN-GRGS.RL02.MEAN-FIELD , more precisely towards the realization of EIGEN-GRGS.RL02.MEAN-FIELD at each given epoch, with a new constraint law that depends on the degree and on the order of each coefficient (in version 1, the law was only degree-dependent and the models were constrained towards the static part of EIGEN-GL04S and later EIGEN-GL04C ).

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.

Missing solutions

There are some gaps in this time series, coming either from GPS, from accelerometers or from KBR data gaps. Twenty 10-day solutions are missing:

Dates (yyyy-mm-dd) Dates (yyyy-doy) Julian days 1950
2002-11-26_2002-12-05 2002-330_2002-339 19322_19331
2002-12-06_2002-12-15 2002-340_2002-349 19332_19341
2002-12-16_2002-12-25 2002-350_2002-359 19342_19351
2002-12-26_2003-01-04 2002-360_2003-004 19352_19361
2003-01-05_2003-01-14 2003-005_2003-014 19362_19371
2003-01-15_2003-01-24 2003-015_2003-024 19372_19381
2003-01-25_2003-02-03 2003-025_2003-034 19382_19391
2003-02-04_2003-02-13 2003-035_2003-044 19392_19401
2003-02-14_2003-02-23 2003-045_2003-054 19402_19411
2003-05-25_2003-06-03 2003-145_2003-154 19502_19511
2003-06-04_2003-06-13 2003-155_2003-164 19512_19521
2003-06-14_2003-06-23 2003-165_2003-174 19522_19531
2003-06-24_2003-07-03 2003-175_2003-184 19532_19541
2004-01-20_2004-01-29 2004-020_2004-029 19742_19751
2010-12-24_2011-01-02 2010-358_2011-002 22272_22281
2011-01-03_2011-01-12 2011-003_2011-012 22282_22291
2011-01-13_2011-01-22 2011-013_2011-022 22292_22301
2011-01-23_2011-02-01 2011-023_2011-032 22302_22311
2011-06-12_2011-06-21 2011-173_2011-182 22442_22451
2011-06-22_2011-07-01 2011-183_2011-192 22452_22461
2011-11-19_2011-11-28 2011-323_2011-332 22602_22611
2011-11-29_2011-12-08 2011-333_2011-342 22612_22621
2011-12-09_2011-12-18 2011-343_2011-352 22622_22631
2012-04-17_2012-04-26 2012-108_2012-117 22752_22761
2012-04-27_2012-05-06 2012-118_2012-127 22762_22771
2012-05-07_2012-05-16 2012-128_2012-137 22772_22781
2012-05-17_2012-05-26 2012-138_2012-147 22782_22791

Grids, images and movies

Grids, images and movies of geoid and equivalent water heights differences with static field are provided. The grids are 1° x 1° global grids of geoid height or equivalent water heights differences (in meters) between time-variable solutions and static field(at reference date if the static field includes time-variable terms). The images represent geoid or equivalent water heights differences (in millimeters) between time-variable solutions and static field (at reference date if the static field includes time-variable terms). Images are compiled in geoid or EWH movies.

Dealiasing products

The files provided here contain the so-called "dealiasing products" used by CNES/GRGS, temporally averaged in a manner consistent with the way the time-variable gravity field models are produced. In the processing of the GRACE data, the gravitational influence of the Earth atmospheric pressure on the satellites' orbits, as well as the oceanic response to it, is taken into account in the form of ECMWF 3-D atmospheric pressure fields over the whole Earth every 6 hours (with linear interpolation in-between) and MOG2D model of the response of the oceanic domain to the atmospheric forcing (pressure and wind) at the same temporal resolution. A conversion from Pascal to normalized gravitational potential units is performed.

Reference

Reference paper : Bruinsma, S., Lemoine, J.-M., Biancale, R., et al: CNES/GRGS 10-day gravity field models (release 02) and their evaluation, Adv. Space Res., 45, 4, 587-601, 2010, doi: 10.1016/j.asr.2009.10.012.

XMASCEN correction

Since 2009/08/31, a recomputed "XMASCEN" correction for the KBR-R measurement has been substituted for the one found in the Level-1B files. The "XMASCEN" correction accounts for the distance, along the measurement line of sight, between the KBR antenna phase centres and the satellites centres of mass. It depends on the satellites position, attitude and KBR antenna phase centre coordinates in the satellite reference frame. We have recomputed this correction, taking into account adjusted coordinates of the KBR antenna phase centres [Horwath et al., 2010], thus greatly reducing the horizontal striping at ~1000 km wavelength sometimes observed in the temporal solutions.

Reference paper : Horwath, M., Lemoine, J.-M., Biancale, R., Bourgogne, S.: Improved GRACE science results after adjustment of geometric biases in the Level-1B K-band ranging data, Journal of Geodesy, 2010/10/06, doi: 10.1007/s00190-010-0414-2. Read article.

Formats

Download archive files (.tar.gz)

We have fixed two bugs in some parts of the data we provide on this site, affecting the period from July 29th 2002 to August 25th 2010:

  • One bug introduced an error on geoid and water grids (GRGS format) at high latitudes (maximum of 10%).
  • The other one is related to the dealiasing products: loading effect was not taken into account in our GAA and GAB files.

These two bugs have been fixed.

Please discard the previous version of grids and dealiasing products (2002-07-29 to 2010-08-25) and download the new ones. If you only downloaded SH models (coefficients), you are not affected by this problem.

RL02 corrected
 (see note above)
SH models Geoid heights
 Grids & Images
EWH
 Grids & Images
Dealiasing
 ATM3D/MOG2D
July 29th 2002
 August 24th 2012

GRGS format

Official GRACE format

GRGS format

Official GRACE format

GRGS format

Official GRACE format

Official GRACE format

Statistics

See/download individual solutions

See this page for interactive visualization and individual downloading.

Interactive tools

Visualization of time series (harmonic coefficients, geoid and water heights) and other interactive tools.

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