The GFZ-GRGS combined-only gravity field model EIGEN-6C
=========================================================
Contact:
Christoph Foerste
e-mail: foer@gfz-potsdam.de

Reference:
----------
Christoph Förste (1), Sean Bruinsma (3), Richard Shako (1), Jean-Charles Marty (3), 
Frank Flechtner (2), Oleh Abrikosov (1), Christoph Dahle (2), Jean-Michel Lemoine (3), 
Hans Neumayer (2), Richard Biancale (3), Franz Barthelmes (1), Rolf König (2)
and Georges Balmino (3) (2011),
EIGEN-6 - A new combined global gravity field model including GOCE data 
from the collaboration of GFZ-Potsdam and GRGS-Toulouse,
Geophysical Research Abstracts
Vol. 13, EGU2011-3242-2, 2011
EGU General Assembly 2011


(1) GeoForschungsZentrum Potsdam
    Dept. 1 'Geodesy and Remote Sensing'
    Telegrafenberg, D-14473 Potsdam
    Germany
    e-mail: foer@gfz-potsdam.de
    fax: ++49 331 288 1169

(2) GeoForschungsZentrum Potsdam
    Department 1 'Geodesy and Remote Sensing'
    c/o DLR Oberpfaffenhofen, D-82234 Weßling
    Germany
    e-mail: flechtne@gfz-potsdam.de
    fax: ++49 331 288 1169

(3) Groupe de Recherche de Geodesie Spatiale 
    18, avenue Edouard Belin, F-31055 Toulouse
    France
    e-mail: richard.biancale@cnes.fr
    fax: ++33 5 61 253098)


EIGEN-6C is a combined global gravity field of a maximum degree/order 1420 
It consists of:
- 6.5 years of LAGEOS (SLR) and GRACE (GPS-SST and K-band
  range rate) data from the time span 1 Jan 2003 till 30 June 2009
- 6.7 months of GOCE data  (Satellite gradiometry only) from the time
  span 1 Nov 2009 till 30 June 2010. As terrestrial data
- the DTU2010 global gravity anomaly data set obtained from altimetry
  and gravimetry.
The combination of the different satellite and terrestrial data has been
done of the basis of normal equations. The solution has been obtained from
one full normal equation to d/o 365 and a block diagonal solution (for the 
terrestrial data only) to d/o 1420.

This gravity field model contains time variable parameters (gfct, trnd, acos, asin, 
t0 and period) up to d/o 50. The computation of the values of the time variable 
spherical coefficients G at a certain epoch t must be done by applying the 
drift parameters trnd as well as the periodic terms acos and asin in the following 
way. In the given rule the two periodic terms are denoted by asin1/acos1 and 
asin2/acos2 in accordance with the two periods p1 = 1.0 year and p2 = 0.5 year.
The reference epoch is denoted by t0.

G(t)=gfct + trnd*(t-t0) + asin1*sin(2pi/p1*(t-t0))+acos1*cos(2pi/p1*(t-t0))
                        + asin2*sin(2pi/p2*(t-t0))+acos2*cos(2pi/p2*(t-t0))
	
The details of the format description are available at 
http://icgem.gfz-potsdam.de/ICGEM/documents/ICGEM-Format-2011.pdf




begin_of_head =====================================
product_type                gravity_field
modelname                   EIGEN-6C
earth_gravity_constant      0.3986004415E+15
radius                      0.6378136460E+07
max_degree                  1420
tide_system                 tide_free
errors                      formal
norm                        fully_normalized





key    L    M         C                  S           sigma C    sigma S   t0[yyyymmdd]
                                                                          period[y]
end_of_head =============================================================