Our analysis strategy summary


We use GINS/DYNAMO software package for the satellites orbit determination and for the computation of 3.5-day NEQ residuals. Weekly station positions and daily ERP are solved together from 7-day NEQ systems.

Models and standards

The table below gives the list of models and standards applied for the processing of the grgwd40 series for the contribution to the ITRF2014.

Data Analysis Summary of the DORIS weekly SINEX series used in the IDS combination for the realization of ITRF2014
Sinex Series
Name grgwd40
Description form TBD
Analysis Center
Contact H. Capdeville
Additionnal contacts J.M. Lemoine, L. Soudarin
Name and version GINS v 13.2d1
Data weights (data reduction) 0.3 mm/s
If COV, Station Constraint 10 m
If COV, EOP Constraint 15 m
satellites included in weekly SINEX start-end
SPOT2 03/01/1993 - 18/07/2009
SPOT3 30/01/1994 - 16/11/1996
SPOT4 03/05/1998 - 22/06/2012
SPOT5 16/06/2002 - 31/12/2013
TOPEX 03/01/1993 - 30/10/2004
ENVISAT 21/07/2002 - 07/04/2012
JASON1 31/10/2004 - 12/07/2008
JASON2 13/07/2008 - 31/12/2013
CRYOSAT2 20/06/2010 - 31/12/2013
HY2A 02/10/2011 - 31/12/2013
Arc cut
Arc lengths 3.5 days nominally (minimum 1 day)
Handle of Manoeuvers Break arc and Restart at 12am or 12pm; estimated from 2012/01/01
Handle of Data gaps Arcs truncated for large data gaps and Restarted.
Additional margins 6hrs before and 6 hrs after for POD but not in SINEX
Reference System
Earth reference system DPOD2008v12
Celestial reference system inertial J2000
Polar motion and UT1 IERS C04 08
Background C21, S21  
Pole model  
Precession/Nutation IERS 2010 using NRO origin
Station coordinates DPOD2008v12
Displacement of reference points
Solid Earth tidal displacement IERS 2010 Conventions
Ocean loading FES 2012
Tidal atmospheric loading S1/S2 Ray & Ponte (2003)
Non tidal atmospheric loading none
Solid pole tide displacement IERS 2010 Conventions
Ocean pole tide displacement none
Tidal Geocenter  
Satellite reference
Mass and center of gravity initial values and time evolution from IDS files "sat"mass.txt
Attitude Model nominal laws
Gravity field (static) EIGEN-6S2
Gravity field (time varying) EIGEN-6S2 up to degree 95 including time variable terms up to degree 50 (bias & drift per yr from 2002 to 2012, periodic 18.6, 1, 0.5yrs)
Solid Earth tides IERS 2010 conventions
Ocean tides FES 2012 (32 principal waves, + 60 admittance waves) up to degree 50
Atmospheric gravity 3hr ERA-interim / ECMWF up to degree 50
Air Tides  
Non tidal oceanic gravity TUGO R12 up to degree 50 TUGO R12 up to degree 50
Atmospheric tides none (considered through the ECMWF atmospheric data)
Earth pole tide IERS 2010 conventions
Ocean pole tide Desai 2002 up to degree 12
Third bodies Sun, Moon, Mars, Venus, Jupiter, Saturn, Uranus and Neptune ephemeris : DE421 (JPL)
Surface forces and empiricals
Radiation Pressure model Thermo-optical coefficient from pre-launch box and wing model, with smoothed Earth shadow model; models from CNES document for all satellites except tuned macromodels for Spot-2, -3, -4, Jason2
Radiation pressure scale coefficient 1 coef/day but strongly constrainted (1. e-4) to: 1.03 for Topex; 1.07 for Spot-2; 1.07 for Spot-3; 1.16 for Spot-4; 1.05 for Spot-5; 1.05 for Envisat; 0.94 for Jason-1, 0.97 for Jason-2; 1.00 for Cryosat-2; 1.13 for HY-2A
Earth radiation Albedo and IR pressure values interpolated from ECMWF 6hr grids
Atmospheric density model DTM 94, with best available solar activity
Drag coefficients Adjusted; Spots, Envisat, Cryosat2, HY-2A: 1 coef/4 hours (1/1hr in high solar activity periods) ; Topex,Jasons: 1 coef/half day
1/rev empiricals 2 coeff cos-sin /orbital period in normal direction ; 2 coeff cos-sin /orbital period in tangential direction ; per arc
DORIS measurements
Troposphere Model GPT2/VMF1
Weather (meteorological data)  
Troposphere mapping function  
Troposphere correction One zenith delay/pass (wet tropo scale factor adjusted) + one daily tropospheric gradient per station in North & East directions
2nd order ionosphere Not applied
Frequency 1 frequency bias adjusted per pass
Relativity Schwarzschild model + Lense-Thirring + geodesic precession
Weight models: 0.3 mm/s; measurements: derived from observation standard deviation in data files
Elevation angle cutoff 12 degrees
Downweighting law Downweighting law for elevation <= 20 deg; Weight of the observation is multiplied by the factor elevation**2/400 with elevation in degrees)
Satellite system Center of mass - antenna phase center vector computed from macro model + attitude law; no phase law applied
Ground system Phase centre / reference point vector from manufacturer values; phase law applied (Alcatel, Starec version 2013)
DORIS System Time Bias  
South Atlantic Anomaly Corrective model for Jason-1; corrected measurements for Spot-5 from 2006 only