Description form for lcawd12 series April 2005: an anomaly detected in Envisat data processing has been corrected (error in our modelling of the satellite's center of mass) All the ENVISAT mission was re-processed with the center of mass correction given in the data files. New sinex for 2002/07/21 (lca02202wd12.snx.Z) to 2004/10/02 (lca04270wd12.snx.Z) were delivered at the CDDIS and the previous ones removed. The same approach is used for all the satellites since 2004/10/03. 1) Purpose Solutions from the lcawd12 series are based on Spot2, Spot3 or Spot4, Spot5, Topex and Envisat data from january,3 1993 to october,2 2004. They give estimations for station coordinates and daily pole position. A new strategy has been applied, different from the one used for series lcamd01,lcamd02, lcamd03, lcawd 01 to 10. 2) Brief description DORIS data have been processed nominally on 3.5-day arc (half a week of the GPS calendar) for all the 5 satellites using the GINS/DYNAMO software. Because of lack of data or manoeuvers, arcs could be shorter but never shorter than 1 day. Stations positions have been combined on a weekly basis. Pole coordinates are estimated daily at 12:00. This times series of site and pole coordinates is expressed in free network with loose constraints (10 meter and 10 mas respectively). 3) Additional comments The coordinate solutions are expressed at the median epoch of the week. Specific information on stations AREA: Arequipa: A seond point has been defined after the 2001, June Earthquake. COLA: Colombo: A second point has been defined after November 1994 DIOA: Dyonisos: A second point has been defined after April 1, 1995 SAKA: Sakhalin: A second point has been defined after Oct 5, 1994 (earthquake on Oct 4, 1994) SAKA: Sakhalin: A third point has been defined after Dec 26, 1999 KRAB: Krasnoyarsk: A second point has been defined after Nov 1999 SODB: Soccorro Is.: A second point has been defined after Oct 3, 2002 (earthquake on Oct 3, 2002) OTTA: Ottawa: A first point has been defined for the period between Feb 1, 1990 and Jan 31, 1994 OTTA: Ottawa: A second point has been defined for the period between Feb 1, 1994 and Jan 31, 1998 (OTTA:the dubious position periods 01-SEP-1993/31-JAN-1994 and 04-JAN-1998/28-JAN-1998 were not processed) ============================================================================= INTERNATIONAL DORIS SERVICE LEGOS/GRGS - CLS Data Analysis Summary ============================================================================= ANALYSIS CENTRE | | LEGOS/GRGS - CLS | | Laboratoire d'Etudes en Géophysique et Océanographie | Spatiales | Groupe de Recherche en Géodésie Spatiale | 14 av. Ed. Belin 31400 Toulouse Cédex 4 | France | | Collecte Localisation satellites | 8-10 rue Hermès | Parc technologique du Canal | 31526 Ramonville cédex | France | ----------------------------------------------------------------------------- CONTACT PERSONS | | Jean-François Crétaux (LEGOS/GRGS) | E-mail : Jean-Francois.Cretaux@cnes.fr | Tél : (33) 05.61.33.29.89 | | Laurent Soudarin (CLS) | E-mail : Laurent.Soudarin@cls.fr | Tél : (33) 05.61.39.48.49 | | | Jean-Jacques Valette (CLS) | E-mail : Jean-Jacques.Valette@cls.fr | Tél : (33) 05.61.39.47.62 | | ----------------------------------------------------------------------------- SOFTWARE USED | | GINS-DYNAMO developed at LEGOS/GRGS | ----------------------------------------------------------------------------- PREPARATION DATE | 2004 | ============================================================================= ----------------------------------------------------------------------------- | MEASUREMENT MODELS | |---------------------------------------------------------------------------| | Data editing | | | | | | | | |---------------------------------------------------------------------------| | Basic measurement| | | | 2 frequencies : 2,03625 GHz (principal channel) and | | | 401.25 MHz | | | | | | entire number of cycles of a beat frequency (first | | | generation instrument on SPOT2, SPOT3, SPOT4, TOPEX/ | | | POSEIDON, SPOT5 satellites) | | | | | | fractional phase differences of a beat frequency | | | (second generation instrument on SPOT5 and JASON1 satel| | | lites) | | | | | | Data in internal CNES format used until Dec, 27th 2003 | | | "2.1 format" data from CDDIS used since Dec, 28th 2003 | | | | | |--------------------------------------------------------| | | elevation angle cutoff : 12 degrees | | | weighting : 0.4 mm/s | | | other : | |---------------------------------------------------------------------------| | Ground antenna | Height dependant on the antenna type | | phase centre cor.| | | | | |---------------------------------------------------------------------------| | Troposphere | CNET1 zenith delay model | | |--------------------------------------------------------| | | CNET1 mapping function | | | | |---------------------------------------------------------------------------| | Ionosphere | Two frequency model first order model (SOD/CNES) | | | | |---------------------------------------------------------------------------| | Relativity | Applied | | clock effects | | |---------------------------------------------------------------------------| | Plate motions | ITRF2000, IGN Doris mail. Nuvel1A for a few stations | | | http://ids.cls.fr/html/report/doris_mails.html | | | | |---------------------------------------------------------------------------| | Tidal | Solid earth tidal displacement : Wahr model | | displacements |--------------------------------------------------------| | | Pole tide : applied | | |--------------------------------------------------------| | | Ocean loading : applied | |---------------------------------------------------------------------------| | Atmospheric | applied from 6 hours ECMWF 3D pressure grids | | loading | | |---------------------------------------------------------------------------| | Clocks frequency | onboard frequency bias deduced from the master beacon | | deviation | (a bias per satellite pass) | |---------------------------------------------------------------------------| | Satellite center | applied | | of mass - antenna| from CDDIS data files for ENVISAT | | phase center | from CDDIS data files for SPOTs, TOPEX since 09/2004 | | correction | from satellite model for SPOTs, TOPEX before 09/2004 | |---------------------------------------------------------------------------| | Satellite | For TOPEX/POSEIDON, JASON and ENVISAT | | attitude | SPOT satellites orientation is geocentric | | | | |---------------------------------------------------------------------------| | Receiver-antenna | depends on the channel and the instrument generation | | propagation delay| | | | | |---------------------------------------------------------------------------| ----------------------------------------------------------------------------- | ORBIT MODELS | |---------------------------------------------------------------------------| | Geopotential | GRIM5-C1 up to degree 99 and order 95 | | |--------------------------------------------------------| | | Constants (IERS96 conventions ?) | | | AE = 6378.13646 km | | | 1/F = 298.25765 | | | GM = 398600.4415 km**3/sec**2 | | | OMEGA = 0.7292115 rad/sec | | | DATE = 1997.0 | |---------------------------------------------------------------------------| | Third-body | planets : Sun, Moon, Mars, Venus, Jupiter, Saturn and | | | Mercury | | |--------------------------------------------------------| | | ephemeris : DE403 (JPL) | |---------------------------------------------------------------------------| | Air drag | Air density model : DTM 94 | | | Satellite shape from macromodel | | | | |---------------------------------------------------------------------------| | Solar radiation | | | pressure | | | | direct radiation : applied | | |--------------------------------------------------------| | | Earth shadow model includes: penumbra from regularising| | | function | | |--------------------------------------------------------| | | reemitted radiation: | | | bef. 06/00 albedo from a monthly mean model IR applied | | | aft. 06/00 numerical model with albedo and IR functions| | |---------------------------------------------------------------------------| | satellite | applied | | thermal thrust | | | | | |---------------------------------------------------------------------------| | Tidal forces | solid earth tides: model of IERS 2000 Conventions | | |--------------------------------------------------------| | | Ocean tides: FES2002 (with admittance) | |---------------------------------------------------------------------------| | Atmospheric | computed from atmospheric pressure (6 hours 3D grids) | | gravitational | over land, inverted barometer model over the ocean | | attraction | | |---------------------------------------------------------------------------| | Relativity | Schwarzschild model + Lense-Thirring term | |---------------------------------------------------------------------------| | Numerical | Cowell type predictor-corrector of order 8 | | Integration | | | |--------------------------------------------------------| | | integration step: | | | 45 seconds for Spots and Envisat | | | 60 seconds for Topex and Jason | | |--------------------------------------------------------| | | arc length (orbits): | | | 3.5 days for all satellites (between 1 and 3.5 in case | | | of manoeuver or important lack of data) | | | cutting is based on GPS week calendar. | | | 3.5 day arcs start on Sunday 0:00 or Wednesday 12:00 | | ----------------------------------------------------------------------------- ----------------------------------------------------------------------------- | ESTIMATED PARAMETERS (APRIORI VALUES & SIGMAS) | |---------------------------------------------------------------------------| | Adjustment | Weighted least-squares with iterations | | | | |---------------------------------------------------------------------------| | Orbital | | | parameters | | | | Initial position and velocity | | | | | | Solar radiaton pressure : 1 coef/arc | | | | | | Air drag (bearing pressure coupled): | | | - Spots, Envisat : 1 coef/4 hours | | | - Topex, Jason: 1 coef/half day | | | | | | Hill empirical accelerations : | | | 2 coeff cos-sin /orbital period in normal direction | | | 2 coeff cos-sin /orbital period in tangential direction| | | per day and constrained for Envisat, | | | per arc without constrains for the others || | | |---------------------------------------------------------------------------| | Stations | | | | Station network coordinates and velocities, cartesian | | | system. Apriori constraint (initial solution) | | | | |---------------------------------------------------------------------------| | Troposphere | | | | 1 zenith path delay bias estimated per satellite pass | | | Apriori values given by meteorological sensors or | | | climatological model (SSALTO preprocessing) in case of | | | sensors failure or saturation | | | | |---------------------------------------------------------------------------| | Ionospheric | no parameters estimated | | correction | | | | | |---------------------------------------------------------------------------| | ERP | x and y pole | | | Current IERS Bulletin B values used as apriori | |---------------------------------------------------------------------------| | Clocks bias | | | | 1 frequency bias mixed receiver-station per satellite | | | pass | |---------------------------------------------------------------------------| | Other | | | parameters | | ----------------------------------------------------------------------------- ----------------------------------------------------------------------------- | REFERENCE FRAMES | |---------------------------------------------------------------------------| | Inertial | Geocentric; mean equator and equinox of 2000 Jan 1 | | | at 12:00 (J2000.0) | | | | |---------------------------------------------------------------------------| | Terrestrial | ITRF2000 reference frame with realization description | | | DORIS station coordinates and velocities sinex file | | | | |---------------------------------------------------------------------------| | Interconnection | Precession: IAU 1976 Precession Theory | | |--------------------------------------------------------| | | Nutation: IAU 1980 Nutation Theory | | |--------------------------------------------------------| | | Celestial pole offsets from IERS Bulletin A | | |--------------------------------------------------------| | | Relationship between UT1 and GMST: | | |--------------------------------------------------------| | | ERP from EOP97C04 | | |--------------------------------------------------------| | | Tidal variations in UT1 and xp: | ----------------------------------------------------------------------------- References : Auriol A., 2000, Modélisation des instruments DORIS. CO-SP-0-OP-2460-CN, CNES Document. Barlier, F., et al., 1977, A thermospheric model based on satellite drag data. Aeronomica Acta, A n°185. Berger, C., R. Biancale, M. III, F. Barlier, 1996, Improvement of the empirical thermospheric model DTM94, a comparative review of various temporal variations and prospects in space geodesy applications, J. of Geodesy, 72, 161-178, 1998. Berrada-Baby H., et al., 1987, Effets de la troposphère sur les mesures de distances Terre-satellite. Application au projet DORIS. Note technique CRPE/158. Biancale R., et al., 2000, A new global Earth's gravity field model from satellite orbit perturbations : GRIM5-S1. Geophys. Res. Lett., 27, 3611. Cartwright D., R.J. Tayler, 1971, New computation of the tides generating potential. Geophys. J. Roy. AStron. Soc. 23, 45-75. Cartwright D., A. Adden, 1973, Corrected tables of tidal harmonics. Geophys. J. Roy. AStron. Soc. 33, 253-264. Costes M., and R. Tribes, 2001, Interface specifications between the DORIS network beacons and the onboard instrument. CO-IF-D1/B-EA-10823-CN, CNES document. Gruber T., et al., 2000, GRIM5-C1: combination solution of the global gravity field to degree and order 120, 27, 4005. Haurwitz, B., A. Cowley, 1973, The diurnal and semi-diurnal barometric oscillations, global distribution and annual variation, Pure Appl. Geophys. 102, 193_222. Huang, C., J.C. Ries, MM. Watkins, 1990, Relativistics effects for near Earth satellite orbit determination. Celestial Mechanics 48 : 167-185. MC.Carthy, D., 1992, IERS Standards, IERS TECHNICAL NOTE 13. MC.Carthy, D., 1996, IERS Conventions, IERS TECHNICAL NOTE 21. Wahr, J., 1981, Body tides on an elliptical, rotating, elactic, and oceanless Earth, Geophys. J. R. Astr. Soc., 64, 677-703. Will, C. M., 1981, Theory and experiment in gravitational physics. Cambridge University Press. Soffel, M., 1989, Relativity in astrometry, Celestial Mechanics and Geodesy, Springer-Verlag, Berlin.