============================================================================= INTERNATIONAL DORIS SERVICE European Space Operations Centre (ESOC) European Space Agency (ESA) Analysis Strategy Summary ============================================================================= | Analysis Center | European Space Agency (ESA) | | | European Space Operation Center (ESOC) | | | Navigation Support Office (OPS-GN) | | | Robert Bosch Strasse 5 | | | D-64293 Darmstadt | | | Fax: +49 6151 90 3129 | |---------------------------------------------------------------------------| | Contact people | Dr. Werner Enderle | | | Werner.Enderle (at) esa.int.nospam | | | +49 6151 90 2272 | | | | | | Michiel Otten | | | Michiel.Otten (at) esa.int.nospam | | | +49 6151 90 2523 | |---------------------------------------------------------------------------| | Software used | NAPEOS Version 4.0 | ----------------------------------------------------------------------------| | IDS Products | Weekly solutions (in SINEX format): | | | Coordinates of global DORIS stations | | | Daily Earth Orientation Parameters | | | X-pole, Y-pole + rates and LOD | |---------------------------------------------------------------------------| | Preperation Date | March 2012 | ----------------------------------------------------------------------------| | Modification dates| 2012/03/04: Creation | | | | |---------------------------------------------------------------------------| | Effective date | All reprocessing | | for data analysis | | ============================================================================= ----------------------------------------------------------------------------- | MEASUREMENT MODELS | |---------------------------------------------------------------------------| | Data editing | null doppler meas. and restart mode | | | | |---------------------------------------------------------------------------| | 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, ENVISAT satellites) | | | | | | fractional phase differences of a beat frequency | | | (second generation instrument on SPOT5 and JASON1 | | | and DGXX intrument on JASON2 and CRYOSAT2, HY-2A) | | | | | | "2.2 format" data from CDDIS | | | | | |--------------------------------------------------------| | | elevation angle cutoff : 10 degrees before 2002 | | | 7 degrees after 2002 | | | weighting : 0.5 mm/s fixed before 2002 after 2002 | | | elevation dependent weighting (sin) | |---------------------------------------------------------------------------| | Ground antenna | Height dependant on the antenna type | | phase centre cor.| | |---------------------------------------------------------------------------| | Troposphere | Zenith delay computed using the Saastamoinen model with| | a priori model | pressure and temperature from the GPT model. | | | The resulting zenith delay is mapped using the dry | | | GMF mapping function. | |---------------------------------------------------------------------------| | Troposphere | zenith delay: estimated as linear parameters | | estimated | every pass after 2002 daily gradient in North and East | | |--------------------------------------------------------| | | mapping function: partial is GMF wet (Boehm, 2006) | |---------------------------------------------------------------------------| | Ionosphere | Two frequency model first order model (SOD/CNES) | |---------------------------------------------------------------------------| | Relativity | Applied | | clock effects | | |---------------------------------------------------------------------------| | Plate motions | DPOD2008v1.13 | | | | |---------------------------------------------------------------------------| | Tidal | solid Earth tide: IERS 2010 (dehanttideinel.f routine) | | displacements | (no change compared to IERS 2003) | | |--------------------------------------------------------| | | permanent tide: zero-frequency contribution left in | |(IERS 2010 | tide model, NOT in site coordinates | | Conventions) |--------------------------------------------------------| | | solid Earth pole tide: IERS 2010 | | | Mean pole removed by: | | | - quadratic trend until 2010 | | | - linear trend from 2010 | | |--------------------------------------------------------| | | oceanic pole tide: not applied | | | | | |--------------------------------------------------------| | | ocean tide loading: consistent with IERS 2010 | | | site-dependent amps & phases from Bos | | | & Scherneck website for FES2004 tide | | | model including CMC. | | | NEU site displacements computed | | | using hardisp.f from D. Agnew | | |--------------------------------------------------------| | | ocean tide geocenter: coeffs corrected for center of | | | mass motion of whole Earth | | |--------------------------------------------------------| | | atmosphere tides: corrections for S1 & S2 tidal | | | pressure loading not applied | |---------------------------------------------------------------------------| | Non-tidal | atmospheric pressure: not applied | | loadings |--------------------------------------------------------| | | ocean bottom pressure: not applied | | |--------------------------------------------------------| | | surface hydrology: not applied | | |--------------------------------------------------------| | | other effects: none applied | |---------------------------------------------------------------------------| | Earth orientation| ocean tidal: diurnal/semidiurnal variations in x,y, & | | variations | UT1 applied according to IERS 2010 (ortho_eop.f)| | |--------------------------------------------------------| | | atmosphere tidal: S1, S2, S3 tides not applied | | |--------------------------------------------------------| | | high-frequency nutation: prograde diurnal polar motion | | | corrections (IERS 2010) applied | | | using IERS routine PMSDNUT2.for | | |--------------------------------------------------------| | | UT1 liberation applied using IERS routine: | | | UT1LIBR.for | |---------------------------------------------------------------------------| | Clocks frequency | onboard frequency bias deduced from the master beacon | | deviation | (a bias per satellite pass) | |---------------------------------------------------------------------------| | Satellite center | derived from center of mass history and attitude | | of mass - antenna| modelling | | phase center | | | correction | | |---------------------------------------------------------------------------| | Satellite | theoretical attitude model | | attitude | | | | | |---------------------------------------------------------------------------| | Receiver-antenna | depends on the channel and the instrument generation | | propagation delay| | | | | |---------------------------------------------------------------------------| ============================================================================= | REFERENCE FRAMES | |---------------------------------------------------------------------------| |Time argument | TDT (not TCG) is used. | | | UTC time as given by observation epochs, which is | | | offset by only a fixed constant (approx.) from TT/TDT | |---------------------------------------------------------------------------| |Inertial | J2000 | | | geocentric; mean equator and equinox of 2000 Jan 1.5 | |---------------------------------------------------------------------------| |Terrestrial | DPOD2008v1.13 (a priori station coordinates and vel.) | |---------------------------------------------------------------------------| |Interconnection | precession: IAU 2006 Precession-Nutation Model | | |---------------------------------------------------------| |(EOP parameter | nutation: IAU 2006 Precession-Nutation Model | |estimation is | The daily dx and dy corrections from the | |below) | IERS Bulletin A are applied. | | |---------------------------------------------------------| | | a priori EOPs: polar motion & UT1 interpolated from | | | IERS Bulletin A, updated daily, with the | | | restoration of subdaily EOP variations using | | | IERS models (see MODELS above) | |============================================================================ ----------------------------------------------------------------------------- | ORBIT MODELS | |---------------------------------------------------------------------------| | Geopotential | EIGEN-6S2ext up to degree 120 including annual and | | | semi-annual terms of the low coefficients (up to 50) | | | | |--------------------------------------------------------| | | GM=398600.4415 km**3/sec**2 (for TT/TDT time argument) | | | | | |--------------------------------------------------------| | | AE = 6378136.55 m Equatorial radius of the Earth | | | 1/f = 298.25769 Flattening factor of the Earth | | | | | | NOTE: | | | The above values are consistent with the "tide free" | | | system which we supposedly use. | | | | | | NOTE: | | | AE = 6378136.46 m for the EIGEN-6S2ext gravity field. | | | This value is used for the Gravity field expansion. | |---------------------------------------------------------------------------| | Tidal variations |solid Earth tides: applied | | in geopotential | Procedure given in IERS Conventions 2010 | | | Anelastic Earth model implemented. | | |--------------------------------------------------------| | | ocean tides: applied | | | Procedure given in IERS Conventions 2010 | | | EOT11a spherical harmonics used. | | |--------------------------------------------------------| | | solid Earth pole tide: applied | | | Procedure given in IERS Conventions 2010 | | | Mean pole removed by: | | | - quadratic trend until 2010 | | | - linear trend from 2010 | | |--------------------------------------------------------| | | oceanic pole tide: applied | | | Procedure given in IERS Conventions 2010 | | | New model of S. Desai for C21 and S21 terms only | | | Mean pole removed IERS 2010 by: | | | - quadratic trend until 2010 | | | - linear trend from 2010 | ----------------------------------------------------------------------------| | Atmospheric | computed from 6-Hourly AGRA Files | | gravitational | | | attraction | | |---------------------------------------------------------------------------| | Third-body | Sun, Moon, Mercury, Venus, Mars, Jupiter, Saturn, | | forces | Uran, Neptune, and Pluto (i.e. All planets) | | |--------------------------------------------------------| | | ephemeris: JPL DE405 | |---------------------------------------------------------------------------| | Air drag | Air density model : MSIS-90 | |---------------------------------------------------------------------------| | Solar radiation | | | pressure | direct radiation : applied | | |--------------------------------------------------------| | | Earth shadow model includes: penumbra from regularising| | | function | | |--------------------------------------------------------| | | reemitted radiation: | | | albedo from a numerical model with albedo and IR | | | functions | |---------------------------------------------------------------------------| | satellite | not applied | | thermal thrust | | |---------------------------------------------------------------------------| | Relativity | Schwarzschild model + Lense-Thirring term + geodetic | | | precession | |---------------------------------------------------------------------------| | Numerical | Adams-Bashforth/Adams-Moulton 8th order prediction- | | integration | correction (multistep) method | | |--------------------------------------------------------| | | integration step: 240 steps per revolution | | |--------------------------------------------------------| | | starter procedure: Eight-order Runge Kutta (RKF) | | |--------------------------------------------------------| | | Daily (24 hours) solutions | ============================================================================= ----------------------------------------------------------------------------- | ESTIMATED PARAMETERS (APRIORI VALUES & SIGMAS) | |---------------------------------------------------------------------------| | Adjustment | Weighted least-squares with iterations | |---------------------------------------------------------------------------| | Orbital | | | parameters | | | | Initial position and velocity | | | | | | Solar radiaton pressure : fixed | | | | | | Air drag: | | | - Spots, Envisat, Cryosat-2, HY-2A : 10 coef per day | | | - Topex, Jason-2: 4 coef per day | | | | | | Hill empirical accelerations : | | | 1 coeff cos-sin /orbital period in normal direction | | | 1 coeff cos-sin /orbital period in tangential direction| | | per day | |---------------------------------------------------------------------------| | Stations | | | | Station network coordinates and velocities, cartesian | | | system. | | | | |---------------------------------------------------------------------------| | Troposphere | | | | 1 zenith path delay bias estimated per satellite pass | | | gradients: North and East Gradient. Linear per day | | | (after 2002) | |---------------------------------------------------------------------------| | Ionospheric | no parameters estimated | | correction | | | | | |---------------------------------------------------------------------------| | ERP | x and y pole and rates and LOD | | | Current IERS C04 values consistent with ITRF2008 used | | | as apriori | |---------------------------------------------------------------------------| | Clocks bias | | | | 1 frequency bias mixed receiver-station per satellite | | | pass | |---------------------------------------------------------------------------| | Other | | | parameters | | ----------------------------------------------------------------------------- ============================================================================= | REFERENCES |---------------------------------------------------------------------------- | | ESOC NAPEOS Software | Springer, T.A., NAPEOS Mathematical Models and Algorithms, | DOPS-SYS-TN-0100-OPS-GN, issue 1.0, Nov 5, 2009. | ftp://dgn6.esoc.esa.int/napeos/DOPS-SYS-TN-0100-OPS-GN-MathModels.pdf | | EIGEN-GL05C - A new global combined high-resolution GRACE-based gravity | field model of the GFZ-GRGS cooperation, | Ch. Foerste (1), F. Flechtner (1), R. Schmidt (1), R. Stubenvoll (1), M. Rothacher (1), | J. Kusche (1), H. Neumayer (1), R. Biancale (2), J.-M. Lemoine (2), | F. Barthelmes (1), S. Bruinsma (2), R. Koenig (1) and Ul. Meyer (1), | Geophysical Research Abstracts, | Vol. 10, EGU2008-A-03426, 2008 | SRef-ID: 1607-7962/gra/EGU2008-A-03426 | | Ocean Loading Service by M.S. Bos and H.-G. Scherneck | http://www.oso.chalmers.se/~loading/ | | IERS Conventions 2010, Gerard Petit and Brian Luzum (editors), IERS Technical | Note 36, Frankfurt am Main: Verlag des Bundesamts fuer Kartographie und | Geodaesie, 2010. | |---------------------------------------------------------------------------- | | Boehm, J, A. Niell, P. Tregoning, and H. Schuh, Global Mapping Function | (GMF): A new empirical mapping function based on numerical weather | model data, Geophysical Research Letters, Vol. 33, L07304, | doi:10.1029/2005GLO25546 | | | Ge, M. et.al, Improving carrier-phase ambiguity resolution in global GPS | network solutions, Journal of Geodesy, Volume 79, number 1-3, June 2005 | | Kouba, J., Improved relativistic transformations in GPS, GPS Solustions, | 8(3), 170-180, 2004. | | Saastamoinen, J., Atmospheric correction for the troposphere and | stratosphere in radio ranging of satellites, in The Use of Artificial | Satellites for Geodesy, Geophys. Monogr. Ser. 15 (S.W. Henriksen et al.,