============================================================================= | ESOC IGS 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 | | | | | | Dr. Tim Springer | | | Tim.Springer (at) esa.int.nospam | | | +49 6151 90 2029 | |---------------------------------------------------------------------------| | Software used | NAPEOS Version 3.6 | |---------------------------------------------------------------------------| | GNSS system(s) | GPS, GLONASS, (Galileo) | |---------------------------------------------------------------------------| | FINAL IGS PRODUCTS| ESAwwwwd.sp3 GNSS ephemeris/clock files in 7 daily | | GENERATED FOR | files using 15 min sampling in sp3c | | GPS WEEK 'wwww' | format including accuracy codes | | DAY OF WEEK 'd' | ESAwwww7.erp ERP (pole, LOD) solutions | | (d=0,1,...,6) | ESAwwww7.sum Processing summary. | | | ESAwwww7.snx SINEX file | | | ESAwwwwd.clk 30 seconds RINEX clock files (GPS+GLO) | | | | | RAPID IGS PRODUCTS| ESRwwwwd.sp3 Orbit files (GPS+GLO) | | | ESRwwwwd.erp ERP files | | | ESRwwwwd.clk 5 minute RINEX clock files (GPS+GLO) | | | | | ULTRARAPID ORBITS | ESUwwwwd_hh.sp3 Orbit files (GPS+GLO) | | (hh=00,06,12,18) | ESUwwwwd_hh.erp ERP files | | | | | IGLOS PRODUCTS | We no longer generate seperate GLONASS products. All | | | our IGS products (FINAL, RAPID, ULTRA) are GNSS | | | | |---------------------------------------------------------------------------| | Preparation date | 2011-06-01 | |---------------------------------------------------------------------------| | Modification dates| 2008-01-31: Creation | | | 2008-03-06: Napeos based rapid products | | | 2008-03-26: Napeos based Ultra-rapid products | | | 2008-09-21: New Napeos version and related changes | | | 2009-07-09: Napeos version 3.3 and related changes | | | 2010-01-08: Napeos version 3.4 and related changes | | | 2010-08-05: Napeos version 3.5 and related changes | | | 2011-06-01: Napeos version 3.6 and related changes | |---------------------------------------------------------------------------| | Effective date | 2008 020: Final products | | for data analysis | 2008 020: IGLOS products | | | 2008 065: Rapid products | | | 2008 071: UltraRapid products | | | 2008 258: Final products | | | 2008 259: UltraRapid products | | | 2009 190 12: UltraRapid products | | | 2009 186: Final products | | | 2010 018: Final and UltraRapid products | | | 2010 213: Final products | | | 2010 217 12: UltraRapid products | | | 2011 142: Final products | | | 2011 151 12: UltraRapid products | ============================================================================= ============================================================================= | MEASUREMENT MODELS | |---------------------------------------------------------------------------| | Preprocessing | RINEX files pre-screened on small/incomplete files. | | | | | | Code biases are corrected to P1/P2 using cc2noncc. | | | | | | The preprocessing starts with a large number of | | | stations (~300). The NAPEOS GnssObs program screens the| | | data looking at different linear combination. This step| | | also initializes the receiver clock offsets and the | | | phase ambiguities. Receivers with little data, many | | | outliers, and/or many cycle slips are rejected. | | | | | | From the remaining stations first the list of | | | "preferred" stations are selected. This list is build | | | up based on the ESA stations and the IGS Reference | | | Frame sites. | | | | | | The accepted list of "reference" stations is enhanced | | | by adding those stations which gives the best network | | | geometry and the most observations. | | | | |---------------------------------------------------------------------------| | Basic observables| undifferenced carrier phases & pseudoranges | | |--------------------------------------------------------| | | elevation angle cutoff: 10 degrees | | | sampling rate: 5 minute (decimated) | | | sampling rate: 30 seconds (for clocks) | | | weighting: carrier phase: 10 mm sigma (for Zenith) | | | pseudo range: 1 m sigma (for Zenith) | | | These sigmas increase with decreasing elevation | | | angle using the function (1/sin(elev)) | | | | | | code biases: C1 & P2' corrected to P1 & P2 using | | | cc2noncc tool depending on receiver type | |---------------------------------------------------------------------------| | Modeled | undifferenced, corrected for 1st order ionosphere | | observables | effect by forming LC & PC | |---------------------------------------------------------------------------| |*Satellite antenna| SV-specific z-offsets & block-specific x- & y-offsets | | -center of mass | from IGS using file igs08_wwww.atx based on ITRF2008 | | offsets | | |---------------------------------------------------------------------------| |*Satellite antenna| block-specific nadir angle-dependent "absolute" PCVs | | phase center | applied from file igs08_wwww.atx; no azimuth-dependent | | corrections | corrections applied | |---------------------------------------------------------------------------| |*Satellite clock | 2nd order relativistic correction for non-zero | | corrections | orbit ellipticity (-2*R*V/c) applied | | | NOTE: Other dynamical relativistic effects under | | | Orbit Models | |---------------------------------------------------------------------------| | GPS attitude | Nominal attitude implemented. | | model | Yaw rates applied for GLONASS (see below) | | | Yaw rates for GPS not yet applied | |---------------------------------------------------------------------------| |*RHC phase | phase wind-up applied according to Wu et al. (1993) | | rotation corr. | | |---------------------------------------------------------------------------| |*Ground antenna | "absolute" elevation- & azimuth-dependent (when | | phase center | available) PCVs & L1/L2 offsets from ARP applied from | | offsets & | file igs08_wwww.atx | | corrections | | |---------------------------------------------------------------------------| |*Antenna radome | calibration applied if given in file igs08_wwww.atx; | | calibrations | otherwise radome effect neglected (radome => NONE) | |---------------------------------------------------------------------------| |*Marker -> antenna| dN, dE, dU eccentricities from site logs applied to | | ARP eccentricity | compute station coordinates | |---------------------------------------------------------------------------| | 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. | | | | | | gradient model: none | |---------------------------------------------------------------------------| |*Ionosphere | 1st order effect: accounted for by dual-frequency | | | observations in linear combination | | |--------------------------------------------------------| | | 2nd order effect: no corrections applied | | |--------------------------------------------------------| | | other effects: no corrections applied | |---------------------------------------------------------------------------| |*Tidal |*solid Earth tide: IERS 2003 (dehanttideinel.f routine) | | displacements |--------------------------------------------------------| | |*permanent tide: zero-frequency contribution left in | | (IERS Conventions| tide model, NOT in site coordinates | | 2003, Ch. 4, eqn |--------------------------------------------------------| | 11) |*solid Earth pole tide: IERS 2003; mean pole removed | | | by linear trend (Ch. 7, eqn 23a & 23b) | | |--------------------------------------------------------| | |*oceanic pole tide: IERS 2003 updated model | | | No yet implemented! | | |--------------------------------------------------------| | |*ocean tide loading: consistent with IERS 2003 (Ch. 7), | | | 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 2003 (ortho_eop.f)| | | (IERS seems to propose interp.f) | | |--------------------------------------------------------| | | atmosphere tidal: S1, S2, S3 tides not applied | | |--------------------------------------------------------| | | high-frequency nutation: prograde diurnal polar motion | | | corrections (IERS 2003, Table 5.1) applied | | | using IERS routine PMsdnut.for | | |--------------------------------------------------------| | | UT1 liberation applied using IERS routine: | * New in 3.6 | | UT1LIBR.for | | |--------------------------------------------------------| ============================================================================= ============================================================================= | REFERENCE FRAMES | |---------------------------------------------------------------------------| | Time argument | TDT (not TCG) is used. | | | GPS time as given by observation epochs, which is | | | offset by only a fixed constant (approx.) from TT/TDT | |---------------------------------------------------------------------------| | Inertial | geocentric; mean equator and equinox of 2000 Jan 1.5 | | frame | (J2000.0) | |---------------------------------------------------------------------------| | Terrestrial | ITRF2008 reference frame realized through the set of up| | frame | station coordinates and velocities given in the IGS | | | internal realization. | | | Number of reference frame stations used: All | |---------------------------------------------------------------------------| | Tracking | We download all RINEX files from the CDDIS archive and | | network | we have all the stations from the "igs.snx" file in our| | | db. | | | | | | Some special GNSS sites are downloaded from the BKG | | | IGLOS archive. | | | | | | From the ~300 files "bad" rinex files are removed. | | | From the remaining files first our "reference" station | | | set is selected (ESA, IGSRF). This set is completed | | | based on geometry and number of observations until the | | | specified maximum number of stations is selected. The | | | rest of the stations is ignored. | | | | | | Maximum number of stations used: | | | FINAL: 110 | | | RAPID: 110 | | | ULTRA: 110 | |---------------------------------------------------------------------------| | Interconnection | precession: IAU 2000A Precession-Nutation Model | | |--------------------------------------------------------| | (EOP parameter | nutation: IAU 2000A 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-GLO5C to degree & order 12; | | (static) | Drifts from model taken into account | | | C21 & S21 computed according to IERS 2003 p.57 | | | | | | NOTE: | | | EIGEN-GLO5C model model has no drifts. | | |--------------------------------------------------------| | | 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-GLO5C gravity field. | | | This value is used for the Gravity field expansion. | |---------------------------------------------------------------------------| | Tidal variations |*solid Earth tides: applied | | in geopotential | Procedure given in IERS Conventions 2003 Chapter 6.1 | | | Anelastic Earth model implemented. | | | Tables 6.1, 6.3a, 6.3b, and 6.3c fully implemented | | |--------------------------------------------------------| | | ocean tides: applied | | | Procedure given in IERS Conventions 2003 Chapter 6.4 | | | FES2004 spherical harmonics used. | | |--------------------------------------------------------| | |*solid Earth pole tide: applied | | | Procedure given in IERS Conventions 2003 Chapter 6.2 | | |--------------------------------------------------------| | | oceanic pole tide: NOT applied | | | Procedure given in IERS Conventions 2003 Chapter 6.x | | | New model of S. Desai for C21 and S21 terms only | |---------------------------------------------------------------------------| | Third-body | Sun, Moon, Mercury, Venus, Mars, Jupiter, Saturn, | | forces | Uran, Neptune, and Pluto (i.e. All planets) | | |--------------------------------------------------------| | | ephemeris: JPL DE405 | |---------------------------------------------------------------------------| | Solar radiation | a priori: none | | pressure model | | | (parameter |--------------------------------------------------------| | estimation is | Earth shadow model: umbra & penumbra included | | below) |--------------------------------------------------------| | | Earth albedo: applied: albedo and IR | | |--------------------------------------------------------| | | Moon shadow: umbra & penumbra included | | |--------------------------------------------------------| | | satellite attitude: nominal attitude | | | Yaw rates applied for GLONASS | | | GLO: Model from Dilssner2011 | * New in 3.6 | | Yaw rates not yet applied for GPS | | | GPS: Under validation | * New in 3.6 | |--------------------------------------------------------| | | other forces: none applied | |---------------------------------------------------------------------------| |*Relativitic | dynamical correction: applied | | effects | IERS 2003, Ch. 10, eqn 1 | | | Lense-Thirring & geodesic precession terms neglected | | |--------------------------------------------------------| | | gravitational time delay: applied | | | IERS 2003, Ch. 11, eqn 17 | |---------------------------------------------------------------------------| | Numerical | Adams-Bashforth/Adams-Moulton 8th order prediction- | | integration | correction (multistep) method | | |--------------------------------------------------------| | | integration step: 120 steps per revolution | | |--------------------------------------------------------| | | starter procedure: Eight-order Runge Kutta (RKF) | | |--------------------------------------------------------| | | Daily (24 hours) solutions | ============================================================================= ============================================================================= | ESTIMATED PARAMETERS (& APRIORI VALUES & CONSTRAINTS) | |---------------------------------------------------------------------------| | Adjustment | Bayesian weighted least squares | | method | | |---------------------------------------------------------------------------| | Data Span | Currently the solutions are based on 1-day (24 hours) | | | solutions without normal equation stacking | | | | | | Multi-day solutions obtained by stacking normal eqns. | | | may follow in the near future. | |---------------------------------------------------------------------------| |*Station | All station coordinates are adjusted, relative to the | | coordinates | a priori values from selected IGS reference frame | | | (see above) | | | | | | SINEX Solution | | | Our SINEX files contain the completely free normal | | | equation system from our parameter estimation. In | | | addition to this our SINEX files also contain our | | | (constrained) solution. | | | | | | NOTE: Our pole estimates are discontineous at the day | | | boundaries! | |---------------------------------------------------------------------------| | Satellite clocks | Solved for at each epoch (30sec sampling). | | |--------------------------------------------------------| | | sp3,clk files: frame for clocks corresponds to ITRF | | | origin by constraining station positions| | | and back-solving for clocks | |---------------------------------------------------------------------------| | Receiver clocks | Solved for at each epoch (30sec sampling). | | | GnssObs initializes the clock estimates and at the | | | same time aligns them to GPS time. The clock | | | estimates are reviewed and the "best" clock is selected| | | as reference clock for the processing. The estimated | | | clock values from the selected reference clock are | | | replaced by a linear polynomial which was fitted | | | through the original epoch estimates. | |---------------------------------------------------------------------------| | Orbits | Deterministic positions and velocities. | | | Parameters from the Enhanced CODE orbit model | | | (Springer, 1999). | | | D0, Y0, B0, Bcos(u) and Bsin(u) | | | In addition we allow for small Along-track accel. | | | A0, Acos(u), Asin(u) | | |--------------------------------------------------------| | | sp3 files: orbits transformed to crust-fixed (rotating)| | | frame accounting for geocenter motions due | | | to ocean tides and for subdaily tidal EOP | | | variations | |---------------------------------------------------------------------------| | Satellite | Nominal attitude used. | | attitude | Yaw rates applied for GLONASS based on Dillsner2011 | ** New in 3.6 |---------------------------------------------------------------------------| | Troposphere | zenith delay: estimated as linear parameters | | | Every 1 hours | | |--------------------------------------------------------| | | mapping function: partial is GMF wet (Boehm, 2006) | | |--------------------------------------------------------| | | zenith delay epochs: Value for middle of 1 hour interv.| | |--------------------------------------------------------| | | gradients: North and East Gradient. Linear per day | |---------------------------------------------------------------------------| | Ionospheric | Not estimated | | correction | | |---------------------------------------------------------------------------| | Ambiguity | Phase cycle ambiguities adjusted except when double- | | | difference ambiguities can be resolved confidently | | | Integer ambiguity resolution scheme from GFZ (Ge 2005) | |---------------------------------------------------------------------------| |*Earth orientation| Daily x & y pole offsets, pole-rates, and LOD at noon | | parameters (EOP) | epochs; | |---------------------------------------------------------------------------| | Other | For the Glonass process 1 bias per observation period | | parameters | for each receiver-Glonass satellite pair is estimated. | | | The values of one receiver are taken as reference by | | | setting them to zero. All others are estimated. This | | | bias is estimated as a clock bias between the GPS part | | | and the Glonass part of the receiver. | | | | | | Satellite antenna offsets are set-up so that they are | | | included in our SINEX submissions. | | | | ============================================================================= ============================================================================= | 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/cool/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 2003, D.D. McCarthy & G. Petit (editors), IERS Technical | Note 32, Frankfurt am Main: Verlag des Bundesamts fuer Kartographie und | Geodaesie, 2004. | |---------------------------------------------------------------------------- | | 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 | | Dilssner, F, T. Springer, G. Gienger, J. Dow, The GLONASS-M satellite yaw- | attitude model, Advances in Space Research, Volum 47, Issue 1, p 160-171 | | 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 Solutions, | 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., | eds.), AGU, Washington, D.C., pp.247-251, 1972. | | Springer, T.A., G. Beutler, M. Rothacher (1999), A new Solar Radiation v | Pressure Model for the GPS Satellites, Adv. Space Res., 23, No. 4, pp. | 673-679. | | Wu, J.T., S.C. Wu, G.A. Hajj, W.I. Bertiger, and S.M. Lichten, Effects of | antenna orientation on GPS carrier phase, Manuscripta Geodaetica,18, | 91-98, 1993. | ============================================================================= |* = strong consistency with IERS/IGS conventions is especially important | | for these items | =============================================================================