=================================================================================== INTERNATIONAL GNSS SERVICE CODE Analysis Strategy Summary for REPRO15 =================================================================================== | Analysis Center | Center for Orbit Determination in Europe (CODE) | | | Astronomical Institute | | | University of Bern | | | Sidlerstrasse 5 | | | CH-3012 Bern | | | Switzerland | | | E-mail: code(at)aiub.unibe.ch (CODE AC Team) | | | Phone: +41-31-631-8591 | | | Fax: +41-31-631-3869 | | | Data archive: ftp://ftp.aiub.unibe.ch/REPRO_2015/ | | | http://www.aiub.unibe.ch/download/REPRO_2015/ | | | Web: http://www.aiub.unibe.ch (CODE at AIUB) | | | http://www.bernese.unibe.ch (Bernese SW) | |---------------------------------------------------------------------------------| | Contact People | Andreja Susnik | | | E-mail: andreja.susnik(at)aiub.unibe.ch | | | Phone: +41-31-631-8506 (8591) | | | Rolf Dach | | | E-mail: rolf.dach(at)aiub.unibe.ch | | | Phone: +41-31-631-8593 (8591) | | | Daniel Arnold | | | E-mail: daniel.arnold(at)aiub.unibe.ch | | | Phone: +41-31-631-3802 (8591) | | | Arturo Villiger | | | E-mail: arturo.villiger(at)aiub.unibe.ch | | | Phone: +41-31-631-8506 (8591) | |---------------------------------------------------------------------------------| | Software Used | Bernese GNSS Software Version 5.3, developed at AIUB | |---------------------------------------------------------------------------------| | GNSS system(s) | 1994..2001: GPS | | | 2002..2014: GPS+GLONASS | |---------------------------------------------------------------------------------| | List of CODE's | The following list of products files has been submitted: | | analysis products | | | | | | Final Products | Product reference: | | generated for | Susnik, Andreja; Dach, Rolf; Villiger, Arturo; | | | Maier, Andrea; Arnold, Daniel; Schaer, Stefan; | | | Jaeggi, Adrian (2016). CODE reprocessing product series. | | GPS week 'wwww' | | | day of week 'n' | Published by Astronomical Institute, University of Bern. | | (n=0,1,...,6) | URL: http://www.aiub.unibe.ch/download/REPRO_2015; | | day of year 'ddd' | DOI: 10.7892/boris.80011. | | year 'yy' | | | | | | | Files generated from three-day long-arc solutions: | | | CODwwwwn.EPH.Z GNSS ephemeris/clock data in 7 daily | | | files at 15-min intervals in SP3 | | | format, including accuracy codes | | | computed from a long-arc analysis | | | CODwwwwn.SNX.Z GNSS daily coordinates/ERP/GC from the | | | long-arc solution in SINEX format | | | CODwwwwn.CLK.Z GNSS satellite and receiver clock | | | corrections at 30-sec intervals | | | referring to the COD-orbits from the | | | long-arc analysis in clock RINEX | | | format | | | CODwwwwn.CLK_05S.Z GNSS satellite and receiver clock | | | corrections at 5-sec intervals | | | referring to the COD-orbits from the | | | long-arc analysis in clock RINEX | | | format | | | CODwwwwn.TRO.Z GNSS 2-hour troposphere delay | | | estimates obtained from the long-arc | | | solution in troposphere SINEX format | | | | | | CODwwww7.ERP.Z GNSS ERP (pole, UT1-UTC) solution, | | | collection of the 7 daily COD-ERP | | | solutions of the week in IGS IERS ERP | | | format | | | CODwwww7.SNX.Z GNSS weekly coordinates/ERP/GC from the | | | long-arc solution in SINEX format | | | CODwwww7.SUM.Z Analysis summary for 1 week on the | | | long-arc solutions of the week | | | | | | Remarks: | | | | | | EPH: Orbit positions correspond to the estimates | | | for the middle day of a 3-day in case of a | | | long-arc analysis. | | | CLK: Clock corrections are consistent with | | | carrier phase as well as P1/P2 pseudorange | | | measurements. | | | CODE P1-C1 pseudorange bias values of a | | | moving 30-day solution are considered to | | | correct C1/X2 and C1/P2 receiver data. | | | EPH/ERP/SNX/TRO: These products are extracted from | | | one inversion of the normal equation based | | | on a long-arc solution. | | | | | Specialties in | - CODE has been generating its products from a | | CODE's analysis | rigorous combination of GPS and GLONASS | | | observations. In this way, best possible | | | consistency of the orbit products is guaranteed. | | | - Uninterrupted POD for all transmitting GNSS | | | satellites, specifically for: | | | . brand new satellites | | | . satellites without any broadcast orbit information | | | . satellites marked unhealthy/unusable | | | . poorly observed (GLONASS) satellites | | | . (GPS) satellites being repositioned | | | - Elevation mask angle of 3 degrees used. | | | - Sophisticated ambiguity resolution scheme, already | | | including GLONASS ambiguity resolution (with | | | restrictions, specifically for baseline lengths | | | longer than 200 km), self-calibrating for GLONASS. | | | - Ambiguity verification scheme: resolved ambiguities | | | are checked in terms of compatibility, also in order | | | to detect unexpected quarter-cycle issues. | | | - GPS quarter-cycle phase bias issue: potentially | | | affected GPS ambiguities are banned from ambiguity | | | resolution. | | | - Continuous parametrization, particularly for EOP, | | | troposphere ZPD and horizontal gradient parameters, | | | ionosphere parameters, allowing for connection of | | | the parameters at day boundaries. | | | - IGS fiducial sites are automatically verified for | | | consistent datum definition for final, rapid, and | | | even the ultra-rapid processing. This is also true | | | with respect to all antenna-sharing fiducial sites. | | | - Inclusion of fast moving South Pole station AMU2. | | | - Inclusion of all available NGA stations. | | | - Generation of high-rate (5-sec) clock products. | | | - Generation of high-rate (1-hour) EOP results | | | (internally). | | | - Setup of GNSS satellite antenna PCV parameters | | | specific to each individual GPS and GLONASS | | | satellite; corresponding patterns are not only | | | available for the ionosphere-free linear | | | combination but also for the geometry-free (L1-L2) | | | linear combination. | | | - A multi-GNSS-capable internal PCV file format is | | | used; receiver antenna PCV models specific to | | | GLONASS (or other) frequencies are applied. | | | - 3 terms of higher-order ionosphere (HOI) effects are | | | taken into account (based on CODE GIM & IGRF11SYN). | | | Scaling factor for 2nd and 3rd order HOI as well as | | | for ray bending for validation purposes and to | | | switch the parameter on or off | | | - Atmospheric non-tidal pressure loading correction | | | at observation level with scaling factors to obtain | | | solutions without applying such corrections | | | - Monitoring of various differential code biases | | | (DCBs), specifically: | | | . GPS/GLONASS P1-P2 satellite and receiver DCBs | | | . GPS/GLONASS P1-C1 and P2-C2 satellite DCBs | | | . biases crucial for GLONASS ambiguity resolution | | | Values are extracted from different data processing | | | steps and directly from the RINEX observation files | | | (where possible) | | | - Extensive monitoring of IGS data flow concerning: | | | . availability | | | . latency | | | . completeness | | | . consistency | | | - SINEX loop: COD & COF SINEX results are routinely | | | imported and re-introduced. First extracted and | | | secondly re-produced station coordinate results are | | | cross-checked to the original analysis results (at | | | 0.01-mm level). The extracted list of fiducial | | | stations is used for this re-production. | | | - Provision of GNSS geocenter coordinates in SINEX. | | | - Production of GNSS rapid SINEX files containing | | | station coordinates and ERPs with a time resolution | | | of 6 hours is foreseen as a contribution for the | | | IERS inter-technique combination. | | | - Regular GNSS orbit validation using SLR data; CODE | | | acts as an AAC of the ILRS. | | | - The latest version of our steadily further | | | developed GNSS analysis software is employed for | | | operational analysis. | | | | | Computer platform | Calculations were performed on UBELIX | | | (http://www.id.unibe.ch/hpc), | | | the HPC cluster at the University of Bern | | | | |---------------------------------------------------------------------------------| | Preparation Date | 17-May-2017 | =================================================================================== =================================================================================== | MEASUREMENT MODELS | |---------------------------------------------------------------------------------| | Preprocessing | Phase preprocessing in a baseline by baseline mode | | | using triple-differences. In most cases, cycle slips | | | are fixed looking simultaneously at different linear | | | combinations of L1 and L2. If a cycle slip cannot be | | | fixed reliably, bad data points are removed or new | | | ambiguities are set up. In addition, a data screening | | | step on the basis of weighted postfit residuals is | | | performed. Outliers are removed. | |---------------------------------------------------------------------------------| | Basic Observables| GPS/GLONASS carrier phase; code only used for receiver | | | clock synchronization and MW ambiguity resolution | | | Priorities for observation selection: | | | G L1 L1P L1C L1X | | | G L2 L2P L2C L2D L2W L2X | | | G C1 C1P C1C C1X | | | G C2 C2P C2C C2D C2W C2X | | | R L1 L1P L1C L1X | | | R L2 L2P L2C L2X | | | R C1 C1P C1C C1X | | | R C2 C2P C2C C2X | | |--------------------------------------------------------------| | | Elevation angle cutoff : 3 degrees | | | Sampling rate : 3 minutes | | | Weighting : 6 mm for double-differenced | | | ionosphere-free phase | | | observations at zenith; | | | elevation-dependent weighting | | | function 1/cos(z)**2 | |---------------------------------------------------------------------------------| | Modeled | Double differences, ionosphere-free linear combination | | observables | of L1 and L2 | |---------------------------------------------------------------------------------| | 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 | | |---------------------------------------------------------------------------------| | RHC phase | Phase polarization effects applied (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 | Receiver antenna models specific to GLONASS are | | | applied (as far as available). | |---------------------------------------------------------------------------------| | 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 | ECMWF-based hydrostatic delay mapped with hydrostatic | | a priori model | VMF1. Coefficients from 6-hourly global grids. | | | (GPT is ECMWF corrections are not available in time) | | | | | | Gradient model: none | |---------------------------------------------------------------------------------| | Ionosphere | 1st order effect: eliminated by forming the | | | ionosphere-free linear combination | | | of L1 and L2. | | |--------------------------------------------------------------| | | 2nd order effect: applied, IGRF11 implementation, TEC | | | from CODE global ionosphere model | | |--------------------------------------------------------------| | | 3rd order effect: applied, TEC from CODE global | | | ionosphere model | | |--------------------------------------------------------------| | | Other effects: ray bending applied, TEC from CODE | | | global ionosphere model | | | | | | GNSS-derived global ionosphere map | | | information is used to support | | | ambiguity resolution when using the | | | QIF strategy. | |---------------------------------------------------------------------------------| | Tidal | Solid Earth tide : complete model from IERS | | displacements | Conventions 2010 | | | | | | Step 1: in-phase: degree 2 and 3 | | | Nominal h02 and l02 : 0.6078, 0.0847 (anela.) | | | Nominal h22 and l22 :-0.0006, 0.0002 | | | Nominal h3 and l3 : 0.292 , 0.015 | | | | | | out-of-phase: degree 2 only semi- and diurnal | | | diurnal: nominal hI, lI :-0.0025,-0.0007 | | | semi-di: nominal hI, lI :-0.0022,-0.0007 | | | | | | latitude dependence | | | diurnal: nominal l1 : 0.0012 | | | semi-di: nominal l1 : 0.0024 | | | | | | Step 2: in-phase: degree 2, diurnal | | | in-phase and out-of-phase: long-period tides | | |--------------------------------------------------------------| | | Permanent tide : applied in tide model, | | | NOT included in site coordinates | | |--------------------------------------------------------------| | | Solid Earth pole tide: applied (IERS 2010) | | |--------------------------------------------------------------| | | Oceanic pole tide : not applied | | |--------------------------------------------------------------| | | Ocean tide loading : IERS 2010, site-dependent amps | | | & phases from Bos & Scherneck | | | website for FES2004 tide model | | | NEU site displacements computed | | | using hardisp.f from D. Agnew | | |--------------------------------------------------------------| | | Ocean tide geocenter : coeffs. corrected for center of | | | mass motion of whole Earth | | |--------------------------------------------------------------| | | Atmospheric tides : S1+S2 tidal corrections from the | | | Vienna atmospheric pressure | | | model | |---------------------------------------------------------------------------------| | Non-tidal | Atmospheric pressure : Non-tidal components from the | | loadings | Vienna atmospheric pressure | | | model with three scaling factors | | | per station (one for each | | | component) for validation | | | purposes. | | | The product files are generated | | | without considering the non- | | | tidal pressure loading by | | | forcing the scaling factors to | | | zero. | | |--------------------------------------------------------------| | | 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, Tables | | | 8.2a, 8.2b, 8.3a, 8.3b | | |--------------------------------------------------------------| | | Atmosphere tidal: S1, S2, S3 tides not applied | | |--------------------------------------------------------------| | | High-frequency nutation: applied according to IERS | | | 2010, Table 5.1a | | |--------------------------------------------------------------| | | UT1 libration: applied according to IERS 2010, Table | | | 5.1.b | =================================================================================== =================================================================================== | REFERENCE FRAMES | |---------------------------------------------------------------------------------| | Time argument | TDT | | | 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 | | frame | at 12:00 (J2000.0) | |---------------------------------------------------------------------------------| | Terrestrial | ITRF2008 reference frame realized through a set of | | frame | station coordinates and velocities given in the IGS | | | internal realization IGb08. | | | | | | Datum definition: | | | . 3 no-net translation conditions (only if geocenter | | | is estimated) | | | . 3 no-net rotation conditions | | | . geocenter coordinates constrained nominally to | | | zero values | | | IGb08 fiducial sites are selected as reference, if: | | | . horizontal deviation < 10 mm | | | . vertical deviation < 30 mm | |---------------------------------------------------------------------------------| | Tracking | Between 50 and 300 stations per day are used. Station | | network | selection is based on repro02. | |---------------------------------------------------------------------------------| | Interconnection | Precession: IAU 2000 Precession Theory | | |--------------------------------------------------------------| | (EOP parameter | Nutation: IAU 2000R06 Nutation Theory | | estimation is |--------------------------------------------------------------| | below) | A priori EOPs: polar motion & UT1 from IERS C04 series | | | aligned to ITRF2008 | =================================================================================== =================================================================================== | ORBIT MODELS | |---------------------------------------------------------------------------------| | Geopotential | EGM2008 model up to degree and order 12 (+C21+S21) | | (static) |--------------------------------------------------------------| | | GM = 398600.4415 km**3/sec**2 | | |--------------------------------------------------------------| | | AE = 6378.1363 km | |---------------------------------------------------------------------------------| | Tidal variations | Solid Earth tides: applied according to IERS 2010 | | in geopotential |--------------------------------------------------------------| | | Ocean tides: applied, FES2004 model | | |--------------------------------------------------------------| | | Solid Earth pole tide: applied according to IERS 2010 | | |--------------------------------------------------------------| | | Oceanic pole tide: applied according to IERS 2010 | |---------------------------------------------------------------------------------| | Third-body | Sun, Moon, Jupiter, Venus, Mars as point masses | | |--------------------------------------------------------------| | | Ephemeris: JPL DE421, Folkner et al. (2009) | | |--------------------------------------------------------------| | | GMsun = 132712500000 km**3/sec**2 | | |--------------------------------------------------------------| | | GMmoon = 4902.7890 km**3/sec**2 | |---------------------------------------------------------------------------------| | Solar radiation | A priori: no a priori model | | pressure model | | | (parameter |--------------------------------------------------------------| | estimation is | Earth shadow model: cylindrical shadow | | below) |--------------------------------------------------------------| | | Earth albedo: numerical model according to | | | Rodriguez et al. (2012) | | |--------------------------------------------------------------| | | Moon shadow model: umbra and penumbra | | |--------------------------------------------------------------| | | Satellite attitude: nominal attitude | | |--------------------------------------------------------------| | | Satellite antenna thrust: | | | Antenna thrust for GPS satellites according to | | | http://acc.igs.org/orbits/thrust-power.txt | | | Block I, II, IIA: 76 W | | | Block IIR: 85 W | | | Block IIR-M: 198 W (including M-code) | | | Block IIF: 249 W (including M-code) | | | SVN62 after 05 April 2011: 154 W (no M-code) | | | | | | Assumption for all GLONASS satellites: 100 W | | |--------------------------------------------------------------| | | Other forces: none applied | |---------------------------------------------------------------------------------| | Relativistic | dynamical correction: applied according to IERS 2010, | | effects | eq. 10.12, Lense-Thirring & | | | geodesic precession neglected | | |--------------------------------------------------------------| | | Gravitational time delay: applied according to | | | IERS 2010, eq. 11.17 | |---------------------------------------------------------------------------------| | Numerical | Integration algorithms developed at AIUB by Gerhard | | Integration | Beutler (1990). Representation of the orbit by a | | | polynomial of degree 10 for 1 hour. | | |--------------------------------------------------------------| | | Integration step: 1 hour | | |--------------------------------------------------------------| | | Starter procedure: no special starter procedure needed | | |--------------------------------------------------------------| | | Arc length: 72 hours for long-arc solutions | | | 24 hours for clean one-day solutions | =================================================================================== =================================================================================== | ESTIMATED PARAMETERS (& APRIORI VALUES & CONSTRAINTS) | |---------------------------------------------------------------------------------| | Adjustment | Weighted least-squares algorithms | | method | | |---------------------------------------------------------------------------------| | Data Span | Long-arc solutions include the data from three days, | | | combined on normal equation level. | | | Final, long-arc: satellite orbits and troposphere | | | parameters are extracted from the middle day | | | Final, one-day: consider only the data from one single | | | day. | |---------------------------------------------------------------------------------| | Station | All station coordinates are adjusted with minimum | | coordinates | constraints, see above. | |---------------------------------------------------------------------------------| | Satellite clocks | Not applicable for double difference processing | |---------------------------------------------------------------------------------| | Receiver clocks | Not applicable for double difference processing | |---------------------------------------------------------------------------------| | Orbital | 6 Keplerian elements plus 9 solar radiation parameters | | parameters | at start of arc; no a priori sigmas used. | | | Estimated RPR parameters (see Beutler 1994): | | | - Constants in D-, Y- and X-direction | | | - Periodic 1 per rev. terms in X-direction | | | - Periodic 2 per rev. terms in D-direction | | | A priori orbits are from a previous reprocessing run | | | or from the CODE rapid orbit solution. | | | Pseudo-stochastic orbit parameters (small velocity | | | changes), every 12 hours, constrained to: | | | . 1.E-6 m/sec in radial | | | . 1.E-5 m/sec in along-track | | | . 1.E-8 m/sec in out-of-plane | |---------------------------------------------------------------------------------| | Satellite | Not estimated | | attitude | | |---------------------------------------------------------------------------------| | Troposphere | Zenith delay: estimated for each station in intervals | | | of 2 hours. Loose relative constraints of | | | 5 m are applied. Piece-wise, linear | | | parametrization, allowing for connection | | | of the parameters at day boundaries. | | |--------------------------------------------------------------| | | Zenith delay epochs: every two hours starting at | | | midnight | | |--------------------------------------------------------------| | | Mapping function: wet VMF1 | | |--------------------------------------------------------------| | | Gradients: pairs of horizontal delay gradient | | | parameters are estimated in N-S and E-W | | | direction for each station in intervals of | | | 24 hours. Loose relative constraints of | | | 5 m are applied. Piece-wise, linear | | | parametrization, allowing for connection of | | | the parameters at day boundaries. | | | Details about the gradient model can be | | | found in Rothacher et al. (1997). | | | Refined gradient model used, see Chen and | | | Herring (1997). | |---------------------------------------------------------------------------------| | Ionospheric | Not estimated in ionosphere-free analyses | | correction | | | | One scaling factor for 2nd and 3rd order terms and ray | | | bending is setup to switch the components on or off | | | on normal equation level. | | | The products are generated with considering all three | | | correction components. | |---------------------------------------------------------------------------------| | Ambiguity | Ambiguities are resolved in a baseline-by-baseline | | | mode performing the following steps: | | | . Melbourne-Wuebbena approach (< 6000 km) | | | . Quasi-Ionosphere-Free (QIF) approach (< 2000 km) | | | (also for GLONASS, same frequencies) | | | . Phase-based widelane/narrowlane method (< 200 km) | | | (also for GLONASS, no restrictions) | | | . Direct L1/L2 method, also for GLONASS (< 20 km) | | | (also for GLONASS, no restrictions) | | | GNSS-derived global ionosphere map information is used | | | to support the code-less methods. | |---------------------------------------------------------------------------------| | Earth Orient. | X- and Y-pole coordinates, and UT1-UTC are represented | | Parameters (EOP) | each with piece-wise linear polynomials which are | | | continuous in time. UT1-UTC is fixed to the a priori | | | value at the beginning of the first day. No further | | | a priori sigmas are used. | | | | | | All reported CODE EOP solutions do include a subdaily | | | EOP model (see above). The estimates therefore | | | correspond to daily averages on top of the introduced | | | a priori model. | | | | | | High-rate (1-hour) X-, Y- and UT1-UTC estimates are | | | also generated in a special 3-day solution. | |---------------------------------------------------------------------------------| | Other | Center of mass coordinates: | | parameters | | | | Center of mass, or geocenter coordinate parameters are | | | commonly set up as part of each solution. The related | | | parameters are usually heavily constrained to zero | | | values. Additional computations on the normal equation | | | level are made regularly in order to retrieve 1-day, | | | 3-day, as well as weekly GNSS geocenter coordinates in | | | the current ITRF. | | | | | | GNSS satellite phase center offsets and patterns: | | | | | | Corresponding parameters are commonly set up as part | | | of each final solution for each individual GNSS | | | satellite. The related parameters are again removed | | | from the normal equation before the solution is | | | computed to fix parameters to the nominal values (as | | | defined by the IGS08 PCV model). Such GNSS PCV | | | parameters are available for the ionosphere-free as | | | well as the geometry-free linear combination. | | | | =================================================================================== =================================================================================== | REFERENCES | |---------------------------------------------------------------------------------| Bassiri, S., and G.A. Hajj (1993), Higher-order ionospheric effects on Global Positioning System observables and means of modeling them, Manuscripta Geodaetica, vol. 18, pp. 280-289 Beutler, G. (1990), Numerische Integration gewoehnlicher Differential- gleichungssysteme: Prinzipien und Algorithmen. Mitteilungen der Satelliten-Beobachtungsstation Zimmerwald, No. 23, Druckerei der Universitaet Bern Beutler, G., E. Brockmann, W. Gurtner, U. Hugentobler, L. Mervart, and M. Rothacher (1994), Extended Orbit Modeling Techniques at the CODE Processing Center of the International GPS Service for Geodynamics (IGS): Theory and Initial Results, Manuscripta Geodaetica, vol. 19, pp. 367-386 Boehm, J., B. Werl, and H. Schuh (2006), Troposphere mapping functions for GPS and very long baseline interferometry from European Centre for Medium-Range Weather Forecasts operational analysis data, Journal of Geophysical Research, vol. 111, B02406, doi:10.1029/2005JB003629 Brunner, FK., and M. Gu (1991), An improved model for the dual frequency ionospheric correction of GPS observations, Manuscripta Geodaetica, vol. 16, pp. 205-214 Chen and Herring (1997), Effects of atmospheric azimuthal asymmetry on the analysis of space geodetic data, Journal of Geophysical Research, vol. 102(B9), pp. 20489-20502, doi:10.1029/97JB01739 Dach, R., E. Brockmann, S. Schaer, G. Beutler, M. Meindl, L. Prange, H. Bock, A. J?ggi, L. Ostini (2009), GNSS processing at CODE: status report, Journal of Geodesy, vol. 83(3-4), pp. 353-366 Dach, R., U. Hugentobler, P. Fridez, M. Meindl (eds.) (2007), Documentation of the Bernese GPS Software Version 5.0 International Association of Geomagnetism and Aeronomy, Working Group V-MOD. Participating members: C.C. Finlay, S. Maus, C.D. Beggan, T.N. Bondar, A. Chambodut, T. A. Chernova, A. Chulliat, V. P. Golovkov, B. Hamilton, M. Hamoudi, R. Holme, G. Hulot, W. Kuang, B. Langlais, V. Lesur, F. J. Lowes, H. Luhr, S. Macmillan, M. Mandea, S. McLean, C. Manoj, M. Menvielle, I. Michaelis, N. Olsen, J. Rauberg, M. Rother, T.J. Sabaka, A. Tangborn, L. Toffner-Clausen, E. Thebault, A.W.P. Thomson, I. Wardinski, Z. Wei, T.I. Zvereva (2010), International Geomagnetic Reference Field: the eleventh generation, Geophysical Journal International, vol. 183(3), pp. 1216-1230, doi:10.1111/j.1365-246X.2010.04804.x Fliegel, H., T. Gallini and E. Swift (1992), Global Positioning System radiation force model for geodetic applications. Journal of Geophysical Research, vol. 97(B1), pp. 559-568 Kouba, J. (2007), Implementation and testing of the gridded Vienna Mapping Function 1 (VMF1), Journal of Geodesy, vol. 82(4-5), pp. 193-205, doi: 10.1007/s00190-007-0170-0 McCarthy, D.D., G. Petit (eds.) (2010), IERS Conventions (2010). IERS Technical Note 36, Bundesamt fuer Kartographie und Geodaesie Pavlis, N.K., S.A. Holmes, S.C. Kenyon, J.K. Factor (2012). The development and evaluation of the Earth Gravitational Model 2008 (EGM2008), Journal of Geophysical Research, vol. 117, B04406, doi:10.1029/2011JB008916 Rodriguez-Solano, C. J., U. Hugentobler, P. Steigenberger (2012) Impact of albedo radiation on GPS satellites; in: S.C. Kenyon, M.C. Pacino, U.J. Marti, (eds.) Geodesy for Planet Earth, IAG Symposia, Vol. 136, pp. 113-119, Springer, DOI: 10.1007/978-3-642-20338-1_14 Rothacher, M., T.A. Springer, S. Schaer, G. Beutler (1997), Processing Strategies for Regional GPS Networks, IAG Symposia, vol. 118, pp. 93-100 Folkner, W.M., J.G. Williams, D.H. Boggs (2009), The Planetary and Lunar Ephemeris DE421, IPN Progress Report 42-178 Schaer, S. (1999), Mapping and Predicting the Earth's Ionosphere Using the Global Positioning System, Geodaetisch-geophysikalische Arbeiten in der Schweiz, vol. 59 Wu, J.T., S.C. Wu, G.A. Hajj, W.I. Bertiger, S.M. Lichten (1993), Effects of antenna orientation on GPS carrier phase. Manuscripta Geodaetica, vol. 18, pp. 91-98