=============================================================================== IGS-RNAAC-SIRGAS ANALYSIS REPORT SECOND SIRGAS REPROCESSING - SIRGAS-Repro2 GPS week 1597: DAYS 227-233, DATES 2010-08-15 - 2010-08-21 =============================================================================== Computed by DGFI-TUM, lm.sanchez@tum.de Deutsches Geodaetisches Forschungsinstitut der Technischen Universitaet Muenchen This report describes DGFI-TUM's analysis procedure applied to obtain homogeneously processed SIRGAS daily and weekly station position solutions referring to the IGS reference frame IGS14/IGb14 since January 2000. - Input GNSS data are provided by the SIRGAS operational and data centres (see https://sirgas.ipgh.org/), the International GNSS Service (see https://igs.org/data/) and UNAVCO (see https://data.unavco.org/). - Basic observable: ionosphere-free linear combination - Sampling rate: 30 sec - Elevation cut-off angle: 3 deg - Elevation-dependent weighting cos(z)**2 - Satellite orbits, satellite clock offsets, and Earth orientation parameters are fixed to the IGS weekly solutions refering to the IGS14/IGb14 frame (https://igs.org/products/, Johnston et al. 2017, https://doi.org/10.1007/978-3-319-42928-1_33). For for the weeks prior to January 29, 2017 (when the IGS14 was adopted as reference frame), the orbits, satellite clocks and Earth orientation parameters based on the second IGS reprocessing (known as IG2 products) are used (Griffiths 2019, https://doi.org/10.1007/s00190-018-1149-8). - Satellite antenna to centre of mass offsets spacecraft-specific z-offsets and block-specific x- and y-offsets from model igs14.atx,(see https://files.igs.org/pub/station/general/) - Phase centre variations (PCV) absolute model for receiver and satellite antennae, file igs14.atx, https://files.igs.org/pub/station/general/ - Antenna radome calibrations applied, if given in file igs14.atx. Otherwise, the radome effect is neglected and the standard antenna model (radome NONE) is used. - Marker to antenna eccentricities (dN, dE, dU) from site logs applied (ftp://ftp.sirgas.org/pub/gps/DGF/station/log/) - Phase ambiguities are solved as follows: Direct L1 and L2 ambiguity solution for baselines from 0 km to 20 km L3 and L5 ambiguity solution for baselines from 18 km to 200 km Wideline strategy for baselines from 180 km to 9000 km Quasi ionosphere free (QIF) strategy for baselines from 18 km to 5600 km. In the ambiguity solution, the ionosphere models of CODE are provided as input to increase the number of ambiguities solved, see http://ftp.aiub.unibe.ch/CODE/, Dach et al. 2020, https://boris.unibe.ch/143807/ - Troposphere modelling: the a-priori zenith delay (dry part) is modelled using the Vienna Mapping Function (Boehm et al. 2006, https://doi.org/10.1029/2005JB003629) and further atmospheric parameters (wet part) are estimated in a 2-hours interval within the network adjustment using also the Vienna Mapping Function. In addition, horizontal gradient parameters are estimated to model azimuthal asymmetries (model described in Chen and Herrring, 1997 https://doi.org/10.1029/97JB01739). The gridded VMF1 coefficients are provided by J. Boehm, TU Vienna, at https://vmf.geo.tuwien.ac.at/trop_products/GRID/ - Tidal corrections for solid Earth tide, permanent tide and solid Earth pole tide as described in Petit and Luzum (2010). Ocean tide loading reduced with the FES2014b model (Lyard et al. 2021, https://doi.org/10.5194/os-17-615-2021) and atmospheric tide loading for S1 and S2 reduced with the model of Van Dam and Ray (2010, https://geophy.uni.lu/atmosphere/tide-loading-calculator/). The reduction coefficients for the ocean tide loading are provided by M.S. Bos and H.-G. Scherneck at http://holt.oso.chalmers.se/loading/. The reduction coefficients for the atmospheric tide loading are provided by T. van Dam at https://geophy.uni.lu/atmosphere/tide-loading-calculator/ATM1OnlineCalculator - Ocean tide geocentre coefficients are not applied since this correction is already contained in the final IGS products. - Non-tidal loadings as atmospheric pressure, ocean bottom pressure, or surface hydrology are not reduced. - Daily free normal equations are computed by applying the double difference strategy (Bernese GNSS Software 5.2, Dach et al. 2015, https://boris.unibe.ch/72297/). The baselines are created according to the maximum number of common observations for the associated stations. - Daily free normal equations are combined for computing a loosely constrained weekly solution for station positions (all station coordinates are loosely constrained to +/-1 m). - Station single daily solutions with residuals larger than 15 mm in the north or east (N/E) components, and more than 30 mm in the height (h) are removed from the daily normal equations. RMS values of the residuals in the weekly combination should not be larger than 10 mm in N/E and 20 mm in h. - Computation of a weekly solution for station positions aligned to the IGb14 Reference Frame. Datum realization through IG2 weekly coordinates of selected IGS reference stations (applied constraint in the Bernese GNSS Software: 1E-04 m). =============================================================================== Results =============================================================================== SI215977.SNX covariance matrix loosely constrained weekly solution SI215977.SUM this text file si210P1597.snx covariance matrix weekly solution aligned to IGb14 si210P1597.ssc weekly station position solution si210P1597.crd list of station positions for week 1597 The results of the second SIRGAS reprocessing are available at ftp://ftp.sirgas.org/pub/gps/SIRGAS/REPRO2 and at https://www.sirgas.org/. =============================================================================== Solution statistics =============================================================================== ------------------------------------------------------------------------- SOL SIRGAS IGb14 RMS* Variance Repeatability [mm] stations stations [mm] factor N E U ------------------------------------------------------------------------- SI2 294 69 1.41 0.49 1.90 2.00 5.42 *A-posteriori RMS of unit weight after aligning the combined solution to IGb14 FIDUCIAL STATIONS ----------------- ALBH ALGO AREQ ARTU BRAZ BRFT BRMU CCJ2 CCJM CHAT CHPI CHTI COCO CRO1 DAEJ DAV1 DGAR FALK GLPS GLSV GODE GUAM GUAT HOB2 HRAO ISPA KELY KERG KOKB KOUR LPGS MAC1 MAS1 MATE MAUI MAW1 MCM4 MDO1 MKEA NRIL NYA1 OHI3 ONSA PARC PDEL PIE1 POL2 QUIN RECF REUN SALU SANT SAVO SCUB STJO SUTH SYOG THTI THU3 TRO1 UFPR UNSA VESL VNDP YAKT YAR2 YELL ZECK ZIMM RESIDUALS WITH RESPECT TO IG2 WEEKLY SOLUTION ------------------------------------------------------------- N [mm] E[mm] Up [mm] ------------------------------------------------------------- IGb14 reference sations (69) 0.75 0.75 0.32 All IGS Stations (168) 0.95 1.00 2.97 RESIDUALS WITH RESPECT TO PREVIOUS SIRGAS WEEKLY SOLUTION ------------------------------------------------------------- N [mm] E[mm] Up [mm] ------------------------------------------------------------- All SIRGAS stations (293) 0.97 1.01 3.44