From stefan.schaer at aiub.unibe.ch Fri Dec 22 06:52:02 2006 From: stefan.schaer at aiub.unibe.ch (Stefan Schaer) Date: Fri, 22 Dec 2006 15:52:02 +0100 Subject: [IGSMAIL-5518]: GPS week 1400 model changes made at CODE Message-ID: <458BF112.8000109@aiub.unibe.ch> ****************************************************************************** IGS Electronic Mail 22 Dec 06:52:16 PST 2006 Message Number 5518 ****************************************************************************** Author: Stefan Schaer, Urs Hugentobler Dear IGS colleagues, A remarkable number of model changes/improvements was activated in CODE's IGS analysis starting with GPS week 1400. Note that changes that must be considered as mandatory for IGS analysis are indicated in our listing with "+": * Absolute GNSS PCV model (APCV): + Switch to the absolute GNSS PCV model IGS05_1400 (latest version: IGS05_1402). For details see: IGS Mails 5272, 5318, 5438. + Consideration of receiver antenna radome codes (actually done since week 1367) became relevant with the use of the absolute PCV model. - For ionosphere analysis, this model change has an effect on L1-L2 receiver PCV, but not on satellite PCV correction (L1-L2=0). * Terrestrial reference frame (TRF): + Use of IGS05 TRF realization. Note: IGS05 and ITRF2005 velocity vectors are identical. IGS05 is conform to the absolute PCV model, ITRF2005 to relative PCV. For details see: IGS Mails 5447, 5455. - List of IGS05 fiducial stations was completed with (12) antenna sharing stations: ----------------------------------- IGS05 Added Category ----------------------------------- DARW 50134M001 DARR IGLOS DAV1 66010M001 DAVR IGLOS GODE 40451M123 GODZ IGLOS GOLD 40405S031 GOL2 IGS IRKT 12313M001 IRKM IGS MADR 13407S012 MAD2 IGS ONSA 10402M004 OS0G IGLOS BAHR 24901M002 S051 NGA THU3 43001M002 THU2 IGLOS TIDB 50103M108 TID1/TID2 IGS YAR1 50107M004 YAR2 IGS ----------------------------------- Note: An interesting detail is the fact that YAR1 (inactive), not YAR2 (active) is declared as IGS05 reference station. * Changes concerning CODE weekly analysis reports: - Verification of geodetic datum definition: Residuals wrt IGS05 are provided for the (extended) list of IGS05 fiducial stations in our weekly analysis summary files. See: http://igscb.jpl.nasa.gov/mail/igsreport/2006/msg01133.html http://igscb.jpl.nasa.gov/mail/igsreport/2006/msg01150.html http://igscb.jpl.nasa.gov/mail/igsreport/2006/msg01168.html http://igscb.jpl.nasa.gov/mail/igsreport/2006/msg01184.html http://igscb.jpl.nasa.gov/mail/igsreport/2006/msg01210.html http://igscb.jpl.nasa.gov/mail/igsreport/2006/msg01234.html "R" indicates fiducial stations rejected from datum definition, like, e.g., MKEA (due to recent earthquake). - The 7 parameters of the corresponding Helmert transformation are listed. These transformation parameters should be consistent to those provided, e.g. for week 1400, in: http://igscb.jpl.nasa.gov/mail/igsreport/2006/msg01137.html http://igscb.jpl.nasa.gov/mail/igsreport/2006/msg01139.html - In addition, retrievals of weekly geocenter coordinates are given (in the TRF used). * SINEX: + GNSS antenna offset parameters (constrained to IGS05 PCV model values) are included in SINEX for both the GPS and the GLONASS satellite constellation. - We do no longer provide CoM weekly station coordinates (translation defined by geocenter, geocenter coordinates assumed to 0/0/0) but started to submit SINEX containing CoN coordinates (conform to the used TRF not only in terms of rotation but also in terms of translation). - Geocenter coordinates (constrained to 0/0/0) are included. * Troposphere modeling: - Mapping function: changed from Niell to GMF (Global MF). - A priori model for hydrostatic component: changed from a Saastamoinen-based to GPT (Global Pressure Temperature) model. Note: GMF/GPT models were developed by Johannes Boehm, TU Vienna. - Gradient model: refined. Note: Elevation mask angle of 3 degrees remains unchanged. * Solar radiation pressure (RPR) a priori model: - Start to use CODE RPR model coefficients for GLONASS. - Use updated model coefficients for GPS. This update is relevant in particular for all Block II-R satellites. - Special RPR handling of R18 (behaving differently compared to other GLONASS satellites) turned out to be erroneous and was switched back to the zero model (starting with week 1406). This RPR modeling problem will be further investigated. * Ocean tide loading (OTL): + CMC (center of mass) correction applied in GNSS POD process, based on the FES2004 OTL model (already used since week 1367). + hardisp.f (developed by Duncan Agnew, UCSD) implemented to consider displacements from a total of 141 constituent tides (see also IGS Mail 5300). * Application of Shapiro effect for GNSS: + Shapiro (relativistic signal propagtion delay) effect is taken into account to be in accordance with the absolute GNSS PCV model. * Mean pole: - Mean pole computed according to IERS2003 standards. * Phase windup: - Not only the geometrical part of the polarization effect is considered but the effect due to the nominal attitude motion of the GNSS satellites is taken into account. Note that this model change does just affect our clock results. * Format changes: + SINEX: Inclusion of satellite antenna offset parameters (see above). + SP3: Added 4th header comment line according to IGS standard: ============================================================ /* PCV:IGS05_1400 OL/AL:FES2004 NONE YN ORB:CoN CLK:CoN ============================================================ Legend: PCV model used Ocean/atmospheric tidal loading (OL/AL) model used CMC applied (for OL and for AL, respectively) Reference frame definition concerning orbits included Reference frame definition concerning clocks included + CLK: Clock RINEX with additional header records to specify PCV model used and DCB (differential code bias) model used (see also IGS Mail 5490): ================================================================================ G GPSEST V5.1 IGS05_1400 SYS / PCVS APPLIED G GPSEST V5.1 P1C1.DCB @ ftp.unibe.ch/aiub/CODE/ SYS / DCBS APPLIED ================================================================================ Note: We did not change the clock RINEX format version number (2.00) because not all mandatory records of format 3.00 can be included. Best regards, The CODE AC Team