Subject: [IGS-ACS-142] IGS Reprocessing (2000-2007) and contribution to ITRF From: Ferland, Rémi Date: Thu, 19 Feb 2009 10:25:50 -0500 To: igs-acs@igscb.jpl.nasa.gov CC: Zuheir Altamimi Author: Remi Ferland Dear All, I have just completed the combination of the contributed reanalysis for the 2000-2007 period. 9 Analysis centers have contributed: AC data span Comments emr 2000 - 2007 esa 2000 - 2007 gfz 2000 - 2007 Excluded apparent geocenter gtz 2000 - 2001 Excluded apparent geocenter mit 2000 - 2007 ngs 2000 - 2007 pdr 2000 - 2007 Excluded ERPs sio 2000 - 2007 Excluded pole rate ulr 2000 - 2007 Excluded apparent geocenter (no ERPs) In all cases of exclude parameters, implicit or explicit unremovable constraints were degrading the combination. In most/all cases, the situations were reported to the individual ACs during the test period. The relatively large number of contributions was very helpful to avoid that one AC dominates the combination and that marginal data significantly degrade the combined product. The rejection critera was set at 8 sigmas & 8 cm. The procedure used is identical to the one used to generate the official products; except that it runs backward in time. The weekly combined solutions include the same parameter types as the official products ie.: - weekly stations position - daily ERPs (pole position & pole rate & LOD) - weekly apparent geocenter position. They are aligned to the IGS05 realization of ITRF2005 in translation, rotation and scale. The ACs have submitted between ~100 and ~300 stations in their weekly solutions. The weekly combined included between ~300 and ~400 stations. There is a grand total of 872 stations. For the contribution to ITRF, two requirements had to be met: 1) Valid DOME # 2) a minimum of two years of data. The following groups were removed. Stations without DOME# and less than 2 years 42 Stations without DOME# and more than 2 years 100 Stations with DOME# but less than 2 years 214 BAKO removed due to antenna height issues 1 ==== 357 This leaves 515 stations that are contributing to ITRF2008. I have taken the liberty to leave in a few NGA stations with slightly less than 2 years... I hope IERS won't mind. The distribution of the number of weeks the stations are available is: Years # Stations < 2 12 2 - 3 43 3 - 4 43 4 - 5 46 5 - 6 43 6 - 7 64 7 - 8 73 8 - 9 191 === 515 2008 was also reviewed with minor corrections to the analysis. The stations selection was also done to be consistent with the above ITRF requirements and the available reprocessed data. Weekly *snx, *res, *sum, *res files are available at CDDIS. Plots of the time series extracted from the weekly summary reports is available at: ftp://macs.geod.nrcan.gc.ca/pub/requests/sinex/repro A few remarks about the statistics evolution: - The North weekly weighted average residuals w.r.t. the reference frame realization and the cumulative solution have an annual signal with an amplitude of 1-2mm. - A similar annual signal can be seen in the estimated scale offset w.r.t. the reference frame. - The number of stations going back to 2000, is holding at above 300 every week. By comparison, when the orignal analysis was done in early 2000, there was ~130 stations in the weekly combinations. - The statistics of the residuals w.r.t. the reference frame are generally best in the weeks 1200-1400 (2003-2006) period. The increase after 1400 is most likely due to extrapolation of the reference frame and a decrease number of available stations; and before 1200 it is mostly due to a decrease of the number of available stations The AC horizontal/vertical consistency is (in mm) w.r.t.: IGS05 Combined Combined Weekly Cumulative 2-3 / 7-9 1-2 / 3-4 2-3 / 5-7 The overall ERP consistency of the ACs w.r.t. weekly combination is: LOD 15 us XPO 0.05 mas YPO 0.04 mas XPOR 0.14 mas/d YPOR 0.14 mas/d Some AC X pole component were sometimes marginal. Since some ACs have already resubmitted updated reanalysis, those may already be fixed. Thanks for the ACs great effort, cooperation and patience, and all those (specially Jim Ray) that have provided ongoing feedbacks, and Carey Noll at CDDIS for keeping up with all the data and products used to generate these results. Best regards, Remi, ---------------------------------------------------------------------------- Subject: [IGS-ACS-144] IGS Reprocessing (2000-2007) coordinates time series and discontinuity table From: Ferland, Rémi Date: Tue, 24 Feb 2009 12:09:10 -0500 To: igs-acs@igscb.jpl.nasa.gov Author: Remi Ferland Dear All, The coordinates (N,E,H) time series plots (*ps) of the stations contributed to ITRF have just been made available at: ftp://macs.geod.nrcan.gc.ca/pub/requests/sinex/coord_r The plots are for the reprocessed data 2000-2007. The latest discontinuity table is in the above directory in the file: ALL_090223.snx. Only the stations contributed to ITRF are included. I started from the official list and added/removed discontinuities as needed. Since there is some subjectivity in this process (specially for the small discontinuities); it almost certain that overlooked some or added some that shouldn't be in. If you have some stations of particular interest, please feel free to check them out, and if you have any concerns please let me know. P.S.: Mail replies may be slow, as I will be away for most of the coming weeks. Best Regards, Remi,