From RFerland at NRCan.gc.ca Tue Apr 20 09:15:26 2004 From: RFerland at NRCan.gc.ca (=?iso-8859-1?Q?=22Ferland=2C_R=E9mi=22?=) Date: Tue, 20 Apr 2004 12:15:26 -0400 Subject: [IGSMAIL-4928]: IGb00 Review - FAIR - MAG0 - SFER - YSSK Message-ID: <5ACEEE96F4F9D41190790002A528B51E78E8E9@s0-ott-x11.nrcan.gc.ca> ****************************************************************************** IGS Electronic Mail 20 Apr 09:47:42 PDT 2004 Message Number 4928 ****************************************************************************** Author: R?mi Ferland Dear IGS colleagues, It has been 10 weeks since the IGb00 realization of ITRF2000 is official. IGb00 was based on information available up to GPS week 1231 (2003/08/16) and became official on GPS week 1253 (2004/01/11). The performance of the reference frame stations as well as the level of agreement between the IGb00 realization and the weekly solutions since GPS week 1253 has been reviewed. The solutions between GPS weeks 1253 and 1262 were examined with emphasis on the reference frame stations. The residuals between IGb00 and the weekly solutions were examined (average and std). Although no stations estimated position differences between IGb00 and the weekly solutions are drastically different, some deserve closer scrutiny. Stations with average residuals exceeding ~7/15 mm in the horizontal/vertical components as well as those with nor- malized average residuals exceeding 5 were checked in detail. Stations that were missing at least 50% of the time were also checked. Table 1 list the stations (19) that did exceed any of the above thresholds. For completeness, the Table 2 (at the end) lists the statistics for the complete set (99). Several of those flagged did not need to be rejected. Some have significant seasonal variations and were at the "peak" of their seasonal fluctuations, thus should not be rejected. There was some concern with the following 19 stations: DGAR EISL FAIR GRAS HOFN IISC IRKT LHAS LPGS MAG0 MCM4 NYAL PERT SFER THU3 TSKB YAKT YAR1 YSSK Of the reference frame stations of concern, it is suggested to keep using the followings 15 stations: DGAR EISL GRAS HOFN IISC IRKT LHAS LPGS MCM4 NYAL PERT THU3 TSKB YAKT YAR1, and NOT the following 4 stations: FAIR MAG0 SFER YSSK, for the IGb00 reference Frame realization. Unfortunately, 3 of the four stations suggested for removal are in the North Pacific area (FAIR MAG0 YSSK). An earlier version of this e-mail was circulated within the Reference Frame Working Group. Although, the effect of this change should be well within the noise level, still the AC should probably synchronize the removal of the 4 stations for the reference frame realization. It is suggested to use next GPS week (1268) to implement this change. If there are any objections or concerns, do not hesitate to contact me. Best Regards, Remi, ========================================================= Station # A V E R A G E Standard deviation N E H N E H (mm) (mm) (mm) (mm) (mm) (mm) DGAR 1 4.0 1.0 -4.1 0.0 0.0 0.0 EISL 0 0.0 0.0 0.0 0.0 0.0 0.0 FAIR 8 10.7 -7.8 -4.3 1.1 4.4 3.7 GRAS 9 1.2 -3.2 -4.1 0.8 0.5 1.7 HOFN 10 2.9 -1.4 -14.2 0.8 0.6 2.8 IISC 10 -0.7 -0.0 -12.4 0.6 0.8 2.2 IRKT 10 -1.6 -3.3 13.9 3.1 2.1 2.6 LHAS 9 0.6 -1.5 -15.7 0.9 1.0 3.0 LPGS 5 -0.1 0.7 -9.1 0.9 0.7 6.2 MAG0 8 8.1 7.0 -1.0 1.1 0.7 3.4 MCM4 10 -0.5 -0.7 12.7 1.5 1.2 2.3 NYAL 10 3.2 3.5 -11.2 1.1 0.7 2.6 PERT 10 6.2 0.1 0.0 1.0 0.9 1.9 SFER 10 -4.7 6.3 0.1 0.7 0.7 1.9 THU3 10 3.0 1.2 -14.9 0.7 0.6 3.2 TSKB 10 2.5 0.5 -10.8 1.1 0.9 1.9 YAKT 6 10.0 -9.4 15.5 2.2 5.5 5.0 YAR1 3 -1.6 1.6 -8.0 2.6 1.5 2.3 YSSK 1 13.3 -4.2 7.3 0.0 0.0 0.0 Table 1 Residuals statistics between IGb00 and the IGS weekly solution between GPS weeks 1253 - 1262. Reference Frame stations with exceeding thresholds (see text). (<50%, 7-15mm, 5sigmas) ========================================================= A map of the IGb00 network can be found at: http://igscb.jpl.nasa.gov/network/refframe.html Time series for recent (last 6 months) residuals between the IGS weekly and cumulative solutions for all stations can be found in: http://igscb.jpl.nasa.gov/network/list.html Longer time series can also be found via ftp (*.ps, *.jpg) in: ftp macs.geod.nrcan.gc.ca cd /pub/requests/sinex/res ========================================================= DGAR: ===== DGAR 1 4.0 1.0 -4.1 0.0 0.0 0.0 == Very limited data since GPS week 1242. Since IGb00 is official, it was only included on GPS week 1257. the differences are within the expected noise level. It is suggested to keep it in the list of RF stations, and hope that this isolated station can resumes normal operations soon. EISL: ===== EISL 0 0.0 0.0 0.0 0.0 0.0 0.0 == No solution available since GPS week 1244 (~03/11/09). There was also a receiver failure (igsmail-4764). The station has since resumed operation (igsmail-4899) with data delivery delays. The station is expected (igsmail-4900) to be active for about one more year. The station is also in an isolate location, thus geographically important. The processing of the measurements from replacement station (ISPA) strongly encouraged. FAIR: ===== FAIR 8 10.7 -7.8 -4.3 1.1 4.4 3.7 ==== ==== ==== The station had experienced a discontinuity in the coordinates time series on 02/11/03 due to the Delani earthquake. The resulting discontinuity was accounted for as a constant shift (see igsmail-4652) There was also some warning by J. Freymueller about the post seismic effects (igsmail-4643). It was hoped at the time that the post seismic effects would be short term and have marginal effect on the estimated position/ velocity parameters. It appears that incomplete account of the post seismic effects in the IGb00 is causing ~11mm in the NS component and ~8mm in the EW direction between the reference frame realization and the recent weekly solutions. The assumption that the station would return to its pre-earthquake steady state velocity may also have been inaccurate (at the required accuracy). For the most demanding applications, it is suggested that the position/velocity estimates provided in IGb00 for this station should not be used. It is not being used any more in the reference frame realization. With the current realization, the effect of FAIR would be about ~1mm on the IGS weekly and cumulative solutions alignement. GRAS: ===== GRAS 9 1.2 -3.2 -4.1 0.8 0.5 1.7 ==== The residuals time series in the East/West direction do not show any obvious jump. They have however a small negative trend. The normalized residuals exceed the threshold, although, the estimated noise level is low. Its is suggested to keep it for the Reference Frame realization. HOFN: ===== HOFN 10 2.9 -1.4 -14.2 0.8 0.6 2.8 ==== The station normalized average height residuals exceed the 5 sigmas threshold. The station is experiencing seasonal variations in the height component. Its is suggested to keep it for the Reference Frame realization. IISC: ===== IISC 10 -0.7 -0.0 -12.4 0.6 0.8 2.2 ==== The exceeding of the threshold is due to some seasonal variations. Its is suggested to keep it for the Reference Frame realization. IRKT: ===== IRKT 10 -1.6 -3.3 13.9 3.1 2.1 2.6 ==== The exceeding of the threshold is also due to some seasonal variations. Its is suggested to keep it for the Reference Frame realization. LHAS: ===== LHAS 9 0.6 -1.5 -15.7 0.9 1.0 3.0 ==== ==== The exceeding of the threshold is also due to some seasonal variations associated with a potentially small discontinuity around GPS week 1225. Its is suggested to keep it for the Reference Frame realization. LPGS: ===== LPGS 5 -0.1 0.7 -9.1 0.9 0.7 6.2 == The station did not contribute coordinates estimates between GPS weeks 1249 and 1257. It has since resumed normal contributions. This is an isolated gap. Older data indicates steady contribution. Its is suggested to keep it for the Reference Frame realization. MAG0: ===== MAG0 8 8.1 7.0 -1.0 1.1 0.7 3.4 ==== ==== ==== The station time series indicates a potential discontinuity around GPS week 1245. At this time it appears to be a permanent shift. Its is suggested NOT to keep it for the Reference Frame realization. MCM4: ===== MCM4 10 -0.5 -0.7 12.7 1.5 1.2 2.3 ==== The exceeding of the threshold is due to some seasonal variations. Its is suggested to keep it for the Reference Frame realization. NYAL: ===== NYAL 10 3.2 3.5 -11.2 1.1 0.7 2.6 ==== In the east/west direction there is a small bias (5 sigmas) between the reference frame realization and the weekly solutions. Although the other components are within the thresholds, the differences are mainly caused by seasonal variations. Its is suggested to keep it for the Reference Frame realization. PERT: ===== PERT 10 6.2 0.1 0.0 1.0 0.9 1.9 ==== There was an equipment change on GPS week 1221 (03/06/05) which affected the north/south component for about 10 weeks. Except for this period, the time series residuals line up nicely. The gradual "drift" of the residuals suggests that the estimated N/S component of the velocity is probably off slightly. Comparisons between recent weekly solutions and corresponding cumulative solutions show residuals in the N/S direction of ~3mm. This is also accompanied by velocity differences between IGb00 and recent cumulative solutions of about 0.6mm/y. Since IGb00 is not updated, the velocity difference will increase. Its is suggested to keep it for the Reference Frame realization. As the differences are very likely to increase, this suggestion may need to be reviewed. SFER: ===== SFER 10 -4.7 6.3 0.1 0.7 0.7 1.9 ==== ==== The horizontal components have experienced a small shift at GPS week 1221 with gradual worsening until GPS week 1231; then it stabilized. Its is suggested NOT to keep it for the Reference Frame realization. THU3: ===== THU3 10 3.0 1.2 -14.9 0.7 0.6 3.2 ==== The exceeding of the threshold is also due to some seasonal variations. Its is suggested to keep it for the Reference Frame realization. TSKB: ===== TSKB 10 2.5 0.5 -10.8 1.1 0.9 1.9 ==== The exceeding of the threshold is also due to some seasonal variations. Its is suggested to keep it for the Reference Frame realization. YAKT: ===== YAKT 6 10.0 -9.4 15.5 2.2 5.5 5.0 ==== ==== ==== Although it may looks troublesome, the exceeding of the threshold appears to be caused by seasonal variations. The estimated sigmas also indicate significant fluctuations. The station has recently been rejected during the combination preventing biasing the solutions alignment. Based on previous years time series, it is expected to return to more normal residuals. Its is suggested to keep it for the Reference Frame realization. YAR1: ===== YAR1 3 -1.6 1.6 -8.0 2.6 1.5 2.3 == Switching to YAR2. Its is suggested to keep it for the Reference Frame realization. YSSK: ===== YSSK 1 13.3 -4.2 7.3 0.0 0.0 0.0 == A discontinuity (~10mm) occurred at GPS week 1238 affecting mainly the horizontal components of the station. The station was rejected most of the time (9/10) during the weekly combinations. This is likely to be a permanent situation. Its is suggested NOT to keep it for the Reference Frame realization. ========================================================= Station # A V E R A G E Standard deviation N E H N E H (mm) (mm) (mm) (mm) (mm) (mm) ALGO 10 0.3 -1.1 11.1 1.1 2.1 2.8 ALIC 10 -0.5 -0.3 0.5 0.9 0.7 2.5 ARTU 10 -0.5 2.1 1.2 0.7 1.4 4.1 ASC1 10 -0.5 1.3 -6.5 0.7 1.2 3.0 AUCK 10 -0.1 -1.4 -9.3 1.4 0.7 3.8 BAHR 10 0.3 -1.5 5.2 0.8 1.1 3.1 BILI 10 -1.8 -2.0 2.6 1.3 0.5 3.3 BOR1 10 0.6 1.1 -3.1 0.6 0.7 4.1 BRUS 10 -0.9 2.4 0.4 0.5 0.6 3.3 CAS1 10 -0.0 0.8 2.0 1.1 0.8 2.0 CEDU 10 0.5 0.3 -3.3 1.4 0.7 2.6 CHAT 10 0.0 -0.3 -6.5 1.4 0.7 2.6 CHUR 8 -3.0 -2.2 10.0 2.0 3.1 2.9 COCO 10 1.5 -1.1 -1.2 1.7 0.6 2.4 CRO1 10 1.3 -3.1 -10.3 0.8 1.3 3.1 DARW 10 0.7 -0.8 6.8 0.9 0.9 5.5 DAV1 10 0.6 1.5 0.7 0.8 0.8 3.3 DGAR 1 4.0 1.0 -4.1 0.0 0.0 0.0 DRAO 10 -0.1 -2.2 2.3 1.0 0.6 1.6 DUBO 10 3.1 -0.6 -0.2 1.0 0.5 5.0 EISL 0 0.0 0.0 0.0 0.0 0.0 0.0 FAIR 8 10.7 -7.8 -4.3 1.1 4.4 3.7 FLIN 10 2.7 -0.4 -0.6 2.8 1.7 2.7 FORT 10 2.0 2.9 -0.5 2.4 1.3 4.7 GLSV 10 -0.9 -0.8 3.6 0.8 1.1 3.5 GODE 10 0.7 2.5 6.1 0.9 1.1 3.6 GOLD 10 -4.2 -2.9 4.0 0.9 1.8 2.7 GOUG 10 -0.1 -0.1 21.3 2.8 2.7 4.4 GRAS 9 1.2 -3.2 -4.1 0.8 0.5 1.7 GRAZ 10 0.3 -0.1 -0.2 0.6 1.0 3.3 GUAM 10 2.4 -2.4 2.4 1.5 1.1 3.4 HOB2 10 0.9 0.3 2.2 1.5 1.1 1.8 HOFN 10 2.9 -1.4 -14.2 0.8 0.6 2.8 HRAO 10 2.0 -0.4 2.8 1.0 1.8 3.0 IISC 10 -0.7 -0.0 -12.4 0.6 0.8 2.2 IRKT 10 -1.6 -3.3 13.9 3.1 2.1 2.6 JAB1 10 -5.1 1.4 5.7 1.4 1.1 3.2 JOZE 10 -1.8 3.2 -8.9 0.8 0.9 10.2 KARR 8 -1.5 -0.3 -2.0 0.6 1.4 2.9 KELY 9 2.0 1.5 -9.1 0.9 2.6 3.9 KERG 10 -0.1 1.1 1.0 0.9 1.2 3.1 KIT3 8 -0.8 0.9 -1.3 1.8 1.5 2.3 KOKB 10 1.3 3.1 3.0 1.2 3.0 3.3 KOUR 10 -2.0 -1.4 1.7 1.0 0.7 5.7 KSTU 6 1.5 -1.9 12.5 2.7 1.8 6.4 LAMA 10 -1.4 -1.1 -7.2 0.6 0.7 4.0 LHAS 9 0.6 -1.5 -15.7 0.9 1.0 3.0 LPGS 5 -0.1 0.7 -9.1 0.9 0.7 6.2 MAC1 10 -2.9 0.9 3.0 1.1 1.0 1.9 MAG0 8 8.1 7.0 -1.0 1.1 0.7 3.4 MALI 10 2.1 -2.3 6.3 0.7 1.6 2.8 MANA 10 -0.6 0.3 1.6 1.0 1.1 1.9 MAS1 10 1.7 -0.5 0.6 0.8 0.5 1.9 MATE 10 -0.1 1.1 0.3 0.8 0.7 1.5 MAW1 10 -0.3 1.1 -3.4 0.9 0.7 3.8 MCM4 10 -0.5 -0.7 12.7 1.5 1.2 2.3 MDO1 10 -2.0 -0.5 -3.6 1.3 0.6 1.4 MKEA 10 -1.3 -1.9 7.8 1.0 0.7 4.2 NICO 10 -1.1 0.7 3.7 0.9 0.6 3.9 NKLG 10 2.1 0.1 -3.1 0.7 1.3 5.4 NLIB 10 -0.6 0.4 5.1 0.6 0.7 2.0 NOUM 9 2.0 -2.0 -8.7 1.8 1.0 7.3 NRC1 10 0.9 0.1 7.7 0.7 0.9 2.4 NTUS 10 -0.1 -1.3 0.3 1.0 0.8 3.1 NYAL 10 3.2 3.5 -11.2 1.1 0.7 2.6 OHI2 10 -1.5 0.6 -5.4 1.3 1.1 3.5 ONSA 10 1.8 0.3 -6.4 0.6 0.9 2.8 PERT 10 6.2 0.1 0.0 1.0 0.9 1.9 PETP 10 1.7 -1.1 -2.9 0.9 0.8 3.7 PIE1 10 -3.2 1.4 -0.5 1.0 0.5 2.3 POL2 10 -2.1 -0.3 0.1 1.6 1.2 1.6 POTS 10 1.2 -0.7 -3.4 0.5 0.5 3.9 RBAY 7 1.2 1.0 1.7 1.4 1.3 3.3 RIOG 10 1.1 -0.8 -8.3 0.9 0.8 3.0 SANT 10 -1.5 -0.2 -4.7 1.0 1.1 1.4 SCH2 10 2.9 2.9 12.6 1.6 1.5 4.3 SFER 10 -4.7 6.3 0.1 0.7 0.7 1.9 STJO 10 -0.4 0.6 4.3 1.4 2.1 3.0 SYOG 10 0.8 0.7 -0.9 0.9 0.7 4.7 THTI 10 -3.2 2.9 4.2 1.3 2.1 4.4 THU3 10 3.0 1.2 -14.9 0.7 0.6 3.2 TIDB 10 1.8 0.8 -3.1 1.7 0.5 1.5 TIXI 10 0.9 1.1 -1.2 1.7 0.7 2.5 TOW2 10 -0.2 1.4 -2.7 1.4 0.8 2.9 TRAB 10 -1.4 1.3 2.8 1.3 0.8 6.5 TRO1 10 1.0 2.1 -5.0 0.7 1.1 1.5 TSKB 10 2.5 0.5 -10.8 1.1 0.9 1.9 UNSA 10 -0.2 1.4 4.4 1.2 1.4 2.9 URUM 6 -0.2 -4.1 9.6 1.3 2.6 3.5 VESL 10 -0.5 0.7 5.7 0.8 0.9 5.3 VILL 10 1.3 -0.4 0.4 0.3 0.7 2.4 WES2 10 0.5 -1.2 13.3 1.1 1.0 3.7 WSRT 10 0.6 0.4 -0.4 0.9 0.7 2.2 WTZR 10 1.2 -1.3 -0.7 0.8 1.2 3.6 YAKT 6 10.0 -9.4 15.5 2.2 5.5 5.0 YAR1 3 -1.6 1.6 -8.0 2.6 1.5 2.3 YELL 9 2.6 -2.1 -7.5 1.4 0.8 5.1 YSSK 1 13.3 -4.2 7.3 0.0 0.0 0.0 ZIMM 10 0.0 1.6 -9.4 0.7 0.8 2.0 Table 2 Residuals statistics between IGb00 and the IGS weekly solution between GPS weeks 1253 - 1262. ========================================================= R?mi Ferland rferland at NRCan.gc.ca, 613-995-4002, fascimile/t?l?copieur 613-995-3215 Natural Resources Canada, 456-615 Booth Street, Ottawa, Ontario K1A 0E9 Ressources naturelles Canada, 456-615 rue Booth, Ottawa, Ontario K1A 0E9 Government of Canada / Gouvernement du Canada