[IGSMAIL-4928]: IGb00 Review - FAIR - MAG0 - SFER - YSSK
"Ferland, Rémi"
RFerland at NRCan.gc.ca
Tue Apr 20 09:15:26 PDT 2004
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IGS Electronic Mail 20 Apr 09:47:42 PDT 2004 Message Number 4928
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Author: Rémi 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.
=========================================================
Rémi Ferland
rferland at NRCan.gc.ca, 613-995-4002, fascimile/télécopieur 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
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