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Assessment of systematic error
estimation
IWLR2016, Potsdam, 10-14 October, 2016
G. Bianco Agenzia Spaziale Italiana, CGS - Matera
V. Luceri, M. Pirri e-GEOS S.p.A., CGS - Matera
Official ILRS analysis products
ILRS provides on a routine basis weekly station coordinates, daily EOP (X, X and LOD) and orbits, estimated from 7-day arcs of Lageos and Etalon data. The solutions are produced following the ILRS/ASC guidelines, bias policy included
ASI/CGS
ILRSA Primary
JCET
ILRSB Backup
ILRS ACs
ILRS CCs
JCET
BKG
DGFI
GFZ
ASI
ESA
GRGS
NSGF
Combined products:
• Weekly Site coordinates
• Daily EOP
• Lageos and Etalon Orbits
ILRS ASC approach for range biases
Engineering bias report from
CDDIS database and from
the stations through SLRMail
Rapid, daily bias analysis
report from the ILRS ACs
Bias time series estimated
from a multi-year solution
ILRS Data handling file adopted by the
Anaysis Standing Committee listing:
• bias to be applied
• sites requiring bias estimation (to be
kept at minimum)
• unrecoverable data to be edited
The ASC strategy was to limit application and estimation of
biases to real events occurred and documented at the station
Zimmerwald: estimated range biases
Riga event timer
Bias start Swapped counters
Bias
stop
Lageos-2
-26 mm -26 mm -20 mm Bias for both satellites
Lageos-1
ILRS Pilot Project on systematic errors
• Weekly estimation of coordinates, EOP and range biases
• Time frame: 2005-2008
• Data: L1 and L2
• 2 time series: unique and separate range biases
• Available time series from 5 Acs: ASI, DGFI, GFZ, JCET, NSGF
Yarragadee range biases
McDonald range biases
Combined range biases
Data handling file:
7810 --- mm B 04:363:00000 06:037:00000 R -26.00
2005 2005.5 2006 2006.5 2007 2007.5 2008 2008.5 2009 2009.5-0.025
-0.02
-0.015
-0.01
-0.005
0
0.005
0.01
0.015
Year
mete
rs
Station: 7810; Satellite: L1;
nsg
gfz
dgf
asi
ILRSA
2005 2005.5 2006 2006.5 2007 2007.5 2008 2008.5 2009 2009.5-0.02
-0.015
-0.01
-0.005
0
0.005
0.01
0.015
Year
mete
rs
Station: 7810; Satellite: L2;
nsg
gfz
dgf
asi
ILRSA
Zimmerwald
LAGEOS LAGEOS-2
Herstmonceux
Data handling file:
7840 --- mm A 02:032:00000 07:042:00000 R -9.00
2005 2005.5 2006 2006.5 2007 2007.5 2008 2008.5 2009 2009.5-0.025
-0.02
-0.015
-0.01
-0.005
0
0.005
0.01
0.015
Year
mete
rs
Station: 7840; Satellite: L1;
nsg
jce
gfz
dgf
asi
ILRSA
2005 2005.5 2006 2006.5 2007 2007.5 2008 2008.5 2009 2009.5-0.025
-0.02
-0.015
-0.01
-0.005
0
0.005
0.01
0.015
Yearm
ete
rs
Station: 7840; Satellite: L2;
nsg
jce
gfz
dgf
asi
ILRSA
Combined range biases
LAGEOS LAGEOS-2
2005 2005.5 2006 2006.5 2007 2007.5 2008 2008.5 2009-50
0
50
mm
2005 2005.5 2006 2006.5 2007 2007.5 2008 2008.5 2009-50
0
50
mm
2005 2005.5 2006 2006.5 2007 2007.5 2008 2008.5 2009-50
0
50
mm
McDonald coordinates
UP
EAST
NORTH
Standard L1-2 bias Common bias
wrms mm
mean sig mm
U Std L1-2 comm
6.7 13.8 13.8
12.0 29.3 23.1
E Std L1-2 comm
6.5 5.4 5.4
12.6 18.5 14.3
N Std L1-2 comm
7.8 6.8 6.9
12.5 25.1 25.3
Impact on the site coordinates
3D coordinate residual WRMS
2005 2005.5 2006 2006.5 2007 2007.5 2008 2008.5 20092
4
6
8
10
12
mm
standard
L1-2 bias
common bias
Standard L1-2 bias Common bias
Impact on EOP
weekly mean residuals w.r.t. USNO
Impact on RF origin
Standard
L1-2 bias
Common bias
TX w.r.t. SLRF2008
Standard
L1-2 bias
Common bias
Impact on RF origin
TY w.r.t. SLRF2008
Standard
L1-2 bias
Common bias
Impact on RF origin
TZ w.r.t. SLRF2008
Standard
L1-2 bias
Common bias
Impact on the scale
Scale w.r.t. SLRF2008
Path forward
ASC approach under discussion:
• make a table of biases using the time series of combined range
biases from 1983 up to now
• apply the bias values in the table for the official ILRS products
• keep the table updated
Points to note:
• Estimating the biases for all the sites together with the coordinates weakens the official products
• The 7-day estimation is a medium/long term monitoring, not a quick QC
• The medium/long term monitoring is essential to trace the range biases at centimeter level
