Figures and Statistics from the IGS Final GPS Orbit Combination
Orbit and clock comparison figures
The WRMS plots below show the Weighted RMS (mm) of the individual AC
orbit solutions with respect to the IGS Final products.
The Clock Std Dev and Clock RMS plots show the standard deviations (ps)
and RMS (ps) of the individual AC clock solutions with respect to the
IGS Final products. The Std Dev values are computed by removing a
separate bias for each satellite/station clock, whereas this is not
done for the clock RMS values. In the case where one uses these products
with carrier phase data and estimates an ambiguity parameter for each
station-satellite pair (such as for precise point positioning), the
satellite clock biases will be absorbed by the ambiguity parameters, so
the Std Dev statistics are appropriate. In other applications where no
station-satellite bias parameter is estimated or where the underlying
satellite time scale itself is of interest, then probably the RMS statistics
are more suitable. For display purposes, the daily clock Std Dev and RMS
values from the Final combination summaries are weekly averaged.
Starting on 19-Aug-2012 (GPS Week 1702; mjd=56158), the IGS Finals products
switched from being based on weekly SINEX integrations to being based on
|WRMS of IGS Final orbits (raw)
|WRMS of IGS Final orbits (smoothed)
|Std Dev of IGS Final clocks
|RMS of IGS Final clocks
ERP comparison figures
The next plots show the difference between individual AC Final ERP solutions
and the IGS Final product. The differences are shown for
X-, and Y-pole, X-, and Y-pole rate, and LOD (length of day).
For the X-, and Y-pole plots the individual series are shifted by 0.5 mas
for recent data and 1 mas for historic data.
For the X-, and Y-pole rate plots the individual series are shifted by
2 mas/day for recent data and 4 mas/day for historic data.
For the LOD plots the individual series are shifted by 0.2 ms/day.
AC Final ERP differences with IGS Finals
Orbit transformation results per AC
The next plots show the weekly averages of the Helmert translation,
rotation, and scale parameters for the individual AC orbit solutions,
with respect to the IGS Final products, compared to each other.
The next plots show the daily Helmert scale, translation, and rotation
parameters for the individual AC orbit solutions separately, with respect
to the IGS Final products. The orbit rotation plots also show associated
polar motion (PM) offsets to check for rotational consistency (-dPMy with RX;
-dPMx with RY). Recall that small AC SINEX rotational offsets were applied
in the orbit combination process to all the AC orbit and PM values in order
to align them consistently to the current IGS reference frame.
The translations are shifted by 50 mm. The rotations are shifted by 1 mas.
01 January 2012, originator IGS ACC