Figures and Statistics from the IGS Final GPS Orbit Combination
Orbit and clock comparison figuresThe 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 daily ones.
|WRMS of IGS Final orbits (raw)||recent weeks||GIF||PS||history||GIF||PS|
|WRMS of IGS Final orbits (smoothed)||recent weeks||GIF||PS||history||GIF||PS|
|Std Dev of IGS Final clocks||recent weeks||GIF||PS||history||GIF||PS|
|RMS of IGS Final clocks||recent weeks||GIF||PS||history||GIF||PS|
ERP comparison figuresThe 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.
|X-Pole Rate||recent weeks||GIF||PS||history||GIF||PS|
|Y-Pole Rate||recent weeks||GIF||PS||history||GIF||PS|
Orbit transformation results per ACThe 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.