Figures and Statistics from the IGS Rapid 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 Rapid (IGR) 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 Rapid 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 Rapid combination summaries are weekly averaged.
On 11 April 2014, this webpage was updated to include following comparisons:
IGR and the observed part (IGA) of the 00h IGS Ultra-rapid product
IGR and the real-time part of the IGS Ultra-rapid product (denoted here as IGU**)
IGR and the IGS Real-time streams (denoted here as IGC**)
Note that IGC** are 24h SP3 files each containing four 6h segments (hours 4
thru 10) from each update interval of the IGS RT streams. The comparison with
IGR is done daily over the full 24h of each IGC SP3. IGU** consists of 4
separate comparisons to IGR done each day over the first 6h of each IGS
Ultra-rapid product.
The IGS Ultra-rapid orbit prediction errors grow with the sqrt. Each 6h
segment within the 24h IGC file has a latency of 4 hours. The WRMS orbit
differences between IGU** and IGC** for the first few weeks of this comparison
are consistent with the errors for hours 4-10 of the IGS Ultra-rapid orbit
predictions.
| WRMS of IGS Rapid orbits (raw) |
recent weeks |
GIF |
PS |
history |
GIF |
PS |
| WRMS of IGS Rapid orbits (smoothed) |
recent weeks |
GIF |
PS |
history |
GIF |
PS |
rm
| Std Dev of IGS Rapid clocks |
recent weeks |
GIF |
PS |
history |
GIF |
PS |
| RMS of IGS Rapid clocks |
recent weeks |
GIF |
PS |
history |
GIF |
PS |
ERP comparison figures
The next plots show the difference between individual AC Rapid 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 figure the individual series are shifted by 1 mas.
For the X-, and Y-pole rate figure the individual series are shifted by
4 mas/day.
For the LOD figure the individual series are shifted by 0.2 ms/day.
AC Rapid ERP differences w.r.t. 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 solutions with respect to the IGS
Rapid products.
"igu" is the 24 hours predicted orbit.
The next plots show the daily Helmert scale, translation, and rotation
parameters for the individual AC orbit solutions separately, with respect
to the IGS Rapid products.
The translations are shifted by 50 mm. The rotations are shifted by 1 mas.
"igu" is the 24 hours predicted orbit.
Scale/Translations from:
Rotations from:
15 November 2023, originator IGS ACC
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