1. CMP Model Effects on ILRS Products
E. C. Pavlis and M. Kuzmicz-Cieslak
2017 IERS Unified Analysis Workshop
10-12 July 2017, Paris, France

2. Introduction
The Conventional Mean Pole (CMP) model has been provided by the IERS Conventions in a linear form since the 2003 edition.
In the 2010 release, the model was initially modified to a cubic one with a linear extrapolation after
By 2015, publications of present-day ice sheet mass losses led to a further modification that directed the users to use:
either a tabular form stored in an online file and maintained by the IERS EOP Center, or
a yearly updated subroutine that essentially reproduced* the tabular data.
The IERS routine was never updated for the current year, and so the Services had no way to use it and were left with the tabular data as the only option.
Several users had noticed that the online tabular data files were being changed without prior notification to the users, which led to a study of some of the versions that were captured at various times to determine the level and the nature of variations introduced.
* Which could not track of course the changes in the online tables!
The SINEX series is not intended to be generated by BKG.
Erricos C. Pavlis 07/11/2017
2017 IERS UAW, Paris, France

3. IERS 2010 Conventions Update
Chapter 7, section 7.1.4
Erricos C. Pavlis 07/11/2017
2017 IERS UAW, Paris, France

4. Rapid ice melting drives Earth's pole to the east J. L. Chen1, C. R
Rapid ice melting drives Earth's pole to the east J. L. Chen1, C. R. Wilson1,2, J. C. Ries1, B. D. Tapley1 DOI:  /grl.50552
GEOPHYSICAL RESEARCH LETTERS, VOL. 40, 2625–2630, doi: /grl.50552, 2013
Erricos C. Pavlis 07/11/2017
2017 IERS UAW, Paris, France

5. Climate-driven Polar Motion: 2003-2015 S. Adhikari & Erik R
Climate-driven Polar Motion: S. Adhikari & Erik R. Ivins /JPL Sci. Adv. 2016;2:e April 2016
Erricos C. Pavlis 07/11/2017
2017 IERS UAW, Paris, France

6. Climate-driven Polar Motion: 2003-2015 S. Adhikari & Erik R. Ivins JPL
Erricos C. Pavlis 07/11/2017
2017 IERS UAW, Paris, France

7. IERS CMP Plots Online Downloaded: 2016.05.17 Downloaded: 2016.09.27
Erricos C. Pavlis 07/11/2017
2017 IERS UAW, Paris, France

8. IERS CMP Comparison Erricos C. Pavlis 07/11/2017
2017 IERS UAW, Paris, France

9. IERS CMP Comparison - detail
Erricos C. Pavlis 07/11/2017
2017 IERS UAW, Paris, France

10. CMP Differences of IERS Updates
These modifications of the series in the special table “mean-pole.tab” were not announced and to this point no one has documented anywhere that they ever happened. Unless someone checked the file often, we do not know how many times it was changed.
Erricos C. Pavlis 07/11/2017
2017 IERS UAW, Paris, France

11. CMP Test Experiment with SLR Data
The ILRS contribution to the ITRF2014 used one of the recent CMP tables as the basis for our data reduction (v70).
In order to get a measure of the effect the CMP definition will have on our products, we adopted the 2003-type CMP, using the values proposed by J. C. Ries (see his earlier presentation):
Xp = (t – 2000)* [mas]
Yp = (t – 2000)* [mas]
t is in years
We reanalyzed the period Jan. 1, 2016 to present.
Although no other changes were made in the modeling of the data, the RMS of the weekly arcs used was systematically lower than the one using the previous CMP model.
The SINEX series is not intended to be generated by BKG.
Erricos C. Pavlis 07/11/2017
2017 IERS UAW, Paris, France

12. Weekly JCET Solutions – CMP Tests

13. Weekly JCET Solutions – CMP Tests
North Hemisphere
South Hemisphere
Erricos C. Pavlis 07/11/2017
2017 IERS UAW, Paris, France

14. Weekly JCET Solutions – CMP Tests
Graz
Matera
Herstmonceux
● OLD CMP
● NEW CMP
Yarragadee
Mt. Stromlo
Hartebeesthoek

15. CMP Test Experiment with SLR Data
The new analysis (v77) shows a 1 mm drop in the average RMS of fit values.
Comparing the height adjustments with respect to SLRF2014 between the two series, we see a mean of 6.8 mm (OLD-NEW) for the 27 strongest participating sites.
An extended period re-analysis with the new CMP model is in progress, which will include the adjustment of velocities as well as positions.
Results expected by end of summer 2017.
The SINEX series is not intended to be generated by BKG.
Erricos C. Pavlis 07/11/2017
2017 IERS UAW, Paris, France

16. Weekly JCET Solutions – MP Tests
● OLD CMP
● NEW CMP
Erricos C. Pavlis 07/11/2017
2017 IERS UAW, Paris, France

17. Weekly JCET Solutions – MP Tests
● OLD CMP
● NEW CMP
Erricos C. Pavlis 07/11/2017
2017 IERS UAW, Paris, France

18. Weekly JCET Solutions – MP Tests
● OLD CMP
● NEW CMP
Erricos C. Pavlis 07/11/2017
2017 IERS UAW, Paris, France

19. Weekly JCET Solutions – MP Tests
● OLD CMP
● NEW CMP
Erricos C. Pavlis 07/11/2017
2017 IERS UAW, Paris, France

20. Weekly JCET Solutions – MP Tests
● OLD CMP
● NEW CMP
Erricos C. Pavlis 07/11/2017
2017 IERS UAW, Paris, France

21. Weekly JCET Solutions – MP Tests
● OLD CMP
● NEW CMP
Erricos C. Pavlis 07/11/2017
2017 IERS UAW, Paris, France

22. Weekly JCET Solutions – CMP Tests
North Hemisphere
South Hemisphere
Sorted in Longitude
Erricos C. Pavlis 07/11/2017
2017 IERS UAW, Paris, France