Subject: IDS-ITRF2004: station discontinuities
From: Martine Feissel-Vernier <[email-masked]>
To: [email-masked]
Cc: [email-masked]
Date: Fri, 10 Jun 2005 15:01:37 +0200 (Paris, Madrid)

Dear colleagues

To help the dicussion of the IDS contribution to ITRF2004, we have set up
a web page http://lareg.ensg.ign.fr/IDS/ITRF2004.html that gives access to
a number of plots and analyses of the time series of DORIS coordinates. 

The first aspect we propose for convergence of opinions is the list of
station discontinuities.

PROPOSED EXTENDED LIST OF DISCONTINUITIES

The list of discontinuities agreed upon by the three Analysis Centers for
their ITRF2004 submissions is available at 
http://lareg.ensg.ign.fr/IDS/ITRF2004/discont.html

An additional list of station discontinuities is under discussion in June
2005. These  discontinuities that were discussed between ign and lca are
listed hereafter, with the Analysis Coordinator (ac) comments and a final
proposal, using the discontinuity qualifier proposed by R. Ferland. 
P: position change; V: velocity change. 

For some proposed discontinuities in the case of a nearby earthquake, we
propose to wait until the expected effect is known. There are ongoing
studies on this problem. 

---------------------------------------------------------------------------------
Sta    Event        Date    Type   Recommendations & Comments
                                   ign lca    ac
---------------------------------------------------------------------------------
COLA Restart     01 Jul 2001   P   yes  yes  YES
EASA Earthquake? 12 Feb 1998   V   yes  yes?  NO  Wait for effect evaluation  
EVEB Restart     01 Jan 1997   P   yes  yes  YES 
EVEB Restart     01 Jan 2003   P   yes  yes  YES 
FAIA             01 Jan 1996   V   yes? yes   NO  Wait for effect evaluation 
FAIB Noisier in 2nd part of 2002     -   -    NO  
KESB Restart     01 Jul 2004   P   yes  yes   NO  Wait for more data      
KRAB Restart     01 Jan 2000   P   yes   no   NO  Non linear motion mostly annual
MARB Restart     01 Apr 2003   P   yes  yes  YES
ROTA             ~ 1996-1997   V    ?   yes   NO  Up motion non linear but smooth
STJB Restart     01 Sep 2002   V   yes  yes   NO  No obvious date for a change
TRIB Earthquake? 31 Jul 2004   P   yes   ?    NO  Wait for more data
---------------------------------------------------------------------------------

The above table is available at  
http://lareg.ensg.ign.fr/IDS/ITRF2004/discont.html#p2, which 
provides links to plots of the station motions measured by ign and lca
and to plots of coordinate residuals for ign, ina, and lca prepared by the
Analysis Coordinator Team.

The topic of our next proposal will be the selection of a core network
suitable to best insure the long term consistency of the IDS
contribution. 

Looking forward to your inputs

The IDS Analysis Coordination team 
Martine Feissel-Vernier     Karine Le Bail    Jean-Jacques Valette