1. An inventory of collocated and nearly-collocated CGPS stations and tide gauges Plan : yBackground ySurvey results (September 2002) yCGPS@TG data availability yOutlooks Guy Wöppelmann, CLDG - Université La Rochelle

2. Rationale for an inventory of CGPS@TG Survey ySurvey started in Autumn 1999 yTo identify existing and planned GPS stations close to tide gauges around the world (up to ~10 km) yInitiative supported by various groups : M.Bevis (IGS/PSMSL), C.Boucher (IERS/IGS), C.Bruyninx (EUREF) and P. Woodworth (GLOSS/PSMSL) Motivations yto get an up-to-date idea about CGPS positioning of TG status, operational and potential (planned or not locally tied yet) yto provide a starting point for discussions (what might be worth to include in international projects, recommendations...) “to update the list of GPS receivers at tide gauge sites at regular intervals” (GLOSS-GE action item, Hawaii 2001)

3. Results of the survey zReported CGPS@TG has increased from 129 to 152 since last progress report in 2001. zThere are still 6 planned stations in 2002, although not exactly the same as in 2001... zProgress Report is available at : http://www.sonel.org/stations/cgps/surv_update.html

4. GLOSS CGPS@TG stations (1)

5. GLOSS CGPS@TG stations (2)

6. Distance separating CGPS and TG CGPS@TG, a vague concept... as collocation as well...

7. CGPS data availability

8. CGPS data availability - TIGA DC (1)

9. CGPS data availability - TIGA DC (2) All data on-line. Easy and simple access by anonymous FTP (ftp.sonel.org)

10. DORIS@TG

11. CONCLUSIONS - OUTLOOKS zData availability and access y1/3 (46 out of 152) of CGPS data at TG seem not available yet yAccess to off-line ancient IGS tracking data ? yNew available stations (UK, New-Zealand, South-America, Turkey...) yMay TIGA DC duplicate sea level data (Coherence, Back-up...) ? yStandard for sea-level data files (action within GLOSS) ? zLocal ties yA crucial point... yDetailed survey ? Action within TIGA (TOS forms) ? zContinuously updated survey yDynamic tables (browse and search facilities into database) yOn-line form to fill up or E-mail (gwoppelm@univ-lr.fr)

12. Survey Form Accessible through the on-line Progress Report http://www.sonel.org/stations/cgps/surv_update.html

13. RONIM tide gauge network (18 operational stations, April 2002) La Rochelle MORS HT 200 Acoustic and Radar Sensors