1. Tide gauge stations: requirements, status, and issues Mark Merrifield University of Hawaii Sea Level Center

2. Requirements: Understanding sea-level rise and variability, WCRP workshop, Paris, 2006 Continued maintenance and enhancement of the global tide-gauge network is essential. The GLOSS Core Network (GCN) and the GCOS Climate subset of that network provide the blueprint for future network development. Address the land-motion problem at the tide gauges. Complement GIA model estimates with direct geodetic measurements at each site. ….placing all of these measurements into a consistent, high-quality global reference frame...

3. GLOSS Core Network Part of JCOMM Observations Programme Area (OPA) Coordinated by IOC GLOSS Group of Experts 290 stations covering most major island groups and ~1000 km sections of continental coastline Delayed mode data: BODC/PSMSL Fast delivery data: QC’d at 4 week intervals, UHSLC Near real-time data: 5-15 min transmissions, VLIZ GPS at Tide Gauges: TIGA, Potsdam, La Rochelle

4. GCOS sea level network 180 station subset of GLOSS for climate monitoring and research Priority on long climate records, even global distribution Geodetic land motion measurements at each station

5. Status of GLOSS Core Network Active stations 79% Near real-time Fast Delivery GPS/DORIS

6. Status of GLOSS Core Network Active stations 79% Near real-time 60% Fast Delivery GPS/DORIS

7. Status of GLOSS Core Network Active stations 79% Near real-time 60% Fast Delivery 69% GPS/DORIS

8. Status of GLOSS Core Network Active stations 79% Near real-time 60% Fast Delivery 69% GPS/DORIS 48%

9. Status of GCOS Network Active stations 85% Near real-time Fast Delivery GPS/DORIS

10. Status of GCOS Network Active stations 85% Near real-time 64% Fast Delivery GPS/DORIS

11. Status of GCOS Network Active stations 85% Near real-time 64% Fast Delivery 71% GPS/DORIS

12. Status of GCOS Network Active stations 85% Near real-time 64% Fast Delivery 71% GPS/DORIS 57%

13. GCOS Network Issues Active stations 85% 90% after upcoming tsunami upgrades in Pacific, Caribbean, Central, and South America Reevaluate station list Fast Delivery 71% 22 stations (12%) in China, India, Russia, Cuba Reevaluate station list GPS/DORIS 57% GLOSS workshop (May 2009) on GPS@TG, call for coordinated, international project to install 50-100 new GPS stations, delayed mode processing centers, consistent global reference frame Seeking $3-5 M for initial installation

14. Global and regional sea level trends from tide gauges Global sea level rise

15. Global sea-level rise reconstructions from tide gauges Merrifield et al. (2009)

16. Recent increase in sea-level rise and decadal variability Regional sea level patterns

17. Sea-level rise and the western tropical Pacific

18. Tide gauge observations in the western tropical Pacific

19. Anomalous rate change since the 1990s

20. Pacific sea-level rise and increasing Trade Winds

21. Surface wind trends “A shift in Pacific sea level trends since the 1990s” Merrifield (2010), submitted to J. Clim. From ESRL/PSD product