Tide gauge stations: requirements, status, and

issuesMark Merrifield

University of Hawaii Sea Level Center

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...

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

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

Status of GLOSS Core Network

• Active stations 79%

• Near real-time

• Fast Delivery

• GPS/DORIS

Status of GLOSS Core Network

• Active stations 79%

• Near real-time 60%

• Fast Delivery

• GPS/DORIS

Status of GLOSS Core Network

• Active stations 79%

• Near real-time 60%

• Fast Delivery 69%

• GPS/DORIS

Status of GLOSS Core Network

• Active stations 79%

• Near real-time 60%

• Fast Delivery 69%

• GPS/DORIS 48%

Status of GCOS Network

• Active stations 85%

• Near real-time

• Fast Delivery

• GPS/DORIS

Status of GCOS Network

• Active stations 85%

• Near real-time 64%

• Fast Delivery

• GPS/DORIS

Status of GCOS Network

• Active stations 85%

• Near real-time 64%

• Fast Delivery 71%

• GPS/DORIS

Status of GCOS Network

• Active stations 85%

• Near real-time 64%

• Fast Delivery 71%

• GPS/DORIS 57%

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

Global and regional sea level trends from tide gauges

• Global sea level rise

Global sea-level rise reconstructions from tide gauges

Merrifield et al. (2009)

Recent increase in sea-level rise and decadal variability

• Regional sea level patterns

Sea-level rise and the western tropical Pacific

Tide gauge observations in the western tropical Pacific

Anomalous rate change since the 1990s

Pacific sea-level rise and increasing Trade Winds

Surface wind trends

“A shift in Pacific sea level trends since the 1990s” Merrifield (2010), submitted to J. Clim.

From ESRL/PSD product